synced docs

1 files changed, 22499 insertions, 16 deletions

diff --git a/docs/docs.html b/docs/docs.html
index b92e9f8..ce8e1b6 100644
--- a/docs/docs.html
+++ b/docs/docs.html
@@ -28,8 +28,8 @@
 <li><a href='#--using--args.state--to-store-your-game-state'>Using <code>args.state</code> To Store Your Game State</a></li>
 <li><a href='#--frequently-asked-questions,-comments,-and-concerns'>Frequently Asked Questions, Comments, and Concerns</a></li>
 <li><a href='#--docs---gtk--runtime-'><code>GTK::Runtime</code></a></li>
-<li><a href='#--docs---gtk--runtime#reset-'><code>GTK::Runtime#reset</code></a></li>
 <li><a href='#--docs---gtk--runtime#calcstringbox-'><code>GTK::Runtime#calcstringbox</code></a></li>
+<li><a href='#--docs---gtk--runtime#reset-'><code>GTK::Runtime#reset</code></a></li>
 <li><a href='#--docs---array-'><code>Array</code></a></li>
 <li><a href='#--docs---array#map-'><code>Array#map</code></a></li>
 <li><a href='#--docs---array#each-'><code>Array#each</code></a></li>
@@ -53,6 +53,127 @@
 <li><a href='#--docs---kernel-'><code>Kernel</code></a></li>
 <li><a href='#--docs---kernel--tick_count-'><code>Kernel::tick_count</code></a></li>
 <li><a href='#--docs---kernel--global_tick_count-'><code>Kernel::global_tick_count</code></a></li>
+<li><a href='#--open-source'>Open Source</a></li>
+<li><a href='#--00_learn_ruby_optional/00_beginner_ruby_primer/app/automation.rb'>00_learn_ruby_optional/00_beginner_ruby_primer/app/automation.rb</a></li>
+<li><a href='#--00_learn_ruby_optional/00_beginner_ruby_primer/app/main.rb'>00_learn_ruby_optional/00_beginner_ruby_primer/app/main.rb</a></li>
+<li><a href='#--00_learn_ruby_optional/00_intermediate_ruby_primer/app/main.rb'>00_learn_ruby_optional/00_intermediate_ruby_primer/app/main.rb</a></li>
+<li><a href='#--00_learn_ruby_optional/00_intermediate_ruby_primer/app/repl.rb'>00_learn_ruby_optional/00_intermediate_ruby_primer/app/repl.rb</a></li>
+<li><a href='#--01_rendering_basics/01_labels/app/main.rb'>01_rendering_basics/01_labels/app/main.rb</a></li>
+<li><a href='#--01_rendering_basics/02_lines/app/main.rb'>01_rendering_basics/02_lines/app/main.rb</a></li>
+<li><a href='#--01_rendering_basics/03_solids_borders/app/main.rb'>01_rendering_basics/03_solids_borders/app/main.rb</a></li>
+<li><a href='#--01_rendering_basics/04_sprites/app/main.rb'>01_rendering_basics/04_sprites/app/main.rb</a></li>
+<li><a href='#--01_rendering_basics/05_sounds/app/main.rb'>01_rendering_basics/05_sounds/app/main.rb</a></li>
+<li><a href='#--02_input_basics/01_keyboard/app/main.rb'>02_input_basics/01_keyboard/app/main.rb</a></li>
+<li><a href='#--02_input_basics/02_mouse/app/main.rb'>02_input_basics/02_mouse/app/main.rb</a></li>
+<li><a href='#--02_input_basics/03_mouse_point_to_rect/app/main.rb'>02_input_basics/03_mouse_point_to_rect/app/main.rb</a></li>
+<li><a href='#--02_input_basics/04_mouse_rect_to_rect/app/main.rb'>02_input_basics/04_mouse_rect_to_rect/app/main.rb</a></li>
+<li><a href='#--02_input_basics/05_controller/app/main.rb'>02_input_basics/05_controller/app/main.rb</a></li>
+<li><a href='#--03_rendering_sprites/01_animation_using_seperate_pngs/app/main.rb'>03_rendering_sprites/01_animation_using_seperate_pngs/app/main.rb</a></li>
+<li><a href='#--03_rendering_sprites/02_animation_using_sprite_sheet/app/main.rb'>03_rendering_sprites/02_animation_using_sprite_sheet/app/main.rb</a></li>
+<li><a href='#--03_rendering_sprites/03_animation_states/app/main.rb'>03_rendering_sprites/03_animation_states/app/main.rb</a></li>
+<li><a href='#--03_rendering_sprites/04_color_and_rotation/app/main.rb'>03_rendering_sprites/04_color_and_rotation/app/main.rb</a></li>
+<li><a href='#--04_physics_and_collisions/01_simple/app/main.rb'>04_physics_and_collisions/01_simple/app/main.rb</a></li>
+<li><a href='#--04_physics_and_collisions/02_moving_objects/app/main.rb'>04_physics_and_collisions/02_moving_objects/app/main.rb</a></li>
+<li><a href='#--04_physics_and_collisions/03_entities/app/main.rb'>04_physics_and_collisions/03_entities/app/main.rb</a></li>
+<li><a href='#--04_physics_and_collisions/04_box_collision/app/main.rb'>04_physics_and_collisions/04_box_collision/app/main.rb</a></li>
+<li><a href='#--04_physics_and_collisions/04_box_collision_2/app/main.rb'>04_physics_and_collisions/04_box_collision_2/app/main.rb</a></li>
+<li><a href='#--04_physics_and_collisions/04_jump_physics/app/main.rb'>04_physics_and_collisions/04_jump_physics/app/main.rb</a></li>
+<li><a href='#--05_mouse/03_mouse_click/app/main.rb'>05_mouse/03_mouse_click/app/main.rb</a></li>
+<li><a href='#--05_mouse/05_mouse_move/app/main.rb'>05_mouse/05_mouse_move/app/main.rb</a></li>
+<li><a href='#--05_mouse/05_mouse_move_paint_app/app/main.rb'>05_mouse/05_mouse_move_paint_app/app/main.rb</a></li>
+<li><a href='#--05_mouse/06_coordinate_systems/app/main.rb'>05_mouse/06_coordinate_systems/app/main.rb</a></li>
+<li><a href='#--06_save_load/10_save_load_game/app/main.rb'>06_save_load/10_save_load_game/app/main.rb</a></li>
+<li><a href='#--07_advanced_rendering/01_simple_render_targets/app/main.rb'>07_advanced_rendering/01_simple_render_targets/app/main.rb</a></li>
+<li><a href='#--07_advanced_rendering/02_render_targets_with_alphas/app/main.rb'>07_advanced_rendering/02_render_targets_with_alphas/app/main.rb</a></li>
+<li><a href='#--07_advanced_rendering/03_render_target_viewports/app/main.rb'>07_advanced_rendering/03_render_target_viewports/app/main.rb</a></li>
+<li><a href='#--07_advanced_rendering/04_render_primitive_hierarchies/app/main.rb'>07_advanced_rendering/04_render_primitive_hierarchies/app/main.rb</a></li>
+<li><a href='#--07_advanced_rendering/11_render_primitives_as_hash/app/main.rb'>07_advanced_rendering/11_render_primitives_as_hash/app/main.rb</a></li>
+<li><a href='#--08_lerping_easing_functions/01_easing_functions/app/main.rb'>08_lerping_easing_functions/01_easing_functions/app/main.rb</a></li>
+<li><a href='#--08_lerping_easing_functions/02_cubic_bezier/app/main.rb'>08_lerping_easing_functions/02_cubic_bezier/app/main.rb</a></li>
+<li><a href='#--08_lerping_easing_functions/03_easing_using_spline/app/main.rb'>08_lerping_easing_functions/03_easing_using_spline/app/main.rb</a></li>
+<li><a href='#--08_lerping_easing_functions/04_parametric_enemy_movement/app/main.rb'>08_lerping_easing_functions/04_parametric_enemy_movement/app/main.rb</a></li>
+<li><a href='#--09_performance/01_sprites_as_hash/app/main.rb'>09_performance/01_sprites_as_hash/app/main.rb</a></li>
+<li><a href='#--09_performance/02_sprites_as_entities/app/main.rb'>09_performance/02_sprites_as_entities/app/main.rb</a></li>
+<li><a href='#--09_performance/03_sprites_as_strict_entities/app/main.rb'>09_performance/03_sprites_as_strict_entities/app/main.rb</a></li>
+<li><a href='#--09_performance/04_sprites_as_classes/app/main.rb'>09_performance/04_sprites_as_classes/app/main.rb</a></li>
+<li><a href='#--09_performance/05_static_sprites_as_classes/app/main.rb'>09_performance/05_static_sprites_as_classes/app/main.rb</a></li>
+<li><a href='#--09_performance/06_static_sprites_as_classes_with_custom_drawing/app/main.rb'>09_performance/06_static_sprites_as_classes_with_custom_drawing/app/main.rb</a></li>
+<li><a href='#--09_performance/07_collision_limits/app/main.rb'>09_performance/07_collision_limits/app/main.rb</a></li>
+<li><a href='#--10_advanced_debugging/01_trace_debugging/app/main.rb'>10_advanced_debugging/01_trace_debugging/app/main.rb</a></li>
+<li><a href='#--10_advanced_debugging/02_trace_debugging_classes/app/main.rb'>10_advanced_debugging/02_trace_debugging_classes/app/main.rb</a></li>
+<li><a href='#--10_advanced_debugging/03_unit_tests/exception_raising_tests.rb'>10_advanced_debugging/03_unit_tests/exception_raising_tests.rb</a></li>
+<li><a href='#--10_advanced_debugging/03_unit_tests/gen_docs.rb'>10_advanced_debugging/03_unit_tests/gen_docs.rb</a></li>
+<li><a href='#--10_advanced_debugging/03_unit_tests/geometry_tests.rb'>10_advanced_debugging/03_unit_tests/geometry_tests.rb</a></li>
+<li><a href='#--10_advanced_debugging/03_unit_tests/http_tests.rb'>10_advanced_debugging/03_unit_tests/http_tests.rb</a></li>
+<li><a href='#--10_advanced_debugging/03_unit_tests/object_to_primitive_tests.rb'>10_advanced_debugging/03_unit_tests/object_to_primitive_tests.rb</a></li>
+<li><a href='#--10_advanced_debugging/03_unit_tests/parsing_tests.rb'>10_advanced_debugging/03_unit_tests/parsing_tests.rb</a></li>
+<li><a href='#--10_advanced_debugging/03_unit_tests/serialize_deserialize_tests.rb'>10_advanced_debugging/03_unit_tests/serialize_deserialize_tests.rb</a></li>
+<li><a href='#--10_advanced_debugging/03_unit_tests/state_serialization_experimental_tests.rb'>10_advanced_debugging/03_unit_tests/state_serialization_experimental_tests.rb</a></li>
+<li><a href='#--11_http/01_retrieve_images/app/main.rb'>11_http/01_retrieve_images/app/main.rb</a></li>
+<li><a href='#--99_genre_3d/3d_cube/app/main.rb'>99_genre_3d/3d_cube/app/main.rb</a></li>
+<li><a href='#--99_genre_arcade/dueling_starships/app/main.rb'>99_genre_arcade/dueling_starships/app/main.rb</a></li>
+<li><a href='#--99_genre_arcade/flappy_dragon/app/main.rb'>99_genre_arcade/flappy_dragon/app/main.rb</a></li>
+<li><a href='#--99_genre_arcade/pong/app/main.rb'>99_genre_arcade/pong/app/main.rb</a></li>
+<li><a href='#--99_genre_arcade/snakemoji/app/main.rb'>99_genre_arcade/snakemoji/app/main.rb</a></li>
+<li><a href='#--99_genre_arcade/solar_system/app/main.rb'>99_genre_arcade/solar_system/app/main.rb</a></li>
+<li><a href='#--99_genre_crafting/craft_game_starting_point/app/main.rb'>99_genre_crafting/craft_game_starting_point/app/main.rb</a></li>
+<li><a href='#--99_genre_dev_tools/animation_creator_starting_point/app/main.rb'>99_genre_dev_tools/animation_creator_starting_point/app/main.rb</a></li>
+<li><a href='#--99_genre_dev_tools/tile_editor_starting_point/app/main.rb'>99_genre_dev_tools/tile_editor_starting_point/app/main.rb</a></li>
+<li><a href='#--99_genre_lowrez/resolution_64x64/app/lowrez.rb'>99_genre_lowrez/resolution_64x64/app/lowrez.rb</a></li>
+<li><a href='#--99_genre_lowrez/resolution_64x64/app/main.rb'>99_genre_lowrez/resolution_64x64/app/main.rb</a></li>
+<li><a href='#--99_genre_narrative_rpg/choose_your_own_adventure/app/decision.rb'>99_genre_narrative_rpg/choose_your_own_adventure/app/decision.rb</a></li>
+<li><a href='#--99_genre_narrative_rpg/choose_your_own_adventure/app/main.rb'>99_genre_narrative_rpg/choose_your_own_adventure/app/main.rb</a></li>
+<li><a href='#--99_genre_narrative_rpg/return_of_serenity/app/lowrez_simulator.rb'>99_genre_narrative_rpg/return_of_serenity/app/lowrez_simulator.rb</a></li>
+<li><a href='#--99_genre_narrative_rpg/return_of_serenity/app/main.rb'>99_genre_narrative_rpg/return_of_serenity/app/main.rb</a></li>
+<li><a href='#--99_genre_narrative_rpg/return_of_serenity/app/repl.rb'>99_genre_narrative_rpg/return_of_serenity/app/repl.rb</a></li>
+<li><a href='#--99_genre_narrative_rpg/return_of_serenity/app/require.rb'>99_genre_narrative_rpg/return_of_serenity/app/require.rb</a></li>
+<li><a href='#--99_genre_narrative_rpg/return_of_serenity/app/storyline.rb'>99_genre_narrative_rpg/return_of_serenity/app/storyline.rb</a></li>
+<li><a href='#--99_genre_narrative_rpg/return_of_serenity/app/storyline_anka.rb'>99_genre_narrative_rpg/return_of_serenity/app/storyline_anka.rb</a></li>
+<li><a href='#--99_genre_narrative_rpg/return_of_serenity/app/storyline_blinking_light.rb'>99_genre_narrative_rpg/return_of_serenity/app/storyline_blinking_light.rb</a></li>
+<li><a href='#--99_genre_narrative_rpg/return_of_serenity/app/storyline_day_one.rb'>99_genre_narrative_rpg/return_of_serenity/app/storyline_day_one.rb</a></li>
+<li><a href='#--99_genre_narrative_rpg/return_of_serenity/app/storyline_final_decision.rb'>99_genre_narrative_rpg/return_of_serenity/app/storyline_final_decision.rb</a></li>
+<li><a href='#--99_genre_narrative_rpg/return_of_serenity/app/storyline_final_message.rb'>99_genre_narrative_rpg/return_of_serenity/app/storyline_final_message.rb</a></li>
+<li><a href='#--99_genre_narrative_rpg/return_of_serenity/app/storyline_serenity_alive.rb'>99_genre_narrative_rpg/return_of_serenity/app/storyline_serenity_alive.rb</a></li>
+<li><a href='#--99_genre_narrative_rpg/return_of_serenity/app/storyline_serenity_bio.rb'>99_genre_narrative_rpg/return_of_serenity/app/storyline_serenity_bio.rb</a></li>
+<li><a href='#--99_genre_narrative_rpg/return_of_serenity/app/storyline_serenity_introduction.rb'>99_genre_narrative_rpg/return_of_serenity/app/storyline_serenity_introduction.rb</a></li>
+<li><a href='#--99_genre_narrative_rpg/return_of_serenity/app/storyline_speed_of_light.rb'>99_genre_narrative_rpg/return_of_serenity/app/storyline_speed_of_light.rb</a></li>
+<li><a href='#--99_genre_platformer/clepto_frog/app/main.rb'>99_genre_platformer/clepto_frog/app/main.rb</a></li>
+<li><a href='#--99_genre_platformer/clepto_frog/app/map.rb'>99_genre_platformer/clepto_frog/app/map.rb</a></li>
+<li><a href='#--99_genre_platformer/gorillas_basic/app/main.rb'>99_genre_platformer/gorillas_basic/app/main.rb</a></li>
+<li><a href='#--99_genre_platformer/gorillas_basic/app/repl.rb'>99_genre_platformer/gorillas_basic/app/repl.rb</a></li>
+<li><a href='#--99_genre_platformer/gorillas_basic/app/tests.rb'>99_genre_platformer/gorillas_basic/app/tests.rb</a></li>
+<li><a href='#--99_genre_platformer/gorillas_basic/app/tests/building_generation_tests.rb'>99_genre_platformer/gorillas_basic/app/tests/building_generation_tests.rb</a></li>
+<li><a href='#--99_genre_platformer/the_little_probe/app/main.rb'>99_genre_platformer/the_little_probe/app/main.rb</a></li>
+<li><a href='#--99_genre_roguelike/roguelike_line_of_sight/app/constants.rb'>99_genre_roguelike/roguelike_line_of_sight/app/constants.rb</a></li>
+<li><a href='#--99_genre_roguelike/roguelike_line_of_sight/app/legend.rb'>99_genre_roguelike/roguelike_line_of_sight/app/legend.rb</a></li>
+<li><a href='#--99_genre_roguelike/roguelike_line_of_sight/app/main.rb'>99_genre_roguelike/roguelike_line_of_sight/app/main.rb</a></li>
+<li><a href='#--99_genre_roguelike/roguelike_line_of_sight/app/sprite_lookup.rb'>99_genre_roguelike/roguelike_line_of_sight/app/sprite_lookup.rb</a></li>
+<li><a href='#--99_genre_roguelike/roguelike_starting_point/app/main.rb'>99_genre_roguelike/roguelike_starting_point/app/main.rb</a></li>
+<li><a href='#--99_genre_tactical_rpg/hexagonal_grid/app/main.rb'>99_genre_tactical_rpg/hexagonal_grid/app/main.rb</a></li>
+<li><a href='#--99_genre_tactical_rpg/isometric_grid/app/main.rb'>99_genre_tactical_rpg/isometric_grid/app/main.rb</a></li>
+<li><a href='#--99_genre_topdown_rpg/topdown_starting_point/app/main.rb'>99_genre_topdown_rpg/topdown_starting_point/app/main.rb</a></li>
+<li><a href='#--./dragon/args.rb'>./dragon/args.rb</a></li>
+<li><a href='#--./dragon/assert.rb'>./dragon/assert.rb</a></li>
+<li><a href='#--./dragon/attr_gtk.rb'>./dragon/attr_gtk.rb</a></li>
+<li><a href='#--./dragon/attr_sprite.rb'>./dragon/attr_sprite.rb</a></li>
+<li><a href='#--./dragon/console.rb'>./dragon/console.rb</a></li>
+<li><a href='#--./dragon/console_color.rb'>./dragon/console_color.rb</a></li>
+<li><a href='#--./dragon/console_font_style.rb'>./dragon/console_font_style.rb</a></li>
+<li><a href='#--./dragon/console_menu.rb'>./dragon/console_menu.rb</a></li>
+<li><a href='#--./dragon/console_prompt.rb'>./dragon/console_prompt.rb</a></li>
+<li><a href='#--./dragon/controller.rb'>./dragon/controller.rb</a></li>
+<li><a href='#--./dragon/controller/config.rb'>./dragon/controller/config.rb</a></li>
+<li><a href='#--./dragon/controller/keys.rb'>./dragon/controller/keys.rb</a></li>
+<li><a href='#--./dragon/directional_input_helper_methods.rb'>./dragon/directional_input_helper_methods.rb</a></li>
+<li><a href='#--./dragon/geometry.rb'>./dragon/geometry.rb</a></li>
+<li><a href='#--./dragon/grid.rb'>./dragon/grid.rb</a></li>
+<li><a href='#--./dragon/inputs.rb'>./dragon/inputs.rb</a></li>
+<li><a href='#--./dragon/log.rb'>./dragon/log.rb</a></li>
+<li><a href='#--./dragon/numeric.rb'>./dragon/numeric.rb</a></li>
+<li><a href='#--./dragon/runtime/framerate_diagnostics.rb'>./dragon/runtime/framerate_diagnostics.rb</a></li>
+<li><a href='#--./dragon/string.rb'>./dragon/string.rb</a></li>
+<li><a href='#--./dragon/tests.rb'>./dragon/tests.rb</a></li>
+<li><a href='#--./dragon/trace.rb'>./dragon/trace.rb</a></li>
 </ul>
     </div>
     <div id='content'>
@@ -230,7 +351,10 @@ Now you can see that this function is getting called a lot!
 Here's a fun Ruby thing: <code>args.state.rotation ||= 0</code> is shorthand for "if args.state.rotation isn't initialized, set it to zero." It's a nice way to embed your initialization code right next to where you need the variable.
 </p>
 <p>
-<code>args.state</code> is a place you can hang your own data and have it survive past the life of the function call. In this case, the current rotation of our sprite, which is happily spinning at 60 frames per second. If you don't specify rotation (or alpha, or color modulation, or a source rectangle, etc), DragonRuby picks a reasonable default, and the array is ordered by the most likely things you need to tell us: position, size, name.
+<code>args.state</code> is a place you can hang your own data. It's an open data structure that allows you to define properties that are arbitrarily nested. You don't need to define any kind of class.
+</p>
+<p>
+In this case, the current rotation of our sprite, which is happily spinning at 60 frames per second. If you don't specify rotation (or alpha, or color modulation, or a source rectangle, etc), DragonRuby picks a reasonable default, and the array is ordered by the most likely things you need to tell us: position, size, name.
 </p>
 <h2>There Is No Delta Time</h2>
 <p>
@@ -440,7 +564,14 @@ But that's how we've always done it.
 <p>
 It's a hard pill to swallow, but forget blindly accepted best practices and try to figure out the underlying motivation for a specific approach to game development. Collaborate with us.
 </p>
-<h3>Release Often And Quickly</h3>
+<h3>Continuity of Design</h3>
+<p>
+There is a programming idiom in software called "the pit of success". The term normalizes up front pain as a necessity in the (hopes that the investment will yield dividends "when you become successful"). This results in more "Enterprise TM" code upfront, and makes it more difficult to get started when you are new to programming.
+</p>
+<p>
+DragonRuby's philosophy is to provide a spectrum across the "make it fast" vs "make it right" spectrum and provide incremental, intuitive transitions between points on that spectrum. This is captured in how render primitives can be represented as tuples/arrays, hashes, open structs/entities, and then finally classes (as opposed to forcing devs to use classes upfront).
+</p>
+<h3>Release Often And Soon</h3>
 <p>
 The biggest mistake game devs make is spending too much time in isolation building their game. Release something, however small, and release it quickly.
 </p>
@@ -736,25 +867,25 @@ To assign a value every frame, just use the <code>=</code> operator, but _make s
 </p>
 <pre>def tick args
   # initialize your game state ONCE
-  args.player.x  ||= 0
-  args.player.y  ||= 0
-  args.player.hp ||= 100
+  args.state.player.x  ||= 0
+  args.state.player.y  ||= 0
+  args.state.player.hp ||= 100
 
   # increment the x position of the character by one every frame
-  args.player.x += 1
+  args.state.player.x += 1
 
   # Render a sprite with a label above the sprite
   args.outputs.sprites << [
-    args.player.x,
-    args.player.y,
+    args.state.player.x,
+    args.state.player.y,
     32, 32,
     "player.png"
   ]
 
   args.outputs.labels << [
-    args.player.x,
-    args.player.y - 50,
-    args.player.hp
+    args.state.player.x,
+    args.state.player.y - 50,
+    args.state.player.hp
   ]
 end
 </pre>
@@ -930,10 +1061,6 @@ But, in the event that sad day comes, our partnership bylaws state that _all_ Dr
 <p>
 The GTK::Runtime class is the core of DragonRuby. It is globally accessible via <code>$gtk</code>.
 </p>
-<h1 id='--docs---gtk--runtime#reset-'><code>GTK::Runtime#reset</code></h1>
-<p>
-This function will reset Kernel.tick_count to 0 and will remove all data from args.state.
-</p>
 <h1 id='--docs---gtk--runtime#calcstringbox-'><code>GTK::Runtime#calcstringbox</code></h1>
 <p>
 This function returns the width and height of a string.
@@ -943,6 +1070,10 @@ This function returns the width and height of a string.
   args.state.string_size_font_size ||= args.gtk.calcstringbox "Hello World"
 end
 </pre>
+<h1 id='--docs---gtk--runtime#reset-'><code>GTK::Runtime#reset</code></h1>
+<p>
+This function will reset Kernel.tick_count to 0 and will remove all data from args.state.
+</p>
 <h1 id='--docs---array-'><code>Array</code></h1>
 <p>
 The Array class has been extend to provide methods that will help in common game development tasks. Array is one of the most powerful classes in Ruby and a very fundamental component of Game Toolkit.
@@ -1564,6 +1695,22358 @@ Returns the current tick of the game. This value is reset if you call $gtk.reset
 <p>
 Returns the current tick of the application from the point it was started. This value is never reset.
 </p>
+<h1 id='--open-source'>Open Source</h1>
+<p>
+Follows is a source code listing for all files that have been open sourced. This code can be found in the <code>./samples</code> directory and online at <a href='https://github.com/DragonRuby/dragonruby-game-toolkit-contrib/'>https://github.com/DragonRuby/dragonruby-game-toolkit-contrib/</a>.
+</p>
+<h1 id='--00_learn_ruby_optional/00_beginner_ruby_primer/app/automation.rb'>00_learn_ruby_optional/00_beginner_ruby_primer/app/automation.rb</h1>
+<pre># ==========================================================================
+#  _    _ ________     __  _      _____  _____ _______ ______ _   _ _ _ _ _
+# | |  | |  ____\ \   / / | |    |_   _|/ ____|__   __|  ____| \ | | | | | |
+# | |__| | |__   \ \_/ /  | |      | | | (___    | |  | |__  |  \| | | | | |
+# |  __  |  __|   \   /   | |      | |  \___ \   | |  |  __| | . ` | | | | |
+# | |  | | |____   | |    | |____ _| |_ ____) |  | |  | |____| |\  |_|_|_|_|
+# |_|  |_|______|  |_|    |______|_____|_____/   |_|  |______|_| \_(_|_|_|_)
+#
+#
+#                                   |
+#                                   |
+#                                   |
+#                                   |
+#                                   |
+#                                   |
+#                                   |
+#                                   |
+#                                   |
+#                                   |
+#                                \  |  /
+#                                 \ | /
+#                                   +
+#
+# If you are new to the programming language Ruby, then you may find the
+# following code a bit overwhelming. Come back to this file when you have
+# a better grasp of Ruby and Game Toolkit.
+#
+# What follows is an automations script # that can be run via terminal:
+# ./samples/00_beginner_ruby_primer $ ../../dragonruby . --eval app/automation.rb
+# ==========================================================================
+
+$gtk.reset
+$gtk.scheduled_callbacks.clear
+$gtk.schedule_callback 10 do
+  $gtk.console.set_command 'puts "Hello DragonRuby!"'
+end
+
+$gtk.schedule_callback 20 do
+  $gtk.console.eval_the_set_command
+end
+
+$gtk.schedule_callback 30 do
+  $gtk.console.set_command 'outputs.solids << [910, 200, 100, 100, 255, 0, 0]'
+end
+
+$gtk.schedule_callback 40 do
+  $gtk.console.eval_the_set_command
+end
+
+$gtk.schedule_callback 50 do
+  $gtk.console.set_command 'outputs.solids << [1010, 200, 100, 100, 0, 0, 255]'
+end
+
+$gtk.schedule_callback 60 do
+  $gtk.console.eval_the_set_command
+end
+
+$gtk.schedule_callback 70 do
+  $gtk.console.set_command 'outputs.sprites << [1110, 200, 100, 100, "sprites/dragon_fly_0.png"]'
+end
+
+$gtk.schedule_callback 80 do
+  $gtk.console.eval_the_set_command
+end
+
+$gtk.schedule_callback 90 do
+  $gtk.console.set_command "outputs.labels << [1210, 200, state.tick_count, 0, 255, 0]"
+end
+
+$gtk.schedule_callback 100 do
+  $gtk.console.eval_the_set_command
+end
+
+$gtk.schedule_callback 110 do
+  $gtk.console.set_command "state.sprite_frame = state.tick_count.idiv(4).mod(6)"
+end
+
+$gtk.schedule_callback 120 do
+  $gtk.console.eval_the_set_command
+end
+
+$gtk.schedule_callback 130 do
+  $gtk.console.set_command "outputs.labels << [1210, 170, state.sprite_frame, 0, 255, 0]"
+end
+
+$gtk.schedule_callback 140 do
+  $gtk.console.eval_the_set_command
+end
+
+$gtk.schedule_callback 150 do
+  $gtk.console.set_command "state.sprite_path =  \"sprites/dragon_fly_\#{state.sprite_frame}.png\""
+end
+
+$gtk.schedule_callback 160 do
+  $gtk.console.eval_the_set_command
+end
+
+$gtk.schedule_callback 170 do
+  $gtk.console.set_command "outputs.labels    << [910, 330, \"path: \#{state.sprite_path}\", 0, 255, 0]"
+end
+
+$gtk.schedule_callback 180 do
+  $gtk.console.eval_the_set_command
+end
+
+$gtk.schedule_callback 190 do
+  $gtk.console.set_command "outputs.sprites   << [910, 330, 370, 370, state.sprite_path]"
+end
+
+$gtk.schedule_callback 200 do
+  $gtk.console.eval_the_set_command
+end
+
+$gtk.schedule_callback 300 do
+  $gtk.console.set_command ":wq"
+end
+
+$gtk.schedule_callback 400 do
+  $gtk.console.eval_the_set_command
+end
+
+</pre>
+<h1 id='--00_learn_ruby_optional/00_beginner_ruby_primer/app/main.rb'>00_learn_ruby_optional/00_beginner_ruby_primer/app/main.rb</h1>
+<pre># ==========================================================================
+#  _    _ ________     __  _      _____  _____ _______ ______ _   _ _ _ _ _
+# | |  | |  ____\ \   / / | |    |_   _|/ ____|__   __|  ____| \ | | | | | |
+# | |__| | |__   \ \_/ /  | |      | | | (___    | |  | |__  |  \| | | | | |
+# |  __  |  __|   \   /   | |      | |  \___ \   | |  |  __| | . ` | | | | |
+# | |  | | |____   | |    | |____ _| |_ ____) |  | |  | |____| |\  |_|_|_|_|
+# |_|  |_|______|  |_|    |______|_____|_____/   |_|  |______|_| \_(_|_|_|_)
+#
+#
+#                                   |
+#                                   |
+#                                   |
+#                                   |
+#                                   |
+#                                   |
+#                                   |
+#                                   |
+#                                   |
+#                                   |
+#                                \  |  /
+#                                 \ | /
+#                                   +
+#
+# If you are new to the programming language Ruby, then you may find the
+# following code a bit overwhelming. This sample is only designed to be
+# run interactively (as opposed to being manipulated via source code).
+#
+# Start up this sample and follow along by visiting:
+# https://s3.amazonaws.com/s3.dragonruby.org/dragonruby-gtk-primer.mp4
+#
+# It is STRONGLY recommended that you work through all the samples before
+# looking at the code in this file.
+# ==========================================================================
+
+class TutorialOutputs
+  attr_accessor :solids, :sprites, :labels, :lines, :borders
+
+  def initialize
+    @solids  = []
+    @sprites = []
+    @labels  = []
+    @lines   = []
+    @borders = []
+  end
+
+  def tick
+    @solids  ||= []
+    @sprites ||= []
+    @labels  ||= []
+    @lines   ||= []
+    @borders ||= []
+    @solids.each  { |p| $gtk.args.outputs.reserved << p.solid  }
+    @sprites.each { |p| $gtk.args.outputs.reserved << p.sprite }
+    @labels.each  { |p| $gtk.args.outputs.reserved << p.label  }
+    @lines.each   { |p| $gtk.args.outputs.reserved << p.line   }
+    @borders.each { |p| $gtk.args.outputs.reserved << p.border }
+  end
+
+  def clear
+    @solids.clear
+    @sprites.clear
+    @labels.clear
+    @borders.clear
+  end
+end
+
+def defaults
+  state.reset_button ||=
+    state.new_entity(
+      :button,
+      label:  [1190, 68, "RESTART", -2, 0, 0, 0, 0].label,
+      background: [1160, 38, 120, 50, 255, 255, 255].solid
+    )
+  $gtk.log_level = :off
+end
+
+def tick_reset_button
+  return unless state.hello_dragonruby_confirmed
+  $gtk.args.outputs.reserved << state.reset_button.background
+  $gtk.args.outputs.reserved << state.reset_button.label
+  if inputs.mouse.click && inputs.mouse.click.point.inside_rect?(state.reset_button.background)
+    restart_tutorial
+  end
+end
+
+def seperator
+  @seperator = "=" * 80
+end
+
+def tick_intro
+  queue_message "Welcome to the DragonRuby GTK primer! Try typing the
+code below and press ENTER:
+
+    puts \"Hello DragonRuby!\"
+"
+end
+
+def tick_hello_dragonruby
+  return unless console_has? "Hello DragonRuby!"
+
+  $gtk.args.state.hello_dragonruby_confirmed = true
+
+  queue_message "Well HELLO to you too!
+
+If you ever want to RESTART the tutorial, just click the \"RESTART\"
+button in the bottom right-hand corner.
+
+Let's continue shall we? Type the code below and press ENTER:
+
+    outputs.solids << [910, 200, 100, 100, 255, 0, 0]
+"
+
+end
+
+def tick_explain_solid
+  return unless $tutorial_outputs.solids.any? {|s| s == [910, 200, 100, 100, 255, 0, 0]}
+
+  queue_message "Sweet!
+
+The code: outputs.solids << [910, 200, 100, 100, 255, 0, 0]
+Does the following:
+1. GET the place where SOLIDS go: outputs.solids
+2. Request that a new SOLID be ADDED: <<
+3. The DEFINITION of a SOLID is the ARRAY:
+   [910, 200, 100, 100, 255, 0, 0]
+
+      GET       ADD     X      Y    WIDTH  HEIGHT RED  GREEN  BLUE
+       |         |      |      |      |      |     |     |     |
+       |         |      |      |      |      |     |     |     |
+outputs.solids  <<    [910,   200,   100,   100,  255,   0,    0]
+                      |_________________________________________|
+                                           |
+                                           |
+                                         ARRAY
+
+Now let's create a blue SOLID. Type:
+
+    outputs.solids << [1010, 200, 100, 100, 0, 0, 255]
+"
+
+  state.explain_solid_confirmed = true
+end
+
+def tick_explain_solid_blue
+  return unless state.explain_solid_confirmed
+  return unless $tutorial_outputs.solids.any? {|s| s == [1010, 200, 100, 100, 0, 0, 255]}
+  state.explain_solid_blue_confirmed = true
+
+  queue_message "And there is our blue SOLID!
+
+The ARRAY is the MOST important thing in DragonRuby GTK.
+
+Let's create a SPRITE using an ARRAY:
+
+  outputs.sprites << [1110, 200, 100, 100, 'sprites/dragon_fly_0.png']
+"
+end
+
+def tick_explain_tick_count
+  return unless $tutorial_outputs.sprites.any? {|s| s == [1110, 200, 100, 100, 'sprites/dragon_fly_0.png']}
+  return if $tutorial_outputs.labels.any? {|l| l == [1210, 200, state.tick_count, 255, 255, 255]}
+  state.explain_tick_count_confirmed = true
+
+  queue_message "Look at the cute little dragon!
+
+We can create a LABEL with ARRAYS too. Let's create a LABEL showing
+THE PASSAGE OF TIME, which is called TICK_COUNT.
+
+  outputs.labels << [1210, 200, state.tick_count, 0, 255, 0]
+"
+end
+
+def tick_explain_mod
+  return unless $tutorial_outputs.labels.any? {|l| l == [1210, 200, state.tick_count, 0, 255, 0]}
+  state.explain_mod_confirmed = true
+  queue_message "
+The code: outputs.labels << [1210, 200, state.tick_count, 0, 255, 0]
+Does the following:
+1. GET the place where labels go: outputs.labels
+2. Request that a new label be ADDED: <<
+3. The DEFINITION of a LABEL is the ARRAY:
+   [1210, 200, state.tick_count, 0, 255, 0]
+
+      GET       ADD     X      Y          TEXT         RED  GREEN  BLUE
+       |         |      |      |            |           |     |     |
+       |         |      |      |            |           |     |     |
+outputs.labels  <<    [1210,  200,   state.tick_count,  0,   255,   0]
+                      |______________________________________________|
+                                              |
+                                              |
+                                            ARRAY
+
+Now let's do some MATH, save the result to STATE, and create a LABEL:
+
+    state.sprite_frame = state.tick_count.idiv(4).mod(6)
+    outputs.labels << [1210, 170, state.sprite_frame, 0, 255, 0]
+
+Type the lines above (pressing ENTER after each line).
+"
+end
+
+def tick_explain_string_interpolation
+  return unless state.explain_mod_confirmed
+  return unless state.sprite_frame == state.tick_count.idiv(4).mod(6)
+  return unless $tutorial_outputs.labels.any? {|l| l == [1210, 170, state.sprite_frame, 0, 255, 0]}
+
+  queue_message "Here is what the mathematical computation you just typed does:
+
+1. Create an item of STATE named SPRITE_FRAME: state.sprite_frame =
+2. Set this SPRITE_FRAME to the PASSAGE OF TIME (tick_count),
+   DIVIDED EVENLY (idiv) into 4,
+   and then compute the REMAINDER (mod) of 6.
+
+   STATE   SPRITE_FRAME    PASSAGE OF      HOW LONG   HOW MANY
+     |          |             TIME         TO SHOW    IMAGES
+     |          |              |           AN IMAGE   TO FLIP THROUGH
+     |          |              |               |      |
+state.sprite_frame =     state.tick_count.idiv(4).mod(6)
+                                           |       |
+                                           |       +- REMAINDER OF DIVIDE
+                                    DIVIDE EVENLY
+                                    (NO DECIMALS)
+
+With the information above, we can animate a SPRITE
+using STRING INTERPOLATION: \#{}
+which creates a unique SPRITE_PATH:
+
+  state.sprite_path =  \"sprites/dragon_fly_\#{state.sprite_frame}.png\"
+  outputs.labels    << [910, 330, \"path: \#{state.sprite_path}\", 0, 255, 0]
+  outputs.sprites   << [910, 330, 370, 370, state.sprite_path]
+
+Type the lines above (pressing ENTER after each line).
+"
+end
+
+def tick_reprint_on_error
+  return unless console.last_command_errored
+  puts $gtk.state.messages.last
+  puts "\nWhoops! Try again."
+  console.last_command_errored = false
+end
+
+def tick_evals
+  state.evals ||= []
+  if console.last_command && (console.last_command.start_with?("outputs.") || console.last_command.start_with?("state."))
+    state.evals << console.last_command
+    console.last_command = nil
+  end
+
+  state.evals.each do |l|
+    Kernel.eval l
+  end
+rescue Exception => e
+  state.evals = state.evals[0..-2]
+end
+
+$tutorial_outputs ||= TutorialOutputs.new
+
+def tick args
+  $gtk.log_level = :off
+  defaults
+  console.show
+  $tutorial_outputs.clear
+  $tutorial_outputs.solids  << [900, 37, 480, 700,   0,   0,   0, 255]
+  $tutorial_outputs.borders << [900, 37, 380, 683, 255, 255, 255]
+  tick_evals
+  $tutorial_outputs.tick
+  tick_intro
+  tick_hello_dragonruby
+  tick_reset_button
+  tick_explain_solid
+  tick_explain_solid_blue
+  tick_reprint_on_error
+  tick_explain_tick_count
+  tick_explain_mod
+  tick_explain_string_interpolation
+end
+
+def console
+  $gtk.console
+end
+
+def queue_message message
+  $gtk.args.state.messages ||= []
+  return if $gtk.args.state.messages.include? message
+  $gtk.args.state.messages << message
+  last_three = [$gtk.console.log[-3], $gtk.console.log[-2], $gtk.console.log[-1]].reject_nil
+  $gtk.console.log.clear
+  puts seperator
+  $gtk.console.log += last_three
+  puts seperator
+  puts message
+  puts seperator
+end
+
+def console_has? message
+  console.log.map(&:upcase).include? "#{message.upcase}\n"
+end
+
+def restart_tutorial
+  $tutorial_outputs.clear
+  $gtk.console.log.clear
+  $gtk.reset
+  puts "Starting the tutorial over!"
+end
+
+def state
+  $gtk.args.state
+end
+
+def inputs
+  $gtk.args.inputs
+end
+
+def outputs
+  $tutorial_outputs
+end
+
+</pre>
+<h1 id='--00_learn_ruby_optional/00_intermediate_ruby_primer/app/main.rb'>00_learn_ruby_optional/00_intermediate_ruby_primer/app/main.rb</h1>
+<pre>def tick args
+  args.outputs.labels << [640, 380, "Open repl.rb in the text editor of your choice and follow the document.", 0, 1]
+end
+
+</pre>
+<h1 id='--00_learn_ruby_optional/00_intermediate_ruby_primer/app/repl.rb'>00_learn_ruby_optional/00_intermediate_ruby_primer/app/repl.rb</h1>
+<pre>
+</pre>
+<h1 id='--01_rendering_basics/01_labels/app/main.rb'>01_rendering_basics/01_labels/app/main.rb</h1>
+<pre>=begin
+
+APIs listing that haven't been encountered in a previous sample apps:
+
+- args.outputs.labels: An array. Values in this array generate labels
+  the screen.
+- args.grid.(left|right|top|bottom): Pixel value for the boundaries of the virtual
+  720 p screen (Dragon Ruby Game Toolkits's virtual resolution is always 1280x720).
+- Numeric#shift_(left|right|up|down): Shifts the Numeric in the correct direction
+  by adding or subracting.
+
+=end
+
+# Labels are used to represent text elements in DragonRuby
+
+# An example of creating a label is:
+# args.outputs.labels << [320, 640, "Example", 3, 1, 255, 0, 0, 200, manaspace.ttf]
+
+# The code above does the following:
+# 1. GET the place where labels go: args.outputs.labels
+# 2. Request a new LABEL be ADDED: <<
+# 3. The DEFINITION of a SOLID is the ARRAY:
+#     [320, 640, "Example", 3,     1,   255,   0,    0,    200,  manaspace.ttf]
+#     [ X ,  Y,    TEXT,   SIZE, ALIGN, RED, GREEN, BLUE, ALPHA, FONT STYLE]
+
+
+# The tick method is called by DragonRuby every frame
+# args contains all the information regarding the game.
+def tick args
+  tick_instructions args, "Sample app shows different version of label sizes and alignments. And how to use hashes instead of arrays."
+  # Here are some examples of simple labels, with the minimum number of parameters
+  # Note that the default values for the other parameters are 0, except for Alpha which is 255 and Font Style which is the default font
+  args.outputs.labels << [400, 620, "Here is a label with just an x, y, and text"]
+
+  args.outputs.labels << [args.grid.left.shift_right(5), args.grid.top.shift_down(5), "This is a label located at the top left."]
+  args.outputs.labels << [args.grid.left.shift_right(5), args.grid.bottom.shift_up(30), "This is a label located at the bottom left."]
+  args.outputs.labels << [args.grid.right.shift_left(420), args.grid.top.shift_down(5), "This is a label located at the top right."]
+  args.outputs.labels << [args.grid.right.shift_left(440), args.grid.bottom.shift_up(30), "This is a label located at the bottom right."]
+
+  # Demonstration of the Size Parameter
+  args.outputs.labels << [175 + 150, 610 - 50, "Smaller label.",  -2]
+  args.outputs.labels << [175 + 150, 580 - 50, "Small label.",    -1]
+  args.outputs.labels << [175 + 150, 550 - 50, "Medium label.",    0]
+  args.outputs.labels << [175 + 150, 520 - 50, "Large label.",     1]
+  args.outputs.labels << [175 + 150, 490 - 50, "Larger label.",    2]
+
+  # Demonstration of the Align Parameter
+  args.outputs.labels << [260 + 150, 345 - 50, "Left aligned.",    0, 2]
+  args.outputs.labels << [260 + 150, 325 - 50, "Center aligned.",  0, 1]
+  args.outputs.labels << [260 + 150, 305 - 50, "Right aligned.",   0, 0]
+
+  # Demonstration of the RGBA parameters
+  args.outputs.labels << [600  + 150, 590 - 50, "Red Label.",       0, 0, 255,   0,   0]
+  args.outputs.labels << [600  + 150, 570 - 50, "Green Label.",     0, 0,   0, 255,   0]
+  args.outputs.labels << [600  + 150, 550 - 50, "Blue Label.",      0, 0,   0,   0, 255]
+  args.outputs.labels << [600  + 150, 530 - 50, "Faded Label.",     0, 0,   0,   0,   0, 128]
+
+  # Demonstration of the Font parameter
+  # In order to use a font of your choice, add its ttf file to the project folder, where the app folder is
+  args.outputs.labels << [690 + 150, 330 - 20, "Custom font (Array)", 0, 1, 125, 0, 200, 255, "manaspc.ttf" ]
+  args.outputs.primitives << { x: 690 + 150,
+                               y: 330 - 50,
+                               text: "Custom font (Hash)",
+                               size_enum: 0,
+                               alignment_enum: 1,
+                               r: 125,
+                               g: 0,
+                               b: 200,
+                               a: 255,
+                               font: "manaspc.ttf" }.label
+
+  # Primitives can hold anything, and can be given a label in the following forms
+  args.outputs.primitives << [690 + 150, 330 - 80, "Custom font (.primitives Array)", 0, 1, 125, 0, 200, 255, "manaspc.ttf" ].label
+
+  args.outputs.primitives << { x: 690 + 150,
+                               y: 330 - 110,
+                               text: "Custom font (.primitives Hash)",
+                               size_enum: 0,
+                               alignment_enum: 1,
+                               r: 125,
+                               g: 0,
+                               b: 200,
+                               a: 255,
+                               font: "manaspc.ttf" }.label
+end
+
+def tick_instructions args, text, y = 715
+  return if args.state.key_event_occurred
+  if args.inputs.mouse.click ||
+     args.inputs.keyboard.directional_vector ||
+     args.inputs.keyboard.key_down.enter ||
+     args.inputs.keyboard.key_down.escape
+    args.state.key_event_occurred = true
+  end
+
+  args.outputs.debug << [0, y - 50, 1280, 60].solid
+  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
+  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
+end
+
+</pre>
+<h1 id='--01_rendering_basics/02_lines/app/main.rb'>01_rendering_basics/02_lines/app/main.rb</h1>
+<pre>=begin
+
+APIs listing that haven't been encountered in a previous sample apps:
+
+- args.outputs.lines: An array. Values in this array generate lines on
+  the screen.
+- args.state.tick_count: This property contains an integer value that
+  represents the current frame. GTK renders at 60 FPS. A value of 0
+  for args.state.tick_count represents the initial load of the game.
+
+=end
+
+# The parameters required for lines are:
+# 1. The initial point (x, y)
+# 2. The end point (x2, y2)
+# 3. The rgba values for the color and transparency (r, g, b, a)
+
+# An example of creating a line would be:
+# args.outputs.lines << [100, 100, 300, 300, 255, 0, 255, 255]
+
+# This would create a line from (100, 100) to (300, 300)
+# The RGB code (255, 0, 255) would determine its color, a purple
+# It would have an Alpha value of 255, making it completely opaque
+
+def tick args
+  tick_instructions args, "Sample app shows how to create lines."
+
+  args.outputs.labels << [480, 620, "Lines (x, y, x2, y2, r, g, b, a)"]
+
+  # Some simple lines
+  args.outputs.lines  << [380, 450, 675, 450]
+  args.outputs.lines  << [380, 410, 875, 410]
+
+  # These examples utilize args.state.tick_count to change the length of the lines over time
+  # args.state.tick_count is the ticks that have occurred in the game
+  # This is accomplished by making either the starting or ending point based on the args.state.tick_count
+  args.outputs.lines  << [380, 370, 875, 370, args.state.tick_count % 255, 0, 0, 255]
+  args.outputs.lines  << [380, 330 - args.state.tick_count % 25, 875, 330, 0, 0, 0, 255]
+  args.outputs.lines  << [380 + args.state.tick_count % 400, 290, 875, 290, 0, 0, 0, 255]
+end
+
+def tick_instructions args, text, y = 715
+  return if args.state.key_event_occurred
+  if args.inputs.mouse.click ||
+     args.inputs.keyboard.directional_vector ||
+     args.inputs.keyboard.key_down.enter ||
+     args.inputs.keyboard.key_down.escape
+    args.state.key_event_occurred = true
+  end
+
+  args.outputs.debug << [0, y - 50, 1280, 60].solid
+  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
+  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
+end
+
+</pre>
+<h1 id='--01_rendering_basics/03_solids_borders/app/main.rb'>01_rendering_basics/03_solids_borders/app/main.rb</h1>
+<pre>=begin
+
+APIs listing that haven't been encountered in a previous sample apps:
+
+- args.outputs.solids: An array. Values in this array generate
+  solid/filled rectangles on the screen.
+
+=end
+
+# Rects are outputted in DragonRuby as rectangles
+# If filled in, they are solids
+# If hollow, they are borders
+
+# Solids are added to args.outputs.solids
+# Borders are added to args.outputs.borders
+
+# The parameters required for rects are:
+# 1. The upper right corner (x, y)
+# 2. The width (w)
+# 3. The height (h)
+# 4. The rgba values for the color and transparency (r, g, b, a)
+
+# Here is an example of a rect definition:
+# [100, 100, 400, 500, 0, 255, 0, 180]
+
+# The example would create a rect from (100, 100)
+# Extending 400 pixels across the x axis
+# and 500 pixels across the y axis
+# The rect would be green (0, 255, 0)
+# and mostly opaque with some transparency (180)
+
+# Whether the rect would be filled or not depends on if
+# it is added to args.outputs.solids or args.outputs.borders
+
+
+def tick args
+  tick_instructions args, "Sample app shows how to create solid squares."
+  args.outputs.labels << [460, 600, "Solids (x, y, w, h, r, g, b, a)"]
+  args.outputs.solids << [470, 520, 50, 50]
+  args.outputs.solids << [530, 520, 50, 50, 0, 0, 0]
+  args.outputs.solids << [590, 520, 50, 50, 255, 0, 0]
+  args.outputs.solids << [650, 520, 50, 50, 255, 0, 0, 128]
+  args.outputs.solids << [710, 520, 50, 50, 0, 0, 0, 128 + args.state.tick_count % 128]
+
+
+  args.outputs.labels <<  [460, 400, "Borders (x, y, w, h, r, g, b, a)"]
+  args.outputs.borders << [470, 320, 50, 50]
+  args.outputs.borders << [530, 320, 50, 50, 0, 0, 0]
+  args.outputs.borders << [590, 320, 50, 50, 255, 0, 0]
+  args.outputs.borders << [650, 320, 50, 50, 255, 0, 0, 128]
+  args.outputs.borders << [710, 320, 50, 50, 0, 0, 0, 128 + args.state.tick_count % 128]
+end
+
+def tick_instructions args, text, y = 715
+  return if args.state.key_event_occurred
+  if args.inputs.mouse.click ||
+     args.inputs.keyboard.directional_vector ||
+     args.inputs.keyboard.key_down.enter ||
+     args.inputs.keyboard.key_down.escape
+    args.state.key_event_occurred = true
+  end
+
+  args.outputs.debug << [0, y - 50, 1280, 60].solid
+  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
+  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
+end
+
+</pre>
+<h1 id='--01_rendering_basics/04_sprites/app/main.rb'>01_rendering_basics/04_sprites/app/main.rb</h1>
+<pre>=begin
+
+APIs listing that haven't been encountered in a previous sample apps:
+
+- args.outputs.sprites: An array. Values in this array generate
+  sprites on the screen. The location of the sprite is assumed to
+  be under the mygame/ directory (the exception being dragonruby.png).
+
+=end
+
+
+# For all other display outputs, Sprites are your solution
+# Sprites import images and display them with a certain rectangular area
+# The image can be of any usual format and should be located within the folder,
+# similar to additional fonts.
+
+# Sprites have the following parameters
+# Rectangular area (x, y, width, height)
+# The image (path)
+# Rotation (angle)
+# Alpha (a)
+
+def tick args
+  tick_instructions args, "Sample app shows how to render a sprite. Set its alpha, and rotate it."
+  args.outputs.labels <<  [460, 600, "Sprites (x, y, w, h, path, angle, a)"]
+  args.outputs.sprites << [460, 470, 128, 101, 'dragonruby.png']
+  args.outputs.sprites << [610, 470, 128, 101, 'dragonruby.png', args.state.tick_count % 360]
+  args.outputs.sprites << [760, 470, 128, 101, 'dragonruby.png', 0, args.state.tick_count % 255]
+end
+
+def tick_instructions args, text, y = 715
+  return if args.state.key_event_occurred
+  if args.inputs.mouse.click ||
+     args.inputs.keyboard.directional_vector ||
+     args.inputs.keyboard.key_down.enter ||
+     args.inputs.keyboard.key_down.escape
+    args.state.key_event_occurred = true
+  end
+
+  args.outputs.debug << [0, y - 50, 1280, 60].solid
+  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
+  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
+end
+
+</pre>
+<h1 id='--01_rendering_basics/05_sounds/app/main.rb'>01_rendering_basics/05_sounds/app/main.rb</h1>
+<pre>=begin
+
+ APIs Listing that haven't been encountered in previous sample apps:
+
+ - sample: Chooses random element from array.
+   In this sample app, the target note is set by taking a sample from the collection
+   of available notes.
+
+ Reminders:
+ - args.grid.(left|right|top|bottom): Pixel value for the boundaries of the virtual
+   720 p screen (Dragon Ruby Game Toolkits's virtual resolution is always 1280x720).
+
+ - args.state.new_entity: Used when we want to create a new object, like a sprite or button.
+   For example, if we want to create a new button, we would declare it as a new entity and
+   then define its properties.
+
+ - String interpolation: Uses #{} syntax; everything between the #{ and the } is evaluated
+   as Ruby code, and the placeholder is replaced with its corresponding value or result.
+
+ - args.outputs.labels: An array. The values generate a label.
+   The parameters are [X, Y, TEXT, SIZE, ALIGNMENT, RED, GREEN, BLUE, ALPHA, FONT STYLE]
+   For more information about labels, go to mygame/documentation/02-labels.md.
+
+ - reject: Removes elements from a collection if they meet certain requirements.
+
+ - first: Returns the first element of an array.
+
+ - inside_rect: Returns true or false depending on if the point is inside the rect.
+
+ - to_sym: Returns symbol corresponding to string. Will create a symbol if it does
+   not already exist.
+
+=end
+
+# This sample app allows users to test their musical skills by matching the piano sound that plays in each
+# level to the correct note.
+
+# Runs all the methods necessary for the game to function properly.
+def tick args
+  defaults args
+  render args
+  calc args
+  input_mouse args
+  tick_instructions args, "Sample app shows how to play sounds. args.outputs.sounds << \"path_to_wav.wav\""
+end
+
+# Sets default values and creates empty collections
+# Initialization happens in the first frame only
+def defaults _
+  _.state.notes ||= []
+  _.state.click_feedbacks ||= []
+  _.state.current_level ||= 1
+  _.state.times_wrong ||= 0 # when game starts, user hasn't guessed wrong yet
+end
+
+# Uses a label to display current level, and shows the score
+# Creates a button to play the sample note, and displays the available notes that could be a potential match
+def render _
+
+  # grid.w_half positions the label in the horizontal center of the screen.
+  _.outputs.labels << [_.grid.w_half, _.grid.top.shift_down(40), "Hole #{_.state.current_level} of 9", 0, 1, 0, 0, 0]
+
+  render_score _ # shows score on screen
+
+  if _.state.game_over # if game is over, a "play again" button is shown
+    # Calculations ensure that Play Again label is displayed in center of border
+    # Remove calculations from y parameters and see what happens to border and label placement
+    _.state.play_again_border ||= _.state.with_meta([560, _.grid.h * 3 / 4 - 40, 160, 60], 'again') # array definition, text/title
+    _.outputs.labels <<  [_.grid.w_half, _.grid.h * 3 / 4, "Play Again", 0, 1, 0, 0, 0] # outputs label
+    _.outputs.borders << _.state.play_again_border # outputs border
+  else # otherwise, if game is not over
+    # Calculations ensure that label appears in center of border
+    _.state.play_note_border ||= _.state.with_meta([560, _.grid.h * 3 / 4 - 40, 160, 60], 'play') # array definition, text/title
+    _.outputs.labels <<  [_.grid.w_half, _.grid.h * 3 / 4, "Play Note ##{_.state.current_level}", 0, 1, 0, 0, 0] # outputs label
+    _.outputs.borders << _.state.play_note_border # outputs border
+  end
+
+  return if _.state.game_over # return if game is over
+
+  _.outputs.labels <<   [_.grid.w_half, 400, "I think the note is a(n)...",  0, 1, 0, 0, 0] # outputs label
+
+  # Shows all of the available notes that can be potential matches.
+  available_notes.each_with_index do |note, i|
+    _.state.notes[i] ||= piano_button(_, note, i + 1) # calls piano_button method on each note (creates label and border)
+    _.outputs.labels <<   _.state.notes[i].label # outputs note on screen with a label and a border
+    _.outputs.borders <<  _.state.notes[i].border
+  end
+
+  # Shows whether or not the user is correct by filling the screen with either red or green
+  _.outputs.solids << _.state.click_feedbacks.map { |c| c.solid }
+end
+
+# Shows the score (number of times the user guesses wrong) onto the screen using labels.
+def render_score _
+  if _.state.times_wrong == 0 # if the user has guessed wrong zero times, the score is par
+    _.outputs.labels << [_.grid.w_half, _.grid.top.shift_down(80), "Score: PAR", 0, 1, 0, 0, 0]
+  else # otherwise, number of times the user has guessed wrong is shown
+    _.outputs.labels << [_.grid.w_half, _.grid.top.shift_down(80), "Score: +#{_.state.times_wrong}", 0, 1, 0, 0, 0] # shows score using string interpolation
+  end
+end
+
+# Sets the target note for the level and performs calculations on click_feedbacks.
+def calc _
+  _.state.target_note ||= available_notes.sample # chooses a note from available_notes collection as target note
+  _.state.click_feedbacks.each    { |c| c.solid[-1] -= 5 } # remove this line and solid color will remain on screen indefinitely
+  # comment this line out and the solid color will keep flashing on screen instead of being removed from click_feedbacks collection
+  _.state.click_feedbacks.reject! { |c| c.solid[-1] <= 0 }
+end
+
+# Uses input from the user to play the target note, as well as the other notes that could be a potential match.
+def input_mouse _
+  return unless _.inputs.mouse.click # return unless the mouse is clicked
+
+  # finds button that was clicked by user
+  button_clicked = _.outputs.borders.find_all do |b| # go through borders collection to find all borders that meet requirements
+    _.inputs.mouse.click.point.inside_rect? b # find button border that mouse was clicked inside of
+  end.reject {|b| !_.state.meta(b)}.first # reject, return first element
+
+  return unless button_clicked # return unless button_clicked as a value (a button was clicked)
+
+  queue_click_feedback _, # calls queue_click_feedback method on the button that was clicked
+                       button_clicked.x,
+                       button_clicked.y,
+                       button_clicked.w,
+                       button_clicked.h,
+                       150, 100, 200 # sets color of button to shade of purple
+
+  if _.state.meta(button_clicked) == 'play' # if "play note" button is pressed
+    _.outputs.sounds << "sounds/#{_.state.target_note}.wav" # sound of target note is output
+  elsif _.state.meta(button_clicked) == 'again' # if "play game again" button is pressed
+    _.state.target_note = nil # no target note
+    _.state.current_level = 1 # starts at level 1 again
+    _.state.times_wrong = 0 # starts off with 0 wrong guesses
+    _.state.game_over = false # the game is not over (because it has just been restarted)
+  else # otherwise if neither of those buttons were pressed
+    _.outputs.sounds << "sounds/#{_.state.meta(button_clicked)}.wav" # sound of clicked note is played
+    if _.state.meta(button_clicked).to_sym == _.state.target_note # if clicked note is target note
+      _.state.target_note = nil # target note is emptied
+
+      if _.state.current_level < 9 # if game hasn't reached level 9
+        _.state.current_level += 1 # game goes to next level
+      else # otherwise, if game has reached level 9
+        _.state.game_over = true # the game is over
+      end
+
+      queue_click_feedback _, 0, 0, _.grid.w, _.grid.h, 100, 200, 100 # green shown if user guesses correctly
+    else # otherwise, if clicked note is not target note
+      _.state.times_wrong += 1 # increments times user guessed wrong
+      queue_click_feedback _, 0, 0, _.grid.w, _.grid.h, 200, 100, 100 # red shown is user guesses wrong
+    end
+  end
+end
+
+# Creates a collection of all of the available notes as symbols
+def available_notes
+  [:C3, :D3, :E3, :F3, :G3, :A3, :B3, :C4]
+end
+
+# Creates buttons for each note, and sets a label (the note's name) and border for each note's button.
+def piano_button _, note, position
+  _.state.new_entity(:button) do |b| # declares button as new entity
+    b.label  =  [460 + 40.mult(position), _.grid.h * 0.4, "#{note}", 0, 1, 0, 0, 0] # label definition
+    b.border =  _.state.with_meta([460 + 40.mult(position) - 20, _.grid.h * 0.4 - 32, 40, 40], note) # border definition, text/title; 20 subtracted so label is in center of border
+  end
+end
+
+# Color of click feedback changes depending on what button was clicked, and whether the guess is right or wrong
+# If a button is clicked, the inside of button is purple (see input_mouse method)
+# If correct note is clicked, screen turns green
+# If incorrect note is clicked, screen turns red (again, see input_mouse method)
+def queue_click_feedback _, x, y, w, h, *color
+  _.state.click_feedbacks << _.state.new_entity(:click_feedback) do |c| # declares feedback as new entity
+    c.solid =  [x, y, w, h, *color, 255] # sets color
+  end
+end
+
+def tick_instructions args, text, y = 715
+  return if args.state.key_event_occurred
+  if args.inputs.mouse.click ||
+     args.inputs.keyboard.directional_vector ||
+     args.inputs.keyboard.key_down.enter ||
+     args.inputs.keyboard.key_down.escape
+    args.state.key_event_occurred = true
+  end
+
+  args.outputs.debug << [0, y - 50, 1280, 60].solid
+  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
+  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
+end
+
+</pre>
+<h1 id='--02_input_basics/01_keyboard/app/main.rb'>02_input_basics/01_keyboard/app/main.rb</h1>
+<pre>=begin
+
+APIs listing that haven't been encountered in a previous sample apps:
+
+- args.inputs.keyboard.key_up.KEY: The value of the properties will be set
+  to the frame  that the key_up event occurred (the frame correlates
+  to args.state.tick_count). Otherwise the value will be nil. For a
+  full listing of keys, take a look at mygame/documentation/06-keyboard.md.
+- args.state.PROPERTY: The state property on args is a dynamic
+  structure. You can define ANY property here with ANY type of
+  arbitrary nesting. Properties defined on args.state will be retained
+  across frames. If you attempt access a property that doesn't exist
+  on args.state, it will simply return nil (no exception will be thrown).
+
+=end
+
+# Along with outputs, inputs are also an essential part of video game development
+# DragonRuby can take input from keyboards, mouse, and controllers.
+# This sample app will cover keyboard input.
+
+# args.inputs.keyboard.key_up.a will check to see if the a key has been pressed
+# This will work with the other keys as well
+
+
+def tick args
+  tick_instructions args, "Sample app shows how keyboard events are registered and accessed.", 360
+  # Notice how small_font accounts for all the remaining parameters
+  args.outputs.labels << [460, row_to_px(args, 0), "Current game time: #{args.state.tick_count}", small_font]
+  args.outputs.labels << [460, row_to_px(args, 2), "Keyboard input: args.inputs.keyboard.key_up.h", small_font]
+  args.outputs.labels << [460, row_to_px(args, 3), "Press \"h\" on the keyboard.", small_font]
+
+  # Input on a specifc key can be found through args.inputs.keyboard.key_up followed by the key
+  if args.inputs.keyboard.key_up.h
+    args.state.h_pressed_at = args.state.tick_count
+  end
+
+  # This code simplifies to if args.state.h_pressed_at has not been initialized, set it to false
+  args.state.h_pressed_at ||= false
+
+  if args.state.h_pressed_at
+    args.outputs.labels << [460, row_to_px(args, 4), "\"h\" was pressed at time: #{args.state.h_pressed_at}", small_font]
+  else
+    args.outputs.labels << [460, row_to_px(args, 4), "\"h\" has never been pressed.", small_font]
+  end
+
+  tick_help_text args
+end
+
+def small_font
+  # This method provides some values for the construction of labels
+  # Specifically, Size, Alignment, & RGBA
+  # This makes it so that custom parameters don't have to be repeatedly typed.
+  # Additionally "small_font" provides programmers with more information than some numbers
+  [-2, 0, 0, 0, 0, 255]
+end
+
+def row_to_px args, row_number
+  # This takes a row_number and converts it to pixels DragonRuby understands.
+  # Row 0 starts 5 units below the top of the grid
+  # Each row afterward is 20 units lower
+  args.grid.top.shift_down(5).shift_down(20 * row_number)
+end
+
+# Don't worry about understanding the code within this method just yet.
+# This method shows you the help text within the game.
+def tick_help_text args
+  return unless args.state.h_pressed_at
+
+  args.state.key_value_history      ||= {}
+  args.state.key_down_value_history ||= {}
+  args.state.key_held_value_history ||= {}
+  args.state.key_up_value_history   ||= {}
+
+  if (args.inputs.keyboard.key_down.truthy_keys.length > 0 ||
+      args.inputs.keyboard.key_held.truthy_keys.length > 0 ||
+      args.inputs.keyboard.key_up.truthy_keys.length > 0)
+    args.state.help_available = true
+    args.state.no_activity_debounce = nil
+  else
+    args.state.no_activity_debounce ||= 5.seconds
+    args.state.no_activity_debounce -= 1
+    if args.state.no_activity_debounce <= 0
+      args.state.help_available = false
+      args.state.key_value_history        = {}
+      args.state.key_down_value_history   = {}
+      args.state.key_held_value_history   = {}
+      args.state.key_up_value_history     = {}
+    end
+  end
+
+  args.outputs.labels << [10, row_to_px(args, 6), "Advanced Help:", small_font]
+
+  if !args.state.help_available
+    args.outputs.labels << [10, row_to_px(args, 7),  "Press a key and I'll show code to access the key and what value will be returned if you used the code.", small_font]
+    return
+  end
+
+  args.outputs.labels << [10 , row_to_px(args, 7), "args.inputs.keyboard", small_font]
+  args.outputs.labels << [330, row_to_px(args, 7), "args.inputs.keyboard.key_down", small_font]
+  args.outputs.labels << [650, row_to_px(args, 7), "args.inputs.keyboard.key_held", small_font]
+  args.outputs.labels << [990, row_to_px(args, 7), "args.inputs.keyboard.key_up", small_font]
+
+  fill_history args, :key_value_history,      :down_or_held, nil
+  fill_history args, :key_down_value_history, :down,        :key_down
+  fill_history args, :key_held_value_history, :held,        :key_held
+  fill_history args, :key_up_value_history,   :up,          :key_up
+
+  render_help_labels args, :key_value_history,      :down_or_held, nil,      10
+  render_help_labels args, :key_down_value_history, :down,        :key_down, 330
+  render_help_labels args, :key_held_value_history, :held,        :key_held, 650
+  render_help_labels args, :key_up_value_history,   :up,          :key_up,   990
+end
+
+def fill_history args, history_key, state_key, keyboard_method
+  fill_single_history args, history_key, state_key, keyboard_method, :raw_key
+  fill_single_history args, history_key, state_key, keyboard_method, :char
+  args.inputs.keyboard.keys[state_key].each do |key_name|
+    fill_single_history args, history_key, state_key, keyboard_method, key_name
+  end
+end
+
+def fill_single_history args, history_key, state_key, keyboard_method, key_name
+  current_value = args.inputs.keyboard.send(key_name)
+  if keyboard_method
+    current_value = args.inputs.keyboard.send(keyboard_method).send(key_name)
+  end
+  args.state.as_hash[history_key][key_name] ||= []
+  args.state.as_hash[history_key][key_name] << current_value
+  args.state.as_hash[history_key][key_name] = args.state.as_hash[history_key][key_name].reverse.uniq.take(3).reverse
+end
+
+def render_help_labels args, history_key, state_key, keyboard_method, x
+  idx = 8
+  args.outputs.labels << args.state
+                           .as_hash[history_key]
+                           .keys
+                           .reverse
+                           .map
+                           .with_index do |k, i|
+    v = args.state.as_hash[history_key][k]
+    current_value = args.inputs.keyboard.send(k)
+    if keyboard_method
+      current_value = args.inputs.keyboard.send(keyboard_method).send(k)
+    end
+    idx += 2
+    [
+      [x, row_to_px(args, idx - 2),
+       "    .#{k} is #{current_value || "nil"}",
+       small_font],
+      [x, row_to_px(args, idx - 1),
+       "       was #{v}",
+       small_font]
+    ]
+  end
+end
+
+
+def tick_instructions args, text, y = 715
+  return if args.state.key_event_occurred
+  if args.inputs.mouse.click ||
+     args.inputs.keyboard.directional_vector ||
+     args.inputs.keyboard.key_down.enter ||
+     args.inputs.keyboard.key_down.escape
+    args.state.key_event_occurred = true
+  end
+
+  args.outputs.debug << [0, y - 50, 1280, 60].solid
+  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
+  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
+end
+
+</pre>
+<h1 id='--02_input_basics/02_mouse/app/main.rb'>02_input_basics/02_mouse/app/main.rb</h1>
+<pre>=begin
+
+APIs that haven't been encountered in a previous sample apps:
+
+- args.inputs.mouse.click: This property will be set if the mouse was clicked.
+- args.inputs.mouse.click.point.(x|y): The x and y location of the mouse.
+- args.inputs.mouse.click.point.created_at: The frame the mouse click occurred in.
+- args.inputs.mouse.click.point.created_at_elapsed: How many frames have passed
+  since the click event.
+
+Reminder:
+
+- args.state.PROPERTY: The state property on args is a dynamic
+  structure. You can define ANY property here with ANY type of
+  arbitrary nesting. Properties defined on args.state will be retained
+  across frames. If you attempt access a property that doesn't exist
+  on args.state, it will simply return nil (no exception will be thrown).
+
+=end
+
+# This code demonstrates DragonRuby mouse input
+
+# To see if the a mouse click occurred
+# Use args.inputs.mouse.click
+# Which returns a boolean
+
+# To see where a mouse click occurred
+# Use args.inputs.mouse.click.point.x AND
+# args.inputs.mouse.click.point.y
+
+# To see which frame the click occurred
+# Use args.inputs.mouse.click.created_at
+
+# To see how many frames its been since the click occurred
+# Use args.inputs.mouse.click.creat_at_elapsed
+
+# Saving the click in args.state can be quite useful
+
+def tick args
+  tick_instructions args, "Sample app shows how mouse events are registered and how to measure elapsed time."
+  x = 460
+
+  args.outputs.labels << small_label(args, x, 11, "Mouse input: args.inputs.mouse")
+
+  if args.inputs.mouse.click
+    args.state.last_mouse_click = args.inputs.mouse.click
+  end
+
+  if args.state.last_mouse_click
+    click = args.state.last_mouse_click
+    args.outputs.labels << small_label(args, x, 12, "Mouse click happened at: #{click.created_at}")
+    args.outputs.labels << small_label(args, x, 13, "Mouse clicked #{click.created_at_elapsed} ticks ago")
+    args.outputs.labels << small_label(args, x, 14, "Mouse click location: #{click.point.x}, #{click.point.y}")
+  else
+    args.outputs.labels << small_label(args, x, 12, "Mouse click has not occurred yet.")
+    args.outputs.labels << small_label(args, x, 13, "Please click mouse.")
+  end
+end
+
+def small_label args, x, row, message
+  # This method effectively combines the row_to_px and small_font methods
+  # It changes the given row value to a DragonRuby pixel value
+  # and adds the customization parameters
+  [x, row_to_px(args, row), message, small_font]
+end
+
+def small_font
+  [-2, 0, 0, 0, 0, 255]
+end
+
+def row_to_px args, row_number
+  args.grid.top.shift_down(5).shift_down(20 * row_number)
+end
+
+def tick_instructions args, text, y = 715
+  return if args.state.key_event_occurred
+  if args.inputs.mouse.click ||
+     args.inputs.keyboard.directional_vector ||
+     args.inputs.keyboard.key_down.enter ||
+     args.inputs.keyboard.key_down.escape
+    args.state.key_event_occurred = true
+  end
+
+  args.outputs.debug << [0, y - 50, 1280, 60].solid
+  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
+  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
+end
+
+</pre>
+<h1 id='--02_input_basics/03_mouse_point_to_rect/app/main.rb'>02_input_basics/03_mouse_point_to_rect/app/main.rb</h1>
+<pre>=begin
+
+APIs that haven't been encountered in a previous sample apps:
+
+- args.outputus.borders: An array. Values in this array will be rendered as
+  unfilled rectangles on the screen.
+- ARRAY#inside_rect?: An array with at least two values is considered a point. An array
+  with at least four values is considered a rect. The inside_rect? function returns true
+  or false depending on if the point is inside the rect.
+
+  ```
+  # Point:  x: 100, y: 100
+  # Rect:   x: 0, y: 0, w: 500, h: 500
+  # Result: true
+
+  [100, 100].inside_rect? [0, 0, 500, 500]
+  ```
+
+  ```
+  # Point:  x: 100, y: 100
+  # Rect:   x: 300, y: 300, w: 100, h: 100
+  # Result: false
+
+  [100, 100].inside_rect? [300, 300, 100, 100]
+  ```
+
+- args.inputs.mouse.click.point.created_at: The frame the mouse click occurred in.
+- args.inputs.mouse.click.point.created_at_elapsed: How many frames have passed
+  since the click event.
+
+=end
+
+# To determine whether a point is in a rect
+# Use point.inside_rect? rect
+
+# This is useful to determine if a click occurred in a rect
+
+def tick args
+  tick_instructions args, "Sample app shows how to determing if a click happened inside a rectangle."
+
+  x = 460
+
+  args.outputs.labels << small_label(args, x, 15, "Click inside the blue box maybe ---->")
+
+  box = [785, 370, 50, 50, 0, 0, 170]
+  args.outputs.borders << box
+
+  # Saves the most recent click into args.state
+  # Unlike the other components of args,
+  # args.state does not reset every tick.
+  if args.inputs.mouse.click
+    args.state.last_mouse_click = args.inputs.mouse.click
+  end
+
+  if args.state.last_mouse_click
+    if args.state.last_mouse_click.point.inside_rect? box
+      args.outputs.labels << small_label(args, x, 16, "Mouse click happened *inside* the box.")
+    else
+      args.outputs.labels << small_label(args, x, 16, "Mouse click happened *outside* the box.")
+    end
+  else
+    args.outputs.labels << small_label(args, x, 16, "Mouse click has not occurred yet.")
+  end
+end
+
+def small_label args, x, row, message
+  [x, row_to_px(args, row), message, small_font]
+end
+
+def small_font
+  [-2, 0, 0, 0, 0, 255]
+end
+
+def row_to_px args, row_number
+  args.grid.top.shift_down(5).shift_down(20 * row_number)
+end
+
+def tick_instructions args, text, y = 715
+  return if args.state.key_event_occurred
+  if args.inputs.mouse.click ||
+     args.inputs.keyboard.directional_vector ||
+     args.inputs.keyboard.key_down.enter ||
+     args.inputs.keyboard.key_down.escape
+    args.state.key_event_occurred = true
+  end
+
+  args.outputs.debug << [0, y - 50, 1280, 60].solid
+  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
+  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
+end
+
+</pre>
+<h1 id='--02_input_basics/04_mouse_rect_to_rect/app/main.rb'>02_input_basics/04_mouse_rect_to_rect/app/main.rb</h1>
+<pre>=begin
+
+APIs that haven't been encountered in a previous sample apps:
+
+- args.outputs.borders: An array. Values in this array will be rendered as
+  unfilled rectangles on the screen.
+- ARRAY#intersect_rect?: An array with at least four values is
+  considered a rect. The intersect_rect? function returns true
+  or false depending on if the two rectangles intersect.
+
+  ```
+  # Rect One: x: 100, y: 100, w: 100, h: 100
+  # Rect Two: x: 0, y: 0, w: 500, h: 500
+  # Result:   true
+
+  [100, 100, 100, 100].intersect_rect? [0, 0, 500, 500]
+  ```
+
+  ```
+  # Rect One: x: 100, y: 100, w: 10, h: 10
+  # Rect Two: x: 500, y: 500, w: 10, h: 10
+  # Result:   false
+
+  [100, 100, 10, 10].intersect_rect? [500, 500, 10, 10]
+  ```
+
+=end
+
+# Similarly, whether rects intersect can be found through
+# rect1.intersect_rect? rect2
+
+def tick args
+  tick_instructions args, "Sample app shows how to determine if two rectangles intersect."
+  x = 460
+
+  args.outputs.labels << small_label(args, x, 3, "Click anywhere on the screen")
+  # red_box = [460, 250, 355, 90, 170, 0, 0]
+  # args.outputs.borders << red_box
+
+  # args.state.box_collision_one and args.state.box_collision_two
+  # Are given values of a solid when they should be rendered
+  # They are stored in game so that they do not get reset every tick
+  if args.inputs.mouse.click
+    if !args.state.box_collision_one
+      args.state.box_collision_one = [args.inputs.mouse.click.point.x - 25, args.inputs.mouse.click.point.y - 25, 125, 125, 180, 0,   0, 180]
+    elsif !args.state.box_collision_two
+      args.state.box_collision_two = [args.inputs.mouse.click.point.x - 25, args.inputs.mouse.click.point.y - 25, 125, 125,   0, 0, 180, 180]
+    else
+      args.state.box_collision_one = nil
+      args.state.box_collision_two = nil
+    end
+  end
+
+  if args.state.box_collision_one
+    args.outputs.solids << args.state.box_collision_one
+  end
+
+  if args.state.box_collision_two
+    args.outputs.solids << args.state.box_collision_two
+  end
+
+  if args.state.box_collision_one && args.state.box_collision_two
+    if args.state.box_collision_one.intersect_rect? args.state.box_collision_two
+      args.outputs.labels << small_label(args, x, 4, 'The boxes intersect.')
+    else
+      args.outputs.labels << small_label(args, x, 4, 'The boxes do not intersect.')
+    end
+  else
+    args.outputs.labels << small_label(args, x, 4, '--')
+  end
+end
+
+def small_label args, x, row, message
+  [x, row_to_px(args, row), message, small_font]
+end
+
+def small_font
+  [-2, 0, 0, 0, 0, 255]
+end
+
+def row_to_px args, row_number
+  args.grid.top.shift_down(5).shift_down(20 * row_number)
+end
+
+def tick_instructions args, text, y = 715
+  return if args.state.key_event_occurred
+  if args.inputs.mouse.click ||
+     args.inputs.keyboard.directional_vector ||
+     args.inputs.keyboard.key_down.enter ||
+     args.inputs.keyboard.key_down.escape
+    args.state.key_event_occurred = true
+  end
+
+  args.outputs.debug << [0, y - 50, 1280, 60].solid
+  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
+  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
+end
+
+</pre>
+<h1 id='--02_input_basics/05_controller/app/main.rb'>02_input_basics/05_controller/app/main.rb</h1>
+<pre>=begin
+
+ APIs listing that haven't been encountered in previous sample apps:
+
+ - args.inputs.controller_one.key_held.KEY: Will check to see if a specific key
+   is being held down on the controller.
+   If there is more than one controller being used, they can be differentiated by
+   using names like controller_one and controller_two.
+
+   For a full listing of buttons, take a look at mygame/documentation/08-controllers.md.
+
+ Reminder:
+
+ - args.state.PROPERTY: The state property on args is a dynamic
+   structure. You can define ANY property here with ANY type of
+   arbitrary nesting. Properties defined on args.state will be retained
+   across frames. If you attempt to access a property that doesn't exist
+   on args.state, it will simply return nil (no exception will be thrown).
+
+   In this sample app, args.state.BUTTONS is an array that stores the buttons of the controller.
+   The parameters of a button are:
+   1. the position (x, y)
+   2. the input key held on the controller
+   3. the text or name of the button
+
+=end
+
+# This sample app provides a visual demonstration of a standard controller, including
+# the placement and function of all buttons.
+
+class ControllerDemo
+  attr_accessor :inputs, :state, :outputs
+
+  # Calls the methods necessary for the app to run successfully.
+  def tick
+    process_inputs
+    render
+  end
+
+  # Starts with an empty collection of buttons.
+  # Adds buttons that are on the controller to the collection.
+  def process_inputs
+    state.buttons = []
+
+    state.buttons << [100, 500, inputs.controller_one.key_held.l1, "L1"]
+    state.buttons << [100, 600, inputs.controller_one.key_held.l2, "L2"]
+
+    state.buttons << [1100, 500, inputs.controller_one.key_held.r1, "R1"]
+    state.buttons << [1100, 600, inputs.controller_one.key_held.r2, "R2"]
+
+    state.buttons << [540, 450, inputs.controller_one.key_held.select, "Select"]
+    state.buttons << [660, 450, inputs.controller_one.key_held.start, "Start"]
+
+    state.buttons << [200, 300, inputs.controller_one.key_held.left, "Left"]
+    state.buttons << [300, 400, inputs.controller_one.key_held.up, "Up"]
+    state.buttons << [400, 300, inputs.controller_one.key_held.right, "Right"]
+    state.buttons << [300, 200, inputs.controller_one.key_held.down, "Down"]
+
+    state.buttons << [800, 300, inputs.controller_one.key_held.x, "X"]
+    state.buttons << [900, 400, inputs.controller_one.key_held.y, "Y"]
+    state.buttons << [1000, 300, inputs.controller_one.key_held.a, "A"]
+    state.buttons << [900, 200, inputs.controller_one.key_held.b, "B"]
+
+    state.buttons << [450 + inputs.controller_one.left_analog_x_perc * 100,
+                      100 + inputs.controller_one.left_analog_y_perc * 100,
+                      inputs.controller_one.key_held.l3,
+                      "L3"]
+
+    state.buttons << [750 + inputs.controller_one.right_analog_x_perc * 100,
+                      100 + inputs.controller_one.right_analog_y_perc * 100,
+                      inputs.controller_one.key_held.r3,
+                      "R3"]
+  end
+
+  # Gives each button a square shape.
+  # If the button is being pressed or held (which means it is considered active),
+  # the square is filled in. Otherwise, the button simply has a border.
+  def render
+    state.buttons.each do |x, y, active, text|
+      rect = [x, y, 75, 75]
+
+      if active # if button is pressed
+        outputs.solids << rect # rect is output as solid (filled in)
+      else
+        outputs.borders << rect # otherwise, output as border
+      end
+
+      # Outputs the text of each button using labels.
+      outputs.labels << [x, y + 95, text] # add 95 to place label above button
+    end
+
+    outputs.labels << [10, 60, "Left Analog x: #{inputs.controller_one.left_analog_x_raw} (#{inputs.controller_one.left_analog_x_perc * 100}%)"]
+    outputs.labels << [10, 30, "Left Analog y: #{inputs.controller_one.left_analog_y_raw} (#{inputs.controller_one.left_analog_y_perc * 100}%)"]
+    outputs.labels << [900, 60, "Right Analog x: #{inputs.controller_one.right_analog_x_raw} (#{inputs.controller_one.right_analog_x_perc * 100}%)"]
+    outputs.labels << [900, 30, "Right Analog y: #{inputs.controller_one.right_analog_y_raw} (#{inputs.controller_one.right_analog_y_perc * 100}%)"]
+  end
+end
+
+$controller_demo = ControllerDemo.new
+
+def tick args
+  tick_instructions args, "Sample app shows how controller input is handled. You'll need to connect a USB controller."
+  $controller_demo.inputs = args.inputs
+  $controller_demo.state = args.state
+  $controller_demo.outputs = args.outputs
+  $controller_demo.tick
+end
+
+# Resets the app.
+def r
+  $gtk.reset
+end
+
+def tick_instructions args, text, y = 715
+  return if args.state.key_event_occurred
+  if args.inputs.mouse.click ||
+     args.inputs.keyboard.directional_vector ||
+     args.inputs.keyboard.key_down.enter ||
+     args.inputs.keyboard.key_down.escape
+    args.state.key_event_occurred = true
+  end
+
+  args.outputs.debug << [0, y - 50, 1280, 60].solid
+  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
+  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
+end
+
+</pre>
+<h1 id='--03_rendering_sprites/01_animation_using_seperate_pngs/app/main.rb'>03_rendering_sprites/01_animation_using_seperate_pngs/app/main.rb</h1>
+<pre>=begin
+
+ Reminders:
+
+ - String interpolation: Uses #{} syntax; everything between the #{ and the } is evaluated
+   as Ruby code, and the placeholder is replaced with its corresponding value or result.
+
+   In this sample app, we're using string interpolation to iterate through images in the
+   sprites folder using their image path names.
+
+ - args.outputs.sprites: An array. Values in this array generate sprites on the screen.
+   The parameters are [X, Y, WIDTH, HEIGHT, IMAGE PATH]
+   For more information about sprites, go to mygame/documentation/05-sprites.md.
+
+ - args.outputs.labels: An array. Values in the array generate labels on the screen.
+   The parameters are [X, Y, TEXT, SIZE, ALIGNMENT, RED, GREEN, BLUE, ALPHA, FONT STYLE]
+   For more information about labels, go to mygame/documentation/02-labels.md.
+
+ - args.inputs.keyboard.key_down.KEY: Determines if a key is in the down state, or pressed.
+   Stores the frame that key was pressed on.
+   For more information about the keyboard, go to mygame/documentation/06-keyboard.md.
+
+=end
+
+# This sample app demonstrates how sprite animations work.
+# There are two sprites that animate forever and one sprite
+# that *only* animates when you press the "f" key on the keyboard.
+
+# This is the entry point to your game. The `tick` method
+# executes at 60 frames per second. There are two methods
+# in this tick "entry point": `looping_animation`, and the
+# second method is `one_time_animation`.
+def tick args
+  looping_animation args
+  one_time_animation args
+end
+
+# This function shows how to animate a sprite that loops forever.
+def looping_animation args
+  # Here we define a few local variables that will be sent
+  # into the magic function that gives us the correct sprite image
+  # over time. There are four things we need in order to figure
+  # out which sprite to show.
+
+  # 1. When to start the animation.
+  start_looping_at = 0
+
+  # 2. The number of pngs that represent the full animation.
+  number_of_sprites = 6
+
+  # 3. How long to show each png.
+  number_of_frames_to_show_each_sprite = 4
+
+  # 4. Whether the animation should loop once, or forever.
+  does_sprite_loop = true
+
+  # With the variables defined above, we can get a number
+  # which represents the sprite to show by calling the `frame_index` function.
+  # In this case the number will be between 0, and 5 (you can see the sprites
+  # in the ./sprites directory).
+  sprite_index = start_looping_at.frame_index number_of_sprites,
+                                              number_of_frames_to_show_each_sprite,
+                                              does_sprite_loop
+
+  # Now that we have `sprite_index, we can present the correct file.
+  args.outputs.sprites << [100, 100, 100, 100, "sprites/dragon_fly_#{sprite_index}.png"]
+
+  # Try changing the numbers below to see how the animation changes:
+  args.outputs.sprites << [100, 200, 100, 100, "sprites/dragon_fly_#{0.frame_index 6, 4, true}.png"]
+end
+
+# This function shows how to animate a sprite that executes
+# only once when the "f" key is pressed.
+def one_time_animation args
+  # This is just a label the shows instructions within the game.
+  args.outputs.labels << [220, 350, "(press f to animate)"]
+
+  # If "f" is pressed on the keyboard...
+  if args.inputs.keyboard.key_down.f
+    # Print the frame that "f" was pressed on.
+    puts "Hello from main.rb! The \"f\" key was in the down state on frame: #{args.inputs.keyboard.key_down.f}"
+
+    # And MOST IMPORTANTLY set the point it time to start the animation,
+    # equal to "now" which is represented as args.state.tick_count.
+
+    # Also IMPORTANT, you'll notice that the value of when to start looping
+    # is stored in `args.state`. This construct's values are retained across
+    # executions of the `tick` method.
+    args.state.start_looping_at = args.state.tick_count
+  end
+
+  # These are the same local variables that were defined
+  # for the `looping_animation` function.
+  number_of_sprites = 6
+  number_of_frames_to_show_each_sprite = 4
+
+  # Except this sprite does not loop again. If the animation time has passed,
+  # then the frame_index function returns nil.
+  does_sprite_loop = false
+
+  sprite_index = args.state
+                     .start_looping_at
+                     .frame_index number_of_sprites,
+                                  number_of_frames_to_show_each_sprite,
+                                  does_sprite_loop
+
+  # This line sets the frame index to zero, if
+  # the animation duration has passed (frame_index returned nil).
+
+  # Remeber: we are not looping forever here.
+  sprite_index ||= 0
+
+  # Present the sprite.
+  args.outputs.sprites << [100, 300, 100, 100, "sprites/dragon_fly_#{sprite_index}.png"]
+
+  tick_instructions args, "Sample app shows how to use Numeric#frame_index and string interpolation to animate a sprite over time."
+end
+
+def tick_instructions args, text, y = 715
+  return if args.state.key_event_occurred
+  if args.inputs.mouse.click ||
+     args.inputs.keyboard.directional_vector ||
+     args.inputs.keyboard.key_down.enter ||
+     args.inputs.keyboard.key_down.escape
+    args.state.key_event_occurred = true
+  end
+
+  args.outputs.debug << [0, y - 50, 1280, 60].solid
+  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
+  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
+end
+
+</pre>
+<h1 id='--03_rendering_sprites/02_animation_using_sprite_sheet/app/main.rb'>03_rendering_sprites/02_animation_using_sprite_sheet/app/main.rb</h1>
+<pre>def tick args
+  args.state.player.x ||= 100
+  args.state.player.y ||= 100
+  args.state.player.w ||= 64
+  args.state.player.h ||= 64
+  args.state.player.direction ||= 1
+
+  args.state.player.is_moving = false
+
+  # get the keyboard input and set player properties
+  if args.inputs.keyboard.right
+    args.state.player.x += 3
+    args.state.player.direction = 1
+    args.state.player.started_running_at ||= args.state.tick_count
+  elsif args.inputs.keyboard.left
+    args.state.player.x -= 3
+    args.state.player.direction = -1
+    args.state.player.started_running_at ||= args.state.tick_count
+  end
+
+  if args.inputs.keyboard.up
+    args.state.player.y += 1
+    args.state.player.started_running_at ||= args.state.tick_count
+  elsif args.inputs.keyboard.down
+    args.state.player.y -= 1
+    args.state.player.started_running_at ||= args.state.tick_count
+  end
+
+  # if no arrow keys are being pressed, set the player as not moving
+  if !args.inputs.keyboard.directional_vector
+    args.state.player.started_running_at = nil
+  end
+
+  # wrap player around the stage
+  if args.state.player.x > 1280
+    args.state.player.x = -64
+    args.state.player.started_running_at ||= args.state.tick_count
+  elsif args.state.player.x < -64
+    args.state.player.x = 1280
+    args.state.player.started_running_at ||= args.state.tick_count
+  end
+
+  if args.state.player.y > 720
+    args.state.player.y = -64
+    args.state.player.started_running_at ||= args.state.tick_count
+  elsif args.state.player.y < -64
+    args.state.player.y = 720
+    args.state.player.started_running_at ||= args.state.tick_count
+  end
+
+  # render player as standing or running
+  if args.state.player.started_running_at
+    args.outputs.sprites << running_sprite(args)
+  else
+    args.outputs.sprites << standing_sprite(args)
+  end
+  args.outputs.labels << [30, 700, "Use arrow keys to move around."]
+end
+
+def standing_sprite args
+  {
+    x: args.state.player.x,
+    y: args.state.player.y,
+    w: args.state.player.w,
+    h: args.state.player.h,
+    path: "sprites/horizontal-stand.png",
+    flip_horizontally: args.state.player.direction > 0
+  }
+end
+
+def running_sprite args
+  if !args.state.player.started_running_at
+    tile_index = 0
+  else
+    how_many_frames_in_sprite_sheet = 6
+    how_many_ticks_to_hold_each_frame = 3
+    should_the_index_repeat = true
+    tile_index = args.state
+                     .player
+                     .started_running_at
+                     .frame_index(how_many_frames_in_sprite_sheet,
+                                  how_many_ticks_to_hold_each_frame,
+                                  should_the_index_repeat)
+  end
+
+  {
+    x: args.state.player.x,
+    y: args.state.player.y,
+    w: args.state.player.w,
+    h: args.state.player.h,
+    path: 'sprites/horizontal-run.png',
+    tile_x: 0 + (tile_index * args.state.player.w),
+    tile_y: 0,
+    tile_w: args.state.player.w,
+    tile_h: args.state.player.h,
+    flip_horizontally: args.state.player.direction > 0,
+  }
+end
+
+</pre>
+<h1 id='--03_rendering_sprites/03_animation_states/app/main.rb'>03_rendering_sprites/03_animation_states/app/main.rb</h1>
+<pre>class Game
+  attr_gtk
+
+  def defaults
+    state.show_debug_layer  = true if state.tick_count == 0
+    player.tile_size        = 64
+    player.speed            = 3
+    player.slash_frames     = 15
+    player.x              ||= 50
+    player.y              ||= 400
+    player.dir_x          ||=  1
+    player.dir_y          ||= -1
+    player.is_moving      ||= false
+    state.watch_list      ||= {}
+    state.enemies         ||= []
+  end
+
+  def add_enemy
+    state.enemies << { x: 1200 * rand, y: 600 * rand, w: 64, h: 64 }
+  end
+
+  def sprite_horizontal_run
+    tile_index = 0.frame_index(6, 3, true)
+    tile_index = 0 if !player.is_moving
+
+    {
+      x: player.x,
+      y: player.y,
+      w: player.tile_size,
+      h: player.tile_size,
+      path: 'sprites/horizontal-run.png',
+      tile_x: 0 + (tile_index * player.tile_size),
+      tile_y: 0,
+      tile_w: player.tile_size,
+      tile_h: player.tile_size,
+      flip_horizontally: player.dir_x > 0,
+      # a: 40
+    }
+  end
+
+  def sprite_horizontal_stand
+    {
+      x: player.x,
+      y: player.y,
+      w: player.tile_size,
+      h: player.tile_size,
+      path: 'sprites/horizontal-stand.png',
+      flip_horizontally: player.dir_x > 0,
+      # a: 40
+    }
+  end
+
+  def sprite_horizontal_slash
+    tile_index   = player.slash_at.frame_index(5, player.slash_frames.idiv(5), false) || 0
+
+    {
+      x: player.x - 41.25,
+      y: player.y - 41.25,
+      w: 165,
+      h: 165,
+      path: 'sprites/horizontal-slash.png',
+      tile_x: 0 + (tile_index * 128),
+      tile_y: 0,
+      tile_w: 128,
+      tile_h: 128,
+      flip_horizontally: player.dir_x > 0
+    }
+  end
+
+  def render_player
+    if player.slash_at
+      outputs.sprites << sprite_horizontal_slash
+    elsif player.is_moving
+      outputs.sprites << sprite_horizontal_run
+    else
+      outputs.sprites << sprite_horizontal_stand
+    end
+  end
+
+  def render_enemies
+    outputs.borders << state.enemies
+  end
+
+  def render_debug_layer
+    return if !state.show_debug_layer
+    outputs.labels << state.watch_list.map.with_index do |(k, v), i|
+       [30, 710 - i * 28, "#{k}: #{v || "(nil)"}"]
+    end
+
+    outputs.borders << player.slash_collision_rect
+  end
+
+  def slash_initiate?
+    # buffalo usb controller has a button and b button swapped lol
+    inputs.controller_one.key_down.a || inputs.keyboard.key_down.j
+  end
+
+  def input
+    # player movement
+    if slash_complete? && (vector = inputs.directional_vector)
+      player.x += vector.x * player.speed
+      player.y += vector.y * player.speed
+    end
+    player.slash_at = slash_initiate? if slash_initiate?
+  end
+
+  def calc_movement
+    # movement
+    if vector = inputs.directional_vector
+      state.debug_label = vector
+      player.dir_x = vector.x
+      player.dir_y = vector.y
+      player.is_moving = true
+    else
+      state.debug_label = vector
+      player.is_moving = false
+    end
+  end
+
+  def calc_slash
+    # re-calc the location of the swords collision box
+    if player.dir_x.positive?
+      player.slash_collision_rect = [player.x + player.tile_size,
+                                     player.y + player.tile_size.half - 10,
+                                     40, 20]
+    else
+      player.slash_collision_rect = [player.x - 32 - 8,
+                                     player.y + player.tile_size.half - 10,
+                                     40, 20]
+    end
+
+    # recalc sword's slash state
+    player.slash_at = nil if slash_complete?
+
+    # determine collision if the sword is at it's point of damaging
+    return unless slash_can_damage?
+
+    state.enemies.reject! { |e| e.intersect_rect? player.slash_collision_rect }
+  end
+
+  def slash_complete?
+    !player.slash_at || player.slash_at.elapsed?(player.slash_frames)
+  end
+
+  def slash_can_damage?
+    # damage occurs half way into the slash animation
+    return false if slash_complete?
+    return false if (player.slash_at + player.slash_frames.idiv(2)) != state.tick_count
+    return true
+  end
+
+  def calc
+    # generate an enemy if there aren't any on the screen
+    add_enemy if state.enemies.length == 0
+    calc_movement
+    calc_slash
+  end
+
+  # source is at http://github.com/amirrajan/dragonruby-link-to-the-past
+  def tick
+    defaults
+    render_enemies
+    render_player
+    outputs.labels << [30, 30, "Gamepad: D-Pad to move. B button to attack."]
+    outputs.labels << [30, 52, "Keyboard: WASD/Arrow keys to move. J to attack."]
+    render_debug_layer
+    input
+    calc
+  end
+
+  def player
+    state.player
+  end
+end
+
+$game = Game.new
+
+def tick args
+  $game.args = args
+  $game.tick
+end
+
+$gtk.reset
+
+</pre>
+<h1 id='--03_rendering_sprites/04_color_and_rotation/app/main.rb'>03_rendering_sprites/04_color_and_rotation/app/main.rb</h1>
+<pre>=begin
+ APIs listing that haven't been encountered in previous sample apps:
+
+ - merge: Returns a hash containing the contents of two original hashes.
+   Merge does not allow duplicate keys, so the value of a repeated key
+   will be overwritten.
+
+   For example, if we had two hashes
+   h1 = { "a" => 1, "b" => 2}
+   h2 = { "b" => 3, "c" => 3}
+   and we called the command
+   h1.merge(h2)
+   the result would the following hash
+   { "a" => 1, "b" => 3, "c" => 3}.
+
+ Reminders:
+
+ - Hashes: Collection of unique keys and their corresponding values. The value can be found
+   using their keys.
+   In this sample app, we're using a hash to create a sprite.
+
+ - args.outputs.sprites: An array. The values generate a sprite.
+   The parameters are [X, Y, WIDTH, HEIGHT, PATH, ANGLE, ALPHA, RED, GREEN, BLUE]
+   Before continuing with this sample app, it is HIGHLY recommended that you look
+   at mygame/documentation/05-sprites.md.
+
+ - args.inputs.keyboard.key_held.KEY: Determines if a key is being pressed.
+   For more information about the keyboard, go to mygame/documentation/06-keyboard.md.
+
+ - args.inputs.controller_one: Takes input from the controller based on what key is pressed.
+   For more information about the controller, go to mygame/documentation/08-controllers.md.
+
+ - num1.lesser(num2): Finds the lower value of the given options.
+
+=end
+
+# This sample app shows a car moving across the screen. It loops back around if it exceeds the dimensions of the screen,
+# and also can be moved in different directions through keyboard input from the user.
+
+# Calls the methods necessary for the game to run successfully.
+def tick args
+  default args
+  render args.grid, args.outputs, args.state
+  calc args.state
+  process_inputs args
+end
+
+# Sets default values for the car sprite
+# Initialization ||= only happens in the first frame
+def default args
+  args.state.sprite.width    = 19
+  args.state.sprite.height   = 10
+  args.state.sprite.scale    = 4
+  args.state.max_speed       = 5
+  args.state.x             ||= 100
+  args.state.y             ||= 100
+  args.state.speed         ||= 1
+  args.state.angle         ||= 0
+end
+
+# Outputs sprite onto screen
+def render grid, outputs, state
+  outputs.solids  <<  [grid.rect, 70, 70, 70] # outputs gray background
+  outputs.sprites <<  [destination_rect(state), # sets first four parameters of car sprite
+  'sprites/86.png', # image path of car
+  state.angle,
+  opacity, # transparency
+  saturation,
+  source_rect(state), # sprite sub division/tile (tile x, y, w, h)
+  false, false,  # don't flip sprites
+  rotation_anchor]
+
+  # also look at the create_sprite helper method
+  #
+  # For example:
+  #
+  # dest   = destination_rect(state)
+  # source = source_rect(state),
+  # outputs.sprites << create_sprite(
+  #   'sprites/86.png',
+  #   x: dest.x,
+  #   y: dest.y,
+  #   w: dest.w,
+  #   h: dest.h,
+  #   angle: state.angle,
+  #   source_x: source.x,
+  #   source_y: source.y,
+  #   source_w: source.w,
+  #   source_h: source.h,
+  #   flip_h: false,
+  #   flip_v: false,
+  #   rotation_anchor_x: 0.7,
+  #   rotation_anchor_y: 0.5
+  # )
+end
+
+# Creates sprite by setting values inside of a hash
+def create_sprite path, options = {}
+  options = {
+
+    # dest x, y, w, h
+    x: 0,
+    y: 0,
+    w: 100,
+    h: 100,
+
+    # angle, rotation
+    angle: 0,
+    rotation_anchor_x: 0.5,
+    rotation_anchor_y: 0.5,
+
+    # color saturation (red, green, blue), transparency
+    r: 255,
+    g: 255,
+    b: 255,
+    a: 255,
+
+    # source x, y, width, height
+    source_x: 0,
+    source_y: 0,
+    source_w: -1,
+    source_h: -1,
+
+    # flip horiztonally, flip vertically
+    flip_h: false,
+    flip_v: false,
+
+  }.merge options
+
+  [
+    options[:x], options[:y], options[:w], options[:h], # dest rect keys
+    path,
+    options[:angle], options[:a], options[:r], options[:g], options[:b], # angle, color, alpha
+    options[:source_x], options[:source_y], options[:source_w], options[:source_h], # source rect keys
+    options[:flip_h], options[:flip_v], # flip
+    options[:rotation_anchor_x], options[:rotation_anchor_y], # rotation anchor
+  ] # hash keys contain corresponding values
+end
+
+# Calls the calc_pos and calc_wrap methods.
+def calc state
+  calc_pos state
+  calc_wrap state
+end
+
+# Changes sprite's position on screen
+# Vectors have magnitude and direction, so the incremented x and y values give the car direction
+def calc_pos state
+  state.x     += state.angle.vector_x * state.speed # increments x by product of angle's x vector and speed
+  state.y     += state.angle.vector_y * state.speed # increments y by product of angle's y vector and speed
+  state.speed *= 1.1 # scales speed up
+  state.speed  = state.speed.lesser(state.max_speed) # speed is either current speed or max speed, whichever has a lesser value (ensures that the car doesn't go too fast or exceed the max speed)
+end
+
+# The screen's dimensions are 1280x720. If the car goes out of scope,
+# it loops back around on the screen.
+def calc_wrap state
+
+  # car returns to left side of screen if it disappears on right side of screen
+  # sprite.width refers to tile's size, which is multipled by scale (4) to make it bigger
+  state.x = -state.sprite.width * state.sprite.scale if state.x - 20 > 1280
+
+  # car wraps around to right side of screen if it disappears on the left side
+  state.x = 1280 if state.x + state.sprite.width * state.sprite.scale + 20 < 0
+
+  # car wraps around to bottom of screen if it disappears at the top of the screen
+  # if you subtract 520 pixels instead of 20 pixels, the car takes longer to reappear (try it!)
+  state.y = 0    if state.y - 20 > 720 # if 20 pixels less than car's y position is greater than vertical scope
+
+  # car wraps around to top of screen if it disappears at the bottom of the screen
+  state.y = 720  if state.y + state.sprite.height * state.sprite.scale + 20 < 0
+end
+
+# Changes angle of sprite based on user input from keyboard or controller
+def process_inputs args
+
+  # NOTE: increasing the angle doesn't mean that the car will continue to go
+  # in a specific direction. The angle is increasing, which means that if the
+  # left key was kept in the "down" state, the change in the angle would cause
+  # the car to go in a counter-clockwise direction and form a circle (360 degrees)
+  if args.inputs.keyboard.key_held.left # if left key is pressed
+    args.state.angle += 2 # car's angle is incremented by 2
+
+  # The same applies to decreasing the angle. If the right key was kept in the
+  # "down" state, the decreasing angle would cause the car to go in a clockwise
+  # direction and form a circle (360 degrees)
+  elsif args.inputs.keyboard.key_held.right # if right key is pressed
+    args.state.angle -= 2 # car's angle is decremented by 2
+
+  # Input from a controller can also change the angle of the car
+  elsif args.inputs.controller_one.left_analog_x_perc != 0
+    args.state.angle += 2 * args.inputs.controller_one.left_analog_x_perc * -1
+  end
+end
+
+# A sprite's center of rotation can be altered
+# Increasing either of these numbers would dramatically increase the
+# car's drift when it turns!
+def rotation_anchor
+  [0.7, 0.5]
+end
+
+# Sets opacity value of sprite to 255 so that it is not transparent at all
+# Change it to 0 and you won't be able to see the car sprite on the screen
+def opacity
+  255
+end
+
+# Sets the color of the sprite to white.
+def saturation
+  [255, 255, 255]
+end
+
+# Sets definition of destination_rect (used to define the car sprite)
+def destination_rect state
+  [state.x, state.y,
+  state.sprite.width  * state.sprite.scale, # multiplies by 4 to set size
+  state.sprite.height * state.sprite.scale]
+end
+
+# Portion of a sprite (a tile)
+# Sub division of sprite is denoted as a rectangle directly related to original size of .png
+# Tile is located at bottom left corner within a 19x10 pixel rectangle (based on sprite.width, sprite.height)
+def source_rect state
+  [0, 0, state.sprite.width, state.sprite.height]
+end
+
+</pre>
+<h1 id='--04_physics_and_collisions/01_simple/app/main.rb'>04_physics_and_collisions/01_simple/app/main.rb</h1>
+<pre>=begin
+
+ Reminders:
+ - ARRAY#intersect_rect?: Returns true or false depending on if the two rectangles intersect.
+
+ - args.outputs.solids: An array. The values generate a solid.
+   The parameters are [X, Y, WIDTH, HEIGHT, RED, GREEN, BLUE]
+
+=end
+
+# This sample app shows collisions between two boxes.
+
+# Runs methods needed for game to run properly.
+def tick args
+  tick_instructions args, "Sample app shows how to move a square over time and determine collision."
+  defaults args
+  render args
+  calc args
+end
+
+# Sets default values.
+def defaults args
+  # These values represent the moving box.
+  args.state.moving_box_speed   = 10
+  args.state.moving_box_size    = 100
+  args.state.moving_box_dx    ||=  1
+  args.state.moving_box_dy    ||=  1
+  args.state.moving_box       ||= [0, 0, args.state.moving_box_size, args.state.moving_box_size] # moving_box_size is set as the width and height
+
+  # These values represent the center box.
+  args.state.center_box ||= [540, 260, 200, 200, 180]
+  args.state.center_box_collision ||= false # initially no collision
+end
+
+def render args
+  # If the game state denotes that a collision has occured,
+  # render a solid square, otherwise render a border instead.
+  if args.state.center_box_collision
+    args.outputs.solids << args.state.center_box
+  else
+    args.outputs.borders << args.state.center_box
+  end
+
+  # Then render the moving box.
+  args.outputs.solids << args.state.moving_box
+end
+
+# Generally in a pipeline for a game engine, you have rendering,
+# game simulation (calculation), and input processing.
+# This fuction represents the game simulation.
+def calc args
+  position_moving_box args
+  determine_collision_center_box args
+end
+
+# Changes the position of the moving box on the screen by multiplying the change in x (dx) and change in y (dy) by the speed,
+# and adding it to the current position.
+# dx and dy are positive if the box is moving right and up, respectively
+# dx and dy are negative if the box is moving left and down, respectively
+def position_moving_box args
+  args.state.moving_box.x += args.state.moving_box_dx * args.state.moving_box_speed
+  args.state.moving_box.y += args.state.moving_box_dy * args.state.moving_box_speed
+
+  # 1280x720 are the virtual pixels you work with (essentially 720p).
+  screen_width  = 1280
+  screen_height = 720
+
+  # Position of the box is denoted by the bottom left hand corner, in
+  # that case, we have to subtract the width of the box so that it stays
+  # in the scene (you can try deleting the subtraction to see how it
+  # impacts the box's movement).
+  if args.state.moving_box.x > screen_width - args.state.moving_box_size
+    args.state.moving_box_dx = -1 # moves left
+  elsif args.state.moving_box.x < 0
+    args.state.moving_box_dx =  1 # moves right
+  end
+
+  # Here, we're making sure the moving box remains within the vertical scope of the screen
+  if args.state.moving_box.y > screen_height - args.state.moving_box_size # if the box moves too high
+    args.state.moving_box_dy = -1 # moves down
+  elsif args.state.moving_box.y < 0 # if the box moves too low
+    args.state.moving_box_dy =  1 # moves up
+  end
+end
+
+def determine_collision_center_box args
+  # Collision is handled by the engine. You simply have to call the
+  # `intersect_rect?` function.
+  if args.state.moving_box.intersect_rect? args.state.center_box # if the two boxes intersect
+    args.state.center_box_collision = true # then a collision happened
+  else
+    args.state.center_box_collision = false # otherwise, no collision happened
+  end
+end
+
+def tick_instructions args, text, y = 715
+  return if args.state.key_event_occurred
+  if args.inputs.mouse.click ||
+     args.inputs.keyboard.directional_vector ||
+     args.inputs.keyboard.key_down.enter ||
+     args.inputs.keyboard.key_down.escape
+    args.state.key_event_occurred = true
+  end
+
+  args.outputs.debug << [0, y - 50, 1280, 60].solid
+  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
+  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
+end
+
+</pre>
+<h1 id='--04_physics_and_collisions/02_moving_objects/app/main.rb'>04_physics_and_collisions/02_moving_objects/app/main.rb</h1>
+<pre>=begin
+
+ APIs listing that haven't been encountered in previous sample apps:
+
+ - Hashes: Collection of unique keys and their corresponding values. The value can be found
+   using their keys.
+
+   For example, if we have a "numbers" hash that stores numbers in English as the
+   key and numbers in Spanish as the value, we'd have a hash that looks like this...
+   numbers = { "one" => "uno", "two" => "dos", "three" => "tres" }
+   and on it goes.
+
+   Now if we wanted to find the corresponding value of the "one" key, we could say
+   puts numbers["one"]
+   which would print "uno" to the console.
+
+ - num1.greater(num2): Returns the greater value.
+   For example, if we have the command
+   puts 4.greater(3)
+   the number 4 would be printed to the console since it has a greater value than 3.
+   Similar to lesser, which returns the lesser value.
+
+ - num1.lesser(num2): Finds the lower value of the given options.
+   For example, in the statement
+   a = 4.lesser(3)
+   3 has a lower value than 4, which means that the value of a would be set to 3,
+   but if the statement had been
+   a = 4.lesser(5)
+   4 has a lower value than 5, which means that the value of a would be set to 4.
+
+ - reject: Removes elements from a collection if they meet certain requirements.
+   For example, you can derive an array of odd numbers from an original array of
+   numbers 1 through 10 by rejecting all elements that are even (or divisible by 2).
+
+ - find_all: Finds all values that satisfy specific requirements.
+   For example, you can find all elements of a collection that are divisible by 2
+   or find all objects that have intersected with another object.
+
+ - abs: Returns the absolute value.
+   For example, the command
+   (-30).abs
+   would return 30 as a result.
+
+ - map: Ruby method used to transform data; used in arrays, hashes, and collections.
+   Can be used to perform an action on every element of a collection, such as multiplying
+   each element by 2 or declaring every element as a new entity.
+
+ Reminders:
+
+ - args.inputs.keyboard.KEY: Determines if a key has been pressed.
+   For more information about the keyboard, take a look at mygame/documentation/06-keyboard.md.
+
+ - ARRAY#intersect_rect?: Returns true or false depending on if the two rectangles intersect.
+
+ - args.outputs.solids: An array. The values generate a solid.
+   The parameters are [X, Y, WIDTH, HEIGHT, RED, GREEN, BLUE]
+   For more information about solids, go to mygame/documentation/03-solids-and-borders.md.
+
+=end
+
+# Calls methods needed for game to run properly
+def tick args
+  tick_instructions args, "Use LEFT and RIGHT arrow keys to move and SPACE to jump."
+  defaults args
+  render args
+  calc args
+  input args
+end
+
+# sets default values and creates empty collections
+# initialization only happens in the first frame
+def defaults args
+  fiddle args
+  args.state.enemy.hammers ||= []
+  args.state.enemy.hammer_queue ||= []
+  args.state.tick_count = args.state.tick_count
+  args.state.bridge_top = 128
+  args.state.player.x  ||= 0                        # initializes player's properties
+  args.state.player.y  ||= args.state.bridge_top
+  args.state.player.w  ||= 64
+  args.state.player.h  ||= 64
+  args.state.player.dy ||= 0
+  args.state.player.dx ||= 0
+  args.state.enemy.x   ||= 800                      # initializes enemy's properties
+  args.state.enemy.y   ||= 0
+  args.state.enemy.w   ||= 128
+  args.state.enemy.h   ||= 128
+  args.state.enemy.dy  ||= 0
+  args.state.enemy.dx  ||= 0
+  args.state.game_over_at ||= 0
+end
+
+# sets enemy, player, hammer values
+def fiddle args
+  args.state.gravity                     = -0.3
+  args.state.enemy_jump_power            = 10       # sets enemy values
+  args.state.enemy_jump_interval         = 60
+  args.state.hammer_throw_interval       = 40       # sets hammer values
+  args.state.hammer_launch_power_default = 5
+  args.state.hammer_launch_power_near    = 2
+  args.state.hammer_launch_power_far     = 7
+  args.state.hammer_upward_launch_power  = 15
+  args.state.max_hammers_per_volley      = 10
+  args.state.gap_between_hammers         = 10
+  args.state.player_jump_power           = 10       # sets player values
+  args.state.player_jump_power_duration  = 10
+  args.state.player_max_run_speed        = 10
+  args.state.player_speed_slowdown_rate  = 0.9
+  args.state.player_acceleration         = 1
+  args.state.hammer_size                 = 32
+end
+
+# outputs objects onto the screen
+def render args
+  args.outputs.solids << 20.map_with_index do |i| # uses 20 squares to form bridge
+    # sets x by multiplying 64 to index to find pixel value (places all squares side by side)
+    # subtracts 64 from bridge_top because position is denoted by bottom left corner
+    [i * 64, args.state.bridge_top - 64, 64, 64]
+  end
+
+  args.outputs.solids << [args.state.x, args.state.y, args.state.w, args.state.h, 255, 0, 0]
+  args.outputs.solids << [args.state.player.x, args.state.player.y, args.state.player.w, args.state.player.h, 255, 0, 0] # outputs player onto screen (red box)
+  args.outputs.solids << [args.state.enemy.x, args.state.enemy.y, args.state.enemy.w, args.state.enemy.h, 0, 255, 0] # outputs enemy onto screen (green box)
+  args.outputs.solids << args.state.enemy.hammers # outputs enemy's hammers onto screen
+end
+
+# Performs calculations to move objects on the screen
+def calc args
+
+  # Since velocity is the change in position, the change in x increases by dx. Same with y and dy.
+  args.state.player.x  += args.state.player.dx
+  args.state.player.y  += args.state.player.dy
+
+  # Since acceleration is the change in velocity, the change in y (dy) increases every frame
+  args.state.player.dy += args.state.gravity
+
+  # player's y position is either current y position or y position of top of
+  # bridge, whichever has a greater value
+  # ensures that the player never goes below the bridge
+  args.state.player.y  = args.state.player.y.greater(args.state.bridge_top)
+
+  # player's x position is either the current x position or 0, whichever has a greater value
+  # ensures that the player doesn't go too far left (out of the screen's scope)
+  args.state.player.x  = args.state.player.x.greater(0)
+
+  # player is not falling if it is located on the top of the bridge
+  args.state.player.falling = false if args.state.player.y == args.state.bridge_top
+  args.state.player.rect = [args.state.player.x, args.state.player.y, args.state.player.h, args.state.player.w] # sets definition for player
+
+  args.state.enemy.x += args.state.enemy.dx # velocity; change in x increases by dx
+  args.state.enemy.y += args.state.enemy.dy # same with y and dy
+
+  # ensures that the enemy never goes below the bridge
+  args.state.enemy.y  = args.state.enemy.y.greater(args.state.bridge_top)
+
+  # ensures that the enemy never goes too far left (outside the screen's scope)
+  args.state.enemy.x  = args.state.enemy.x.greater(0)
+
+  # objects that go up must come down because of gravity
+  args.state.enemy.dy += args.state.gravity
+
+  args.state.enemy.y  = args.state.enemy.y.greater(args.state.bridge_top)
+
+  #sets definition of enemy
+  args.state.enemy.rect = [args.state.enemy.x, args.state.enemy.y, args.state.enemy.h, args.state.enemy.w]
+
+  if args.state.enemy.y == args.state.bridge_top # if enemy is located on the top of the bridge
+    args.state.enemy.dy = 0 # there is no change in y
+  end
+
+  # if 60 frames have passed and the enemy is not moving vertically
+  if args.state.tick_count.mod_zero?(args.state.enemy_jump_interval) && args.state.enemy.dy == 0
+    args.state.enemy.dy = args.state.enemy_jump_power # the enemy jumps up
+  end
+
+  # if 40 frames have passed or 5 frames have passed since the game ended
+  if args.state.tick_count.mod_zero?(args.state.hammer_throw_interval) || args.state.game_over_at.elapsed_time == 5
+    # rand will return a number greater than or equal to 0 and less than given variable's value (since max is excluded)
+    # that is why we're adding 1, to include the max possibility
+    volley_dx   = (rand(args.state.hammer_launch_power_default) + 1) * -1 # horizontal movement (follow order of operations)
+
+    # if the horizontal distance between the player and enemy is less than 128 pixels
+    if (args.state.player.x - args.state.enemy.x).abs < 128
+      # the change in x won't be that great since the enemy and player are closer to each other
+      volley_dx = (rand(args.state.hammer_launch_power_near) + 1) * -1
+    end
+
+    # if the horizontal distance between the player and enemy is greater than 300 pixels
+    if (args.state.player.x - args.state.enemy.x).abs > 300
+      # change in x will be more drastic since player and enemy are so far apart
+      volley_dx = (rand(args.state.hammer_launch_power_far) + 1) * -1 # more drastic change
+    end
+
+    (rand(args.state.max_hammers_per_volley) + 1).map_with_index do |i|
+      args.state.enemy.hammer_queue << { # stores hammer values in a hash
+        x: args.state.enemy.x,
+        w: args.state.hammer_size,
+        h: args.state.hammer_size,
+        dx: volley_dx, # change in horizontal position
+        # multiplication operator takes precedence over addition operator
+        throw_at: args.state.tick_count + i * args.state.gap_between_hammers
+      }
+    end
+  end
+
+  # add elements from hammer_queue collection to the hammers collection by
+  # finding all hammers that were thrown before the current frame (have already been thrown)
+  args.state.enemy.hammers += args.state.enemy.hammer_queue.find_all do |h|
+    h[:throw_at] < args.state.tick_count
+  end
+
+  args.state.enemy.hammers.each do |h| # sets values for all hammers in collection
+    h[:y]  ||= args.state.enemy.y + 130
+    h[:dy] ||= args.state.hammer_upward_launch_power
+    h[:dy]  += args.state.gravity # acceleration is change in gravity
+    h[:x]   += h[:dx] # incremented by change in position
+    h[:y]   += h[:dy]
+    h[:rect] = [h[:x], h[:y], h[:w], h[:h]] # sets definition of hammer's rect
+  end
+
+  # reject hammers that have been thrown before current frame (have already been thrown)
+  args.state.enemy.hammer_queue = args.state.enemy.hammer_queue.reject do |h|
+    h[:throw_at] < args.state.tick_count
+  end
+
+  # any hammers with a y position less than 0 are rejected from the hammers collection
+  # since they have gone too far down (outside the scope's screen)
+  args.state.enemy.hammers = args.state.enemy.hammers.reject { |h| h[:y] < 0 }
+
+  # if there are any hammers that intersect with (or hit) the player,
+  # the reset_player method is called (so the game can start over)
+  if args.state.enemy.hammers.any? { |h| h[:rect].intersect_rect?(args.state.player.rect) }
+    reset_player args
+  end
+
+  # if the enemy's rect intersects with (or hits) the player,
+  # the reset_player method is called (so the game can start over)
+  if args.state.enemy.rect.intersect_rect? args.state.player.rect
+    reset_player args
+  end
+end
+
+# Resets the player by changing its properties back to the values they had at initialization
+def reset_player args
+  args.state.player.x = 0
+  args.state.player.y = args.state.bridge_top
+  args.state.player.dy = 0
+  args.state.player.dx = 0
+  args.state.enemy.hammers.clear # empties hammer collection
+  args.state.enemy.hammer_queue.clear # empties hammer_queue
+  args.state.game_over_at = args.state.tick_count # game_over_at set to current frame (or passage of time)
+end
+
+# Processes input from the user to move the player
+def input args
+  if args.inputs.keyboard.space # if the user presses the space bar
+    args.state.player.jumped_at ||= args.state.tick_count # jumped_at is set to current frame
+
+    # if the time that has passed since the jump is less than the player's jump duration and
+    # the player is not falling
+    if args.state.player.jumped_at.elapsed_time < args.state.player_jump_power_duration && !args.state.player.falling
+      args.state.player.dy = args.state.player_jump_power # change in y is set to power of player's jump
+    end
+  end
+
+  # if the space bar is in the "up" state (or not being pressed down)
+  if args.inputs.keyboard.key_up.space
+    args.state.player.jumped_at = nil # jumped_at is empty
+    args.state.player.falling = true # the player is falling
+  end
+
+  if args.inputs.keyboard.left # if left key is pressed
+    args.state.player.dx -= args.state.player_acceleration # dx decreases by acceleration (player goes left)
+    # dx is either set to current dx or the negative max run speed (which would be -10),
+    # whichever has a greater value
+    args.state.player.dx = args.state.player.dx.greater(-args.state.player_max_run_speed)
+  elsif args.inputs.keyboard.right # if right key is pressed
+    args.state.player.dx += args.state.player_acceleration # dx increases by acceleration (player goes right)
+    # dx is either set to current dx or max run speed (which would be 10),
+    # whichever has a lesser value
+    args.state.player.dx = args.state.player.dx.lesser(args.state.player_max_run_speed)
+  else
+    args.state.player.dx *= args.state.player_speed_slowdown_rate # dx is scaled down
+  end
+end
+
+def tick_instructions args, text, y = 715
+  return if args.state.key_event_occurred
+  if args.inputs.mouse.click ||
+     args.inputs.keyboard.directional_vector ||
+     args.inputs.keyboard.key_down.enter ||
+     args.inputs.keyboard.key_down.space ||
+     args.inputs.keyboard.key_down.escape
+    args.state.key_event_occurred = true
+  end
+
+  args.outputs.debug << [0, y - 50, 1280, 60].solid
+  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
+  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
+end
+
+</pre>
+<h1 id='--04_physics_and_collisions/03_entities/app/main.rb'>04_physics_and_collisions/03_entities/app/main.rb</h1>
+<pre>=begin
+
+ Reminders:
+
+ - map: Ruby method used to transform data; used in arrays, hashes, and collections.
+   Can be used to perform an action on every element of a collection, such as multiplying
+   each element by 2 or declaring every element as a new entity.
+
+ - reject: Removes elements from a collection if they meet certain requirements.
+   For example, you can derive an array of odd numbers from an original array of
+   numbers 1 through 10 by rejecting all elements that are even (or divisible by 2).
+
+ - args.state.new_entity: Used when we want to create a new object, like a sprite or button.
+   In this sample app, new_entity is used to define the properties of enemies and bullets.
+   (Remember, you can use state to define ANY property and it will be retained across frames.)
+
+ - args.outputs.labels: An array. The values generate a label on the screen.
+   The parameters are [X, Y, TEXT, SIZE, ALIGN, RED, GREEN, BLUE, ALPHA, FONT STYLE]
+
+ - ARRAY#intersect_rect?: Returns true or false depending on if the two rectangles intersect.
+
+ - args.inputs.mouse.click.point.(x|y): The x and y location of the mouse.
+
+=end
+
+# This sample app shows enemies that contain an id value and the time they were created.
+# These enemies can be removed by shooting at them with bullets.
+
+# Calls all methods necessary for the game to function properly.
+def tick args
+  tick_instructions args, "Sample app shows how to use args.state.new_entity along with collisions. CLICK to shoot a bullet."
+  defaults args
+  render args
+  calc args
+  process_inputs args
+end
+
+# Sets default values
+# Enemies and bullets start off as empty collections
+def defaults args
+  args.state.enemies ||= []
+  args.state.bullets ||= []
+end
+
+# Provides each enemy in enemies collection with rectangular border,
+# as well as a label showing id and when they were created
+def render args
+  # When you're calling a method that takes no arguments, you can use this & syntax on map.
+  # Numbers are being added to x and y in order to keep the text within the enemy's borders.
+  args.outputs.borders << args.state.enemies.map(&:rect)
+  args.outputs.labels  << args.state.enemies.flat_map do |enemy|
+    [
+      [enemy.x + 4, enemy.y + 29, "id: #{enemy.entity_id}", -3, 0],
+      [enemy.x + 4, enemy.y + 17, "created_at: #{enemy.created_at}", -3, 0] # frame enemy was created
+    ]
+  end
+
+  # Outputs bullets in bullets collection as rectangular solids
+  args.outputs.solids << args.state.bullets.map(&:rect)
+end
+
+# Calls all methods necessary for performing calculations
+def calc args
+  add_new_enemies_if_needed args
+  move_bullets args
+  calculate_collisions args
+  remove_bullets_of_screen args
+end
+
+# Adds enemies to the enemies collection and sets their values
+def add_new_enemies_if_needed args
+  return if args.state.enemies.length >= 10 # if 10 or more enemies, enemies are not added
+  return unless args.state.bullets.length == 0 # if user has not yet shot bullet, no enemies are added
+
+  args.state.enemies += (10 - args.state.enemies.length).map do # adds enemies so there are 10 total
+    args.state.new_entity(:enemy) do |e| # each enemy is declared as a new entity
+      e.x = 640 + 500 * rand # each enemy is given random position on screen
+      e.y = 600 * rand + 50
+      e.rect = [e.x, e.y, 130, 30] # sets definition for enemy's rect
+    end
+  end
+end
+
+# Moves bullets across screen
+# Sets definition of the bullets
+def move_bullets args
+  args.state.bullets.each do |bullet| # perform action on each bullet in collection
+    bullet.x += bullet.speed # increment x by speed (bullets fly horizontally across screen)
+
+    # By randomizing the value that increments bullet.y, the bullet does not fly straight up and out
+    # of the scope of the screen. Try removing what follows bullet.speed, or changing 0.25 to 1.25 to
+    # see what happens to the bullet's movement.
+    bullet.y += bullet.speed.*(0.25).randomize(:ratio, :sign)
+    bullet.rect = [bullet.x, bullet.y, bullet.size, bullet.size] # sets definition of bullet's rect
+  end
+end
+
+# Determines if a bullet hits an enemy
+def calculate_collisions args
+  args.state.bullets.each do |bullet| # perform action on every bullet and enemy in collections
+    args.state.enemies.each do |enemy|
+      # if bullet has not exploded yet and the bullet hits an enemy
+      if !bullet.exploded && bullet.rect.intersect_rect?(enemy.rect)
+        bullet.exploded = true # bullet explodes
+        enemy.dead = true # enemy is killed
+      end
+    end
+  end
+
+  # All exploded bullets are rejected or removed from the bullets collection
+  # and any dead enemy is rejected from the enemies collection.
+  args.state.bullets = args.state.bullets.reject(&:exploded)
+  args.state.enemies = args.state.enemies.reject(&:dead)
+end
+
+# Bullets are rejected from bullets collection once their position exceeds the width of screen
+def remove_bullets_of_screen args
+  args.state.bullets = args.state.bullets.reject { |bullet| bullet.x > 1280 } # screen width is 1280
+end
+
+# Calls fire_bullet method
+def process_inputs args
+  fire_bullet args
+end
+
+# Once mouse is clicked by the user to fire a bullet, a new bullet is added to bullets collection
+def fire_bullet args
+  return unless args.inputs.mouse.click # return unless mouse is clicked
+  args.state.bullets << args.state.new_entity(:bullet) do |bullet| # new bullet is declared a new entity
+    bullet.y = args.inputs.mouse.click.point.y # set to the y value of where the mouse was clicked
+    bullet.x = 0 # starts on the left side of the screen
+    bullet.size = 10
+    bullet.speed = 10 * rand + 2 # speed of a bullet is randomized
+    bullet.rect = [bullet.x, bullet.y, bullet.size, bullet.size] # definition is set
+  end
+end
+
+def tick_instructions args, text, y = 715
+  return if args.state.key_event_occurred
+  if args.inputs.mouse.click ||
+     args.inputs.keyboard.directional_vector ||
+     args.inputs.keyboard.key_down.enter ||
+     args.inputs.keyboard.key_down.space ||
+     args.inputs.keyboard.key_down.escape
+    args.state.key_event_occurred = true
+  end
+
+  args.outputs.debug << [0, y - 50, 1280, 60].solid
+  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
+  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
+end
+
+</pre>
+<h1 id='--04_physics_and_collisions/04_box_collision/app/main.rb'>04_physics_and_collisions/04_box_collision/app/main.rb</h1>
+<pre>=begin
+
+ APIs listing that haven't been encountered in previous sample apps:
+
+ - first: Returns the first element of the array.
+   For example, if we have an array
+   numbers = [1, 2, 3, 4, 5]
+   and we call first by saying
+   numbers.first
+   the number 1 will be returned because it is the first element of the numbers array.
+
+ - num1.idiv(num2): Divides two numbers and returns an integer.
+   For example,
+   16.idiv(3) = 5, because 16 / 3 is 5.33333 returned as an integer.
+   16.idiv(4) = 4, because 16 / 4 is 4 and already has no decimal.
+
+ Reminders:
+
+ - find_all: Finds all values that satisfy specific requirements.
+
+ - ARRAY#intersect_rect?: An array with at least four values is
+   considered a rect. The intersect_rect? function returns true
+   or false depending on if the two rectangles intersect.
+
+ - reject: Removes elements from a collection if they meet certain requirements.
+
+=end
+
+# This sample app allows users to create tiles and place them anywhere on the screen as obstacles.
+# The player can then move and maneuver around them.
+
+class PoorManPlatformerPhysics
+  attr_accessor :grid, :inputs, :state, :outputs
+
+  # Calls all methods necessary for the app to run successfully.
+  def tick
+    defaults
+    render
+    calc
+    process_inputs
+  end
+
+  # Sets default values for variables.
+  # The ||= sign means that the variable will only be set to the value following the = sign if the value has
+  # not already been set before. Intialization happens only in the first frame.
+  def defaults
+    state.tile_size               = 64
+    state.gravity                 = -0.2
+    state.previous_tile_size    ||= state.tile_size
+    state.x                     ||= 0
+    state.y                     ||= 800
+    state.dy                    ||= 0
+    state.dx                    ||= 0
+    state.world                 ||= []
+    state.world_lookup          ||= {}
+    state.world_collision_rects ||= []
+  end
+
+  # Outputs solids and borders of different colors for the world and collision_rects collections.
+  def render
+
+    # Sets a black background on the screen (Comment this line out and the background will become white.)
+    # Also note that black is the default color for when no color is assigned.
+    outputs.solids << grid.rect
+
+    # The position, size, and color (white) are set for borders given to the world collection.
+    # Try changing the color by assigning different numbers (between 0 and 255) to the last three parameters.
+    outputs.borders << state.world.map do |x, y|
+      [x * state.tile_size,
+       y * state.tile_size,
+       state.tile_size,
+       state.tile_size, 255, 255, 255]
+    end
+
+    # The top, bottom, and sides of the borders for collision_rects are different colors.
+    outputs.borders << state.world_collision_rects.map do |e|
+      [
+        [e[:top],                             0, 170,   0], # top is a shade of green
+        [e[:bottom],                          0, 100, 170], # bottom is a shade of greenish-blue
+        [e[:left_right],                    170,   0,   0], # left and right are a shade of red
+      ]
+    end
+
+    # Sets the position, size, and color (a shade of green) of the borders of only the player's
+    # box and outputs it. If you change the 180 to 0, the player's box will be black and you
+    # won't be able to see it (because it will match the black background).
+    outputs.borders << [state.x,
+                        state.y,
+                        state.tile_size,
+                        state.tile_size,  0, 180, 0]
+  end
+
+  # Calls methods needed to perform calculations.
+  def calc
+    calc_world_lookup
+    calc_player
+  end
+
+  # Performs calculations on world_lookup and sets values.
+  def calc_world_lookup
+
+    # If the tile size isn't equal to the previous tile size,
+    # the previous tile size is set to the tile size,
+    # and world_lookup hash is set to empty.
+    if state.tile_size != state.previous_tile_size
+      state.previous_tile_size = state.tile_size
+      state.world_lookup = {} # empty hash
+    end
+
+    # return if the world_lookup hash has keys (or, in other words, is not empty)
+    # return unless the world collection has values inside of it (or is not empty)
+    return if state.world_lookup.keys.length > 0
+    return unless state.world.length > 0
+
+    # Starts with an empty hash for world_lookup.
+    # Searches through the world and finds the coordinates that exist.
+    state.world_lookup = {}
+    state.world.each { |x, y| state.world_lookup[[x, y]] = true }
+
+    # Assigns world_collision_rects for every sprite drawn.
+    state.world_collision_rects =
+      state.world_lookup
+          .keys
+          .map do |coord_x, coord_y|
+            s = state.tile_size
+            # multiply by tile size so the grid coordinates; sets pixel value
+            # don't forget that position is denoted by bottom left corner
+            # set x = coord_x or y = coord_y and see what happens!
+            x = s * coord_x
+            y = s * coord_y
+            {
+              # The values added to x, y, and s position the world_collision_rects so they all appear
+              # stacked (on top of world rects) but don't directly overlap.
+              # Remove these added values and mess around with the rect placement!
+              args:       [coord_x, coord_y],
+              left_right: [x,     y + 4, s,     s - 6], # hash keys and values
+              top:        [x + 4, y + 6, s - 8, s - 6],
+              bottom:     [x + 1, y - 1, s - 2, s - 8],
+            }
+          end
+  end
+
+  # Performs calculations to change the x and y values of the player's box.
+  def calc_player
+
+    # Since acceleration is the change in velocity, the change in y (dy) increases every frame.
+    # What goes up must come down because of gravity.
+    state.dy += state.gravity
+
+    # Calls the calc_box_collision and calc_edge_collision methods.
+    calc_box_collision
+    calc_edge_collision
+
+    # Since velocity is the change in position, the change in y increases by dy. Same with x and dx.
+    state.y += state.dy
+    state.x += state.dx
+
+    # Scales dx down.
+    state.dx *= 0.8
+  end
+
+  # Calls methods needed to determine collisions between player and world_collision rects.
+  def calc_box_collision
+    return unless state.world_lookup.keys.length > 0 # return unless hash has atleast 1 key
+    collision_floor!
+    collision_left!
+    collision_right!
+    collision_ceiling!
+  end
+
+  # Finds collisions between the bottom of the player's rect and the top of a world_collision_rect.
+  def collision_floor!
+    return unless state.dy <= 0 # return unless player is going down or is as far down as possible
+    player_rect = [state.x, state.y - 0.1, state.tile_size, state.tile_size] # definition of player
+
+    # Goes through world_collision_rects to find all intersections between the bottom of player's rect and
+    # the top of a world_collision_rect (hence the "-0.1" above)
+    floor_collisions = state.world_collision_rects
+                           .find_all { |r| r[:top].intersect_rect?(player_rect, collision_tollerance) }
+                           .first
+
+    return unless floor_collisions # return unless collision occurred
+    state.y = floor_collisions[:top].top # player's y is set to the y of the top of the collided rect
+    state.dy = 0 # if a collision occurred, the player's rect isn't moving because its path is blocked
+  end
+
+  # Finds collisions between the player's left side and the right side of a world_collision_rect.
+  def collision_left!
+    return unless state.dx < 0 # return unless player is moving left
+    player_rect = [state.x - 0.1, state.y, state.tile_size, state.tile_size]
+
+    # Goes through world_collision_rects to find all intersections beween the player's left side and the
+    # right side of a world_collision_rect.
+    left_side_collisions = state.world_collision_rects
+                               .find_all { |r| r[:left_right].intersect_rect?(player_rect, collision_tollerance) }
+                               .first
+
+    return unless left_side_collisions # return unless collision occurred
+
+    # player's x is set to the value of the x of the collided rect's right side
+    state.x = left_side_collisions[:left_right].right
+    state.dx = 0 # player isn't moving left because its path is blocked
+  end
+
+  # Finds collisions between the right side of the player and the left side of a world_collision_rect.
+  def collision_right!
+    return unless state.dx > 0 # return unless player is moving right
+    player_rect = [state.x + 0.1, state.y, state.tile_size, state.tile_size]
+
+    # Goes through world_collision_rects to find all intersections between the player's right side
+    # and the left side of a world_collision_rect (hence the "+0.1" above)
+    right_side_collisions = state.world_collision_rects
+                                .find_all { |r| r[:left_right].intersect_rect?(player_rect, collision_tollerance) }
+                                .first
+
+    return unless right_side_collisions # return unless collision occurred
+
+    # player's x is set to the value of the collided rect's left, minus the size of a rect
+    # tile size is subtracted because player's position is denoted by bottom left corner
+    state.x = right_side_collisions[:left_right].left - state.tile_size
+    state.dx = 0 # player isn't moving right because its path is blocked
+  end
+
+  # Finds collisions between the top of the player's rect and the bottom of a world_collision_rect.
+  def collision_ceiling!
+    return unless state.dy > 0 # return unless player is moving up
+    player_rect = [state.x, state.y + 0.1, state.tile_size, state.tile_size]
+
+    # Goes through world_collision_rects to find intersections between the bottom of a
+    # world_collision_rect and the top of the player's rect (hence the "+0.1" above)
+    ceil_collisions = state.world_collision_rects
+                          .find_all { |r| r[:bottom].intersect_rect?(player_rect, collision_tollerance) }
+                          .first
+
+    return unless ceil_collisions # return unless collision occurred
+
+    # player's y is set to the bottom y of the rect it collided with, minus the size of a rect
+    state.y = ceil_collisions[:bottom].y - state.tile_size
+    state.dy = 0 # if a collision occurred, the player isn't moving up because its path is blocked
+  end
+
+  # Makes sure the player remains within the screen's dimensions.
+  def calc_edge_collision
+
+    #Ensures that the player doesn't fall below the map.
+    if state.y < 0
+      state.y = 0
+      state.dy = 0
+
+    #Ensures that the player doesn't go too high.
+    # Position of player is denoted by bottom left hand corner, which is why we have to subtract the
+    # size of the player's box (so it remains visible on the screen)
+    elsif state.y > 720 - state.tile_size # if the player's y position exceeds the height of screen
+      state.y = 720 - state.tile_size # the player will remain as high as possible while staying on screen
+      state.dy = 0
+    end
+
+    # Ensures that the player remains in the horizontal range that it is supposed to.
+    if state.x >= 1280 - state.tile_size && state.dx > 0 # if player moves too far right
+      state.x = 1280 - state.tile_size # player will remain as right as possible while staying on screen
+      state.dx = 0
+    elsif state.x <= 0 && state.dx < 0 # if player moves too far left
+      state.x = 0 # player will remain as left as possible while remaining on screen
+      state.dx = 0
+    end
+  end
+
+  # Processes input from the user on the keyboard.
+  def process_inputs
+    if inputs.mouse.down
+      state.world_lookup = {}
+      x, y = to_coord inputs.mouse.down.point  # gets x, y coordinates for the grid
+
+      if state.world.any? { |loc| loc == [x, y] }  # checks if coordinates duplicate
+        state.world = state.world.reject { |loc| loc == [x, y] }  # erases tile space
+      else
+        state.world << [x, y] # If no duplicates, adds to world collection
+      end
+    end
+
+    # Sets dx to 0 if the player lets go of arrow keys.
+    if inputs.keyboard.key_up.right
+      state.dx = 0
+    elsif inputs.keyboard.key_up.left
+      state.dx = 0
+    end
+
+    # Sets dx to 3 in whatever direction the player chooses.
+    if inputs.keyboard.key_held.right # if right key is pressed
+      state.dx =  3
+    elsif inputs.keyboard.key_held.left # if left key is pressed
+      state.dx = -3
+    end
+
+    #Sets dy to 5 to make the player ~fly~ when they press the space bar
+    if inputs.keyboard.key_held.space
+      state.dy = 5
+    end
+  end
+
+  def to_coord point
+
+    # Integer divides (idiv) point.x to turn into grid
+    # Then, you can just multiply each integer by state.tile_size later so the grid coordinates.
+    [point.x.idiv(state.tile_size), point.y.idiv(state.tile_size)]
+  end
+
+  # Represents the tolerance for a collision between the player's rect and another rect.
+  def collision_tollerance
+    0.0
+  end
+end
+
+$platformer_physics = PoorManPlatformerPhysics.new
+
+def tick args
+  $platformer_physics.grid    = args.grid
+  $platformer_physics.inputs  = args.inputs
+  $platformer_physics.state    = args.state
+  $platformer_physics.outputs = args.outputs
+  $platformer_physics.tick
+  tick_instructions args, "Sample app shows platformer collisions. CLICK to place box. ARROW keys to move around. SPACE to jump."
+end
+
+def tick_instructions args, text, y = 715
+  return if args.state.key_event_occurred
+  if args.inputs.mouse.click ||
+     args.inputs.keyboard.directional_vector ||
+     args.inputs.keyboard.key_down.enter ||
+     args.inputs.keyboard.key_down.escape
+    args.state.key_event_occurred = true
+  end
+
+  args.outputs.debug << [0, y - 50, 1280, 60].solid
+  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
+  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
+end
+
+</pre>
+<h1 id='--04_physics_and_collisions/04_box_collision_2/app/main.rb'>04_physics_and_collisions/04_box_collision_2/app/main.rb</h1>
+<pre>=begin
+ APIs listing that haven't been encountered in previous sample apps:
+
+ - times: Performs an action a specific number of times.
+   For example, if we said
+   5.times puts "Hello DragonRuby",
+   then we'd see the words "Hello DragonRuby" printed on the console 5 times.
+
+ - split: Divides a string into substrings based on a delimiter.
+   For example, if we had a command
+   "DragonRuby is awesome".split(" ")
+   then the result would be
+   ["DragonRuby", "is", "awesome"] because the words are separated by a space delimiter.
+
+ - join: Opposite of split; converts each element of array to a string separated by delimiter.
+   For example, if we had a command
+   ["DragonRuby","is","awesome"].join(" ")
+   then the result would be
+   "DragonRuby is awesome".
+
+ Reminders:
+
+ - to_s: Returns a string representation of an object.
+   For example, if we had
+   500.to_s
+   the string "500" would be returned.
+   Similar to to_i, which returns an integer representation of an object.
+
+ - elapsed_time: How many frames have passed since the click event.
+
+ - args.outputs.labels: An array. Values in the array generate labels on the screen.
+   The parameters are: [X, Y, TEXT, SIZE, ALIGN, RED, GREEN, BLUE, ALPHA, FONT STYLE]
+   For more information about labels, go to mygame/documentation/02-labels.md.
+
+ - inputs.mouse.down: Determines whether or not the mouse is being pressed down.
+   The position of the mouse when it is pressed down can be found using inputs.mouse.down.point.(x|y).
+
+ - first: Returns the first element of the array.
+
+ - num1.idiv(num2): Divides two numbers and returns an integer.
+
+ - find_all: Finds all values that satisfy specific requirements.
+
+ - ARRAY#intersect_rect?: Returns true or false depending on if two rectangles intersect.
+
+ - reject: Removes elements from a collection if they meet certain requirements.
+
+ - String interpolation: Uses #{} syntax; everything between the #{ and the } is evaluated
+   as Ruby code, and the placeholder is replaced with its corresponding value or result.
+
+=end
+
+MAP_FILE_PATH = 'app/map.txt' # the map.txt file in the app folder contains exported map
+
+class MetroidvaniaStarter
+  attr_accessor :grid, :inputs, :state, :outputs, :gtk
+
+  # Calls methods needed to run the game properly.
+  def tick
+    defaults
+    render
+    calc
+    process_inputs
+  end
+
+  # Sets all the default variables.
+  # '||' states that initialization occurs only in the first frame.
+  def defaults
+    state.tile_size                = 64
+    state.gravity                  = -0.2
+    state.player_width             = 60
+    state.player_height            = 64
+    state.collision_tolerance      = 0.0
+    state.previous_tile_size     ||= state.tile_size
+    state.x                      ||= 0
+    state.y                      ||= 800
+    state.dy                     ||= 0
+    state.dx                     ||= 0
+    attempt_load_world_from_file
+    state.world_lookup           ||= { }
+    state.world_collision_rects  ||= []
+    state.mode                   ||= :creating # alternates between :creating and :selecting for sprite selection
+    state.select_menu            ||= [0, 720, 1280, 720]
+    #=======================================IMPORTANT=======================================#
+    # When adding sprites, please label them "image1.png", "image2.png", image3".png", etc.
+    # Once you have done that, adjust "state.sprite_quantity" to how many sprites you have.
+    #=======================================================================================#
+    state.sprite_quantity        ||= 20 # IMPORTANT TO ALTER IF SPRITES ADDED IF YOU ADD MORE SPRITES
+    state.sprite_coords          ||= []
+    state.banner_coords          ||= [640, 680 + 720]
+    state.sprite_selected        ||= 1
+    state.map_saved_at           ||= 0
+
+    # Sets all the cordinate values for the sprite selection screen into a grid
+    # Displayed when 's' is pressed by player to access sprites
+    if state.sprite_coords == [] # if sprite_coords is an empty array
+      count = 1
+      temp_x = 165 # sets a starting x and y position for display
+      temp_y = 500 + 720
+      state.sprite_quantity.times do # for the number of sprites you have
+        state.sprite_coords += [[temp_x, temp_y, count]] # add element to sprite_coords array
+        temp_x += 100 # increment temp_x
+        count += 1 # increment count
+        if temp_x > 1280 - (165 + 50) # if exceeding specific horizontal width on screen
+          temp_x = 165 # a new row of sprites starts
+          temp_y -= 75 # new row of sprites starts 75 units lower than the previous row
+        end
+      end
+    end
+  end
+
+  # Places sprites
+  def render
+
+    # Sets the x, y, width, height, and image path for each sprite in the world collection.
+    outputs.sprites << state.world.map do |x, y, sprite|
+      [x * state.tile_size, # multiply by size so grid coordinates; pixel value of location
+       y * state.tile_size,
+       state.tile_size,
+       state.tile_size,
+       'sprites/image' + sprite.to_s + '.png'] # uses concatenation to create unique image path
+    end
+
+    # Outputs sprite for the player by setting x, y, width, height, and image path
+    outputs.sprites << [state.x,
+                        state.y,
+                        state.player_width,
+                        state.player_height,'sprites/player.png']
+
+    # Outputs labels as primitives in top right of the screen
+    outputs.primitives << [920, 700, 'Press 
+    </div>
+  </body>
+</html>
+s
+    </div>
+  </body>
+</html>
+ to access sprites.', 1, 0].label
+    outputs.primitives << [920, 675, 'Click existing sprite to delete.', 1, 0].label
+
+    outputs.primitives << [920, 640, '<- and -> to move.', 1, 0].label
+    outputs.primitives << [920, 615, 'Press and hold space to jump.', 1, 0].label
+
+    outputs.primitives << [920, 580, 'Press 
+    </div>
+  </body>
+</html>
+e
+    </div>
+  </body>
+</html>
+ to export current map.', 1, 0].label
+
+    # if the map is saved and less than 120 frames have passed, the label is displayed
+    if state.map_saved_at > 0 && state.map_saved_at.elapsed_time < 120
+      outputs.primitives << [920, 555, 'Map has been exported!', 1, 0, 50, 100, 50].label
+    end
+
+    # If player hits 's', following appears
+    if state.mode == :selecting
+      # White background for sprite selection
+      outputs.primitives << [state.select_menu, 255, 255, 255].solid
+
+      # Select tile label at the top of the screen
+      outputs.primitives << [state.banner_coords.x, state.banner_coords.y, "Select Sprite (sprites located in \"sprites\" folder)", 10, 1, 0, 0, 0, 255].label
+
+      # Places sprites in locations calculated in the defaults function
+      outputs.primitives << state.sprite_coords.map do |x, y, order|
+        [x, y, 50, 50, 'sprites/image' + order.to_s + ".png"].sprite
+      end
+    end
+
+    # Creates sprite following mouse to help indicate which sprite you have selected
+    # 10 is subtracted from the mouse's x position so that the sprite is not covered by the mouse icon
+    outputs.primitives << [inputs.mouse.position.x - 10, inputs.mouse.position.y,
+                           10, 10, 'sprites/image' + state.sprite_selected.to_s + ".png"].sprite
+  end
+
+  # Calls methods that perform calculations
+  def calc
+    calc_in_game
+    calc_sprite_selection
+  end
+
+  # Calls methods that perform calculations (if in creating mode)
+  def calc_in_game
+    return unless state.mode == :creating
+    calc_world_lookup
+    calc_player
+  end
+
+  def calc_world_lookup
+    # If the tile size isn't equal to the previous tile size,
+    # the previous tile size is set to the tile size,
+    # and world_lookup hash is set to empty.
+    if state.tile_size != state.previous_tile_size
+      state.previous_tile_size = state.tile_size
+      state.world_lookup = {}
+    end
+
+    # return if world_lookup is not empty or if world is empty
+    return if state.world_lookup.keys.length > 0
+    return unless state.world.length > 0
+
+    # Searches through the world and finds the coordinates that exist
+    state.world_lookup = {}
+    state.world.each { |x, y| state.world_lookup[[x, y]] = true }
+
+    # Assigns collision rects for every sprite drawn
+    state.world_collision_rects =
+      state.world_lookup
+           .keys
+           .map do |coord_x, coord_y|
+             s = state.tile_size
+             # Multiplying by s (the size of a tile) ensures that the rect is
+             # placed exactly where you want it to be placed (causes grid to coordinate)
+             # How many pixels horizontally across and vertically up and down
+             x = s * coord_x
+             y = s * coord_y
+             {
+               args:       [coord_x, coord_y],
+               left_right: [x,     y + 4, s,     s - 6], # hash keys and values
+               top:        [x + 4, y + 6, s - 8, s - 6],
+               bottom:     [x + 1, y - 1, s - 2, s - 8],
+             }
+           end
+  end
+
+  # Calculates movement of player and calls methods that perform collision calculations
+  def calc_player
+    state.dy += state.gravity  # what goes up must come down because of gravity
+    calc_box_collision
+    calc_edge_collision
+    state.y  += state.dy       # Since velocity is the change in position, the change in y increases by dy
+    state.x  += state.dx       # Ditto line above but dx and x
+    state.dx *= 0.8            # Scales dx down
+  end
+
+  # Calls methods that determine whether the player collides with any world_collision_rects.
+  def calc_box_collision
+    return unless state.world_lookup.keys.length > 0 # return unless hash has atleast 1 key
+    collision_floor
+    collision_left
+    collision_right
+    collision_ceiling
+  end
+
+  # Finds collisions between the bottom of the player's rect and the top of a world_collision_rect.
+  def collision_floor
+    return unless state.dy <= 0 # return unless player is going down or is as far down as possible
+    player_rect = [state.x, next_y, state.tile_size, state.tile_size] # definition of player
+
+    # Runs through all the sprites on the field and finds all intersections between player's
+    # bottom and the top of a rect.
+    floor_collisions = state.world_collision_rects
+                         .find_all { |r| r[:top].intersect_rect?(player_rect, state.collision_tolerance) }
+                         .first
+
+    return unless floor_collisions # performs following changes if a collision has occurred
+    state.y = floor_collisions[:top].top # y of player is set to the y of the colliding rect's top
+    state.dy = 0 # no change in y because the player's path is blocked
+  end
+
+  # Finds collisions between the player's left side and the right side of a world_collision_rect.
+  def collision_left
+    return unless state.dx < 0 # return unless player is moving left
+    player_rect = [next_x, state.y, state.tile_size, state.tile_size]
+
+    # Runs through all the sprites on the field and finds all intersections between the player's left side
+    # and the right side of a rect.
+    left_side_collisions = state.world_collision_rects
+                             .find_all { |r| r[:left_right].intersect_rect?(player_rect, state.collision_tolerance) }
+                             .first
+
+    return unless left_side_collisions # return unless collision occurred
+    state.x = left_side_collisions[:left_right].right # sets player's x to the x of the colliding rect's right side
+    state.dx = 0 # no change in x because the player's path is blocked
+  end
+
+  # Finds collisions between the right side of the player and the left side of a world_collision_rect.
+  def collision_right
+    return unless state.dx > 0 # return unless player is moving right
+    player_rect = [next_x, state.y, state.tile_size, state.tile_size]
+
+    # Runs through all the sprites on the field and finds all intersections between the  player's
+    # right side and the left side of a rect.
+    right_side_collisions = state.world_collision_rects
+                              .find_all { |r| r[:left_right].intersect_rect?(player_rect, state.collision_tolerance) }
+                              .first
+
+    return unless right_side_collisions # return unless collision occurred
+    state.x = right_side_collisions[:left_right].left - state.tile_size # player's x is set to the x of colliding rect's left side (minus tile size since x is the player's bottom left corner)
+    state.dx = 0 # no change in x because the player's path is blocked
+  end
+
+  # Finds collisions between the top of the player's rect and the bottom of a world_collision_rect.
+  def collision_ceiling
+    return unless state.dy > 0 # return unless player is moving up
+    player_rect = [state.x, next_y, state.player_width, state.player_height]
+
+    # Runs through all the sprites on the field and finds all intersections between the player's top
+    # and the bottom of a rect.
+    ceil_collisions = state.world_collision_rects
+                        .find_all { |r| r[:bottom].intersect_rect?(player_rect, state.collision_tolerance) }
+                        .first
+
+    return unless ceil_collisions # return unless collision occurred
+    state.y = ceil_collisions[:bottom].y - state.tile_size # player's y is set to the y of the colliding rect's bottom (minus tile size)
+    state.dy = 0 # no change in y because the player's path is blocked
+  end
+
+  # Makes sure the player remains within the screen's dimensions.
+  def calc_edge_collision
+    # Ensures that player doesn't fall below the map
+    if next_y < 0 && state.dy < 0 # if player is moving down and is about to fall (next_y) below the map's scope
+      state.y = 0 # 0 is the lowest the player can be while staying on the screen
+      state.dy = 0
+    # Ensures player doesn't go insanely high
+    elsif next_y > 720 - state.tile_size && state.dy > 0 # if player is moving up, about to exceed map's scope
+      state.y = 720 - state.tile_size # if we don't subtract tile_size, we won't be able to see the player on the screen
+      state.dy = 0
+    end
+
+    # Ensures that player remains in the horizontal range its supposed to
+    if state.x >= 1280 - state.tile_size && state.dx > 0 # if the player is moving too far right
+      state.x = 1280 - state.tile_size # farthest right the player can be while remaining in the screen's scope
+      state.dx = 0
+    elsif state.x <= 0 && state.dx < 0 # if the player is moving too far left
+      state.x = 0 # farthest left the player can be while remaining in the screen's scope
+      state.dx = 0
+    end
+  end
+
+  def calc_sprite_selection
+    # Does the transition to bring down the select sprite screen
+    if state.mode == :selecting && state.select_menu.y != 0
+      state.select_menu.y = 0  # sets y position of select menu (shown when 's' is pressed)
+      state.banner_coords.y = 680 # sets y position of Select Sprite banner
+      state.sprite_coords = state.sprite_coords.map do |x, y, w, h|
+        [x, y - 720, w, h] # sets definition of sprites (change '-' to '+' and the sprites can't be seen)
+      end
+    end
+
+    # Does the transition to leave the select sprite screen
+    if state.mode == :creating  && state.select_menu.y != 720
+      state.select_menu.y = 720 # sets y position of select menu (menu is retreated back up)
+      state.banner_coords.y = 1000 # sets y position of Select Sprite banner
+      state.sprite_coords = state.sprite_coords.map do |x, y, w, h|
+        [x, y + 720, w, h] # sets definition of all elements in collection
+      end
+    end
+  end
+
+  def process_inputs
+    # If the state.mode is back and if the menu has retreated back up
+    # call methods that process user inputs
+    if state.mode == :creating
+      process_inputs_player_movement
+      process_inputs_place_tile
+    end
+
+    # For each sprite_coordinate added, check what sprite was selected
+    if state.mode == :selecting
+      state.sprite_coords.map do |x, y, order| # goes through all sprites in collection
+        # checks that a specific sprite was pressed based on x, y position
+        if inputs.mouse.down && # the && (and) sign means ALL statements must be true for the evaluation to be true
+           inputs.mouse.down.point.x >= x      && # x is greater than or equal to sprite's x and
+           inputs.mouse.down.point.x <= x + 50 && # x is less than or equal to 50 pixels to the right
+           inputs.mouse.down.point.y >= y      && # y is greater than or equal to sprite's y
+           inputs.mouse.down.point.y <= y + 50 # y is less than or equal to 50 pixels up
+          state.sprite_selected = order # sprite is chosen
+        end
+      end
+    end
+
+    inputs_export_stage
+    process_inputs_show_available_sprites
+  end
+
+  # Moves the player based on the keys they press on their keyboard
+  def process_inputs_player_movement
+    # Sets dx to 0 if the player lets go of arrow keys (player won't move left or right)
+    if inputs.keyboard.key_up.right
+      state.dx = 0
+    elsif inputs.keyboard.key_up.left
+      state.dx = 0
+    end
+
+    # Sets dx to 3 in whatever direction the player chooses when they hold down (or press) the left or right keys
+    if inputs.keyboard.key_held.right
+      state.dx =  3
+    elsif inputs.keyboard.key_held.left
+      state.dx = -3
+    end
+
+    # Sets dy to 5 to make the player ~fly~ when they press the space bar on their keyboard
+    if inputs.keyboard.key_held.space
+      state.dy = 5
+    end
+  end
+
+  # Adds tile in the place the user holds down the mouse
+  def process_inputs_place_tile
+    if inputs.mouse.down # if mouse is pressed
+      state.world_lookup = {}
+      x, y = to_coord inputs.mouse.down.point # gets x, y coordinates for the grid
+
+      # Checks if any coordinates duplicate (already exist in world)
+      if state.world.any? { |existing_x, existing_y, n| existing_x == x && existing_y == y }
+        #erases existing tile space by rejecting them from world
+        state.world = state.world.reject do |existing_x, existing_y, n|
+          existing_x == x && existing_y == y
+        end
+      else
+        state.world << [x, y, state.sprite_selected] # If no duplicates, add the sprite
+      end
+    end
+  end
+
+  # Stores/exports world collection's info (coordinates, sprite number) into a file
+  def inputs_export_stage
+    if inputs.keyboard.key_down.e # if "e" is pressed
+      export_string = state.world.map do |x, y, sprite_number| # stores world info in a string
+        "#{x},#{y},#{sprite_number}"                           # using string interpolation
+      end
+      gtk.write_file(MAP_FILE_PATH, export_string.join("\n")) # writes string into a file
+      state.map_saved_at = state.tick_count # frame number (passage of time) when the map was saved
+    end
+  end
+
+  def process_inputs_show_available_sprites
+    # Based on keyboard input, the entity (:creating and :selecting) switch
+    if inputs.keyboard.key_held.s && state.mode == :creating # if "s" is pressed and currently creating
+      state.mode = :selecting # will change to selecting
+      inputs.keyboard.clear # VERY IMPORTANT! If not present, it'll flicker between on and off
+    elsif inputs.keyboard.key_held.s && state.mode == :selecting # if "s" is pressed and currently selecting
+      state.mode = :creating # will change to creating
+      inputs.keyboard.clear # VERY IMPORTANT! If not present, it'll flicker between on and off
+    end
+  end
+
+  # Loads the world collection by reading from the map.txt file in the app folder
+  def attempt_load_world_from_file
+    return if state.world # return if the world collection is already populated
+    state.world ||= [] # initialized as an empty collection
+    exported_world = gtk.read_file(MAP_FILE_PATH) # reads the file using the path mentioned at top of code
+    return unless exported_world # return unless the file read was successful
+    state.world = exported_world.each_line.map do |l| # perform action on each line of exported_world
+        l.split(',').map(&:to_i) # calls split using ',' as a delimiter, and invokes .map on the collection,
+                                 # calling to_i (converts to integers) on each element
+    end
+  end
+
+  # Adds the change in y to y to determine the next y position of the player.
+  def next_y
+    state.y + state.dy
+  end
+
+  # Determines next x position of player
+  def next_x
+    if state.dx < 0 # if the player moves left
+      return state.x - (state.tile_size - state.player_width) # subtracts since the change in x is negative (player is moving left)
+    else
+      return state.x + (state.tile_size - state.player_width) # adds since the change in x is positive (player is moving right)
+    end
+  end
+
+  def to_coord point
+    # Integer divides (idiv) point.x to turn into grid
+    # Then, you can just multiply each integer by state.tile_size
+    # later and huzzah. Grid coordinates
+    [point.x.idiv(state.tile_size), point.y.idiv(state.tile_size)]
+  end
+end
+
+$metroidvania_starter = MetroidvaniaStarter.new
+
+def tick args
+    $metroidvania_starter.grid    = args.grid
+    $metroidvania_starter.inputs  = args.inputs
+    $metroidvania_starter.state   = args.state
+    $metroidvania_starter.outputs = args.outputs
+    $metroidvania_starter.gtk     = args.gtk
+    $metroidvania_starter.tick
+end
+
+</pre>
+<h1 id='--04_physics_and_collisions/04_jump_physics/app/main.rb'>04_physics_and_collisions/04_jump_physics/app/main.rb</h1>
+<pre>=begin
+
+ Reminders:
+
+ - args.state.new_entity: Used when we want to create a new object, like a sprite or button.
+   For example, if we want to create a new button, we would declare it as a new entity and
+   then define its properties. (Remember, you can use state to define ANY property and it will
+   be retained across frames.)
+
+ - args.outputs.solids: An array. The values generate a solid.
+   The parameters for a solid are [X, Y, WIDTH, HEIGHT, RED, GREEN, BLUE]
+   For more information about solids, go to mygame/documentation/03-solids-and-borders.md.
+
+ - num1.greater(num2): Returns the greater value.
+
+ - Hashes: Collection of unique keys and their corresponding values. The value can be found
+   using their keys.
+
+ - ARRAY#inside_rect?: Returns true or false depending on if the point is inside the rect.
+
+=end
+
+# This sample app is a game that requires the user to jump from one platform to the next.
+# As the player successfully clears platforms, they become smaller and move faster.
+
+class VerticalPlatformer
+  attr_gtk
+
+  # declares vertical platformer as new entity
+  def s
+    state.vertical_platformer ||= state.new_entity(:vertical_platformer)
+    state.vertical_platformer
+  end
+
+  # creates a new platform using a hash
+  def new_platform hash
+    s.new_entity_strict(:platform, hash) # platform key
+  end
+
+  # calls methods needed for game to run properly
+  def tick
+    defaults
+    render
+    calc
+    input
+  end
+
+  # Sets default values
+  def defaults
+    s.platforms ||= [ # initializes platforms collection with two platforms using hashes
+      new_platform(x: 0, y: 0, w: 700, h: 32, dx: 1, speed: 0, rect: nil),
+      new_platform(x: 0, y: 300, w: 700, h: 32, dx: 1, speed: 0, rect: nil), # 300 pixels higher
+    ]
+
+    s.tick_count  = args.state.tick_count
+    s.gravity     = -0.3 # what goes up must come down because of gravity
+    s.player.platforms_cleared ||= 0 # counts how many platforms the player has successfully cleared
+    s.player.x  ||= 0           # sets player values
+    s.player.y  ||= 100
+    s.player.w  ||= 64
+    s.player.h  ||= 64
+    s.player.dy ||= 0           # change in position
+    s.player.dx ||= 0
+    s.player_jump_power           = 15
+    s.player_jump_power_duration  = 10
+    s.player_max_run_speed        = 5
+    s.player_speed_slowdown_rate  = 0.9
+    s.player_acceleration         = 1
+    s.camera ||= { y: -100 } # shows view on screen (as the player moves upward, the camera does too)
+  end
+
+  # Outputs objects onto the screen
+  def render
+    outputs.solids << s.platforms.map do |p| # outputs platforms onto screen
+      [p.x + 300, p.y - s.camera[:y], p.w, p.h] # add 300 to place platform in horizontal center
+      # don't forget, position of platform is denoted by bottom left hand corner
+    end
+
+    # outputs player using hash
+    outputs.solids << {
+      x: s.player.x + 300, # player positioned on top of platform
+      y: s.player.y - s.camera[:y],
+      w: s.player.w,
+      h: s.player.h,
+      r: 100,              # color saturation
+      g: 100,
+      b: 200
+    }
+  end
+
+  # Performs calculations
+  def calc
+    s.platforms.each do |p| # for each platform in the collection
+      p.rect = [p.x, p.y, p.w, p.h] # set the definition
+    end
+
+    # sets player point by adding half the player's width to the player's x
+    s.player.point = [s.player.x + s.player.w.half, s.player.y] # change + to - and see what happens!
+
+    # search the platforms collection to find if the player's point is inside the rect of a platform
+    collision = s.platforms.find { |p| s.player.point.inside_rect? p.rect }
+
+    # if collision occurred and player is moving down (or not moving vertically at all)
+    if collision && s.player.dy <= 0
+      s.player.y = collision.rect.y + collision.rect.h - 2 # player positioned on top of platform
+      s.player.dy = 0 if s.player.dy < 0 # player stops moving vertically
+      if !s.player.platform
+        s.player.dx = 0 # no horizontal movement
+      end
+      # changes horizontal position of player by multiplying collision change in x (dx) by speed and adding it to current x
+      s.player.x += collision.dx * collision.speed
+      s.player.platform = collision # player is on the platform that it collided with (or landed on)
+      if s.player.falling # if player is falling
+        s.player.dx = 0  # no horizontal movement
+      end
+      s.player.falling = false
+      s.player.jumped_at = nil
+    else
+      s.player.platform = nil # player is not on a platform
+      s.player.y  += s.player.dy # velocity is the change in position
+      s.player.dy += s.gravity # acceleration is the change in velocity; what goes up must come down
+    end
+
+    s.platforms.each do |p| # for each platform in the collection
+      p.x += p.dx * p.speed # x is incremented by product of dx and speed (causes platform to move horizontally)
+      # changes platform's x so it moves left and right across the screen (between -300 and 300 pixels)
+      if p.x < -300 # if platform goes too far left
+        p.dx *= -1 # dx is scaled down
+        p.x = -300 # as far left as possible within scope
+      elsif p.x > (1000 - p.w) # if platform's x is greater than 300
+        p.dx *= -1
+        p.x = (1000 - p.w) # set to 300 (as far right as possible within scope)
+      end
+    end
+
+    delta = (s.player.y - s.camera[:y] - 100) # used to position camera view
+
+    if delta > -200
+      s.camera[:y] += delta * 0.01 # allows player to see view as they move upwards
+      s.player.x  += s.player.dx # velocity is change in position; change in x increases by dx
+
+      # searches platform collection to find platforms located more than 300 pixels above the player
+      has_platforms = s.platforms.find { |p| p.y > (s.player.y + 300) }
+      if !has_platforms # if there are no platforms 300 pixels above the player
+        width = 700 - (700 * (0.1 * s.player.platforms_cleared)) # the next platform is smaller than previous
+        s.player.platforms_cleared += 1 # player successfully cleared another platform
+        last_platform = s.platforms[-1] # platform just cleared becomes last platform
+        # another platform is created 300 pixels above the last platform, and this
+        # new platform has a smaller width and moves faster than all previous platforms
+        s.platforms << new_platform(x: (700 - width) * rand, # random x position
+                                    y: last_platform.y + 300,
+                                    w: width,
+                                    h: 32,
+                                    dx: 1.randomize(:sign), # random change in x
+                                    speed: 2 * s.player.platforms_cleared,
+                                    rect: nil)
+      end
+    else
+      s.as_hash.clear # otherwise clear the hash (no new platform is necessary)
+    end
+  end
+
+  # Takes input from the user to move the player
+  def input
+    if inputs.keyboard.space # if the space bar is pressed
+      s.player.jumped_at ||= s.tick_count # set to current frame
+
+      # if the time that has passed since the jump is less than the duration of a jump (10 frames)
+      # and the player is not falling
+      if s.player.jumped_at.elapsed_time < s.player_jump_power_duration && !s.player.falling
+        s.player.dy = s.player_jump_power # player jumps up
+      end
+    end
+
+    if inputs.keyboard.key_up.space # if space bar is in "up" state
+      s.player.falling = true # player is falling
+    end
+
+    if inputs.keyboard.left # if left key is pressed
+      s.player.dx -= s.player_acceleration # player's position changes, decremented by acceleration
+      s.player.dx = s.player.dx.greater(-s.player_max_run_speed) # dx is either current dx or -5, whichever is greater
+    elsif inputs.keyboard.right # if right key is pressed
+      s.player.dx += s.player_acceleration # player's position changes, incremented by acceleration
+      s.player.dx  = s.player.dx.lesser(s.player_max_run_speed) # dx is either current dx or 5, whichever is lesser
+    else
+      s.player.dx *= s.player_speed_slowdown_rate # scales dx down
+    end
+  end
+end
+
+$game = VerticalPlatformer.new
+
+def tick args
+  $game.args = args
+  $game.tick
+end
+
+</pre>
+<h1 id='--05_mouse/03_mouse_click/app/main.rb'>05_mouse/03_mouse_click/app/main.rb</h1>
+<pre>=begin
+
+ APIs listing that haven't been encountered in previous sample apps:
+
+ - product: Returns an array of all combinations of elements from all arrays.
+
+   For example, [1,2].product([1,2]) would return the following array...
+   [[1,1], [1,2], [2,1], [2,2]]
+   More than two arrays can be given to product and it will still work,
+   such as [1,2].product([1,2],[3,4]). What would product return in this case?
+
+   Answer:
+   [[1,1,3],[1,1,4],[1,2,3],[1,2,4],[2,1,3],[2,1,4],[2,2,3],[2,2,4]]
+
+ - num1.fdiv(num2): Returns the float division (will have a decimal) of the two given numbers.
+   For example, 5.fdiv(2) = 2.5 and 5.fdiv(5) = 1.0
+
+ - yield: Allows you to call a method with a code block and yield to that block.
+
+ Reminders:
+
+ - ARRAY#inside_rect?: Returns true or false depending on if the point is inside the rect.
+
+ - String interpolation: Uses #{} syntax; everything between the #{ and the } is evaluated
+   as Ruby code, and the placeholder is replaced with its corresponding value or result.
+
+ - args.inputs.mouse.click: This property will be set if the mouse was clicked.
+
+ - Ternary operator (?): Will evaluate a statement (just like an if statement)
+   and perform an action if the result is true or another action if it is false.
+
+ - reject: Removes elements from a collection if they meet certain requirements.
+
+ - args.outputs.borders: An array. The values generate a border.
+   The parameters are [X, Y, WIDTH, HEIGHT, RED, GREEN, BLUE]
+   For more information about borders, go to mygame/documentation/03-solids-and-borders.md.
+
+ - args.outputs.labels: An array. The values generate a label.
+   The parameters are [X, Y, TEXT, SIZE, ALIGNMENT, RED, GREEN, BLUE, ALPHA, FONT STYLE]
+   For more information about labels, go to mygame/documentation/02-labels.
+
+=end
+
+# This sample app is a classic game of Tic Tac Toe.
+
+class TicTacToe
+  attr_accessor :_, :state, :outputs, :inputs, :grid, :gtk
+
+  # Starts the game with player x's turn and creates an array (to_a) for space combinations.
+  # Calls methods necessary for the game to run properly.
+  def tick
+    state.current_turn ||= :x
+    state.space_combinations = [-1, 0, 1].product([-1, 0, 1]).to_a
+    render_board
+    input_board
+  end
+
+  # Uses borders to create grid squares for the game's board. Also outputs the game pieces using labels.
+  def render_board
+    square_size = 80
+
+    # Positions the game's board in the center of the screen.
+    # Try removing what follows grid.w_half or grid.h_half and see how the position changes!
+    board_left = grid.w_half - square_size * 1.5
+    board_top  = grid.h_half - square_size * 1.5
+
+    # At first glance, the add(1) looks pretty trivial. But if you remove it,
+    # you'll see that the positioning of the board would be skewed without it!
+    # Or if you put 2 in the parenthesis, the pieces will be placed in the wrong squares
+    # due to the change in board placement.
+    outputs.borders << all_spaces do |x, y, space| # outputs borders for all board spaces
+      space.border ||= [
+        board_left + x.add(1) * square_size, # space.border is initialized using this definition
+        board_top  + y.add(1) * square_size,
+        square_size,
+        square_size
+      ]
+    end
+
+    # Again, the calculations ensure that the piece is placed in the center of the grid square.
+    # Remove the '- 20' and the piece will be placed at the top of the grid square instead of the center.
+    outputs.labels << filled_spaces do |x, y, space| # put label in each filled space of board
+          label board_left + x.add(1) * square_size + square_size.fdiv(2),
+          board_top  + y.add(1) * square_size + square_size - 20,
+          space.piece # text of label, either "x" or "o"
+    end
+
+    # Uses a label to output whether x or o won, or if a draw occurred.
+    # If the game is ongoing, a label shows whose turn it currently is.
+    outputs.labels << if state.x_won
+                        label grid.w_half, grid.top - 80, "x won" # the '-80' positions the label 80 pixels lower than top
+                      elsif state.o_won
+                        label grid.w_half, grid.top - 80, "o won" # grid.w_half positions the label in the center horizontally
+                      elsif state.draw
+                        label grid.w_half, grid.top - 80, "a draw"
+                      else # if no one won and the game is ongoing
+                        label grid.w_half, grid.top - 80, "turn: #{state.current_turn}"
+                      end
+  end
+
+  # Calls the methods responsible for handling user input and determining the winner.
+  # Does nothing unless the mouse is clicked.
+  def input_board
+    return unless inputs.mouse.click
+    input_place_piece
+    input_restart_game
+    determine_winner
+  end
+
+  # Handles user input for placing pieces on the board.
+  def input_place_piece
+    return if state.game_over
+
+    # Checks to find the space that the mouse was clicked inside of, and makes sure the space does not already
+    # have a piece in it.
+    __, __, space = all_spaces.find do |__, __, space|
+      inputs.mouse.click.point.inside_rect?(space.border) && !space.piece
+    end
+
+    # The piece that goes into the space belongs to the player whose turn it currently is.
+    return unless space
+    space.piece = state.current_turn
+
+    # This ternary operator statement allows us to change the current player's turn.
+    # If it is currently x's turn, it becomes o's turn. If it is not x's turn, it become's x's turn.
+    state.current_turn = state.current_turn == :x ? :o : :x
+  end
+
+  # Resets the game.
+  def input_restart_game
+    return unless state.game_over
+    gtk.reset
+  end
+
+  # Checks if x or o won the game.
+  # If neither player wins and all nine squares are filled, a draw happens.
+  # Once a player is chosen as the winner or a draw happens, the game is over.
+  def determine_winner
+    state.x_won = won? :x # evaluates to either true or false (boolean values)
+    state.o_won = won? :o
+    state.draw = true if filled_spaces.length == 9 && !state.x_won && !state.o_won
+    state.game_over = state.x_won || state.o_won || state.draw
+  end
+
+  # Determines if a player won by checking if there is a horizontal match or vertical match.
+  # Horizontal_match and vertical_match have boolean values. If either is true, the game has been won.
+  def won? piece
+    # performs action on all space combinations
+    won = [[-1, 0, 1]].product([-1, 0, 1]).map do |xs, y|
+
+      # Checks if the 3 grid spaces with the same y value (or same row) and
+      # x values that are next to each other have pieces that belong to the same player.
+      # Remember, the value of piece is equal to the current turn (which is the player).
+      horizontal_match = state.spaces[xs[0]][y].piece == piece &&
+                         state.spaces[xs[1]][y].piece == piece &&
+                         state.spaces[xs[2]][y].piece == piece
+
+      # Checks if the 3 grid spaces with the same x value (or same column) and
+      # y values that are next to each other have pieces that belong to the same player.
+      # The && represents an "and" statement: if even one part of the statement is false,
+      # the entire statement evaluates to false.
+      vertical_match = state.spaces[y][xs[0]].piece == piece &&
+                       state.spaces[y][xs[1]].piece == piece &&
+                       state.spaces[y][xs[2]].piece == piece
+
+      horizontal_match || vertical_match # if either is true, true is returned
+    end
+
+    # Sees if there is a diagonal match, starting from the bottom left and ending at the top right.
+    # Is added to won regardless of whether the statement is true or false.
+    won << (state.spaces[-1][-1].piece == piece && # bottom left
+            state.spaces[ 0][ 0].piece == piece && # center
+            state.spaces[ 1][ 1].piece == piece)   # top right
+
+    # Sees if there is a diagonal match, starting at the bottom right and ending at the top left
+    # and is added to won.
+    won << (state.spaces[ 1][-1].piece == piece && # bottom right
+            state.spaces[ 0][ 0].piece == piece && # center
+            state.spaces[-1][ 1].piece == piece)   # top left
+
+    # Any false statements (meaning false diagonal matches) are rejected from won
+    won.reject_false.any?
+  end
+
+  # Defines filled spaces on the board by rejecting all spaces that do not have game pieces in them.
+  # The ! before a statement means "not". For example, we are rejecting any space combinations that do
+  # NOT have pieces in them.
+  def filled_spaces
+    state.space_combinations
+      .reject { |x, y| !state.spaces[x][y].piece } # reject spaces with no pieces in them
+      .map do |x, y|
+        if block_given?
+          yield x, y, state.spaces[x][y]
+        else
+          [x, y, state.spaces[x][y]] # sets definition of space
+        end
+    end
+  end
+
+  # Defines all spaces on the board.
+  def all_spaces
+    if !block_given?
+      state.space_combinations.map do |x, y|
+        [x, y, state.spaces[x][y]] # sets definition of space
+      end
+    else # if a block is given (block_given? is true)
+      state.space_combinations.map do |x, y|
+        yield x, y, state.spaces[x][y] # yield if a block is given
+      end
+    end
+  end
+
+  # Sets values for a label, such as the position, value, size, alignment, and color.
+  def label x, y, value
+    [x, y + 10, value, 20, 1, 0, 0, 0]
+  end
+end
+
+$tic_tac_toe = TicTacToe.new
+
+def tick args
+  $tic_tac_toe._       = args
+  $tic_tac_toe.state   = args.state
+  $tic_tac_toe.outputs = args.outputs
+  $tic_tac_toe.inputs  = args.inputs
+  $tic_tac_toe.grid    = args.grid
+  $tic_tac_toe.gtk     = args.gtk
+  $tic_tac_toe.tick
+  tick_instructions args, "Sample app shows how to work with mouse clicks."
+end
+
+def tick_instructions args, text, y = 715
+  return if args.state.key_event_occurred
+  if args.inputs.mouse.click ||
+     args.inputs.keyboard.directional_vector ||
+     args.inputs.keyboard.key_down.enter ||
+     args.inputs.keyboard.key_down.escape
+    args.state.key_event_occurred = true
+  end
+
+  args.outputs.debug << [0, y - 50, 1280, 60].solid
+  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
+  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
+end
+
+</pre>
+<h1 id='--05_mouse/05_mouse_move/app/main.rb'>05_mouse/05_mouse_move/app/main.rb</h1>
+<pre>=begin
+
+ Reminders:
+
+ - num1.greater(num2): Returns the greater value.
+   For example, if we have the command
+   puts 4.greater(3)
+   the number 4 would be printed to the console since it has a greater value than 3.
+   Similar to lesser, which returns the lesser value.
+
+ - find_all: Finds all elements of a collection that meet certain requirements.
+   For example, in this sample app, we're using find_all to find all zombies that have intersected
+   or hit the player's sprite since these zombies have been killed.
+
+ - args.inputs.keyboard.key_down.KEY: Determines if a key is being held or pressed.
+   Stores the frame the "down" event occurred.
+   For more information about the keyboard, go to mygame/documentation/06-keyboard.md.
+
+ - args.outputs.sprites: An array. The values generate a sprite.
+   The parameters are [X, Y, WIDTH, HEIGHT, PATH, ANGLE, ALPHA, RED, GREEN, BLUE]
+   For more information about sprites, go to mygame/documentation/05-sprites.md.
+
+ - args.state.new_entity: Used when we want to create a new object, like a sprite or button.
+   When we want to create a new object, we can declare it as a new entity and then define
+   its properties. (Remember, you can use state to define ANY property and it will
+   be retained across frames.)
+
+ - String interpolation: Uses #{} syntax; everything between the #{ and the } is evaluated
+   as Ruby code, and the placeholder is replaced with its corresponding value or result.
+
+ - map: Ruby method used to transform data; used in arrays, hashes, and collections.
+   Can be used to perform an action on every element of a collection, such as multiplying
+   each element by 2 or declaring every element as a new entity.
+
+ - sample: Chooses a random element from the array.
+
+ - reject: Removes elements that meet certain requirements.
+   In this sample app, we're removing/rejecting zombies that reach the center of the screen. We're also
+   rejecting zombies that were killed more than 30 frames ago.
+
+=end
+
+# This sample app allows users to move around the screen in order to kill zombies. Zombies appear from every direction so the goal
+# is to kill the zombies as fast as possible!
+
+class ProtectThePuppiesFromTheZombies
+  attr_accessor :grid, :inputs, :state, :outputs
+
+  # Calls the methods necessary for the game to run properly.
+  def tick
+    defaults
+    render
+    calc
+    input
+  end
+
+  # Sets default values for the zombies and for the player.
+  # Initialization happens only in the first frame.
+  def defaults
+    state.flash_at               ||= 0
+    state.zombie_min_spawn_rate  ||= 60
+    state.zombie_spawn_countdown ||= random_spawn_countdown state.zombie_min_spawn_rate
+    state.zombies                ||= []
+    state.killed_zombies         ||= []
+
+    # Declares player as a new entity and sets its properties.
+    # The player begins the game in the center of the screen, not moving in any direction.
+    state.player ||= state.new_entity(:player, { x: 640,
+                                               y: 360,
+                                               attack_angle: 0,
+                                               dx: 0,
+                                               dy: 0 })
+  end
+
+  # Outputs a gray background.
+  # Calls the methods needed to output the player, zombies, etc onto the screen.
+  def render
+    outputs.solids << [grid.rect, 100, 100, 100]
+    render_zombies
+    render_killed_zombies
+    render_player
+    render_flash
+  end
+
+  # Outputs the zombies on the screen and sets values for the sprites, such as the position, width, height, and animation.
+  def render_zombies
+    outputs.sprites << state.zombies.map do |z| # performs action on all zombies in the collection
+      z.sprite = [z.x, z.y, 4 * 3, 8 * 3, animation_sprite(z)].sprite # sets definition for sprite, calls animation_sprite method
+      z.sprite
+    end
+  end
+
+  # Outputs sprites of killed zombies, and displays a slash image to show that a zombie has been killed.
+  def render_killed_zombies
+    outputs.sprites << state.killed_zombies.map do |z| # performs action on all killed zombies in collection
+      z.sprite = [z.x,
+                  z.y,
+                  4 * 3,
+                  8 * 3,
+                  animation_sprite(z, z.death_at), # calls animation_sprite method
+                  0, # angle
+                  255 * z.death_at.ease(30, :flip)].sprite # transparency of a zombie changes when they die
+                  # change the value of 30 and see what happens when a zombie is killed
+
+      # Sets values to output the slash over the zombie's sprite when a zombie is killed.
+      # The slash is tilted 45 degrees from the angle of the player's attack.
+      # Change the 3 inside scale_rect to 30 and the slash will be HUGE! Scale_rect positions
+      # the slash over the killed zombie's sprite.
+      [z.sprite, [z.sprite.rect, 'sprites/slash.png', 45 + state.player.attack_angle_on_click, z.sprite.a].scale_rect(3, 0.5, 0.5)]
+    end
+  end
+
+  # Outputs the player sprite using the images in the sprites folder.
+  def render_player
+    state.player_sprite = [state.player.x,
+                           state.player.y,
+                          4 * 3,
+                          8 * 3, "sprites/player-#{animation_index(state.player.created_at_elapsed)}.png"] # string interpolation
+    outputs.sprites << state.player_sprite
+
+    # Outputs a small red square that previews the angles that the player can attack in.
+    # It can be moved in a perfect circle around the player to show possible movements.
+    # Change the 60 in the parenthesis and see what happens to the movement of the red square.
+    outputs.solids <<  [state.player.x + state.player.attack_angle.vector_x(60),
+                        state.player.y + state.player.attack_angle.vector_y(60),
+                        3, 3, 255, 0, 0]
+  end
+
+  # Renders flash as a solid. The screen turns white for 10 frames when a zombie is killed.
+  def render_flash
+    return if state.flash_at.elapsed_time > 10 # return if more than 10 frames have passed since flash.
+    # Transparency gradually changes (or eases) during the 10 frames of flash.
+    outputs.primitives << [grid.rect, 255, 255, 255, 255 * state.flash_at.ease(10, :flip)].solid
+  end
+
+  # Calls all methods necessary for performing calculations.
+  def calc
+    calc_spawn_zombie
+    calc_move_zombies
+    calc_player
+    calc_kill_zombie
+  end
+
+  # Decreases the zombie spawn countdown by 1 if it has a value greater than 0.
+  def calc_spawn_zombie
+    if state.zombie_spawn_countdown > 0
+      state.zombie_spawn_countdown -= 1
+      return
+    end
+
+    # New zombies are created, positioned on the screen, and added to the zombies collection.
+    state.zombies << state.new_entity(:zombie) do |z| # each zombie is declared a new entity
+      if rand > 0.5
+        z.x = grid.rect.w.randomize(:ratio) # random x position on screen (within grid scope)
+        z.y = [-10, 730].sample # y position is set to either -10 or 730 (randomly chosen)
+        # the possible values exceed the screen's scope so zombies appear to be coming from far away
+      else
+        z.x = [-10, 1290].sample # x position is set to either -10 or 1290 (randomly chosen)
+        z.y = grid.rect.w.randomize(:ratio) # random y position on screen
+      end
+    end
+
+    # Calls random_spawn_countdown method (determines how fast new zombies appear)
+    state.zombie_spawn_countdown = random_spawn_countdown state.zombie_min_spawn_rate
+    state.zombie_min_spawn_rate -= 1
+    # set to either the current zombie_min_spawn_rate or 0, depending on which value is greater
+    state.zombie_min_spawn_rate  = state.zombie_min_spawn_rate.greater(0)
+  end
+
+  # Moves all zombies towards the center of the screen.
+  # All zombies that reach the center (640, 360) are rejected from the zombies collection and disappear.
+  def calc_move_zombies
+    state.zombies.each do |z| # for each zombie in the collection
+      z.y = z.y.towards(360, 0.1) # move the zombie towards the center (640, 360) at a rate of 0.1
+      z.x = z.x.towards(640, 0.1) # change 0.1 to 1.1 and see how much faster the zombies move to the center
+    end
+    state.zombies = state.zombies.reject { |z| z.y == 360 && z.x == 640 } # remove zombies that are in center
+  end
+
+  # Calculates the position and movement of the player on the screen.
+  def calc_player
+    state.player.x += state.player.dx # changes x based on dx (change in x)
+    state.player.y += state.player.dy # changes y based on dy (change in y)
+
+    state.player.dx *= 0.9 # scales dx down
+    state.player.dy *= 0.9 # scales dy down
+
+    # Compares player's x to 1280 to find lesser value, then compares result to 0 to find greater value.
+    # This ensures that the player remains within the screen's scope.
+    state.player.x = state.player.x.lesser(1280).greater(0)
+    state.player.y = state.player.y.lesser(720).greater(0) # same with player's y
+  end
+
+  # Finds all zombies that intersect with the player's sprite. These zombies are removed from the zombies collection
+  # and added to the killed_zombies collection since any zombie that intersects with the player is killed.
+  def calc_kill_zombie
+
+    # Find all zombies that intersect with the player. They are considered killed.
+    killed_this_frame = state.zombies.find_all { |z| z.sprite.intersect_rect? state.player_sprite }
+    state.zombies = state.zombies - killed_this_frame # remove newly killed zombies from zombies collection
+    state.killed_zombies += killed_this_frame # add newly killed zombies to killed zombies
+
+    if killed_this_frame.length > 0 # if atleast one zombie was killed in the frame
+      state.flash_at = state.tick_count # flash_at set to the frame when the zombie was killed
+    # Don't forget, the rendered flash lasts for 10 frames after the zombie is killed (look at render_flash method)
+    end
+
+    # Sets the tick_count (passage of time) as the value of the death_at variable for each killed zombie.
+    # Death_at stores the frame a zombie was killed.
+    killed_this_frame.each do |z|
+      z.death_at = state.tick_count
+    end
+
+    # Zombies are rejected from the killed_zombies collection depending on when they were killed.
+    # They are rejected if more than 30 frames have passed since their death.
+    state.killed_zombies = state.killed_zombies.reject { |z| state.tick_count - z.death_at > 30 }
+  end
+
+  # Uses input from the user to move the player around the screen.
+  def input
+
+    # If the "a" key or left key is pressed, the x position of the player decreases.
+    # Otherwise, if the "d" key or right key is pressed, the x position of the player increases.
+    if inputs.keyboard.key_held.a || inputs.keyboard.key_held.left
+      state.player.x -= 5
+    elsif inputs.keyboard.key_held.d || inputs.keyboard.key_held.right
+      state.player.x += 5
+    end
+
+    # If the "w" or up key is pressed, the y position of the player increases.
+    # Otherwise, if the "s" or down key is pressed, the y position of the player decreases.
+    if inputs.keyboard.key_held.w || inputs.keyboard.key_held.up
+      state.player.y += 5
+    elsif inputs.keyboard.key_held.s || inputs.keyboard.key_held.down
+      state.player.y -= 5
+    end
+
+    # Sets the attack angle so the player can move and attack in the precise direction it wants to go.
+    # If the mouse is moved, the attack angle is changed (based on the player's position and mouse position).
+    # Attack angle also contributes to the position of red square.
+    if inputs.mouse.moved
+      state.player.attack_angle = inputs.mouse.position.angle_from [state.player.x, state.player.y]
+    end
+
+    if inputs.mouse.click && state.player.dx < 0.5 && state.player.dy < 0.5
+      state.player.attack_angle_on_click = inputs.mouse.position.angle_from [state.player.x, state.player.y]
+      state.player.attack_angle = state.player.attack_angle_on_click # player's attack angle is set
+      state.player.dx = state.player.attack_angle.vector_x(25) # change in player's position
+      state.player.dy = state.player.attack_angle.vector_y(25)
+    end
+  end
+
+  # Sets the zombie spawn's countdown to a random number.
+  # How fast zombies appear (change the 60 to 6 and too many zombies will appear at once!)
+  def random_spawn_countdown minimum
+    10.randomize(:ratio, :sign).to_i + 60
+  end
+
+  # Helps to iterate through the images in the sprites folder by setting the animation index.
+  # 3 frames is how long to show an image, and 6 is how many images to flip through.
+  def animation_index at
+    at.idiv(3).mod(6)
+  end
+
+  # Animates the zombies by using the animation index to go through the images in the sprites folder.
+  def animation_sprite zombie, at = nil
+    at ||= zombie.created_at_elapsed # how long it is has been since a zombie was created
+    index = animation_index at
+    "sprites/zombie-#{index}.png" # string interpolation to iterate through images
+  end
+end
+
+$protect_the_puppies_from_the_zombies = ProtectThePuppiesFromTheZombies.new
+
+def tick args
+  $protect_the_puppies_from_the_zombies.grid    = args.grid
+  $protect_the_puppies_from_the_zombies.inputs  = args.inputs
+  $protect_the_puppies_from_the_zombies.state    = args.state
+  $protect_the_puppies_from_the_zombies.outputs = args.outputs
+  $protect_the_puppies_from_the_zombies.tick
+  tick_instructions args, "How to get the mouse position and translate it to an x, y position using .vector_x and .vector_y. CLICK to play."
+end
+
+def tick_instructions args, text, y = 715
+  return if args.state.key_event_occurred
+  if args.inputs.mouse.click ||
+     args.inputs.keyboard.directional_vector ||
+     args.inputs.keyboard.key_down.enter ||
+     args.inputs.keyboard.key_down.escape
+    args.state.key_event_occurred = true
+  end
+
+  args.outputs.debug << [0, y - 50, 1280, 60].solid
+  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
+  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
+end
+
+</pre>
+<h1 id='--05_mouse/05_mouse_move_paint_app/app/main.rb'>05_mouse/05_mouse_move_paint_app/app/main.rb</h1>
+<pre>=begin
+
+ APIs listing that haven't been encountered in previous sample apps:
+
+ - Floor: Method that returns an integer number smaller than or equal to the original with no decimal.
+
+   For example, if we have a variable, a = 13.7, and we called floor on it, it would look like this...
+   puts a.floor()
+   which would print out 13.
+   (There is also a ceil method, which returns an integer number greater than or equal to the original
+   with no decimal. If we had called ceil on the variable a, the result would have been 14.)
+
+ Reminders:
+
+ - Hashes: Collection of unique keys and their corresponding values. The value can be found
+   using their keys.
+
+   For example, if we have a "numbers" hash that stores numbers in English as the
+   key and numbers in Spanish as the value, we'd have a hash that looks like this...
+   numbers = { "one" => "uno", "two" => "dos", "three" => "tres" }
+   and on it goes.
+
+   Now if we wanted to find the corresponding value of the "one" key, we could say
+   puts numbers["one"]
+   which would print "uno" to the console.
+
+ - args.state.new_entity: Used when we want to create a new object, like a sprite or button.
+   In this sample app, new_entity is used to create a new button that clears the grid.
+   (Remember, you can use state to define ANY property and it will be retained across frames.)
+
+ - args.inputs.mouse.click.point.(x|y): The x and y location of the mouse.
+
+ - args.inputs.mouse.click.point.created_at: The frame the mouse click occurred in.
+
+ - args.outputs.labels: An array. The values in the array generate a label.
+   The parameters are [X, Y, TEXT, SIZE, ALIGN, RED, GREEN, BLUE, ALPHA, FONT STYLE]
+   For more information about labels, go to mygame/documentation/02-labels.md.
+
+ - ARRAY#inside_rect?: Returns true or false depending on if the point is inside the rect.
+
+=end
+
+# This sample app shows an empty grid that the user can paint on.
+# To paint, the user must keep their mouse presssed and drag it around the grid.
+# The "clear" button allows users to clear the grid so they can start over.
+
+class PaintApp
+  attr_accessor :inputs, :state, :outputs, :grid, :args
+
+  # Runs methods necessary for the game to function properly.
+  def tick
+    print_title
+    add_grid
+    check_click
+    draw_buttons
+  end
+
+  # Prints the title onto the screen by using a label.
+  # Also separates the title from the grid with a line as a horizontal separator.
+  def print_title
+    args.outputs.labels << [ 640, 700, 'Paint!', 0, 1 ]
+    outputs.lines << horizontal_separator(660, 0, 1280)
+  end
+
+  # Sets the starting position, ending position, and color for the horizontal separator.
+  # The starting and ending positions have the same y values.
+  def horizontal_separator y, x, x2
+    [x, y, x2, y, 150, 150, 150]
+  end
+
+  # Sets the starting position, ending position, and color for the vertical separator.
+  # The starting and ending positions have the same x values.
+  def vertical_separator x, y, y2
+    [x, y, x, y2, 150, 150, 150]
+  end
+
+  # Outputs a border and a grid containing empty squares onto the screen.
+  def add_grid
+
+    # Sets the x, y, height, and width of the grid.
+    # There are 31 horizontal lines and 31 vertical lines in the grid.
+    # Feel free to count them yourself before continuing!
+    x, y, h, w = 640 - 500/2, 640 - 500, 500, 500 # calculations done so the grid appears in screen's center
+    lines_h = 31
+    lines_v = 31
+
+    # Sets values for the grid's border, grid lines, and filled squares.
+    # The filled_squares variable is initially set to an empty array.
+    state.grid_border ||= [ x, y, h, w ] # definition of grid's outer border
+    state.grid_lines ||= draw_grid(x, y, h, w, lines_h, lines_v) # calls draw_grid method
+    state.filled_squares ||= [] # there are no filled squares until the user fills them in
+
+    # Outputs the grid lines, border, and filled squares onto the screen.
+    outputs.lines.concat state.grid_lines
+    outputs.borders << state.grid_border
+    outputs.solids << state.filled_squares
+  end
+
+  # Draws the grid by adding in vertical and horizontal separators.
+  def draw_grid x, y, h, w, lines_h, lines_v
+
+    # The grid starts off empty.
+    grid = []
+
+    # Calculates the placement and adds horizontal lines or separators into the grid.
+    curr_y = y # start at the bottom of the box
+    dist_y = h / (lines_h + 1) # finds distance to place horizontal lines evenly throughout 500 height of grid
+    lines_h.times do
+      curr_y += dist_y # increment curr_y by the distance between the horizontal lines
+      grid << horizontal_separator(curr_y, x, x + w - 1) # add a separator into the grid
+    end
+
+    # Calculates the placement and adds vertical lines or separators into the grid.
+    curr_x = x # now start at the left of the box
+    dist_x = w / (lines_v + 1) # finds distance to place vertical lines evenly throughout 500 width of grid
+    lines_v.times do
+      curr_x += dist_x # increment curr_x by the distance between the vertical lines
+      grid << vertical_separator(curr_x, y + 1, y  + h) # add separator
+    end
+
+    # paint_grid uses a hash to assign values to keys.
+    state.paint_grid ||= {"x" => x, "y" => y, "h" => h, "w" => w, "lines_h" => lines_h,
+                          "lines_v" => lines_v, "dist_x" => dist_x,
+                          "dist_y" => dist_y }
+
+    return grid
+  end
+
+  # Checks if the user is keeping the mouse pressed down and sets the mouse_hold variable accordingly using boolean values.
+  # If the mouse is up, the user cannot drag the mouse.
+  def check_click
+    if inputs.mouse.down #is mouse up or down?
+      state.mouse_held = true # mouse is being held down
+    elsif inputs.mouse.up # if mouse is up
+    state.mouse_held = false # mouse is not being held down or dragged
+      state.mouse_dragging = false
+    end
+
+    if state.mouse_held &&    # mouse needs to be down
+      !inputs.mouse.click &&     # must not be first click
+      ((inputs.mouse.previous_click.point.x - inputs.mouse.position.x).abs > 15) # Need to move 15 pixels before "drag"
+      state.mouse_dragging = true
+    end
+
+    # If the user clicks their mouse inside the grid, the search_lines method is called with a click input type.
+    if ((inputs.mouse.click) && (inputs.mouse.click.point.inside_rect? state.grid_border))
+      search_lines(inputs.mouse.click.point, :click)
+
+    # If the user drags their mouse inside the grid, the search_lines method is called with a drag input type.
+    elsif ((state.mouse_dragging) && (inputs.mouse.position.inside_rect? state.grid_border))
+      search_lines(inputs.mouse.position, :drag)
+    end
+  end
+
+  # Sets the definition of a grid box and handles user input to fill in or clear grid boxes.
+  def search_lines (point, input_type)
+    point.x -= state.paint_grid["x"] # subtracts the value assigned to the "x" key in the paint_grid hash
+    point.y -= state.paint_grid["y"] # subtracts the value assigned to the "y" key in the paint_grid hash
+
+    # Remove code following the .floor and see what happens when you try to fill in grid squares
+    point.x = (point.x / state.paint_grid["dist_x"]).floor * state.paint_grid["dist_x"]
+    point.y = (point.y / state.paint_grid["dist_y"]).floor * state.paint_grid["dist_y"]
+
+    point.x += state.paint_grid["x"]
+    point.y += state.paint_grid["y"]
+
+    # Sets definition of a grid box, meaning its x, y, width, and height.
+    # Floor is called on the point.x and point.y variables.
+    # Ceil method is called on values of the distance hash keys, setting the width and height of a box.
+    grid_box = [ point.x.floor, point.y.floor, state.paint_grid["dist_x"].ceil, state.paint_grid["dist_y"].ceil ]
+
+    if input_type == :click # if user clicks their mouse
+      if state.filled_squares.include? grid_box # if grid box is already filled in
+        state.filled_squares.delete grid_box # box is cleared and removed from filled_squares
+      else
+        state.filled_squares << grid_box # otherwise, box is filled in and added to filled_squares
+      end
+    elsif input_type == :drag # if user drags mouse
+      unless state.filled_squares.include? grid_box # unless the grid box dragged over is already filled in
+        state.filled_squares << grid_box # the box is filled in and added to filled_squares
+      end
+    end
+  end
+
+  # Creates and outputs a "Clear" button on the screen using a label and a border.
+  # If the button is clicked, the filled squares are cleared, making the filled_squares collection empty.
+  def draw_buttons
+    x, y, w, h = 390, 50, 240, 50
+    state.clear_button        ||= state.new_entity(:button_with_fade)
+
+    # The x and y positions are set to display the label in the center of the button.
+    # Try changing the first two parameters to simply x, y and see what happens to the text placement!
+    state.clear_button.label  ||= [x + w.half, y + h.half + 10, "Clear", 0, 1] # placed in center of border
+    state.clear_button.border ||= [x, y, w, h]
+
+    # If the mouse is clicked inside the borders of the clear button,
+    # the filled_squares collection is emptied and the squares are cleared.
+    if inputs.mouse.click && inputs.mouse.click.point.inside_rect?(state.clear_button.border)
+      state.clear_button.clicked_at = inputs.mouse.click.created_at # time (frame) the click occurred
+      state.filled_squares.clear
+      inputs.mouse.previous_click = nil
+    end
+
+    outputs.labels << state.clear_button.label
+    outputs.borders << state.clear_button.border
+
+    # When the clear button is clicked, the color of the button changes
+    # and the transparency changes, as well. If you change the time from
+    # 0.25.seconds to 1.25.seconds or more, the change will last longer.
+    if state.clear_button.clicked_at
+      outputs.solids << [x, y, w, h, 0, 180, 80, 255 * state.clear_button.clicked_at.ease(0.25.seconds, :flip)]
+    end
+  end
+end
+
+$paint_app = PaintApp.new
+
+def tick args
+  $paint_app.inputs = args.inputs
+  $paint_app.state = args.state
+  $paint_app.grid = args.grid
+  $paint_app.args = args
+  $paint_app.outputs = args.outputs
+  $paint_app.tick
+  tick_instructions args, "How to create a simple paint app. CLICK and HOLD to draw."
+end
+
+def tick_instructions args, text, y = 715
+  return if args.state.key_event_occurred
+  if args.inputs.mouse.click ||
+     args.inputs.keyboard.directional_vector ||
+     args.inputs.keyboard.key_down.enter ||
+     args.inputs.keyboard.key_down.escape
+    args.state.key_event_occurred = true
+  end
+
+  args.outputs.debug << [0, y - 50, 1280, 60].solid
+  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
+  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
+end
+
+</pre>
+<h1 id='--05_mouse/06_coordinate_systems/app/main.rb'>05_mouse/06_coordinate_systems/app/main.rb</h1>
+<pre>=begin
+
+ APIs listing that haven't been encountered in previous sample apps:
+
+ - args.inputs.mouse.click.position: Coordinates of the mouse's position on the screen.
+   Unlike args.inputs.mouse.click.point, the mouse does not need to be pressed down for
+   position to know the mouse's coordinates.
+   For more information about the mouse, go to mygame/documentation/07-mouse.md.
+
+ Reminders:
+
+ - args.inputs.mouse.click: This property will be set if the mouse was clicked.
+
+ - args.inputs.mouse.click.point.(x|y): The x and y location of the mouse.
+
+ - String interpolation: Uses #{} syntax; everything between the #{ and the } is evaluated
+   as Ruby code, and the placeholder is replaced with its corresponding value or result.
+
+   In this sample app, string interpolation is used to show the current position of the mouse
+   in a label.
+
+ - args.outputs.labels: An array that generates a label.
+   The parameters are [X, Y, TEXT, SIZE, ALIGN, RED, GREEN, BLUE, ALPHA, FONT STYLE]
+   For more information about labels, go to mygame/documentation/02-labels.md.
+
+ - args.outputs.solids: An array that generates a solid.
+   The parameters are [X, Y, WIDTH, HEIGHT, RED, GREEN, BLUE, ALPHA]
+   For more information about solids, go to mygame/documentation/03-solids-and-borders.md.
+
+ - args.outputs.lines: An array that generates a line.
+   The parameters are [X, Y, X2, Y2, RED, GREEN, BLUE, ALPHA]
+   For more information about lines, go to mygame/documentation/04-lines.md.
+
+=end
+
+# This sample app shows a coordinate system or grid. The user can move their mouse around the screen and the
+# coordinates of their position on the screen will be displayed. Users can choose to view one quadrant or
+# four quadrants by pressing the button.
+
+def tick args
+
+  # The addition and subtraction in the first two parameters of the label and solid
+  # ensure that the outputs don't overlap each other. Try removing them and see what happens.
+  pos = args.inputs.mouse.position # stores coordinates of mouse's position
+  args.outputs.labels << [pos.x + 10, pos.y + 10, "#{pos}"] # outputs label of coordinates
+  args.outputs.solids << [pos.x -  2, pos.y - 2, 5, 5] # outputs small blackk box placed where mouse is hovering
+
+  button = [0, 0, 370, 50] # sets definition of toggle button
+  args.outputs.borders << button # outputs button as border (not filled in)
+  args.outputs.labels << [10, 35, "click here toggle coordinate system"] # label of button
+  args.outputs.lines << [    0, -720,    0, 720] # vertical line dividing quadrants
+  args.outputs.lines << [-1280,    0, 1280,   0] # horizontal line dividing quadrants
+
+  if args.inputs.mouse.click # if the user clicks the mouse
+    pos = args.inputs.mouse.click.point # pos's value is point where user clicked (coordinates)
+    if pos.inside_rect? button # if the click occurred inside the button
+      if args.grid.name == :bottom_left # if the grid shows bottom left as origin
+        args.grid.origin_center! # origin will be shown in center
+      else
+        args.grid.origin_bottom_left! # otherwise, the view will change to show bottom left as origin
+      end
+    end
+  end
+
+  tick_instructions args, "Sample app shows the two supported coordinate systems in Game Toolkit."
+end
+
+def tick_instructions args, text, y = 715
+  return if args.state.key_event_occurred
+  if args.inputs.mouse.click ||
+     args.inputs.keyboard.directional_vector ||
+     args.inputs.keyboard.key_down.enter ||
+     args.inputs.keyboard.key_down.escape
+    args.state.key_event_occurred = true
+  end
+
+  args.outputs.debug << [0, y - 50, 1280, 60].solid
+  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
+  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
+end
+
+</pre>
+<h1 id='--06_save_load/10_save_load_game/app/main.rb'>06_save_load/10_save_load_game/app/main.rb</h1>
+<pre>=begin
+
+ APIs listing that haven't been encountered in previous sample apps:
+
+ - Symbol (:): Ruby object with a name and an internal ID. Symbols are useful
+   because with a given symbol name, you can refer to the same object throughout
+   a Ruby program.
+
+   In this sample app, we're using symbols for our buttons. We have buttons that
+   light fires, save, load, etc. Each of these buttons has a distinct symbol like
+   :light_fire, :save_game, :load_game, etc.
+
+ - to_sym: Returns the symbol corresponding to the given string; creates the symbol
+   if it does not already exist.
+   For example,
+   'car'.to_sym
+   would return the symbol :car.
+
+ - last: Returns the last element of an array.
+
+ Reminders:
+
+ - num1.lesser(num2): finds the lower value of the given options.
+   For example, in the statement
+   a = 4.lesser(3)
+   3 has a lower value than 4, which means that the value of a would be set to 3,
+   but if the statement had been
+   a = 4.lesser(5)
+   4 has a lower value than 5, which means that the value of a would be set to 4.
+
+ - num1.fdiv(num2): returns the float division (will have a decimal) of the two given numbers.
+   For example, 5.fdiv(2) = 2.5 and 5.fdiv(5) = 1.0
+
+ - String interpolation: uses #{} syntax; everything between the #{ and the } is evaluated
+   as Ruby code, and the placeholder is replaced with its corresponding value or result.
+
+ - args.outputs.labels: An array. Values generate a label.
+   Parameters are [X, Y, TEXT, SIZE, ALIGN, RED, GREEN, BLUE, ALPHA, FONT STYLE]
+   For more information, go to mygame/documentation/02-labels.md.
+
+ - ARRAY#inside_rect?: An array with at least two values is considered a point. An array
+   with at least four values is considered a rect. The inside_rect? function returns true
+   or false depending on if the point is inside the rect.
+
+=end
+
+# This code allows users to perform different tasks, such as saving and loading the game.
+# Users also have options to reset the game and light a fire.
+
+class TextedBasedGame
+
+  # Contains methods needed for game to run properly.
+  # Increments tick count by 1 each time it runs (60 times in a single second)
+  def tick
+    default
+    show_intro
+    state.engine_tick_count += 1
+    tick_fire
+  end
+
+  # Sets default values.
+  # The ||= ensures that a variable's value is only set to the value following the = sign
+  # if the value has not already been set before. Intialization happens only in the first frame.
+  def default
+    state.engine_tick_count ||= 0
+    state.active_module     ||= :room
+    state.fire_progress     ||= 0
+    state.fire_ready_in     ||= 10
+    state.previous_fire     ||= :dead
+    state.fire              ||= :dead
+  end
+
+  def show_intro
+    return unless state.engine_tick_count == 0 # return unless the game just started
+    set_story_line "awake." # calls set_story_line method, sets to "awake"
+  end
+
+  # Sets story line.
+  def set_story_line story_line
+    state.story_line    = story_line # story line set to value of parameter
+    state.active_module = :alert # active module set to alert
+  end
+
+  # Clears story line.
+  def clear_storyline
+    state.active_module = :none # active module set to none
+    state.story_line = nil # story line is cleared, set to nil (or empty)
+  end
+
+  # Determines fire progress (how close the fire is to being ready to light).
+  def tick_fire
+    return if state.active_module == :alert # return if active module is alert
+    state.fire_progress += 1 # increment fire progress
+    # fire_ready_in is 10. The fire_progress is either the current value or 10, whichever has a lower value.
+    state.fire_progress = state.fire_progress.lesser(state.fire_ready_in)
+  end
+
+  # Sets the value of fire (whether it is dead or roaring), and the story line
+  def light_fire
+    return unless fire_ready? # returns unless the fire is ready to be lit
+    state.fire = :roaring # fire is lit, set to roaring
+    state.fire_progress = 0 # the fire progress returns to 0, since the fire has been lit
+    if state.fire != state.previous_fire
+      set_story_line "the fire is #{state.fire}." # the story line is set using string interpolation
+      state.previous_fire = state.fire
+    end
+  end
+
+  # Checks if the fire is ready to be lit. Returns a boolean value.
+  def fire_ready?
+    # If fire_progress (value between 0 and 10) is equal to fire_ready_in (value of 10),
+    # the fire is ready to be lit.
+    state.fire_progress == state.fire_ready_in
+  end
+
+  # Divides the value of the fire_progress variable by 10 to determine how close the user is to
+  # being able to light a fire.
+  def light_fire_progress
+    state.fire_progress.fdiv(10) # float division
+  end
+
+  # Defines fire as the state.fire variable.
+  def fire
+    state.fire
+  end
+
+  # Sets the title of the room.
+  def room_title
+    return "a room that is dark" if state.fire == :dead # room is dark if the fire is dead
+    return "a room that is lit" # room is lit if the fire is not dead
+  end
+
+  # Sets the active_module to room.
+  def go_to_room
+    state.active_module = :room
+  end
+
+  # Defines active_module as the state.active_module variable.
+  def active_module
+    state.active_module
+  end
+
+  # Defines story_line as the state.story_line variable.
+  def story_line
+    state.story_line
+  end
+
+  # Update every 60 frames (or every second)
+  def should_tick?
+    state.tick_count.mod_zero?(60)
+  end
+
+  # Sets the value of the game state provider.
+  def initialize game_state_provider
+    @game_state_provider = game_state_provider
+  end
+
+  # Defines the game state.
+  # Any variable prefixed with an @ symbol is an instance variable.
+  def state
+    @game_state_provider.state
+  end
+
+  # Saves the state of the game in a text file called game_state.txt.
+  def save
+    $gtk.serialize_state('game_state.txt', state)
+  end
+
+  # Loads the game state from the game_state.txt text file.
+  # If the load is unsuccessful, the user is informed since the story line indicates the failure.
+  def load
+    parsed_state = $gtk.deserialize_state('game_state.txt')
+    if !parsed_state
+      set_story_line "no game to load. press save first."
+    else
+      $gtk.args.state = parsed_state
+    end
+  end
+
+  # Resets the game.
+  def reset
+    $gtk.reset
+  end
+end
+
+class TextedBasedGamePresenter
+  attr_accessor :state, :outputs, :inputs
+
+  # Creates empty collection called highlights.
+  # Calls methods necessary to run the game.
+  def tick
+    state.layout.highlights ||= []
+    game.tick if game.should_tick?
+    render
+    process_input
+  end
+
+  # Outputs a label of the tick count (passage of time) and calls all render methods.
+  def render
+    outputs.labels << [10, 30, state.tick_count]
+    render_alert
+    render_room
+    render_highlights
+  end
+
+  # Outputs a label onto the screen that shows the story line, and also outputs a "close" button.
+  def render_alert
+    return unless game.active_module == :alert
+
+    outputs.labels << [640, 480, game.story_line, 5, 1]  # outputs story line label
+    outputs.primitives << button(:alert_dismiss, 490, 380, "close")  # positions "close" button under story line
+  end
+
+  def render_room
+    return unless game.active_module == :room
+    outputs.labels << [640, 700, game.room_title, 4, 1] # outputs room title label at top of screen
+
+    # The parameters for these outputs are (symbol, x, y, text, value/percentage) and each has a y value
+    # that positions it 60 pixels lower than the previous output.
+
+    # outputs the light_fire_progress bar, uses light_fire_progress for its percentage (which changes bar's appearance)
+    outputs.primitives << progress_bar(:light_fire, 490, 600, "light fire", game.light_fire_progress)
+    outputs.primitives << button(       :save_game, 490, 540, "save") # outputs save button
+    outputs.primitives << button(       :load_game, 490, 480, "load") # outputs load button
+    outputs.primitives << button(      :reset_game, 490, 420, "reset") # outputs reset button
+    outputs.labels << [640, 30, "the fire is #{game.fire}", 0, 1] # outputs fire label at bottom of screen
+  end
+
+  # Outputs a collection of highlights using an array to set their values, and also rejects certain values from the collection.
+  def render_highlights
+    state.layout.highlights.each do |h| # for each highlight in the collection
+        h.lifetime -= 1 # decrease the value of its lifetime
+      end
+
+      outputs.solids << state.layout.highlights.map do |h| # outputs highlights collection
+        [h.x, h.y, h.w, h.h, h.color, 255 * h.lifetime / h.max_lifetime] # sets definition for each highlight
+        # transparency changes; divide lifetime by max_lifetime, multiply result by 255
+      end
+
+      # reject highlights from collection that have no remaining lifetime
+      state.layout.highlights = state.layout.highlights.reject { |h| h.lifetime <= 0 }
+  end
+
+  # Checks whether or not a button was clicked.
+  # Returns a boolean value.
+  def process_input
+    button = button_clicked? # calls button_clicked? method
+  end
+
+  # Returns a boolean value.
+  # Finds the button that was clicked from the button list and determines what method to call.
+  # Adds a highlight to the highlights collection.
+  def button_clicked?
+    return nil unless click_pos # return nil unless click_pos holds coordinates of mouse click
+      button = @button_list.find do |k, v| # goes through button_list to find button clicked
+        click_pos.inside_rect? v[:primitives].last.rect # was the mouse clicked inside the rect of button?
+      end
+      return unless button # return unless a button was clicked
+      method_to_call = "#{button[0]}_clicked".to_sym # sets method_to_call to symbol (like :save_game or :load_game)
+      if self.respond_to? method_to_call # returns true if self responds to the given method (method actually exists)
+        border = button[1][:primitives].last # sets border definition using value of last key in button list hash
+
+        # declares each highlight as a new entity, sets properties
+        state.layout.highlights << state.new_entity(:highlight) do |h|
+            h.x = border.x
+            h.y = border.y
+            h.w = border.w
+            h.h = border.h
+            h.max_lifetime = 10
+            h.lifetime = h.max_lifetime
+            h.color = [120, 120, 180] # sets color to shade of purple
+          end
+
+          self.send method_to_call # invoke method identified by symbol
+        else # otherwise, if self doesn't respond to given method
+          border = button[1][:primitives].last # sets border definition using value of last key in hash
+
+          # declares each highlight as a new entity, sets properties
+          state.layout.highlights << state.new_entity(:highlight) do |h|
+            h.x = border.x
+            h.y = border.y
+            h.w = border.w
+            h.h = border.h
+            h.max_lifetime = 4 # different max_lifetime than the one set if respond_to? had been true
+            h.lifetime = h.max_lifetime
+            h.color = [120, 80, 80] # sets color to dark color
+          end
+
+          # instructions for users on how to add the missing method_to_call to the code
+          puts "It looks like #{method_to_call} doesn't exists on TextedBasedGamePresenter. Please add this method:"
+          puts "Just copy the code below and put it in the #{TextedBasedGamePresenter} class definition."
+          puts ""
+          puts "```"
+          puts "class TextedBasedGamePresenter <--- find this class and put the method below in it"
+          puts ""
+          puts "  def #{method_to_call}"
+          puts "    puts 'Yay that worked!'"
+          puts "  end"
+          puts ""
+          puts "end <-- make sure to put the #{method_to_call} method in between the `class` word and the final `end` statement."
+          puts "```"
+          puts ""
+      end
+  end
+
+  # Returns the position of the mouse when it is clicked.
+  def click_pos
+    return nil unless inputs.mouse.click # returns nil unless the mouse was clicked
+    return inputs.mouse.click.point # returns location of mouse click (coordinates)
+  end
+
+  # Creates buttons for the button_list and sets their values using a hash (uses symbols as keys)
+  def button id, x, y, text
+    @button_list[id] ||= { # assigns values to hash keys
+      id: id,
+      text: text,
+      primitives: [
+        [x + 10, y + 30, text, 2, 0].label, # positions label inside border
+        [x, y, 300, 50].border,             # sets definition of border
+      ]
+    }
+
+    @button_list[id][:primitives] # returns label and border for buttons
+  end
+
+  # Creates a progress bar (used for lighting the fire) and sets its values.
+  def progress_bar id, x, y, text, percentage
+    @button_list[id] = { # assigns values to hash keys
+      id: id,
+      text: text,
+      primitives: [
+        [x, y, 300, 50, 100, 100, 100].solid, # sets definition for solid (which fills the bar with gray)
+        [x + 10, y + 30, text, 2, 0].label, # sets definition for label, positions inside border
+        [x, y, 300, 50].border, # sets definition of border
+      ]
+    }
+
+    # Fills progress bar based on percentage. If the fire was ready to be lit (100%) and we multiplied by
+    # 100, only 1/3 of the bar would only be filled in. 200 would cause only 2/3 to be filled in.
+    @button_list[id][:primitives][0][2] = 300 * percentage
+    @button_list[id][:primitives]
+  end
+
+  # Defines the game.
+  def game
+    @game
+  end
+
+  # Initalizes the game and creates an empty list of buttons.
+  def initialize
+    @game = TextedBasedGame.new self
+    @button_list ||= {}
+  end
+
+  # Clears the storyline and takes the user to the room.
+  def alert_dismiss_clicked
+    game.clear_storyline
+    game.go_to_room
+  end
+
+  # Lights the fire when the user clicks the "light fire" option.
+  def light_fire_clicked
+    game.light_fire
+  end
+
+  # Saves the game when the user clicks the "save" option.
+  def save_game_clicked
+    game.save
+  end
+
+  # Resets the game when the user clicks the "reset" option.
+  def reset_game_clicked
+    game.reset
+  end
+
+  # Loads the game when the user clicks the "load" option.
+  def load_game_clicked
+    game.load
+  end
+end
+
+$text_based_rpg = TextedBasedGamePresenter.new
+
+def tick args
+  $text_based_rpg.state = args.state
+  $text_based_rpg.outputs = args.outputs
+  $text_based_rpg.inputs = args.inputs
+  $text_based_rpg.tick
+end
+
+</pre>
+<h1 id='--07_advanced_rendering/01_simple_render_targets/app/main.rb'>07_advanced_rendering/01_simple_render_targets/app/main.rb</h1>
+<pre>def tick args
+  # args.outputs.render_targets are really really powerful.
+  # They essentially allow you to create a sprite programmatically and cache the result.
+
+  # Create a render_target of a :block and a :gradient on tick zero.
+  if args.state.tick_count == 0
+    args.render_target(:block).solids << [0, 0, 1280, 100]
+
+    # The gradient is actually just a collection of black solids with increasing
+    # opacities.
+    args.render_target(:gradient).solids << 90.map_with_index do |x|
+      50.map_with_index do |y|
+        [x * 15, y * 15, 15, 15, 0, 0, 0, (x * 3).fdiv(255) * 255]
+      end
+    end
+  end
+
+  # Take the :block render_target and present it horizontally centered.
+  # Use a subsection of the render_targetd specified by source_x,
+  # source_y, source_w, source_h.
+  args.outputs.sprites << { x: 0,
+                            y: 310,
+                            w: 1280,
+                            h: 100,
+                            path: :block,
+                            source_x: 0,
+                            source_y: 0,
+                            source_w: 1280,
+                            source_h: 100 }
+
+  # After rendering :block, render gradient on top of :block.
+  args.outputs.sprites << [0, 0, 1280, 720, :gradient]
+
+  args.outputs.labels  << [1270, 710, args.gtk.current_framerate, 0, 2, 255, 255, 255]
+  tick_instructions args, "Sample app shows how to use render_targets (programmatically create cached sprites)."
+end
+
+def tick_instructions args, text, y = 715
+  return if args.state.key_event_occurred
+  if args.inputs.mouse.click ||
+     args.inputs.keyboard.directional_vector ||
+     args.inputs.keyboard.key_down.enter ||
+     args.inputs.keyboard.key_down.escape
+    args.state.key_event_occurred = true
+  end
+
+  args.outputs.debug << [0, y - 50, 1280, 60].solid
+  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
+  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
+end
+
+$gtk.reset
+
+</pre>
+<h1 id='--07_advanced_rendering/02_render_targets_with_alphas/app/main.rb'>07_advanced_rendering/02_render_targets_with_alphas/app/main.rb</h1>
+<pre># This sample is meant to show you how to do that dripping transition thing
+#  at the start of the original Doom. Most of this file is here to animate
+#  a scene to wipe away; the actual wipe effect is in the last 20 lines or
+#  so.
+
+$gtk.reset   # reset all game state if reloaded.
+
+def circle_of_blocks pass, xoffset, yoffset, angleoffset, blocksize, distance
+  numblocks = 10
+
+  for i in 1..numblocks do
+    angle = ((360 / numblocks) * i) + angleoffset
+    radians = angle * (Math::PI / 180)
+    x = (xoffset + (distance * Math.cos(radians))).round
+    y = (yoffset + (distance * Math.sin(radians))).round
+    pass.solids << [ x, y, blocksize, blocksize, 255, 255, 0 ]
+  end
+end
+
+def draw_scene args, pass
+  pass.solids << [0, 360, 1280, 360, 0, 0, 200]
+  pass.solids << [0, 0, 1280, 360, 0, 127, 0]
+
+  blocksize = 100
+  angleoffset = args.state.tick_count * 2.5
+  centerx = (1280 - blocksize) / 2
+  centery = (720 - blocksize) / 2
+
+  circle_of_blocks pass, centerx, centery, angleoffset, blocksize * 2, 500
+  circle_of_blocks pass, centerx, centery, angleoffset, blocksize, 325
+  circle_of_blocks pass, centerx, centery, angleoffset, blocksize / 2, 200
+  circle_of_blocks pass, centerx, centery, angleoffset, blocksize / 4, 100
+end
+
+def tick args
+  segments = 160
+
+  # On the first tick, initialize some stuff.
+  if !args.state.yoffsets
+    args.state.baseyoff = 0
+    args.state.yoffsets = []
+    for i in 0..segments do
+      args.state.yoffsets << rand * 100
+    end
+  end
+
+  # Just draw some random stuff for a few seconds.
+  args.state.static_debounce ||= 60 * 2.5
+  if args.state.static_debounce > 0
+    last_frame = args.state.static_debounce == 1
+    target = last_frame ? args.render_target(:last_frame) : args.outputs
+    draw_scene args, target
+    args.state.static_debounce -= 1
+    return unless last_frame
+  end
+
+  # build up the wipe...
+
+  # this is the thing we're wiping to.
+  args.outputs.sprites << [ 0, 0, 1280, 720, 'dragonruby.png' ]
+
+  return if (args.state.baseyoff > (1280 + 100))  # stop when done sliding
+
+  segmentw = 1280 / segments
+
+  x = 0
+  for i in 0..segments do
+    yoffset = 0
+    if args.state.yoffsets[i] < args.state.baseyoff
+      yoffset = args.state.baseyoff - args.state.yoffsets[i]
+    end
+
+    # (720 - yoffset) flips the coordinate system, (- 720) adjusts for the height of the segment.
+    args.outputs.sprites << [ x, (720 - yoffset) - 720, segmentw, 720, 'last_frame', 0, 255, 255, 255, 255, x, 0, segmentw, 720 ]
+    x += segmentw
+  end
+
+  args.state.baseyoff += 4
+
+  tick_instructions args, "Sample app shows an advanced usage of render_target."
+end
+
+def tick_instructions args, text, y = 715
+  return if args.state.key_event_occurred
+  if args.inputs.mouse.click ||
+     args.inputs.keyboard.directional_vector ||
+     args.inputs.keyboard.key_down.enter ||
+     args.inputs.keyboard.key_down.escape
+    args.state.key_event_occurred = true
+  end
+
+  args.outputs.debug << [0, y - 50, 1280, 60].solid
+  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
+  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
+end
+
+</pre>
+<h1 id='--07_advanced_rendering/03_render_target_viewports/app/main.rb'>07_advanced_rendering/03_render_target_viewports/app/main.rb</h1>
+<pre>=begin
+
+ APIs listing that haven't been encountered in previous sample apps:
+
+ - args.state.new_entity: Used when we want to create a new object, like a sprite or button.
+   For example, if we want to create a new button, we would declare it as a new entity and
+   then define its properties. (Remember, you can use state to define ANY property and it will
+   be retained across frames.)
+
+   If you have a solar system and you're creating args.state.sun and setting its image path to an
+   image in the sprites folder, you would do the following:
+   (See samples/99_sample_nddnug_workshop for more details.)
+
+   args.state.sun ||= args.state.new_entity(:sun) do |s|
+   s.path = 'sprites/sun.png'
+   end
+
+ - String interpolation: Uses #{} syntax; everything between the #{ and the } is evaluated
+   as Ruby code, and the placeholder is replaced with its corresponding value or result.
+
+   For example, if we have a variable
+   name = "Ruby"
+   then the line
+   puts "How are you, #{name}?"
+   would print "How are you, Ruby?" to the console.
+   (Remember, string interpolation only works with double quotes!)
+
+ - Ternary operator (?): Similar to if statement; first evalulates whether a statement is
+   true or false, and then executes a command depending on that result.
+   For example, if we had a variable
+   grade = 75
+   and used the ternary operator in the command
+   pass_or_fail = grade > 65 ? "pass" : "fail"
+   then the value of pass_or_fail would be "pass" since grade's value was greater than 65.
+
+ Reminders:
+
+ - args.grid.(left|right|top|bottom): Pixel value for the boundaries of the virtual
+   720 p screen (Dragon Ruby Game Toolkits's virtual resolution is always 1280x720).
+
+ - Numeric#shift_(left|right|up|down): Shifts the Numeric in the correct direction
+   by adding or subracting.
+
+ - ARRAY#inside_rect?: An array with at least two values is considered a point. An array
+   with at least four values is considered a rect. The inside_rect? function returns true
+   or false depending on if the point is inside the rect.
+
+ - ARRAY#intersect_rect?: Returns true or false depending on if the two rectangles intersect.
+
+ - args.inputs.mouse.click: This property will be set if the mouse was clicked.
+   For more information about the mouse, go to mygame/documentation/07-mouse.md.
+
+ - args.inputs.keyboard.key_up.KEY: The value of the properties will be set
+   to the frame  that the key_up event occurred (the frame correlates
+   to args.state.tick_count).
+   For more information about the keyboard, go to mygame/documentation/06-keyboard.md.
+
+ - args.state.labels:
+   The parameters for a label are
+   1. the position (x, y)
+   2. the text
+   3. the size
+   4. the alignment
+   5. the color (red, green, and blue saturations)
+   6. the alpha (or transparency)
+   For more information about labels, go to mygame/documentation/02-labels.md.
+
+ - args.state.lines:
+   The parameters for a line are
+   1. the starting position (x, y)
+   2. the ending position (x2, y2)
+   3. the color (red, green, and blue saturations)
+   4. the alpha (or transparency)
+   For more information about lines, go to mygame/documentation/04-lines.md.
+
+ - args.state.solids (and args.state.borders):
+   The parameters for a solid (or border) are
+   1. the position (x, y)
+   2. the width (w)
+   3. the height (h)
+   4. the color (r, g, b)
+   5. the alpha (or transparency)
+   For more information about solids and borders, go to mygame/documentation/03-solids-and-borders.md.
+
+ - args.state.sprites:
+   The parameters for a sprite are
+   1. the position (x, y)
+   2. the width (w)
+   3. the height (h)
+   4. the image path
+   5. the angle
+   6. the alpha (or transparency)
+   For more information about sprites, go to mygame/documentation/05-sprites.md.
+=end
+
+# This sample app shows different objects that can be used when making games, such as labels,
+# lines, sprites, solids, buttons, etc. Each demo section shows how these objects can be used.
+
+# Also note that state.tick_count refers to the passage of time, or current frame.
+
+class TechDemo
+  attr_accessor :inputs, :state, :outputs, :grid, :args
+
+  # Calls all methods necessary for the app to run properly.
+  def tick
+    labels_tech_demo
+    lines_tech_demo
+    solids_tech_demo
+    borders_tech_demo
+    sprites_tech_demo
+    keyboards_tech_demo
+    controller_tech_demo
+    mouse_tech_demo
+    point_to_rect_tech_demo
+    rect_to_rect_tech_demo
+    button_tech_demo
+    export_game_state_demo
+    window_state_demo
+    render_seperators
+  end
+
+  # Shows output of different kinds of labels on the screen
+  def labels_tech_demo
+    outputs.labels << [grid.left.shift_right(5), grid.top.shift_down(5), "This is a label located at the top left."]
+    outputs.labels << [grid.left.shift_right(5), grid.bottom.shift_up(30), "This is a label located at the bottom left."]
+    outputs.labels << [ 5, 690, "Labels (x, y, text, size, align, r, g, b, a)"]
+    outputs.labels << [ 5, 660, "Smaller label.",  -2]
+    outputs.labels << [ 5, 630, "Small label.",    -1]
+    outputs.labels << [ 5, 600, "Medium label.",    0]
+    outputs.labels << [ 5, 570, "Large label.",     1]
+    outputs.labels << [ 5, 540, "Larger label.",    2]
+    outputs.labels << [300, 660, "Left aligned.",    0, 2]
+    outputs.labels << [300, 640, "Center aligned.",  0, 1]
+    outputs.labels << [300, 620, "Right aligned.",   0, 0]
+    outputs.labels << [175, 595, "Red Label.",       0, 0, 255,   0,   0]
+    outputs.labels << [175, 575, "Green Label.",     0, 0,   0, 255,   0]
+    outputs.labels << [175, 555, "Blue Label.",      0, 0,   0,   0, 255]
+    outputs.labels << [175, 535, "Faded Label.",     0, 0,   0,   0,   0, 128]
+  end
+
+  # Shows output of lines on the screen
+  def lines_tech_demo
+    outputs.labels << [5, 500, "Lines (x, y, x2, y2, r, g, b, a)"]
+    outputs.lines  << [5, 450, 100, 450]
+    outputs.lines  << [5, 430, 300, 430]
+    outputs.lines  << [5, 410, 300, 410, state.tick_count % 255, 0, 0, 255] # red saturation changes
+    outputs.lines  << [5, 390 - state.tick_count % 25, 300, 390, 0, 0, 0, 255] # y position changes
+    outputs.lines  << [5 + state.tick_count % 200, 360, 300, 360, 0, 0, 0, 255] # x position changes
+  end
+
+  # Shows output of different kinds of solids on the screen
+  def solids_tech_demo
+    outputs.labels << [  5, 350, "Solids (x, y, w, h, r, g, b, a)"]
+    outputs.solids << [ 10, 270, 50, 50]
+    outputs.solids << [ 70, 270, 50, 50, 0, 0, 0]
+    outputs.solids << [130, 270, 50, 50, 255, 0, 0]
+    outputs.solids << [190, 270, 50, 50, 255, 0, 0, 128]
+    outputs.solids << [250, 270, 50, 50, 0, 0, 0, 128 + state.tick_count % 128] # transparency changes
+  end
+
+  # Shows output of different kinds of borders on the screen
+  # The parameters for a border are the same as the parameters for a solid
+  def borders_tech_demo
+    outputs.labels <<  [  5, 260, "Borders (x, y, w, h, r, g, b, a)"]
+    outputs.borders << [ 10, 180, 50, 50]
+    outputs.borders << [ 70, 180, 50, 50, 0, 0, 0]
+    outputs.borders << [130, 180, 50, 50, 255, 0, 0]
+    outputs.borders << [190, 180, 50, 50, 255, 0, 0, 128]
+    outputs.borders << [250, 180, 50, 50, 0, 0, 0, 128 + state.tick_count % 128] # transparency changes
+  end
+
+  # Shows output of different kinds of sprites on the screen
+  def sprites_tech_demo
+    outputs.labels <<  [   5, 170, "Sprites (x, y, w, h, path, angle, a)"]
+    outputs.sprites << [  10, 40, 128, 101, 'dragonruby.png']
+    outputs.sprites << [ 150, 40, 128, 101, 'dragonruby.png', state.tick_count % 360] # angle changes
+    outputs.sprites << [ 300, 40, 128, 101, 'dragonruby.png', 0, state.tick_count % 255] # transparency changes
+  end
+
+  # Holds size, alignment, color (black), and alpha (transparency) parameters
+  # Using small_font as a parameter accounts for all remaining parameters
+  # so they don't have to be repeatedly typed
+  def small_font
+    [-2, 0, 0, 0, 0, 255]
+  end
+
+  # Sets position of each row
+  # Converts given row value to pixels that DragonRuby understands
+  def row_to_px row_number
+
+    # Row 0 starts 5 units below the top of the grid.
+    # Each row afterward is 20 units lower.
+    grid.top.shift_down(5).shift_down(20 * row_number)
+  end
+
+  # Uses labels to output current game time (passage of time), and whether or not "h" was pressed
+  # If "h" is pressed, the frame is output when the key_up event occurred
+  def keyboards_tech_demo
+    outputs.labels << [460, row_to_px(0), "Current game time: #{state.tick_count}", small_font]
+    outputs.labels << [460, row_to_px(2), "Keyboard input: inputs.keyboard.key_up.h", small_font]
+    outputs.labels << [460, row_to_px(3), "Press \"h\" on the keyboard.", small_font]
+
+    if inputs.keyboard.key_up.h # if "h" key_up event occurs
+      state.h_pressed_at = state.tick_count # frame it occurred is stored
+    end
+
+    # h_pressed_at is initially set to false, and changes once the user presses the "h" key.
+    state.h_pressed_at ||= false
+
+    if state.h_pressed_at # if h is pressed (pressed_at has a frame number and is no longer false)
+      outputs.labels << [460, row_to_px(4), "\"h\" was pressed at time: #{state.h_pressed_at}", small_font]
+    else # otherwise, label says "h" was never pressed
+      outputs.labels << [460, row_to_px(4), "\"h\" has never been pressed.", small_font]
+    end
+
+    # border around keyboard input demo section
+    outputs.borders << [455, row_to_px(5), 360, row_to_px(2).shift_up(5) - row_to_px(5)]
+  end
+
+  # Sets definition for a small label
+  # Makes it easier to position labels in respect to the position of other labels
+  def small_label x, row, message
+    [x, row_to_px(row), message, small_font]
+  end
+
+  # Uses small labels to show whether the "a" button on the controller is down, held, or up.
+  # y value of each small label is set by calling the row_to_px method
+  def controller_tech_demo
+    x = 460
+    outputs.labels << small_label(x, 6, "Controller one input: inputs.controller_one")
+    outputs.labels << small_label(x, 7, "Current state of the \"a\" button.")
+    outputs.labels << small_label(x, 8, "Check console window for more info.")
+
+    if inputs.controller_one.key_down.a # if "a" is in "down" state
+      outputs.labels << small_label(x, 9, "\"a\" button down: #{inputs.controller_one.key_down.a}")
+      puts "\"a\" button down at #{inputs.controller_one.key_down.a}" # prints frame the event occurred
+    elsif inputs.controller_one.key_held.a # if "a" is held down
+      outputs.labels << small_label(x, 9, "\"a\" button held: #{inputs.controller_one.key_held.a}")
+    elsif inputs.controller_one.key_up.a # if "a" is in up state
+      outputs.labels << small_label(x, 9, "\"a\" button up: #{inputs.controller_one.key_up.a}")
+      puts "\"a\" key up at #{inputs.controller_one.key_up.a}"
+    else # if no event has occurred
+      outputs.labels << small_label(x, 9, "\"a\" button state is nil.")
+    end
+
+    # border around controller input demo section
+    outputs.borders << [455, row_to_px(10), 360, row_to_px(6).shift_up(5) - row_to_px(10)]
+  end
+
+  # Outputs when the mouse was clicked, as well as the coordinates on the screen
+  # of where the click occurred
+  def mouse_tech_demo
+    x = 460
+
+    outputs.labels << small_label(x, 11, "Mouse input: inputs.mouse")
+
+    if inputs.mouse.click # if click has a value and is not nil
+      state.last_mouse_click = inputs.mouse.click # coordinates of click are stored
+    end
+
+    if state.last_mouse_click # if mouse is clicked (has coordinates as value)
+      # outputs the time (frame) the click occurred, as well as how many frames have passed since the event
+      outputs.labels << small_label(x, 12, "Mouse click happened at: #{state.last_mouse_click.created_at}, #{state.last_mouse_click.created_at_elapsed}")
+      # outputs coordinates of click
+      outputs.labels << small_label(x, 13, "Mouse click location: #{state.last_mouse_click.point.x}, #{state.last_mouse_click.point.y}")
+    else # otherwise if the mouse has not been clicked
+      outputs.labels << small_label(x, 12, "Mouse click has not occurred yet.")
+      outputs.labels << small_label(x, 13, "Please click mouse.")
+    end
+  end
+
+  # Outputs whether a mouse click occurred inside or outside of a box
+  def point_to_rect_tech_demo
+    x = 460
+
+    outputs.labels << small_label(x, 15, "Click inside the blue box maybe ---->")
+
+    box = [765, 370, 50, 50, 0, 0, 170] # blue box
+    outputs.borders << box
+
+    if state.last_mouse_click # if the mouse was clicked
+      if state.last_mouse_click.point.inside_rect? box # if mouse clicked inside box
+        outputs.labels << small_label(x, 16, "Mouse click happened inside the box.")
+      else # otherwise, if mouse was clicked outside the box
+        outputs.labels << small_label(x, 16, "Mouse click happened outside the box.")
+      end
+    else # otherwise, if was not clicked at all
+      outputs.labels << small_label(x, 16, "Mouse click has not occurred yet.") # output if the mouse was not clicked
+    end
+
+    # border around mouse input demo section
+    outputs.borders << [455, row_to_px(14), 360, row_to_px(11).shift_up(5) - row_to_px(14)]
+  end
+
+  # Outputs a red box onto the screen. A mouse click from the user inside of the red box will output
+  # a smaller box. If two small boxes are inside of the red box, it will be determined whether or not
+  # they intersect.
+  def rect_to_rect_tech_demo
+    x = 460
+
+    outputs.labels << small_label(x, 17.5, "Click inside the red box below.") # label with instructions
+    red_box = [460, 250, 355, 90, 170, 0, 0] # definition of the red box
+    outputs.borders << red_box # output as a border (not filled in)
+
+    # If the mouse is clicked inside the red box, two collision boxes are created.
+    if inputs.mouse.click
+      if inputs.mouse.click.point.inside_rect? red_box
+        if !state.box_collision_one # if the collision_one box does not yet have a definition
+          # Subtracts 25 from the x and y positions of the click point in order to make the click point the center of the box.
+          # You can try deleting the subtraction to see how it impacts the box placement.
+          state.box_collision_one = [inputs.mouse.click.point.x - 25, inputs.mouse.click.point.y - 25, 50, 50, 180, 0,   0, 180]  # sets definition
+        elsif !state.box_collision_two # if collision_two does not yet have a definition
+          state.box_collision_two = [inputs.mouse.click.point.x - 25, inputs.mouse.click.point.y - 25, 50, 50,   0, 0, 180, 180] # sets definition
+        else
+          state.box_collision_one = nil # both boxes are empty
+          state.box_collision_two = nil
+        end
+      end
+    end
+
+    # If collision boxes exist, they are output onto screen inside the red box as solids
+    if state.box_collision_one
+      outputs.solids << state.box_collision_one
+    end
+
+    if state.box_collision_two
+      outputs.solids << state.box_collision_two
+    end
+
+    # Outputs whether or not the two collision boxes intersect.
+    if state.box_collision_one && state.box_collision_two # if both collision_boxes are defined (and not nil or empty)
+      if state.box_collision_one.intersect_rect? state.box_collision_two # if the two boxes intersect
+        outputs.labels << small_label(x, 23.5, 'The boxes intersect.')
+      else # otherwise, if the two boxes do not intersect
+        outputs.labels << small_label(x, 23.5, 'The boxes do not intersect.')
+      end
+    else
+      outputs.labels << small_label(x, 23.5, '--') # if the two boxes are not defined (are nil or empty), this label is output
+    end
+  end
+
+  # Creates a button and outputs it onto the screen using labels and borders.
+  # If the button is clicked, the color changes to make it look faded.
+  def button_tech_demo
+    x, y, w, h = 460, 160, 300, 50
+    state.button        ||= state.new_entity(:button_with_fade)
+
+    # Adds w.half to x and h.half + 10 to y in order to display the text inside the button's borders.
+    state.button.label  ||= [x + w.half, y + h.half + 10, "click me and watch me fade", 0, 1]
+    state.button.border ||= [x, y, w, h]
+
+    if inputs.mouse.click && inputs.mouse.click.point.inside_rect?(state.button.border) # if mouse is clicked, and clicked inside button's border
+      state.button.clicked_at = inputs.mouse.click.created_at # stores the time the click occurred
+    end
+
+    outputs.labels << state.button.label
+    outputs.borders << state.button.border
+
+    if state.button.clicked_at # if button was clicked (variable has a value and is not nil)
+
+      # The appearance of the button changes for 0.25 seconds after the time the button is clicked at.
+      # The color changes (rgb is set to 0, 180, 80) and the transparency gradually changes.
+      # Change 0.25 to 1.25 and notice that the transparency takes longer to return to normal.
+      outputs.solids << [x, y, w, h, 0, 180, 80, 255 * state.button.clicked_at.ease(0.25.seconds, :flip)]
+    end
+  end
+
+  # Creates a new button by declaring it as a new entity, and sets values.
+  def new_button_prefab x, y, message
+    w, h = 300, 50
+    button        = state.new_entity(:button_with_fade)
+    button.label  = [x + w.half, y + h.half + 10, message, 0, 1] # '+ 10' keeps label's text within button's borders
+    button.border = [x, y, w, h] # sets border definition
+    button
+  end
+
+  # If the mouse has been clicked and the click's location is inside of the button's border, that means
+  # that the button has been clicked. This method returns a boolean value.
+  def button_clicked? button
+    inputs.mouse.click && inputs.mouse.click.point.inside_rect?(button.border)
+  end
+
+  # Determines if button was clicked, and changes its appearance if it is clicked
+  def tick_button_prefab button
+    outputs.labels << button.label # outputs button's label and border
+    outputs.borders << button.border
+
+    if button_clicked? button # if button is clicked
+      button.clicked_at = inputs.mouse.click.created_at # stores the time that the button was clicked
+    end
+
+    if button.clicked_at # if clicked_at has a frame value and is not nil
+      # button is output; color changes and transparency changes for 0.25 seconds after click occurs
+      outputs.solids << [button.border.x, button.border.y, button.border.w, button.border.h,
+                         0, 180, 80, 255 * button.clicked_at.ease(0.25.seconds, :flip)] # transparency changes for 0.25 seconds
+    end
+  end
+
+  # Exports the app's game state if the export button is clicked.
+  def export_game_state_demo
+    state.export_game_state_button ||= new_button_prefab(460, 100, "click to export app state")
+    tick_button_prefab(state.export_game_state_button) # calls method to output button
+    if button_clicked? state.export_game_state_button # if the export button is clicked
+      args.gtk.export! "Exported from clicking the export button in the tech demo." # the export occurs
+    end
+  end
+
+  # The mouse and keyboard focus are set to "yes" when the Dragonruby window is the active window.
+  def window_state_demo
+    m = $gtk.args.inputs.mouse.has_focus ? 'Y' : 'N' # ternary operator (similar to if statement)
+    k = $gtk.args.inputs.keyboard.has_focus ? 'Y' : 'N'
+    outputs.labels << [460, 20, "mouse focus: #{m}   keyboard focus: #{k}", small_font]
+  end
+
+  #Sets values for the horizontal separator (divides demo sections)
+  def horizontal_seperator y, x, x2
+    [x, y, x2, y, 150, 150, 150]
+  end
+
+  #Sets the values for the vertical separator (divides demo sections)
+  def vertical_seperator x, y, y2
+    [x, y, x, y2, 150, 150, 150]
+  end
+
+  # Outputs vertical and horizontal separators onto the screen to separate each demo section.
+  def render_seperators
+    outputs.lines << horizontal_seperator(505, grid.left, 445)
+    outputs.lines << horizontal_seperator(353, grid.left, 445)
+    outputs.lines << horizontal_seperator(264, grid.left, 445)
+    outputs.lines << horizontal_seperator(174, grid.left, 445)
+
+    outputs.lines << vertical_seperator(445, grid.top, grid.bottom)
+
+    outputs.lines << horizontal_seperator(690, 445, 820)
+    outputs.lines << horizontal_seperator(426, 445, 820)
+
+    outputs.lines << vertical_seperator(820, grid.top, grid.bottom)
+  end
+end
+
+$tech_demo = TechDemo.new
+
+def tick args
+  $tech_demo.inputs = args.inputs
+  $tech_demo.state = args.state
+  $tech_demo.grid = args.grid
+  $tech_demo.args = args
+  $tech_demo.outputs = args.render_target(:mini_map)
+  $tech_demo.tick
+  args.outputs.labels  << [830, 715, "Render target:", [-2, 0, 0, 0, 0, 255]]
+  args.outputs.sprites << [0, 0, 1280, 720, :mini_map]
+  args.outputs.sprites << [830, 300, 675, 379, :mini_map]
+  tick_instructions args, "Sample app shows all the rendering apis available."
+end
+
+def tick_instructions args, text, y = 715
+  return if args.state.key_event_occurred
+  if args.inputs.mouse.click ||
+     args.inputs.keyboard.directional_vector ||
+     args.inputs.keyboard.key_down.enter ||
+     args.inputs.keyboard.key_down.escape
+    args.state.key_event_occurred = true
+  end
+
+  args.outputs.debug << [0, y - 50, 1280, 60].solid
+  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
+  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
+end
+
+</pre>
+<h1 id='--07_advanced_rendering/04_render_primitive_hierarchies/app/main.rb'>07_advanced_rendering/04_render_primitive_hierarchies/app/main.rb</h1>
+<pre>=begin
+
+ APIs listing that haven't been encountered in previous sample apps:
+
+ - Nested array: An array whose individual elements are also arrays; useful for
+   storing groups of similar data.  Also called multidimensional arrays.
+
+   In this sample app, we see nested arrays being used in object definitions.
+   Notice the parameters for solids, listed below. Parameters 1-3 set the
+   definition for the rect, and parameter 4 sets the definition of the color.
+
+   Instead of having a solid definition that looks like this,
+   [X, Y, W, H, R, G, B]
+   we can separate it into two separate array definitions in one, like this
+   [[X, Y, W, H], [R, G, B]]
+   and both options work fine in defining our solid (or any object).
+
+ - Collections: Lists of data; useful for organizing large amounts of data.
+   One element of a collection could be an array (which itself contains many elements).
+   For example, a collection that stores two solid objects would look like this:
+   [
+    [100, 100, 50, 50, 0, 0, 0],
+    [100, 150, 50, 50, 255, 255, 255]
+   ]
+   If this collection was added to args.outputs.solids, two solids would be output
+   next to each other, one black and one white.
+   Nested arrays can be used in collections, as you will see in this sample app.
+
+ Reminders:
+
+ - args.outputs.solids: An array. The values generate a solid.
+   The parameters for a solid are
+   1. The position on the screen (x, y)
+   2. The width (w)
+   3. The height (h)
+   4. The color (r, g, b) (if a color is not assigned, the object's default color will be black)
+   NOTE: THE PARAMETERS ARE THE SAME FOR BORDERS!
+
+   Here is an example of a (red) border or solid definition:
+   [100, 100, 400, 500, 255, 0, 0]
+   It will be a solid or border depending on if it is added to args.outputs.solids or args.outputs.borders.
+   For more information about solids and borders, go to mygame/documentation/03-solids-and-borders.md.
+
+ - args.outputs.sprites: An array. The values generate a sprite.
+   The parameters for sprites are
+   1. The position on the screen (x, y)
+   2. The width (w)
+   3. The height (h)
+   4. The image path (p)
+
+   Here is an example of a sprite definition:
+   [100, 100, 400, 500, 'sprites/dragonruby.png']
+   For more information about sprites, go to mygame/documentation/05-sprites.md.
+
+=end
+
+# This code demonstrates the creation and output of objects like sprites, borders, and solids
+# If filled in, they are solids
+# If hollow, they are borders
+# If images, they are sprites
+
+# Solids are added to args.outputs.solids
+# Borders are added to args.outputs.borders
+# Sprites are added to args.outputs.sprites
+
+# The tick method runs 60 frames every second.
+# Your game is going to happen under this one function.
+def tick args
+  border_as_solid_and_solid_as_border args
+  sprite_as_border_or_solids args
+  collection_of_borders_and_solids args
+  collection_of_sprites args
+end
+
+# Shows a border being output onto the screen as a border and a solid
+# Also shows how colors can be set
+def border_as_solid_and_solid_as_border args
+  border = [0, 0, 50, 50]
+  args.outputs.borders << border
+  args.outputs.solids  << border
+
+  # Red, green, blue saturations (last three parameters) can be any number between 0 and 255
+  border_with_color = [0, 100, 50, 50, 255, 0, 0]
+  args.outputs.borders << border_with_color
+  args.outputs.solids  << border_with_color
+
+  border_with_nested_color = [0, 200, 50, 50, [0, 255, 0]] # nested color
+  args.outputs.borders << border_with_nested_color
+  args.outputs.solids  << border_with_nested_color
+
+  border_with_nested_rect = [[0, 300, 50, 50], 0, 0, 255] # nested rect
+  args.outputs.borders << border_with_nested_rect
+  args.outputs.solids  << border_with_nested_rect
+
+  border_with_nested_color_and_rect = [[0, 400, 50, 50], [255, 0, 255]] # nested rect and color
+  args.outputs.borders << border_with_nested_color_and_rect
+  args.outputs.solids  << border_with_nested_color_and_rect
+end
+
+# Shows a sprite output onto the screen as a sprite, border, and solid
+# Demonstrates that all three outputs appear differently on screen
+def sprite_as_border_or_solids args
+  sprite = [100, 0, 50, 50, 'sprites/ship.png']
+  args.outputs.sprites << sprite
+
+  # Sprite_as_border variable has same parameters (excluding position) as above object,
+  # but will appear differently on screen because it is added to args.outputs.borders
+  sprite_as_border = [100, 100, 50, 50, 'sprites/ship.png']
+  args.outputs.borders << sprite_as_border
+
+  # Sprite_as_solid variable has same parameters (excluding position) as above object,
+  # but will appear differently on screen because it is added to args.outputs.solids
+  sprite_as_solid = [100, 200, 50, 50, 'sprites/ship.png']
+  args.outputs.solids << sprite_as_solid
+end
+
+# Holds and outputs a collection of borders and a collection of solids
+# Collections are created by using arrays to hold parameters of each individual object
+def collection_of_borders_and_solids args
+  collection_borders = [
+    [
+      [200,  0, 50, 50],                    # black border
+      [200,  100, 50, 50, 255, 0, 0],       # red border
+      [200,  200, 50, 50, [0, 255, 0]],     # nested color
+    ],
+    [[200, 300, 50, 50], 0, 0, 255],        # nested rect
+    [[200, 400, 50, 50], [255, 0, 255]]     # nested rect and nested color
+  ]
+
+  args.outputs.borders << collection_borders
+
+  collection_solids = [
+    [
+      [[300, 300, 50, 50], 0, 0, 255],      # nested rect
+      [[300, 400, 50, 50], [255, 0, 255]]   # nested rect and nested color
+    ],
+    [300,  0, 50, 50],
+    [300,  100, 50, 50, 255, 0, 0],
+    [300,  200, 50, 50, [0, 255, 0]],       # nested color
+  ]
+
+  args.outputs.solids << collection_solids
+end
+
+# Holds and outputs a collection of sprites by adding it to args.outputs.sprites
+# Also outputs a collection with same parameters (excluding position) by adding
+# it to args.outputs.solids and another to args.outputs.borders
+def collection_of_sprites args
+  sprites_collection = [
+    [
+      [400, 0, 50, 50, 'sprites/ship.png'],
+      [400, 100, 50, 50, 'sprites/ship.png'],
+    ],
+    [400, 200, 50, 50, 'sprites/ship.png']
+  ]
+
+  args.outputs.sprites << sprites_collection
+
+  args.outputs.solids << [
+    [500, 0, 50, 50, 'sprites/ship.png'],
+    [500, 100, 50, 50, 'sprites/ship.png'],
+    [[[500, 200, 50, 50, 'sprites/ship.png']]]
+  ]
+
+  args.outputs.borders << [
+    [
+      [600, 0, 50, 50, 'sprites/ship.png'],
+      [600, 100, 50, 50, 'sprites/ship.png'],
+    ],
+    [600, 200, 50, 50, 'sprites/ship.png']
+  ]
+end
+
+</pre>
+<h1 id='--07_advanced_rendering/11_render_primitives_as_hash/app/main.rb'>07_advanced_rendering/11_render_primitives_as_hash/app/main.rb</h1>
+<pre>=begin
+
+ Reminders:
+
+ - Hashes: Collection of unique keys and their corresponding values. The value can be found
+   using their keys.
+
+   For example, if we have a "numbers" hash that stores numbers in English as the
+   key and numbers in Spanish as the value, we'd have a hash that looks like this...
+   numbers = { "one" => "uno", "two" => "dos", "three" => "tres" }
+   and on it goes.
+
+   Now if we wanted to find the corresponding value of the "one" key, we could say
+   puts numbers["one"]
+   which would print "uno" to the console.
+
+ - args.outputs.sprites: An array. The values generate a sprite.
+   The parameters are [X, Y, WIDTH, HEIGHT, PATH, ANGLE, ALPHA, RED, GREEN, BLUE]
+   For more information about sprites, go to mygame/documentation/05-sprites.md.
+
+ - args.outputs.labels: An array. The values generate a label.
+   The parameters are [X, Y, TEXT, SIZE, ALIGNMENT, RED, GREEN, BLUE, ALPHA, FONT STYLE]
+   For more information about labels, go to mygame/documentation/02-labels.md.
+
+ - args.outputs.solids: An array. The values generate a solid.
+   The parameters are [X, Y, WIDTH, HEIGHT, RED, GREEN, BLUE, ALPHA]
+   For more information about solids, go to mygame/documentation/03-solids-and-borders.md.
+
+ - args.outputs.borders: An array. The values generate a border.
+   The parameters are the same as a solid.
+   For more information about borders, go to mygame/documentation/03-solids-and-borders.md.
+
+ - args.outputs.lines: An array. The values generate a line.
+   The parameters are [X1, Y1, X2, Y2, RED, GREEN, BLUE]
+   For more information about labels, go to mygame/documentation/02-labels.md.
+
+=end
+
+# This sample app demonstrates how hashes can be used to output different kinds of objects.
+
+def tick args
+  args.state.angle ||= 0 # initializes angle to 0
+  args.state.angle  += 1 # increments angle by 1 every frame (60 times a second)
+
+  # Outputs sprite using a hash
+  args.outputs.sprites << {
+    x: 30,                          # sprite position
+    y: 550,
+    w: 128,                         # sprite size
+    h: 101,
+    path: "dragonruby.png",         # image path
+    angle: args.state.angle,        # angle
+    a: 255,                         # alpha (transparency)
+    r: 255,                         # color saturation
+    g: 255,
+    b: 255,
+    tile_x:  0,                     # sprite sub division/tile
+    tile_y:  0,
+    tile_w: -1,
+    tile_h: -1,
+    flip_vertically: false,         # don't flip sprite
+    flip_horizontally: false,
+    angle_anchor_x: 0.5,            # rotation center set to middle
+    angle_anchor_y: 0.5
+  }
+
+  # Outputs label using a hash
+  args.outputs.labels << {
+    x:              200,                 # label position
+    y:              550,
+    text:           "dragonruby",        # label text
+    size_enum:      2,
+    alignment_enum: 1,
+    r:              155,                 # color saturation
+    g:              50,
+    b:              50,
+    a:              255,                 # transparency
+    font:           "fonts/manaspc.ttf"  # font style; without mentioned file, label won't output correctly
+  }
+
+  # Outputs solid using a hash
+  # [X, Y, WIDTH, HEIGHT, RED, GREEN, BLUE, ALPHA]
+  args.outputs.solids << {
+    x: 400,                         # position
+    y: 550,
+    w: 160,                         # size
+    h:  90,
+    r: 120,                         # color saturation
+    g:  50,
+    b:  50,
+    a: 255                          # transparency
+  }
+
+  # Outputs border using a hash
+  # Same parameters as a solid
+  args.outputs.borders << {
+    x: 600,
+    y: 550,
+    w: 160,
+    h:  90,
+    r: 120,
+    g:  50,
+    b:  50,
+    a: 255
+  }
+
+  # Outputs line using a hash
+  args.outputs.lines << {
+    x:  900,                        # starting position
+    y:  550,
+    x2: 1200,                       # ending position
+    y2: 550,
+    r:  120,                        # color saturation
+    g:   50,
+    b:   50,
+    a:  255                         # transparency
+  }
+
+  # Outputs sprite as a primitive using a hash
+  args.outputs.primitives << {
+    x: 30,                          # position
+    y: 200,
+    w: 128,                         # size
+    h: 101,
+    path: "dragonruby.png",         # image path
+    angle: args.state.angle,        # angle
+    a: 255,                         # transparency
+    r: 255,                         # color saturation
+    g: 255,
+    b: 255,
+    tile_x:  0,                     # sprite sub division/tile
+    tile_y:  0,
+    tile_w: -1,
+    tile_h: -1,
+    flip_vertically: false,         # don't flip
+    flip_horizontally: false,
+    angle_anchor_x: 0.5,            # rotation center set to middle
+    angle_anchor_y: 0.5
+  }.sprite
+
+  # Outputs label as primitive using a hash
+  args.outputs.primitives << {
+    x:         200,                 # position
+    y:         200,
+    text:      "dragonruby",        # text
+    size:      2,
+    alignment: 1,
+    r:         155,                 # color saturation
+    g:         50,
+    b:         50,
+    a:         255,                 # transparency
+    font:      "fonts/manaspc.ttf"  # font style
+  }.label
+
+  # Outputs solid as primitive using a hash
+  args.outputs.primitives << {
+    x: 400,                         # position
+    y: 200,
+    w: 160,                         # size
+    h:  90,
+    r: 120,                         # color saturation
+    g:  50,
+    b:  50,
+    a: 255                          # transparency
+  }.solid
+
+  # Outputs border as primitive using a hash
+  # Same parameters as solid
+  args.outputs.primitives << {
+    x: 600,                         # position
+    y: 200,
+    w: 160,                         # size
+    h:  90,
+    r: 120,                         # color saturation
+    g:  50,
+    b:  50,
+    a: 255                          # transparency
+  }.border
+
+  # Outputs line as primitive using a hash
+  args.outputs.primitives << {
+    x:  900,                        # starting position
+    y:  200,
+    x2: 1200,                       # ending position
+    y2: 200,
+    r:  120,                        # color saturation
+    g:   50,
+    b:   50,
+    a:  255                         # transparency
+  }.line
+end
+
+</pre>
+<h1 id='--08_lerping_easing_functions/01_easing_functions/app/main.rb'>08_lerping_easing_functions/01_easing_functions/app/main.rb</h1>
+<pre>def tick args
+  # STOP! Watch the following presentation first!!!!
+  # Math for Game Programmers: Fast and Funky 1D Nonlinear Transformations
+  # https://www.youtube.com/watch?v=mr5xkf6zSzk
+
+  # You've watched the talk, yes? YES???
+
+  # define starting and ending points of properties to animate
+  args.state.target_x = 1180
+  args.state.target_y = 620
+  args.state.target_w = 100
+  args.state.target_h = 100
+  args.state.starting_x = 0
+  args.state.starting_y = 0
+  args.state.starting_w = 300
+  args.state.starting_h = 300
+
+  # define start time and duration of animation
+  args.state.start_animate_at = 3.seconds # this is the same as writing 60 * 5 (or 300)
+  args.state.duration = 2.seconds # this is the same as writing 60 * 2 (or 120)
+
+  # define type of animations
+  # Here are all the options you have for values you can put in the array:
+  # :identity, :quad, :cube, :quart, :quint, :flip
+
+  # Linear is defined as:
+  # [:identity]
+  #
+  # Smooth start variations are:
+  # [:quad]
+  # [:cube]
+  # [:quart]
+  # [:quint]
+
+  # Linear reversed, and smooth stop are the same as the animations defined above, but reversed:
+  # [:flip, :identity]
+  # [:flip, :quad, :flip]
+  # [:flip, :cube, :flip]
+  # [:flip, :quart, :flip]
+  # [:flip, :quint, :flip]
+
+  # You can also do custom definitions. See the bottom of the file details
+  # on how to do that. I've defined a couple for you:
+  # [:smoothest_start]
+  # [:smoothest_stop]
+
+  # CHANGE THIS LINE TO ONE OF THE LINES ABOVE TO SEE VARIATIONS
+  args.state.animation_type = [:identity]
+  # args.state.animation_type = [:quad]
+  # args.state.animation_type = [:cube]
+  # args.state.animation_type = [:quart]
+  # args.state.animation_type = [:quint]
+  # args.state.animation_type = [:flip, :identity]
+  # args.state.animation_type = [:flip, :quad, :flip]
+  # args.state.animation_type = [:flip, :cube, :flip]
+  # args.state.animation_type = [:flip, :quart, :flip]
+  # args.state.animation_type = [:flip, :quint, :flip]
+  # args.state.animation_type = [:smoothest_start]
+  # args.state.animation_type = [:smoothest_stop]
+
+  # THIS IS WHERE THE MAGIC HAPPENS!
+  # Numeric#ease
+  progress = args.state.start_animate_at.ease(args.state.duration, args.state.animation_type)
+
+  # Numeric#ease needs to called:
+  # 1. On the number that represents the point in time you want to start, and takes two parameters:
+  #   a. The first parameter is how long the animation should take.
+  #   b. The second parameter represents the functions that need to be called.
+  #
+  # For example, if I wanted an animate to start 3 seconds in, and last for 10 seconds,
+  # and I want to animation to start fast and end slow, I would do:
+  # (60 * 3).ease(60 * 10, :flip, :quint, :flip)
+
+  #        initial value           delta to the final value
+  calc_x = args.state.starting_x + (args.state.target_x - args.state.starting_x) * progress
+  calc_y = args.state.starting_y + (args.state.target_y - args.state.starting_y) * progress
+  calc_w = args.state.starting_w + (args.state.target_w - args.state.starting_w) * progress
+  calc_h = args.state.starting_h + (args.state.target_h - args.state.starting_h) * progress
+
+  args.outputs.solids << [calc_x, calc_y, calc_w, calc_h, 0, 0, 0]
+
+  # count down
+  count_down = args.state.start_animate_at - args.state.tick_count
+  if count_down > 0
+    args.outputs.labels << [640, 375, "Running: #{args.state.animation_type} in...", 3, 1]
+    args.outputs.labels << [640, 345, "%.2f" % count_down.fdiv(60), 3, 1]
+  elsif progress >= 1
+    args.outputs.labels << [640, 360, "Click screen to reset.", 3, 1]
+    if args.inputs.click
+      $gtk.reset
+    end
+  end
+end
+
+# $gtk.reset
+
+# you can make own variations of animations using this
+module Easing
+  # you have access to all the built in functions: identity, flip, quad, cube, quart, quint
+  def self.smoothest_start x
+    quad(quint(x))
+  end
+
+  def self.smoothest_stop x
+    flip(quad(quint(flip(x))))
+  end
+
+  # this is the source for the existing easing functions
+  def self.identity x
+    x
+  end
+
+  def self.flip x
+    1 - x
+  end
+
+  def self.quad x
+    x * x
+  end
+
+  def self.cube x
+    x * x * x
+  end
+
+  def self.quart x
+    x * x * x * x * x
+  end
+
+  def self.quint x
+    x * x * x * x * x * x
+  end
+end
+
+</pre>
+<h1 id='--08_lerping_easing_functions/02_cubic_bezier/app/main.rb'>08_lerping_easing_functions/02_cubic_bezier/app/main.rb</h1>
+<pre>def tick args
+  args.outputs.background_color = [33, 33, 33]
+  args.outputs.lines << bezier(100, 100,
+                               100, 620,
+                               1180, 620,
+                               1180, 100,
+                               0)
+
+  args.outputs.lines << bezier(100, 100,
+                               100, 620,
+                               1180, 620,
+                               1180, 100,
+                               20)
+end
+
+
+def bezier x1, y1, x2, y2, x3, y3, x4, y4, step
+  step ||= 0
+  color = [200, 200, 200]
+  points = points_for_bezier [x1, y1], [x2, y2], [x3, y3], [x4, y4], step
+
+  points.each_cons(2).map do |p1, p2|
+    [p1, p2, color]
+  end
+end
+
+def points_for_bezier p1, p2, p3, p4, step
+  points = []
+  if step == 0
+    [p1, p2, p3, p4]
+  else
+    t_step = 1.fdiv(step + 1)
+    t = 0
+    t += t_step
+    points = []
+    while t < 1
+      points << [
+        b_for_t(p1.x, p2.x, p3.x, p4.x, t),
+        b_for_t(p1.y, p2.y, p3.y, p4.y, t),
+      ]
+      t += t_step
+    end
+
+    [
+      p1,
+      *points,
+      p4
+    ]
+  end
+end
+
+def b_for_t v0, v1, v2, v3, t
+  pow(1 - t, 3) * v0 +
+  3 * pow(1 - t, 2) * t * v1 +
+  3 * (1 - t) * pow(t, 2) * v2 +
+  pow(t, 3) * v3
+end
+
+def pow n, to
+  n ** to
+end
+
+</pre>
+<h1 id='--08_lerping_easing_functions/03_easing_using_spline/app/main.rb'>08_lerping_easing_functions/03_easing_using_spline/app/main.rb</h1>
+<pre>def tick args
+  args.state.duration = 10.seconds
+  args.state.spline = [
+    [0.0, 0.33, 0.66, 1.0],
+    [1.0, 1.0,  1.0,  1.0],
+    [1.0, 0.66, 0.33, 0.0],
+  ]
+
+  args.state.simulation_tick = args.state.tick_count % args.state.duration
+  progress = 0.ease_spline_extended args.state.simulation_tick, args.state.duration, args.state.spline
+  args.outputs.borders << args.grid.rect
+  args.outputs.solids << [20 + 1240 * progress,
+                          20 +  680 * progress,
+                          20, 20].anchor_rect(0.5, 0.5)
+  args.outputs.labels << [10,
+                          710,
+                          "perc: #{"%.2f" % (args.state.simulation_tick / args.state.duration)} t: #{args.state.simulation_tick}"]
+end
+
+</pre>
+<h1 id='--08_lerping_easing_functions/04_parametric_enemy_movement/app/main.rb'>08_lerping_easing_functions/04_parametric_enemy_movement/app/main.rb</h1>
+<pre>def new_star args
+  { x: 1280.randomize(:ratio),
+    starting_y: 800,
+    distance_to_travel: 900 + 100.randomize(:ratio),
+    duration: 100.randomize(:ratio) + 60,
+    created_at: args.state.tick_count,
+    max_alpha: 128.randomize(:ratio) + 128,
+    b: 255.randomize(:ratio),
+    g: 200.randomize(:ratio),
+    w: 1.randomize(:ratio) + 1,
+    h: 1.randomize(:ratio) + 1 }
+end
+
+def new_enemy args
+  { x: 1280.randomize(:ratio),
+    starting_y: 800,
+    distance_to_travel: -900,
+    duration: 60.randomize(:ratio) + 180,
+    created_at: args.state.tick_count,
+    w: 32,
+    h: 32,
+    fire_rate: (30.randomize(:ratio) + (60 - args.state.score)).to_i }
+end
+
+def new_bullet args, starting_x, starting_y, enemy_speed
+  { x: starting_x,
+    starting_y: starting_y,
+    distance_to_travel: -900,
+    created_at: args.state.tick_count,
+    duration: 900 / (enemy_speed.abs + 2.0 + (5.0 * args.state.score.fdiv(100))).abs,
+    w: 5,
+    h: 5 }
+end
+
+def new_player_bullet args, starting_x, starting_y, player_speed
+  { x: starting_x,
+    starting_y: starting_y,
+    distance_to_travel: 900,
+    created_at: args.state.tick_count,
+    duration: 900 / (player_speed + 2.0),
+    w: 5,
+    h: 5 }
+end
+
+def defaults args
+  args.outputs.background_color  = [0, 0, 0]
+  args.state.score             ||= 0
+  args.state.stars             ||= []
+  args.state.enemies           ||= []
+  args.state.bullets           ||= []
+  args.state.player_bullets    ||= []
+  args.state.max_stars           = 50
+  args.state.max_enemies         = 10
+  args.state.player.x          ||= 640
+  args.state.player.y          ||= 100
+  args.state.player.w          ||= 32
+  args.state.player.h          ||= 32
+
+  if args.state.tick_count == 0
+    args.state.stars.clear
+    args.state.max_stars.times do
+      s = new_star args
+      s[:created_at] += s[:duration].randomize(:ratio)
+      args.state.stars << s
+    end
+  end
+
+  if args.state.tick_count == 0
+    args.state.enemies.clear
+    args.state.max_enemies.times do
+      s = new_enemy args
+      s[:created_at] += s[:duration].randomize(:ratio)
+      args.state.enemies << s
+    end
+  end
+end
+
+def input args
+  if args.inputs.keyboard.left
+    args.state.player.x -= 5
+  elsif args.inputs.keyboard.right
+    args.state.player.x += 5
+  end
+
+  if args.inputs.keyboard.up
+    args.state.player.y += 5
+  elsif args.inputs.keyboard.down
+    args.state.player.y -= 5
+  end
+
+  if args.inputs.keyboard.key_down.space
+    args.state.player_bullets << new_player_bullet(args,
+                                                   args.state.player.x + args.state.player.w.half,
+                                                   args.state.player.y + args.state.player.h, 5)
+  end
+
+  args.state.player.y = args.state.player.y.greater(0).lesser(720 - args.state.player.w)
+  args.state.player.x = args.state.player.x.greater(0).lesser(1280 - args.state.player.h)
+end
+
+def completed? entity
+  (entity[:created_at] + entity[:duration]).elapsed_time > 0
+end
+
+def calc_stars args
+  if (stars_to_add = args.state.max_stars - args.state.stars.length) > 0
+    stars_to_add.times { args.state.stars << new_star(args) }
+  end
+  args.state.stars = args.state.stars.reject { |s| completed? s }
+end
+
+def move_enemies args
+  if (enemies_to_add = args.state.max_enemies - args.state.enemies.length) > 0
+    enemies_to_add.times { args.state.enemies << new_enemy(args) }
+  end
+
+  args.state.enemies = args.state.enemies.reject { |s| completed? s }
+end
+
+def move_bullets args
+  args.state.enemies.each do |e|
+    if args.state.tick_count.mod_zero?(e[:fire_rate])
+      args.state.bullets << new_bullet(args, e[:x] + e[:w].half, current_y(e), e[:distance_to_travel] / e[:duration])
+    end
+  end
+
+  args.state.bullets = args.state.bullets.reject { |s| completed? s }
+  args.state.player_bullets = args.state.player_bullets.reject { |s| completed? s }
+end
+
+def intersect? entity_one, entity_two
+  entity_one.merge(y: current_y(entity_one))
+            .intersect_rect? entity_two.merge(y: current_y(entity_two))
+end
+
+def kill args
+  bullets_hitting_enemies = []
+  dead_bullets = []
+  dead_enemies = []
+
+  args.state.player_bullets.each do |b|
+    args.state.enemies.each do |e|
+      if intersect? b, e
+        dead_bullets << b
+        dead_enemies << e
+      end
+    end
+  end
+
+  args.state.score += dead_enemies.length
+
+  args.state.player_bullets.reject! { |b| dead_bullets.include? b }
+  args.state.enemies.reject! { |e| dead_enemies.include? e }
+
+  dead = args.state.bullets.any? do |b|
+    [args.state.player.x,
+     args.state.player.y,
+     args.state.player.w,
+     args.state.player.h].intersect_rect? b.merge(y: current_y(b))
+  end
+  return unless dead
+  args.gtk.reset
+  defaults args
+end
+
+def calc args
+  calc_stars args
+  move_enemies args
+  move_bullets args
+  kill args
+end
+
+def current_y entity
+  entity[:starting_y] + (entity[:distance_to_travel] * entity[:created_at].ease(entity[:duration], :identity))
+end
+
+def render args
+  args.outputs.solids << args.state.stars.map do |s|
+    [s[:x],
+     current_y(s),
+     s[:w], s[:h], 0, s[:g], s[:b], s[:max_alpha] * s[:created_at].ease(20, :identity)]
+  end
+
+  args.outputs.borders << args.state.enemies.map do |s|
+    [s[:x],
+     current_y(s),
+     s[:w], s[:h], 255, 0, 0]
+  end
+
+  args.outputs.borders << args.state.bullets.map do |b|
+    [b[:x],
+     current_y(b),
+     b[:w], b[:h], 255, 0, 0]
+  end
+
+  args.outputs.borders << args.state.player_bullets.map do |b|
+    [b[:x],
+     current_y(b),
+     b[:w], b[:h], 255, 255, 255]
+  end
+
+  args.borders << [args.state.player.x,
+                   args.state.player.y,
+                   args.state.player.w,
+                   args.state.player.h, 255, 255, 255]
+end
+
+def tick args
+  defaults args
+  input args
+  calc args
+  render args
+end
+
+</pre>
+<h1 id='--09_performance/01_sprites_as_hash/app/main.rb'>09_performance/01_sprites_as_hash/app/main.rb</h1>
+<pre># Sprites represented as Hashes using the queue ~args.outputs.sprites~
+# code up, but are the "slowest" to render.
+# The reason for this is the access of the key in the Hash and also
+# because the data args.outputs.sprites is cleared every tick.
+def random_x args
+  (args.grid.w.randomize :ratio) * -1
+end
+
+def random_y args
+  (args.grid.h.randomize :ratio) * -1
+end
+
+def random_speed
+  1 + (4.randomize :ratio)
+end
+
+def new_star args
+  {
+    x: (random_x args),
+    y: (random_y args),
+    w: 4, h: 4, path: 'sprites/tiny-star.png',
+    s: random_speed
+  }
+end
+
+def move_star args, star
+  star.x += star[:s]
+  star.y += star[:s]
+  if star.x > args.grid.w || star.y > args.grid.h
+    star.x = (random_x args)
+    star.y = (random_y args)
+    star[:s] = random_speed
+  end
+end
+
+def tick args
+  args.state.star_count ||= 0
+
+  # sets console command when sample app initially opens
+  if Kernel.global_tick_count == 0
+    puts "* INFO - Please specify the number of sprites to render."
+    args.gtk.console.set_command "reset_with count: 100"
+  end
+
+  # init
+  if args.state.tick_count == 0
+    args.state.stars = args.state.star_count.map { |i| new_star args }
+  end
+
+  # update
+  args.state.stars.each { |s| move_star args, s }
+
+  # render
+  args.outputs.sprites << args.state.stars
+  args.outputs.background_color = [0, 0, 0]
+  args.outputs.primitives << args.gtk.current_framerate_primitives
+end
+
+# resets game, and assigns star count given by user
+def reset_with count: count
+  $gtk.reset
+  $gtk.args.state.star_count = count
+end
+
+</pre>
+<h1 id='--09_performance/02_sprites_as_entities/app/main.rb'>09_performance/02_sprites_as_entities/app/main.rb</h1>
+<pre># Sprites represented as Entities using the queue ~args.outputs.sprites~
+# yields nicer access apis over Hashes, but require a bit more code upfront.
+# The hash sample has to use star[:s] to get the speed of the star, but
+# an entity can use .s instead.
+def random_x args
+  (args.grid.w.randomize :ratio) * -1
+end
+
+def random_y args
+  (args.grid.h.randomize :ratio) * -1
+end
+
+def random_speed
+  1 + (4.randomize :ratio)
+end
+
+def new_star args
+  args.state.new_entity :star, {
+    x: (random_x args),
+    y: (random_y args),
+    w: 4, h: 4,
+    path: 'sprites/tiny-star.png',
+    s: random_speed
+  }
+end
+
+def move_star args, star
+  star.x += star.s
+  star.y += star.s
+  if star.x > args.grid.w || star.y > args.grid.h
+    star.x = (random_x args)
+    star.y = (random_y args)
+    star.s = random_speed
+  end
+end
+
+def tick args
+  args.state.star_count ||= 0
+
+  # sets console command when sample app initially opens
+  if Kernel.global_tick_count == 0
+    puts "* INFO - Please specify the number of sprites to render."
+    args.gtk.console.set_command "reset_with count: 100"
+  end
+
+  # init
+  if args.state.tick_count == 0
+    args.state.stars = args.state.star_count.map { |i| new_star args }
+  end
+
+  # update
+  args.state.stars.each { |s| move_star args, s }
+
+  # render
+  args.outputs.sprites << args.state.stars
+  args.outputs.background_color = [0, 0, 0]
+  args.outputs.primitives << args.gtk.current_framerate_primitives
+end
+
+# resets game, and assigns star count given by user
+def reset_with count: count
+  $gtk.reset
+  $gtk.args.state.star_count = count
+end
+
+</pre>
+<h1 id='--09_performance/03_sprites_as_strict_entities/app/main.rb'>09_performance/03_sprites_as_strict_entities/app/main.rb</h1>
+<pre># Sprites represented as StrictEntities using the queue ~args.outputs.sprites~
+# yields apis access similar to Entities, but all properties that can be set on the
+# entity must be predefined with a default value. Strict entities do not support the
+# addition of new properties after the fact. They are more performant than OpenEntities
+# because of this constraint.
+def random_x args
+  (args.grid.w.randomize :ratio) * -1
+end
+
+def random_y args
+  (args.grid.h.randomize :ratio) * -1
+end
+
+def random_speed
+  1 + (4.randomize :ratio)
+end
+
+def new_star args
+  args.state.new_entity_strict(:star,
+                               x: (random_x args),
+                               y: (random_y args),
+                               w: 4, h: 4,
+                               path: 'sprites/tiny-star.png',
+                               s: random_speed) do |entity|
+    # invoke attr_sprite so that it responds to
+    # all properties that are required to render a sprite
+    entity.attr_sprite
+  end
+end
+
+def move_star args, star
+  star.x += star.s
+  star.y += star.s
+  if star.x > args.grid.w || star.y > args.grid.h
+    star.x = (random_x args)
+    star.y = (random_y args)
+    star.s = random_speed
+  end
+end
+
+def tick args
+  args.state.star_count ||= 0
+
+  # sets console command when sample app initially opens
+  if Kernel.global_tick_count == 0
+    puts "* INFO - Please specify the number of sprites to render."
+    args.gtk.console.set_command "reset_with count: 100"
+  end
+
+  # init
+  if args.state.tick_count == 0
+    args.state.stars = args.state.star_count.map { |i| new_star args }
+  end
+
+  # update
+  args.state.stars.each { |s| move_star args, s }
+
+  # render
+  args.outputs.sprites << args.state.stars
+  args.outputs.background_color = [0, 0, 0]
+  args.outputs.primitives << args.gtk.current_framerate_primitives
+end
+
+# resets game, and assigns star count given by user
+def reset_with count: count
+  $gtk.reset
+  $gtk.args.state.star_count = count
+end
+
+</pre>
+<h1 id='--09_performance/04_sprites_as_classes/app/main.rb'>09_performance/04_sprites_as_classes/app/main.rb</h1>
+<pre># Sprites represented as Classes using the queue ~args.outputs.sprites~.
+# gives you full control of property declaration and method invocation.
+# They are more performant than OpenEntities and StrictEntities, but more code upfront.
+class Star
+  attr_sprite
+
+  def initialize grid
+    @grid = grid
+    @x = (rand @grid.w) * -1
+    @y = (rand @grid.h) * -1
+    @w    = 4
+    @h    = 4
+    @s    = 1 + (4.randomize :ratio)
+    @path = 'sprites/tiny-star.png'
+  end
+
+  def move
+    @x += @s
+    @y += @s
+    @x = (rand @grid.w) * -1 if @x > @grid.right
+    @y = (rand @grid.h) * -1 if @y > @grid.top
+  end
+end
+
+# calls methods needed for game to run properly
+def tick args
+  # sets console command when sample app initially opens
+  if Kernel.global_tick_count == 0
+    args.gtk.console.set_command "reset_with count: 100"
+  end
+
+  # init
+  if args.state.tick_count == 0
+    args.state.stars = args.state.star_count.map { |i| Star.new args.grid }
+  end
+
+  # update
+  args.state.stars.each(&:move)
+
+  # render
+  args.outputs.sprites << args.state.stars
+  args.outputs.background_color = [0, 0, 0]
+  args.outputs.primitives << args.gtk.current_framerate_primitives
+end
+
+# resets game, and assigns star count given by user
+def reset_with count: count
+  $gtk.reset
+  $gtk.args.state.star_count = count
+end
+
+</pre>
+<h1 id='--09_performance/05_static_sprites_as_classes/app/main.rb'>09_performance/05_static_sprites_as_classes/app/main.rb</h1>
+<pre># Sprites represented as Classes using the queue ~args.outputs.static_sprites~.
+# bypasses the queue behavior of ~args.outputs.sprites~. All instances are held
+# by reference. You get better performance, but you are mutating state of held objects
+# which is less functional/data oriented.
+class Star
+  attr_sprite
+
+  def initialize grid
+    @grid = grid
+    @x = (rand @grid.w) * -1
+    @y = (rand @grid.h) * -1
+    @w    = 4
+    @h    = 4
+    @s    = 1 + (4.randomize :ratio)
+    @path = 'sprites/tiny-star.png'
+  end
+
+  def move
+    @x += @s
+    @y += @s
+    @x = (rand @grid.w) * -1 if @x > @grid.right
+    @y = (rand @grid.h) * -1 if @y > @grid.top
+  end
+end
+
+# calls methods needed for game to run properly
+def tick args
+  # sets console command when sample app initially opens
+  if Kernel.global_tick_count == 0
+    args.gtk.console.set_command "reset_with count: 100"
+  end
+
+  # init
+  if args.state.tick_count == 0
+    args.state.stars = args.state.star_count.map { |i| Star.new args.grid }
+  end
+
+  # update
+  args.state.stars.each(&:move)
+
+  # render
+  args.outputs.sprites << args.state.stars
+  args.outputs.background_color = [0, 0, 0]
+  args.outputs.primitives << args.gtk.current_framerate_primitives
+end
+
+# resets game, and assigns star count given by user
+def reset_with count: count
+  $gtk.reset
+  $gtk.args.state.star_count = count
+end
+
+</pre>
+<h1 id='--09_performance/06_static_sprites_as_classes_with_custom_drawing/app/main.rb'>09_performance/06_static_sprites_as_classes_with_custom_drawing/app/main.rb</h1>
+<pre># Sprites represented as Classes, with a draw_override method, and using the queue ~args.outputs.static_sprites~.
+# is the fastest approach. This is comparable to what other game engines set as the default behavior.
+# There are tradeoffs for all this speed if the creation of a full blown class, and bypassing
+# functional/data-oriented practices.
+class Star
+  def initialize grid
+    @grid = grid
+    @x = (rand @grid.w) * -1
+    @y = (rand @grid.h) * -1
+    @w    = 4
+    @h    = 4
+    @s    = 1 + (4.randomize :ratio)
+    @path = 'sprites/tiny-star.png'
+  end
+
+  def move
+    @x += @s
+    @y += @s
+    @x = (rand @grid.w) * -1 if @x > @grid.right
+    @y = (rand @grid.h) * -1 if @y > @grid.top
+  end
+
+  # if the object that is in args.outputs.sprites (or static_sprites)
+  # respond_to? :draw_override, then the method is invoked giving you
+  # access to the class used to draw to the canvas.
+  def draw_override ffi_draw
+    # first move then draw
+    move
+
+    # The argument order for ffi.draw_sprite is:
+    # x, y, w, h, path
+    ffi_draw.draw_sprite @x, @y, @w, @h, @path
+
+    # The argument order for ffi_draw.draw_sprite_2 is (pass in nil for default value):
+    # x, y, w, h, path,
+    # angle, alpha
+
+    # The argument order for ffi_draw.draw_sprite_3 is:
+    # x, y, w, h,
+    # path,
+    # angle,
+    # alpha, red_saturation, green_saturation, blue_saturation
+    # flip_horizontally, flip_vertically,
+    # tile_x, tile_y, tile_w, tile_h
+    # angle_anchor_x, angle_anchor_y,
+    # source_x, source_y, source_w, source_h
+  end
+end
+
+# calls methods needed for game to run properly
+def tick args
+  # sets console command when sample app initially opens
+  if Kernel.global_tick_count == 0
+    args.gtk.console.set_command "reset_with count: 100"
+  end
+
+  # init
+  if args.state.tick_count == 0
+    args.state.stars = args.state.star_count.map { |i| Star.new args.grid }
+    args.outputs.static_sprites << args.state.stars
+  end
+
+  # render framerate
+  args.outputs.background_color = [0, 0, 0]
+  args.outputs.primitives << args.gtk.current_framerate_primitives
+end
+
+# resets game, and assigns star count given by user
+def reset_with count: count
+  $gtk.reset
+  $gtk.args.state.star_count = count
+end
+
+</pre>
+<h1 id='--09_performance/07_collision_limits/app/main.rb'>09_performance/07_collision_limits/app/main.rb</h1>
+<pre>=begin
+
+ Reminders:
+ - find_all: Finds all elements of a collection that meet certain requirements.
+   In this sample app, we're finding all bodies that intersect with the center body.
+
+ - args.outputs.solids: An array. The values generate a solid.
+   The parameters are [X, Y, WIDTH, HEIGHT, RED, GREEN, BLUE]
+   For more information about solids, go to mygame/documentation/03-solids-and-borders.md.
+
+ - args.outputs.labels: An array. The values generate a label.
+   The parameters are [X, Y, TEXT, SIZE, ALIGNMENT, RED, GREEN, BLUE, ALPHA, FONT STYLE]
+   For more information about labels, go to mygame/documentation/02-labels.md.
+
+ - ARRAY#intersect_rect?: Returns true or false depending on if two rectangles intersect.
+
+=end
+
+# This code demonstrates moving objects that loop around once they exceed the scope of the screen,
+# which has dimensions of 1280 by 720, and also detects collisions between objects called "bodies".
+
+def body_count num
+  $gtk.args.state.other_bodies = num.map { [1280 * rand, 720 * rand, 10, 10] } # other_bodies set using num collection
+end
+
+def tick args
+
+  # Center body's values are set using an array
+  # Map is used to set values of 2000 other bodies
+  # All bodies that intersect with center body are stored in collisions collection
+  args.state.center_body  ||= [640 - 100, 360 - 100, 200, 200] # calculations done to place body in center
+  args.state.other_bodies ||= 2000.map { [1280 * rand, 720 * rand, 10, 10] } # 2000 bodies given random position on screen
+
+  # finds all bodies that intersect with center body, stores them in collisions
+  collisions = args.state.other_bodies.find_all { |b| b.intersect_rect? args.state.center_body }
+
+  args.borders << args.state.center_body # outputs center body as a black border
+
+  # transparency changes based on number of collisions; the more collisions, the redder (more transparent) the box becomes
+  args.solids  << [args.state.center_body, 255, 0, 0, collisions.length * 5] # center body is red solid
+  args.solids  << args.state.other_bodies # other bodies are output as (black) solids, as well
+
+  args.labels  << [10, 30, args.gtk.current_framerate] # outputs frame rate in bottom left corner
+
+  # Bodies are returned to bottom left corner if positions exceed scope of screen
+  args.state.other_bodies.each do |b| # for each body in the other_bodies collection
+    b.x += 5 # x and y are both incremented by 5
+    b.y += 5
+    b.x = 0 if b.x > 1280 # x becomes 0 if star exceeds scope of screen (goes too far right)
+    b.y = 0 if b.y > 720 # y becomes 0 if star exceeds scope of screen (goes too far up)
+  end
+end
+
+# Resets the game.
+$gtk.reset
+
+</pre>
+<h1 id='--10_advanced_debugging/01_trace_debugging/app/main.rb'>10_advanced_debugging/01_trace_debugging/app/main.rb</h1>
+<pre>class Game
+  attr_gtk
+
+  def method1 num
+    method2 num
+  end
+
+  def method2 num
+    method3 num
+  end
+
+  def method3 num
+    method4 num
+  end
+
+  def method4 num
+    if num == 1
+      puts "UNLUCKY #{num}."
+      state.unlucky_count += 1
+      if state.unlucky_count > 3
+        raise "NAT 1 finally occurred. Check app/trace.txt for all method invocation history."
+      end
+    else
+      puts "LUCKY #{num}."
+    end
+  end
+
+  def tick
+    state.roll_history ||= []
+    state.roll_history << rand(20) + 1
+    state.countdown ||= 600
+    state.countdown  -= 1
+    state.unlucky_count ||= 0
+    outputs.labels << [640, 360, "A dice roll of 1 will cause an exception.", 0, 1]
+    if state.countdown > 0
+      outputs.labels << [640, 340, "Dice roll countdown: #{state.countdown}", 0, 1]
+    else
+      state.attempts ||= 0
+      state.attempts  += 1
+      outputs.labels << [640, 340, "ROLLING! #{state.attempts}", 0, 1]
+    end
+    return if state.countdown > 0
+    method1 state.roll_history[-1]
+  end
+end
+
+$game = Game.new
+
+def tick args
+  trace! $game # <------------------- TRACING ENABLED FOR THIS OBJECT
+  $game.args = args
+  $game.tick
+end
+
+</pre>
+<h1 id='--10_advanced_debugging/02_trace_debugging_classes/app/main.rb'>10_advanced_debugging/02_trace_debugging_classes/app/main.rb</h1>
+<pre>class Foobar
+  def initialize
+    trace! # Trace is added to the constructor.
+  end
+
+  def clicky args
+    return unless args.inputs.mouse.click
+    try_rand rand
+  end
+
+  def try_rand num
+    return if num < 0.9
+    raise "Exception finally occurred. Take a look at logs/trace.txt #{num}."
+  end
+end
+
+def tick args
+  args.labels << [640, 360, "Start clicking. Eventually an exception will be thrown. Then look at logs/trace.txt.", 0, 1]
+  args.state.foobar = Foobar.new if args.tick_count
+  return unless args.state.foobar
+  args.state.foobar.clicky args
+end
+
+</pre>
+<h1 id='--10_advanced_debugging/03_unit_tests/exception_raising_tests.rb'>10_advanced_debugging/03_unit_tests/exception_raising_tests.rb</h1>
+<pre>begin :shared
+  class ExceptionalClass
+    def initialize exception_to_throw = nil
+      raise exception_to_throw if exception_to_throw
+    end
+  end
+end
+
+def test_exception_in_newing_object args, assert
+  begin
+    ExceptionalClass.new TypeError
+    raise "Exception wasn't thrown!"
+  rescue Exception => e
+    assert.equal! e.class, TypeError, "Exceptions within constructor should be retained."
+  end
+end
+
+puts "running tests"
+$gtk.reset 100
+$gtk.log_level = :off
+$gtk.tests.start
+
+</pre>
+<h1 id='--10_advanced_debugging/03_unit_tests/gen_docs.rb'>10_advanced_debugging/03_unit_tests/gen_docs.rb</h1>
+<pre># sh ./amir-build-and-run.sh --eval samples/99_zz_gtk_unit_tests/gen_docs.rb --no-tick
+Kernel.export_docs!
+
+</pre>
+<h1 id='--10_advanced_debugging/03_unit_tests/geometry_tests.rb'>10_advanced_debugging/03_unit_tests/geometry_tests.rb</h1>
+<pre>begin :shared
+  def primitive_representations x, y, w, h
+    [
+      [x, y, w, h],
+      { x: x, y: y, w: w, h: h },
+      RectForTest.new(x, y, w, h)
+    ]
+  end
+
+  class RectForTest
+    attr_sprite
+
+    def initialize x, y, w, h
+      @x = x
+      @y = y
+      @w = w
+      @h = h
+    end
+
+    def to_s
+      "RectForTest: #{[x, y, w, h]}"
+    end
+  end
+end
+
+begin :intersect_rect?
+  def test_intersect_rect_point args, assert
+    assert.true! [16, 13].intersect_rect?([13, 12, 4, 4]), "point intersects with rect."
+  end
+
+  def test_intersect_rect args, assert
+    intersecting = primitive_representations(0, 0, 100, 100) +
+                   primitive_representations(20, 20, 20, 20)
+
+    intersecting.product(intersecting).each do |rect_one, rect_two|
+      assert.true! rect_one.intersect_rect?(rect_two),
+                   "intersect_rect? assertion failed for #{rect_one}, #{rect_two} (expected true)."
+    end
+
+    not_intersecting = [
+      [ 0, 0, 5, 5],
+      { x: 10, y: 10, w: 5, h: 5 },
+      RectForTest.new(20, 20, 5, 5)
+    ]
+
+    not_intersecting.product(not_intersecting)
+      .reject { |rect_one, rect_two| rect_one == rect_two }
+      .each do |rect_one, rect_two|
+      assert.false! rect_one.intersect_rect?(rect_two),
+                    "intersect_rect? assertion failed for #{rect_one}, #{rect_two} (expected false)."
+    end
+  end
+end
+
+begin :inside_rect?
+  def assert_inside_rect outer: nil, inner: nil, expected: nil, assert: nil
+    assert.true! inner.inside_rect?(outer) == expected,
+                 "inside_rect? assertion failed for outer: #{outer} inner: #{inner} (expected #{expected})."
+  end
+
+  def test_inside_rect args, assert
+    outer_rects = primitive_representations(0, 0, 10, 10)
+    inner_rects = primitive_representations(1, 1, 5, 5)
+    primitive_representations(0, 0, 10, 10).product(primitive_representations(1, 1, 5, 5))
+      .each do |outer, inner|
+      assert_inside_rect outer: outer, inner: inner,
+                         expected: true, assert: assert
+    end
+  end
+end
+
+begin :angle_to
+  def test_angle_to args, assert
+    origins = primitive_representations(0, 0, 0, 0)
+    rights = primitive_representations(1, 0, 0, 0)
+    aboves = primitive_representations(0, 1, 0, 0)
+
+    origins.product(aboves).each do |origin, above|
+      assert.equal! origin.angle_to(above), 90,
+                    "A point directly above should be 90 degrees."
+
+      assert.equal! above.angle_from(origin), 90,
+                    "A point coming from above should be 90 degrees."
+    end
+
+    origins.product(rights).each do |origin, right|
+      assert.equal! origin.angle_to(right) % 360, 0,
+                    "A point directly to the right should be 0 degrees."
+
+      assert.equal! right.angle_from(origin) % 360, 0,
+                    "A point coming from the right should be 0 degrees."
+
+    end
+  end
+end
+
+begin :scale_rect
+  def test_scale_rect args, assert
+    assert.equal! [0, 0, 100, 100].scale_rect(0.5, 0.5),
+                  [25.0, 25.0, 50.0, 50.0]
+
+    assert.equal! [0, 0, 100, 100].scale_rect(0.5),
+                  [0.0, 0.0, 50.0, 50.0]
+
+    assert.equal! [0, 0, 100, 100].scale_rect_extended(percentage_x: 0.5, percentage_y: 0.5, anchor_x: 0.5, anchor_y: 0.5),
+                  [25.0, 25.0, 50.0, 50.0]
+
+    assert.equal! [0, 0, 100, 100].scale_rect_extended(percentage_x: 0.5, percentage_y: 0.5, anchor_x: 0, anchor_y: 0),
+                  [0.0, 0.0, 50.0, 50.0]
+  end
+end
+
+puts "running tests"
+$gtk.reset 100
+$gtk.log_level = :off
+$gtk.tests.start
+
+</pre>
+<h1 id='--10_advanced_debugging/03_unit_tests/http_tests.rb'>10_advanced_debugging/03_unit_tests/http_tests.rb</h1>
+<pre>def try_assert_or_schedule args, assert
+  if $result[:complete]
+    log_info "Request completed! Verifying."
+    if $result[:http_response_code] != 200
+      log_info "The request yielded a result of #{$result[:http_response_code]} instead of 200."
+      exit
+    end
+    log_info ":try_assert_or_schedule succeeded!"
+  else
+    args.gtk.schedule_callback Kernel.tick_count + 10 do
+      try_assert_or_schedule args, assert
+    end
+  end
+end
+
+def test_http args, assert
+  $result = $gtk.http_get 'http://dragonruby.org'
+  try_assert_or_schedule args, assert
+end
+
+puts "running tests"
+$gtk.reset 100
+$gtk.log_level = :off
+$gtk.tests.start
+
+</pre>
+<h1 id='--10_advanced_debugging/03_unit_tests/object_to_primitive_tests.rb'>10_advanced_debugging/03_unit_tests/object_to_primitive_tests.rb</h1>
+<pre>class PlayerSpriteForTest
+end
+
+def test_array_to_sprite args, assert
+  array = [[0, 0, 100, 100, "test.png"]].sprites
+  puts "No exception was thrown. Sweet!"
+end
+
+def test_class_to_sprite args, assert
+  array = [PlayerSprite.new].sprites
+  assert.true! array.first.is_a?(PlayerSprite)
+  puts "No exception was thrown. Sweet!"
+end
+
+$gtk.reset 100
+$gtk.log_level = :off
+$gtk.tests.start
+
+</pre>
+<h1 id='--10_advanced_debugging/03_unit_tests/parsing_tests.rb'>10_advanced_debugging/03_unit_tests/parsing_tests.rb</h1>
+<pre>def test_parse_json args, assert
+  result = args.gtk.parse_json '{ "name": "John Doe", "aliases": ["JD"] }'
+  assert.equal! result, { "name"=>"John Doe", "aliases"=>["JD"] }, "Parsing JSON failed."
+end
+
+def test_parse_xml args, assert
+  result = args.gtk.parse_xml <<-S
+<Person id="100">
+  <Name>John Doe</Name>
+</Person>
+S
+
+ expected = {:type=>:element,
+             :name=>nil,
+             :children=>[{:type=>:element,
+                          :name=>"Person",
+                          :children=>[{:type=>:element,
+                                       :name=>"Name",
+                                       :children=>[{:type=>:content,
+                                                    :data=>"John Doe"}]}],
+                          :attributes=>{"id"=>"100"}}]}
+
+ assert.equal! result, expected, "Parsing xml failed."
+end
+
+puts "running tests"
+$gtk.reset 100
+$gtk.log_level = :off
+$gtk.tests.start
+
+</pre>
+<h1 id='--10_advanced_debugging/03_unit_tests/serialize_deserialize_tests.rb'>10_advanced_debugging/03_unit_tests/serialize_deserialize_tests.rb</h1>
+<pre>def test_serialize args, assert
+  GTK::Entity.__reset_id__!
+  args.state.player_one = "test"
+  result = args.gtk.serialize_state args.state
+  assert.equal! result, "{:entity_id=>3, :tick_count=>-1, :player_one=>\"test\"}"
+
+  GTK::Entity.__reset_id__!
+  args.gtk.write_file 'state.txt', ''
+  result = args.gtk.serialize_state 'state.txt', args.state
+  assert.equal! result, "{:entity_id=>3, :tick_count=>-1, :player_one=>\"test\"}"
+end
+
+def test_deserialize args, assert
+  GTK::Entity.__reset_id__!
+  result = args.gtk.deserialize_state '{:entity_id=>3, :tick_count=>-1, :player_one=>"test"}'
+  assert.equal! result.player_one, "test"
+
+  GTK::Entity.__reset_id__!
+  args.gtk.write_file 'state.txt',  '{:entity_id=>3, :tick_count=>-1, :player_one=>"test"}'
+  result = args.gtk.deserialize_state 'state.txt'
+  assert.equal! result.player_one, "test"
+end
+
+def test_very_large_serialization args, assert
+  GTK::Entity.__reset_id__!
+  size = 3000
+  size.map_with_index do |i|
+    args.state.send("k#{i}=".to_sym, i)
+  end
+
+  result = args.gtk.serialize_state args.state
+  assert.true! (args.gtk.console.log.join.include? "unlikely a string this large will deserialize correctly")
+end
+
+def test_strict_entity_serialization args, assert
+  GTK::Entity.__reset_id__!
+  args.state.player_one = args.state.new_entity(:player, name: "Ryu")
+  args.state.player_two = args.state.new_entity_strict(:player_strict, name: "Ken")
+
+  serialized_state = args.gtk.serialize_state args.state
+  assert.equal! serialized_state, '{:entity_id=>1, :tick_count=>-1, :player_one=>{:entity_id=>1, :entity_name=>:player, :entity_type=>:player, :created_at=>-1, :global_created_at=>-1, :name=>"Ryu"}, :player_two=>{:entity_id=>3, :entity_name=>:player_strict, :created_at=>-1, :global_created_at_elapsed=>-1, :entity_strict=>true, :name=>"Ken"}}'
+
+  deserialize_state = args.gtk.deserialize_state serialized_state
+
+  assert.equal! args.state.player_one.name, deserialize_state.player_one.name
+  assert.true! args.state.player_one.is_a? GTK::OpenEntity
+
+  assert.equal! args.state.player_two.name, deserialize_state.player_two.name
+  assert.true! args.state.player_two.is_a? GTK::StrictEntity
+end
+
+def test_strict_entity_serialization_with_nil args, assert
+  GTK::Entity.__reset_id__!
+  args.state.player_one = args.state.new_entity(:player, name: "Ryu")
+  args.state.player_two = args.state.new_entity_strict(:player_strict, name: "Ken", blood_type: nil)
+
+  serialized_state = args.gtk.serialize_state args.state
+  assert.equal! serialized_state, '{:entity_id=>3, :tick_count=>-1, :player_one=>{:entity_id=>1, :entity_name=>:player, :entity_type=>:player, :created_at=>-1, :global_created_at=>-1, :name=>"Ryu"}, :player_two=>{:entity_id=>3, :entity_name=>:player_strict, :created_at=>-1, :global_created_at_elapsed=>-1, :entity_strict=>true, :name=>"Ken", :blood_type=>nil}}'
+
+  deserialized_state = args.gtk.deserialize_state serialized_state
+
+  assert.equal! args.state.player_one.name, deserialized_state.player_one.name
+  assert.true! args.state.player_one.is_a? GTK::OpenEntity
+
+  assert.equal! args.state.player_two.name, deserialized_state.player_two.name
+  assert.equal! args.state.player_two.blood_type, deserialized_state.player_two.blood_type
+  assert.equal! deserialized_state.player_two.blood_type, nil
+  assert.true! args.state.player_two.is_a? GTK::StrictEntity
+
+  deserialized_state.player_two.blood_type = :O
+  assert.equal! deserialized_state.player_two.blood_type, :O
+end
+
+def test_multiple_strict_entities args, assert
+  GTK::Entity.__reset_id__!
+  args.state.player = args.state.new_entity_strict(:player_one, name: "Ryu")
+  args.state.enemy = args.state.new_entity_strict(:enemy, name: "Bison", other_property: 'extra mean')
+
+  serialized_state = args.gtk.serialize_state args.state
+  deserialized_state = args.gtk.deserialize_state serialized_state
+
+  assert.equal! deserialized_state.player.name, "Ryu"
+  assert.equal! deserialized_state.enemy.other_property, "extra mean"
+end
+
+$tests.start
+
+</pre>
+<h1 id='--10_advanced_debugging/03_unit_tests/state_serialization_experimental_tests.rb'>10_advanced_debugging/03_unit_tests/state_serialization_experimental_tests.rb</h1>
+<pre>MAX_CODE_GEN_LENGTH = 50
+
+# NOTE: This is experimental/advanced stuff.
+def needs_partitioning? target
+  target[:value].to_s.length > MAX_CODE_GEN_LENGTH
+end
+
+def partition target
+  return [] unless needs_partitioning? target
+  if target[:value].is_a? GTK::OpenEntity
+    target[:value] = target[:value].hash
+  end
+
+  results = []
+  idx = 0
+  left, right = target[:value].partition do
+    idx += 1
+    idx.even?
+  end
+  left, right = Hash[left], Hash[right]
+  left = { value: left }
+  right = { value: right}
+  [left, right]
+end
+
+def add_partition target, path, aggregate, final_result
+  partitions = partition target
+  partitions.each do |part|
+    if needs_partitioning? part
+      if part[:value].keys.length == 1
+        first_key = part[:value].keys[0]
+        new_part = { value: part[:value][first_key] }
+        path.push first_key
+        add_partition new_part, path, aggregate, final_result
+        path.pop
+      else
+        add_partition part, path, aggregate, final_result
+      end
+    else
+      final_result << { value: { __path__: [*path] } }
+      final_result << { value: part[:value] }
+    end
+  end
+end
+
+def state_to_string state
+  parts_queue = []
+  final_queue = []
+  add_partition({ value: state.hash },
+                [],
+                parts_queue,
+                final_queue)
+  final_queue.reject {|i| i[:value].keys.length == 0}.map do |i|
+    i[:value].to_s
+  end.join("\n#==================================================#\n")
+end
+
+def state_from_string string
+  Kernel.eval("$load_data = {}")
+  lines = string.split("\n#==================================================#\n")
+  lines.each do |l|
+    puts "todo: #{l}"
+  end
+
+  GTK::OpenEntity.parse_from_hash $load_data
+end
+
+def test_save_and_load args, assert
+  args.state.item_1.name = "Jane"
+  string = state_to_string args.state
+  state = state_from_string string
+  assert.equal! args.state.item_1.name, state.item_1.name
+end
+
+def test_save_and_load_big args, assert
+  size = 1000
+  size.map_with_index do |i|
+    args.state.send("k#{i}=".to_sym, i)
+  end
+
+  string = state_to_string args.state
+  state = state_from_string string
+  size.map_with_index do |i|
+    assert.equal! args.state.send("k#{i}".to_sym), state.send("k#{i}".to_sym)
+    assert.equal! args.state.send("k#{i}".to_sym), i
+    assert.equal! state.send("k#{i}".to_sym), i
+  end
+end
+
+def test_save_and_load_big_nested args, assert
+  args.state.player_one.friend.nested_hash.k0 = 0
+  args.state.player_one.friend.nested_hash.k1 = 1
+  args.state.player_one.friend.nested_hash.k2 = 2
+  args.state.player_one.friend.nested_hash.k3 = 3
+  args.state.player_one.friend.nested_hash.k4 = 4
+  args.state.player_one.friend.nested_hash.k5 = 5
+  args.state.player_one.friend.nested_hash.k6 = 6
+  args.state.player_one.friend.nested_hash.k7 = 7
+  args.state.player_one.friend.nested_hash.k8 = 8
+  args.state.player_one.friend.nested_hash.k9 = 9
+  string = state_to_string args.state
+  state = state_from_string string
+end
+
+$gtk.reset 100
+$gtk.log_level = :off
+$gtk.tests.start
+
+</pre>
+<h1 id='--11_http/01_retrieve_images/app/main.rb'>11_http/01_retrieve_images/app/main.rb</h1>
+<pre>def tick args
+  args.outputs.background_color = [0, 0, 0]
+
+  # Show a warning at the start.
+  args.state.warning_debounce ||= 11 * 60
+  if args.state.warning_debounce > 0
+    args.state.warning_debounce -= 1
+    args.outputs.labels << [640, 600, "This app shows random images from the Internet.", 10, 1, 255, 255, 255]
+    args.outputs.labels << [640, 500, "Quit in the next few seconds if this is a problem.", 10, 1, 255, 255, 255]
+    args.outputs.labels << [640, 350, "#{(args.state.warning_debounce / 60.0).to_i}", 10, 1, 255, 255, 255]
+    return
+  end
+
+  args.state.download_debounce ||= 0   # start immediately, reset to non zero later.
+  args.state.photos ||= []
+
+  # Put a little pause between each download.
+  if args.state.download.nil?
+    if args.state.download_debounce > 0
+      args.state.download_debounce -= 1
+    else
+      args.state.download = $gtk.http_get 'https://picsum.photos/200/300.jpg'
+    end
+  end
+
+  if !args.state.download.nil?
+    if args.state.download[:complete]
+      if args.state.download[:http_response_code] == 200
+        fname = "sprites/#{args.state.photos.length}.jpg"
+        $gtk.write_file fname, args.state.download[:response_data]
+        args.state.photos << [ 100 + rand(1080), 500 - rand(480), fname, rand(80) - 40 ]
+      end
+      args.state.download = nil
+      args.state.download_debounce = (rand(3) + 2) * 60
+    end
+  end
+
+  # draw any downloaded photos...
+  args.state.photos.each { |i|
+    args.outputs.primitives << [i[0], i[1], 200, 300, i[2], i[3]].sprite
+  }
+
+  # Draw a download progress bar...
+  args.outputs.primitives << [0, 0, 1280, 30, 0, 0, 0, 255].solid
+  if !args.state.download.nil?
+    br = args.state.download[:response_read]
+    total = args.state.download[:response_total]
+    if total != 0
+      pct = br.to_f / total.to_f
+      args.outputs.primitives << [0, 0, 1280 * pct, 30, 0, 0, 255, 255].solid
+    end
+  end
+end
+
+</pre>
+<h1 id='--99_genre_3d/3d_cube/app/main.rb'>99_genre_3d/3d_cube/app/main.rb</h1>
+<pre>STARTX             = 0.0
+STARTY             = 0.0
+ENDY               = 20.0
+ENDX               = 20.0
+SPINPOINT          = 10
+SPINDURATION       = 400
+POINTSIZE          = 8
+BOXDEPTH           = 40
+YAW                = 1
+DISTANCE           = 10
+
+def tick args
+  args.outputs.background_color = [0, 0, 0]
+  a = Math.sin(args.state.tick_count / SPINDURATION) * Math.tan(args.state.tick_count / SPINDURATION)
+  s = Math.sin(a)
+  c = Math.cos(a)
+  x = STARTX
+  y = STARTY
+  offset_x = (1280 - (ENDX - STARTX)) / 2
+  offset_y =  (360 - (ENDY - STARTY)) / 2
+
+  srand(1)
+  while y < ENDY do
+    while x < ENDX do
+      if (y == STARTY ||
+          y == (ENDY / 0.5) * 2 ||
+          y == (ENDY / 0.5) * 2 + 0.5 ||
+          y == ENDY - 0.5 ||
+          x == STARTX ||
+          x == ENDX - 0.5)
+        z = rand(BOXDEPTH)
+        z *= Math.sin(a / 2)
+        x -= SPINPOINT
+        u = (x * c) - (z * s)
+        v = (x * s) + (z * c)
+        k = DISTANCE.fdiv(100) + (v / 500 * YAW)
+        u = u / k
+        v = y / k
+        w = POINTSIZE / 10 / k
+        args.outputs.sprites << { x: offset_x + u - w, y: offset_y + v - w, w: w, h: w, path: 'sprites/square-blue.png'}
+        x += SPINPOINT
+      end
+      x += 0.5
+    end
+    y += 0.5
+    x = STARTX
+  end
+end
+
+$gtk.reset
+
+</pre>
+<h1 id='--99_genre_arcade/dueling_starships/app/main.rb'>99_genre_arcade/dueling_starships/app/main.rb</h1>
+<pre>class DuelingSpaceships
+  attr_accessor :state, :inputs, :outputs, :grid
+
+  def tick
+    defaults
+    render
+    calc
+    input
+  end
+
+  def defaults
+    outputs.background_color = [0, 0, 0]
+    state.ship_blue       ||= new_blue_ship
+    state.ship_red        ||= new_red_ship
+    state.flames          ||= []
+    state.bullets         ||= []
+    state.ship_blue_score ||= 0
+    state.ship_red_score  ||= 0
+    state.stars           ||= 100.map do
+      [rand.add(2).to_square(grid.w_half.randomize(:sign, :ratio),
+                             grid.h_half.randomize(:sign, :ratio)),
+       128 + 128.randomize(:ratio), 255, 255]
+    end
+  end
+
+  def default_ship x, y, angle, sprite_path, bullet_sprite_path, color
+    state.new_entity(:ship,
+                    { x: x,
+                      y: y,
+                      dy: 0,
+                      dx: 0,
+                      damage: 0,
+                      dead: false,
+                      angle: angle,
+                      max_alpha: 255,
+                      sprite_path: sprite_path,
+                      bullet_sprite_path: bullet_sprite_path,
+                      color: color })
+  end
+
+  def new_red_ship
+    default_ship(400, 250.randomize(:sign, :ratio),
+                 180, 'sprites/ship_red.png', 'sprites/red_bullet.png',
+                 [255, 90, 90])
+  end
+
+  def new_blue_ship
+    default_ship(-400, 250.randomize(:sign, :ratio),
+                 0, 'sprites/ship_blue.png', 'sprites/blue_bullet.png',
+                 [110, 140, 255])
+  end
+
+  def render
+    render_instructions
+    render_score
+    render_universe
+    render_flames
+    render_ships
+    render_bullets
+  end
+
+  def render_ships
+    update_ship_outputs(state.ship_blue)
+    update_ship_outputs(state.ship_red)
+    outputs.sprites << [state.ship_blue.sprite, state.ship_red.sprite]
+    outputs.labels  << [state.ship_blue.label, state.ship_red.label]
+  end
+
+  def render_instructions
+    return if state.ship_blue.dx  > 0  || state.ship_blue.dy > 0  ||
+              state.ship_red.dx   > 0  || state.ship_red.dy  > 0  ||
+              state.flames.length > 0
+
+    outputs.labels << [grid.left.shift_right(30),
+                       grid.bottom.shift_up(30),
+                       "Two gamepads needed to play. R1 to accelerate. Left and right on D-PAD to turn ship. Hold A to shoot. Press B to drop mines.",
+                       0, 0, 255, 255, 255]
+  end
+
+  def calc
+    calc_thrusts
+    calc_ships
+    calc_bullets
+    calc_winner
+  end
+
+  def input
+    input_accelerate
+    input_turn
+    input_bullets_and_mines
+  end
+
+  def render_score
+    outputs.labels << [grid.left.shift_right(80),
+                       grid.top.shift_down(40),
+                       state.ship_blue_score, 30, 1, state.ship_blue.color]
+
+    outputs.labels << [grid.right.shift_left(80),
+                       grid.top.shift_down(40),
+                       state.ship_red_score,  30, 1, state.ship_red.color]
+  end
+
+  def render_universe
+    return if outputs.static_solids.any?
+    outputs.static_solids << grid.rect
+    outputs.static_solids << state.stars
+  end
+
+  def apply_round_finished_alpha entity
+    return entity unless state.round_finished_debounce
+    entity.a *= state.round_finished_debounce.percentage_of(2.seconds)
+    return entity
+  end
+
+  def update_ship_outputs ship, sprite_size = 66
+    ship.sprite =
+      apply_round_finished_alpha [sprite_size.to_square(ship.x, ship.y),
+                                  ship.sprite_path,
+                                  ship.angle,
+                                  ship.dead ? 0 : 255 * ship.created_at.ease(2.seconds)].sprite
+    ship.label =
+      apply_round_finished_alpha [ship.x,
+                                  ship.y + 100,
+                                  "." * 5.minus(ship.damage).greater(0), 20, 1, ship.color, 255].label
+  end
+
+  def render_flames sprite_size = 6
+    outputs.sprites << state.flames.map do |p|
+      apply_round_finished_alpha [sprite_size.to_square(p.x, p.y),
+                                  'sprites/flame.png', 0,
+                                  p.max_alpha * p.created_at.ease(p.lifetime, :flip)].sprite
+    end
+  end
+
+  def render_bullets sprite_size = 10
+    outputs.sprites << state.bullets.map do |b|
+      apply_round_finished_alpha [b.sprite_size.to_square(b.x, b.y),
+                                  b.owner.bullet_sprite_path,
+                                  0, b.max_alpha].sprite
+    end
+  end
+
+  def wrap_location! location
+    location.x = grid.left    if location.x > grid.right
+    location.x = grid.right   if location.x < grid.left
+    location.y = grid.top     if location.y < grid.bottom
+    location.y = grid.bottom  if location.y > grid.top
+    location
+  end
+
+  def calc_thrusts
+    state.flames =
+      state.flames
+        .reject(&:old?)
+        .map do |p|
+          p.speed *= 0.9
+          p.y += p.angle.vector_y(p.speed)
+          p.x += p.angle.vector_x(p.speed)
+          wrap_location! p
+      end
+  end
+
+  def all_ships
+    [state.ship_blue, state.ship_red]
+  end
+
+  def alive_ships
+    all_ships.reject { |s| s.dead }
+  end
+
+  def calc_bullet bullet
+    bullet.y += bullet.angle.vector_y(bullet.speed)
+    bullet.x += bullet.angle.vector_x(bullet.speed)
+    wrap_location! bullet
+    explode_bullet! bullet if bullet.old?
+    return if bullet.exploded
+    return if state.round_finished
+    alive_ships.each do |s|
+      if s != bullet.owner &&
+         s.sprite.intersect_rect?(bullet.sprite_size.to_square(bullet.x, bullet.y))
+        explode_bullet! bullet, 10, 5, 30
+        s.damage += 1
+      end
+    end
+  end
+
+  def calc_bullets
+    state.bullets.each    { |b| calc_bullet b }
+    state.bullets.reject! { |b| b.exploded }
+  end
+
+  def create_explosion! type, entity, flame_count, max_speed, lifetime, max_alpha = 255
+    flame_count.times do
+      state.flames << state.new_entity(type,
+                                     { angle: 360.randomize(:ratio),
+                                       speed: max_speed.randomize(:ratio),
+                                       lifetime: lifetime,
+                                       x: entity.x,
+                                       y: entity.y,
+                                       max_alpha: max_alpha })
+    end
+  end
+
+  def explode_bullet! bullet, flame_override = 5, max_speed = 5, lifetime = 10
+    bullet.exploded = true
+    create_explosion! :bullet_explosion,
+                      bullet,
+                      flame_override,
+                      max_speed,
+                      lifetime,
+                      bullet.max_alpha
+  end
+
+  def calc_ship ship
+    ship.x += ship.dx
+    ship.y += ship.dy
+    wrap_location! ship
+  end
+
+  def calc_ships
+    all_ships.each { |s| calc_ship s }
+    return if all_ships.any? { |s| s.dead }
+    return if state.round_finished
+    return unless state.ship_blue.sprite.intersect_rect?(state.ship_red.sprite)
+    state.ship_blue.damage = 5
+    state.ship_red.damage  = 5
+  end
+
+  def create_thruster_flames! ship
+    state.flames << state.new_entity(:ship_thruster,
+                                   { angle: ship.angle + 180 + 60.randomize(:sign, :ratio),
+                                     speed: 5.randomize(:ratio),
+                                     max_alpha: 255 * ship.created_at_elapsed.percentage_of(2.seconds),
+                                     lifetime: 30,
+                                     x: ship.x - ship.angle.vector_x(40) + 5.randomize(:sign, :ratio),
+                                     y: ship.y - ship.angle.vector_y(40) + 5.randomize(:sign, :ratio) })
+  end
+
+  def input_accelerate_ship should_move_ship, ship
+    return if ship.dead
+
+    should_move_ship &&= (ship.dx + ship.dy).abs < 5
+
+    if should_move_ship
+      create_thruster_flames! ship
+      ship.dx += ship.angle.vector_x 0.050
+      ship.dy += ship.angle.vector_y 0.050
+    else
+      ship.dx *= 0.99
+      ship.dy *= 0.99
+    end
+  end
+
+  def input_accelerate
+    input_accelerate_ship inputs.controller_one.key_held.r1 || inputs.keyboard.up, state.ship_blue
+    input_accelerate_ship inputs.controller_two.key_held.r1, state.ship_red
+  end
+
+  def input_turn_ship direction, ship
+    ship.angle -= 3 * direction
+  end
+
+  def input_turn
+    input_turn_ship inputs.controller_one.left_right + inputs.keyboard.left_right, state.ship_blue
+    input_turn_ship inputs.controller_two.left_right, state.ship_red
+  end
+
+  def input_bullet create_bullet, ship
+    return unless create_bullet
+    return if ship.dead
+
+    state.bullets << state.new_entity(:ship_bullet,
+                                    { owner: ship,
+                                      angle: ship.angle,
+                                      max_alpha: 255 * ship.created_at_elapsed.percentage_of(2.seconds),
+                                      speed: 5 + ship.dx.mult(ship.angle.vector_x) + ship.dy.mult(ship.angle.vector_y),
+                                      lifetime: 120,
+                                      sprite_size: 10,
+                                      x: ship.x + ship.angle.vector_x * 32,
+                                      y: ship.y + ship.angle.vector_y * 32 })
+  end
+
+  def input_mine create_mine, ship
+    return unless create_mine
+    return if ship.dead
+
+    state.bullets << state.new_entity(:ship_bullet,
+                                    { owner: ship,
+                                      angle: 360.randomize(:sign, :ratio),
+                                      max_alpha: 255 * ship.created_at_elapsed.percentage_of(2.seconds),
+                                      speed: 0.02,
+                                      sprite_size: 10,
+                                      lifetime: 600,
+                                      x: ship.x + ship.angle.vector_x * -50,
+                                      y: ship.y + ship.angle.vector_y * -50 })
+  end
+
+  def input_bullets_and_mines
+    return if state.bullets.length > 100
+
+    [
+      [inputs.controller_one.key_held.a || inputs.keyboard.key_held.space,
+       inputs.controller_one.key_down.b || inputs.keyboard.key_down.down,
+       state.ship_blue],
+      [inputs.controller_two.key_held.a, inputs.controller_two.key_down.b, state.ship_red]
+    ].each do |a_held, b_down, ship|
+      input_bullet(a_held && state.tick_count.mod_zero?(10).or(a_held == 0), ship)
+      input_mine(b_down, ship)
+    end
+  end
+
+  def calc_kill_ships
+    alive_ships.find_all { |s| s.damage >= 5 }.each do |s|
+      s.dead = true
+      create_explosion! :ship_explosion, s, 20, 20, 30, s.max_alpha
+    end
+  end
+
+  def calc_score
+    return if state.round_finished
+    return if alive_ships.length > 1
+
+    if alive_ships.first == state.ship_red
+      state.ship_red_score += 1
+    elsif alive_ships.first == state.ship_blue
+      state.ship_blue_score += 1
+    end
+
+    state.round_finished = true
+  end
+
+  def calc_reset_ships
+    return unless state.round_finished
+    state.round_finished_debounce ||= 2.seconds
+    state.round_finished_debounce -= 1
+    return if state.round_finished_debounce > 0
+    start_new_round!
+  end
+
+  def start_new_round!
+    state.ship_blue = new_blue_ship
+    state.ship_red  = new_red_ship
+    state.round_finished = false
+    state.round_finished_debounce = nil
+    state.flames.clear
+    state.bullets.clear
+  end
+
+  def calc_winner
+    calc_kill_ships
+    calc_score
+    calc_reset_ships
+  end
+end
+
+$dueling_spaceship = DuelingSpaceships.new
+
+def tick args
+  args.grid.origin_center!
+  $dueling_spaceship.inputs  = args.inputs
+  $dueling_spaceship.outputs = args.outputs
+  $dueling_spaceship.state    = args.state
+  $dueling_spaceship.grid    = args.grid
+  $dueling_spaceship.tick
+end
+
+</pre>
+<h1 id='--99_genre_arcade/flappy_dragon/app/main.rb'>99_genre_arcade/flappy_dragon/app/main.rb</h1>
+<pre>class FlappyDragon
+  attr_accessor :grid, :inputs, :state, :outputs
+
+  def tick
+    defaults
+    render
+    calc
+    process_inputs
+  end
+
+  def defaults
+    state.flap_power              = 11
+    state.gravity                 = 0.9
+    state.ceiling                 = 600
+    state.ceiling_flap_power      = 6
+    state.wall_countdown_length   = 100
+    state.wall_gap_size           = 100
+    state.wall_countdown        ||= 0
+    state.hi_score              ||= 0
+    state.score                 ||= 0
+    state.walls                 ||= []
+    state.x                     ||= 50
+    state.y                     ||= 500
+    state.dy                    ||= 0
+    state.scene                 ||= :menu
+    state.scene_at              ||= 0
+    state.difficulty            ||= :normal
+    state.new_difficulty        ||= :normal
+    state.countdown             ||= 4.seconds
+    state.flash_at              ||= 0
+  end
+
+  def render
+    outputs.sounds << "sounds/flappy-song.ogg" if state.tick_count == 1
+    render_score
+    render_menu
+    render_game
+  end
+
+  def render_score
+    outputs.primitives << [10, 710, "HI SCORE: #{state.hi_score}", large_white_typeset].label
+    outputs.primitives << [10, 680, "SCORE: #{state.score}", large_white_typeset].label
+    outputs.primitives << [10, 650, "DIFFICULTY: #{state.difficulty.upcase}", large_white_typeset].label
+  end
+
+  def render_menu
+    return unless state.scene == :menu
+    render_overlay
+
+    outputs.labels << [640, 700, "Flappy Dragon", 50, 1, 255, 255, 255]
+    outputs.labels << [640, 500, "Instructions: Press Spacebar to flap. Don't die.", 4, 1, 255, 255, 255]
+    outputs.labels << [430, 430, "[Tab]    Change difficulty", 4, 0, 255, 255, 255]
+    outputs.labels << [430, 400, "[Enter]  Start at New Difficulty ", 4, 0, 255, 255, 255]
+    outputs.labels << [430, 370, "[Escape] Cancel/Resume ", 4, 0, 255, 255, 255]
+    outputs.labels << [640, 300, "(mouse, touch, and game controllers work, too!) ", 4, 1, 255, 255, 255]
+    outputs.labels << [640, 200, "Difficulty: #{state.new_difficulty.capitalize}", 4, 1, 255, 255, 255]
+
+    outputs.labels << [10, 100, "Code:   @amirrajan",     255, 255, 255]
+    outputs.labels << [10,  80, "Art:    @mobypixel",     255, 255, 255]
+    outputs.labels << [10,  60, "Music:  @mobypixel",     255, 255, 255]
+    outputs.labels << [10,  40, "Engine: DragonRuby GTK", 255, 255, 255]
+  end
+
+  def render_overlay
+    outputs.primitives << [grid.rect.scale_rect(1.1, 0, 0), 0, 0, 0, 230].solid
+  end
+
+  def render_game
+    render_game_over
+    render_background
+    render_walls
+    render_dragon
+    render_flash
+  end
+
+  def render_game_over
+    return unless state.scene == :game
+    outputs.labels << [638, 358, score_text, 20, 1]
+    outputs.labels << [635, 360, score_text, 20, 1, 255, 255, 255]
+    outputs.labels << [638, 428, countdown_text, 20, 1]
+    outputs.labels << [635, 430, countdown_text, 20, 1, 255, 255, 255]
+  end
+
+  def render_background
+    outputs.sprites << [0, 0, 1280, 720, 'sprites/background.png']
+
+    scroll_point_at   = state.tick_count
+    scroll_point_at   = state.scene_at if state.scene == :menu
+    scroll_point_at   = state.death_at if state.countdown > 0
+    scroll_point_at ||= 0
+
+    outputs.sprites << scrolling_background(scroll_point_at, 'sprites/parallax_back.png',   0.25)
+    outputs.sprites << scrolling_background(scroll_point_at, 'sprites/parallax_middle.png', 0.50)
+    outputs.sprites << scrolling_background(scroll_point_at, 'sprites/parallax_front.png',  1.00, -80)
+  end
+
+  def render_walls
+    state.walls.each do |w|
+      w.sprites = [
+        [w.x, w.bottom_height - 720, 100, 720, 'sprites/wall.png', 180],
+        [w.x, w.top_y,               100, 720, 'sprites/wallbottom.png', 0]
+      ]
+    end
+    outputs.sprites << state.walls.map(&:sprites)
+  end
+
+  def render_dragon
+    state.show_death = true if state.countdown == 3.seconds
+
+    render_debug_hitbox false
+
+    if state.show_death == false || !state.death_at
+      animation_index = state.flapped_at.frame_index 6, 2, false if state.flapped_at
+      sprite_name = "sprites/dragon_fly#{animation_index.or(0) + 1}.png"
+      state.dragon_sprite = [state.x, state.y, 100, 80, sprite_name, state.dy * 1.2]
+    else
+      sprite_name = "sprites/dragon_die.png"
+      state.dragon_sprite = [state.x, state.y, 100, 80, sprite_name, state.dy * 1.2]
+      sprite_changed_elapsed    = state.death_at.elapsed_time - 1.seconds
+      state.dragon_sprite.angle += (sprite_changed_elapsed ** 1.3) * state.death_fall_direction * -1
+      state.dragon_sprite.x     += (sprite_changed_elapsed ** 1.2) * state.death_fall_direction
+      state.dragon_sprite.y     += (sprite_changed_elapsed * 14 - sprite_changed_elapsed ** 1.6)
+    end
+
+    outputs.sprites << state.dragon_sprite
+  end
+
+  def render_debug_hitbox show
+    return unless show
+    outputs.borders << [dragon_collision_box.rect, 255, 0, 0] if state.dragon_sprite
+    outputs.borders << state.walls.flat_map do |w|
+       w.sprites.map { |s| [s.rect, 255, 0, 0] }
+    end
+  end
+
+  def render_flash
+    return unless state.flash_at
+
+    outputs.primitives << [grid.rect,
+                           white,
+                           255 * state.flash_at.ease(20, :flip)].solid
+
+    state.flash_at = 0 if state.flash_at.elapsed_time > 20
+  end
+
+  def calc
+    return unless state.scene == :game
+    reset_game if state.countdown == 1
+    state.countdown -= 1 and return if state.countdown > 0
+    calc_walls
+    calc_flap
+    calc_game_over
+  end
+
+  def calc_walls
+    state.walls.each { |w| w.x -= 8 }
+
+    walls_count_before_removal = state.walls.length
+
+    state.walls.reject! { |w| w.x < -100 }
+
+    state.score += 1 if state.walls.count < walls_count_before_removal
+
+    state.wall_countdown -= 1 and return if state.wall_countdown > 0
+
+    state.walls << state.new_entity(:wall) do |w|
+      w.x             = grid.right
+      w.opening       = grid.top
+                            .randomize(:ratio)
+                            .greater(200)
+                            .lesser(520)
+      w.bottom_height = w.opening - state.wall_gap_size
+      w.top_y         = w.opening + state.wall_gap_size
+    end
+
+    state.wall_countdown = state.wall_countdown_length
+  end
+
+  def calc_flap
+    state.y += state.dy
+    state.dy = state.dy.lesser state.flap_power
+    state.dy -= state.gravity
+    return if state.y < state.ceiling
+    state.y  = state.ceiling
+    state.dy = state.dy.lesser state.ceiling_flap_power
+  end
+
+  def calc_game_over
+    return unless game_over?
+
+    state.death_at = state.tick_count
+    state.death_from = state.walls.first
+    state.death_fall_direction = -1
+    state.death_fall_direction =  1 if state.x > state.death_from.x
+    outputs.sounds << "sounds/hit-sound.wav"
+    begin_countdown
+  end
+
+  def process_inputs
+    process_inputs_menu
+    process_inputs_game
+  end
+
+  def process_inputs_menu
+    return unless state.scene == :menu
+
+    changediff = inputs.keyboard.key_down.tab || inputs.controller_one.key_down.select
+    if inputs.mouse.click
+      p = inputs.mouse.click.point
+      if (p.y >= 165) && (p.y < 200) && (p.x >= 500) && (p.x < 800)
+        changediff = true
+      end
+    end
+
+    if changediff
+      case state.new_difficulty
+      when :easy
+        state.new_difficulty = :normal
+      when :normal
+        state.new_difficulty = :hard
+      when :hard
+        state.new_difficulty = :flappy
+      when :flappy
+        state.new_difficulty = :easy
+      end
+    end
+
+    if inputs.keyboard.key_down.enter || inputs.controller_one.key_down.start || inputs.controller_one.key_down.a
+      state.difficulty = state.new_difficulty
+      change_to_scene :game
+      reset_game false
+      state.hi_score = 0
+      begin_countdown
+    end
+
+    if inputs.keyboard.key_down.escape || (inputs.mouse.click && !changediff) || inputs.controller_one.key_down.b
+      state.new_difficulty = state.difficulty
+      change_to_scene :game
+    end
+  end
+
+  def process_inputs_game
+    return unless state.scene == :game
+
+    clicked_menu = false
+    if inputs.mouse.click
+      p = inputs.mouse.click.point
+      clicked_menu = (p.y >= 620) && (p.x < 275)
+    end
+
+    if clicked_menu || inputs.keyboard.key_down.escape || inputs.keyboard.key_down.enter || inputs.controller_one.key_down.start
+      change_to_scene :menu
+    elsif (inputs.mouse.down || inputs.mouse.click || inputs.keyboard.key_down.space || inputs.controller_one.key_down.a) && state.countdown == 0
+      state.dy = 0
+      state.dy += state.flap_power
+      state.flapped_at = state.tick_count
+      outputs.sounds << "sounds/fly-sound.wav"
+    end
+  end
+
+  def scrolling_background at, path, rate, y = 0
+    [
+      [   0 - at.*(rate) % 1440, y, 1440, 720, path],
+      [1440 - at.*(rate) % 1440, y, 1440, 720, path]
+    ]
+  end
+
+  def white
+    [255, 255, 255]
+  end
+
+  def large_white_typeset
+    [5, 0, 255, 255, 255]
+  end
+
+  def at_beginning?
+    state.walls.count == 0
+  end
+
+  def dragon_collision_box
+    state.dragon_sprite
+        .scale_rect(1.0 - collision_forgiveness, 0.5, 0.5)
+        .rect_shift_right(10)
+        .rect_shift_up(state.dy * 2)
+  end
+
+  def game_over?
+    return true if state.y <= 0.-(500 * collision_forgiveness) && !at_beginning?
+
+    state.walls
+        .flat_map { |w| w.sprites }
+        .any? do |s|
+          s.intersect_rect?(dragon_collision_box)
+        end
+  end
+
+  def collision_forgiveness
+    case state.difficulty
+    when :easy
+      0.9
+    when :normal
+      0.7
+    when :hard
+      0.5
+    when :flappy
+      0.3
+    else
+      0.9
+    end
+  end
+
+  def countdown_text
+    state.countdown ||= -1
+    return ""          if state.countdown == 0
+    return "GO!"       if state.countdown.idiv(60) == 0
+    return "GAME OVER" if state.death_at
+    return "READY?"
+  end
+
+  def begin_countdown
+    state.countdown = 4.seconds
+  end
+
+  def score_text
+    return ""                        unless state.countdown > 1.seconds
+    return ""                        unless state.death_at
+    return "SCORE: 0 (LOL)"          if state.score == 0
+    return "HI SCORE: #{state.score}" if state.score == state.hi_score
+    return "SCORE: #{state.score}"
+  end
+
+  def reset_game set_flash = true
+    state.flash_at = state.tick_count if set_flash
+    state.walls = []
+    state.y = 500
+    state.dy = 0
+    state.hi_score = state.hi_score.greater(state.score)
+    state.score = 0
+    state.wall_countdown = state.wall_countdown_length.fdiv(2)
+    state.show_death = false
+    state.death_at = nil
+  end
+
+  def change_to_scene scene
+    state.scene = scene
+    state.scene_at = state.tick_count
+    inputs.keyboard.clear
+    inputs.controller_one.clear
+  end
+end
+
+$flappy_dragon = FlappyDragon.new
+
+def tick args
+  $flappy_dragon.grid = args.grid
+  $flappy_dragon.inputs = args.inputs
+  $flappy_dragon.state = args.state
+  $flappy_dragon.outputs = args.outputs
+  $flappy_dragon.tick
+end
+
+</pre>
+<h1 id='--99_genre_arcade/pong/app/main.rb'>99_genre_arcade/pong/app/main.rb</h1>
+<pre>def tick args
+  defaults args
+  render args
+  calc args
+  input args
+end
+
+def defaults args
+  args.state.ball.debounce       ||= 3 * 60
+  args.state.ball.size           ||= 10
+  args.state.ball.size_half      ||= args.state.ball.size / 2
+  args.state.ball.x              ||= 640
+  args.state.ball.y              ||= 360
+  args.state.ball.dx             ||= 5.randomize(:sign)
+  args.state.ball.dy             ||= 5.randomize(:sign)
+  args.state.left_paddle.y       ||= 360
+  args.state.right_paddle.y      ||= 360
+  args.state.paddle.h            ||= 120
+  args.state.paddle.w            ||= 10
+  args.state.left_paddle.score   ||= 0
+  args.state.right_paddle.score  ||= 0
+end
+
+def render args
+  render_center_line args
+  render_scores args
+  render_countdown args
+  render_ball args
+  render_paddles args
+  render_instructions args
+end
+
+begin :render_methods
+  def render_center_line args
+    args.outputs.lines  << [640, 0, 640, 720]
+  end
+
+  def render_scores args
+    args.outputs.labels << [
+      [320, 650, args.state.left_paddle.score, 10, 1],
+      [960, 650, args.state.right_paddle.score, 10, 1]
+    ]
+  end
+
+  def render_countdown args
+    return unless args.state.ball.debounce > 0
+    args.outputs.labels << [640, 360, "%.2f" % args.state.ball.debounce.fdiv(60), 10, 1]
+  end
+
+  def render_ball args
+    args.outputs.solids << solid_ball(args)
+  end
+
+  def render_paddles args
+    args.outputs.solids << solid_left_paddle(args)
+    args.outputs.solids << solid_right_paddle(args)
+  end
+
+  def render_instructions args
+    args.outputs.labels << [320, 30, "W and S keys to move left paddle.",  0, 1]
+    args.outputs.labels << [920, 30, "O and L keys to move right paddle.", 0, 1]
+  end
+end
+
+def calc args
+  args.state.ball.debounce -= 1 and return if args.state.ball.debounce > 0
+  calc_move_ball args
+  calc_collision_with_left_paddle args
+  calc_collision_with_right_paddle args
+  calc_collision_with_walls args
+end
+
+begin :calc_methods
+  def calc_move_ball args
+    args.state.ball.x += args.state.ball.dx
+    args.state.ball.y += args.state.ball.dy
+  end
+
+  def calc_collision_with_left_paddle args
+    if solid_left_paddle(args).intersect_rect? solid_ball(args)
+      args.state.ball.dx *= -1
+    elsif args.state.ball.x < 0
+      args.state.right_paddle.score += 1
+      calc_reset_round args
+    end
+  end
+
+  def calc_collision_with_right_paddle args
+    if solid_right_paddle(args).intersect_rect? solid_ball(args)
+      args.state.ball.dx *= -1
+    elsif args.state.ball.x > 1280
+      args.state.left_paddle.score += 1
+      calc_reset_round args
+    end
+  end
+
+  def calc_collision_with_walls args
+    if args.state.ball.y + args.state.ball.size_half > 720
+      args.state.ball.y = 720 - args.state.ball.size_half
+      args.state.ball.dy *= -1
+    elsif args.state.ball.y - args.state.ball.size_half < 0
+      args.state.ball.y = args.state.ball.size_half
+      args.state.ball.dy *= -1
+    end
+  end
+
+  def calc_reset_round args
+    args.state.ball.x = 640
+    args.state.ball.y = 360
+    args.state.ball.dx = 5.randomize(:sign)
+    args.state.ball.dy = 5.randomize(:sign)
+    args.state.ball.debounce = 3 * 60
+  end
+end
+
+def input args
+  input_left_paddle args
+  input_right_paddle args
+end
+
+begin :input_methods
+  def input_left_paddle args
+    if args.inputs.controller_one.key_down.down  || args.inputs.keyboard.key_down.s
+      args.state.left_paddle.y -= 40
+    elsif args.inputs.controller_one.key_down.up || args.inputs.keyboard.key_down.w
+      args.state.left_paddle.y += 40
+    end
+  end
+
+  def input_right_paddle args
+    if args.inputs.controller_two.key_down.down  || args.inputs.keyboard.key_down.l
+      args.state.right_paddle.y -= 40
+    elsif args.inputs.controller_two.key_down.up || args.inputs.keyboard.key_down.o
+      args.state.right_paddle.y += 40
+    end
+  end
+end
+
+begin :assets
+  def solid_ball args
+    centered_rect args.state.ball.x, args.state.ball.y, args.state.ball.size, args.state.ball.size
+  end
+
+  def solid_left_paddle args
+    centered_rect_vertically 0, args.state.left_paddle.y, args.state.paddle.w, args.state.paddle.h
+  end
+
+  def solid_right_paddle args
+    centered_rect_vertically 1280 - args.state.paddle.w, args.state.right_paddle.y, args.state.paddle.w, args.state.paddle.h
+  end
+
+  def centered_rect x, y, w, h
+    [x - w / 2, y - h / 2, w, h]
+  end
+
+  def centered_rect_vertically x, y, w, h
+    [x, y - h / 2, w, h]
+  end
+end
+
+</pre>
+<h1 id='--99_genre_arcade/snakemoji/app/main.rb'>99_genre_arcade/snakemoji/app/main.rb</h1>
+<pre># coding: utf-8
+################################
+#  So I was working on a snake game while
+#  learning DragonRuby, and at some point I had a thought
+#  what if I use "😀" as a function name, surely it wont work right...?
+#  RIGHT....?
+#  BUT IT DID, IT WORKED
+#  it all went downhill from then
+#  Created by Anton K. (ai Doge)
+#  https://gist.github.com/scorp200
+#############LICENSE############
+#  Feel free to use this anywhere and however you want
+#  You can sell this to EA for $1,000,000 if you want, its completely free.
+#  Just rememeber you are helping this... thing... to spread...
+#  ALSO! I am not liable for any mental, physical or financial damage caused.
+#############LICENSE############
+
+
+class Array
+  #Helper function
+  def move! vector
+    self.x += vector.x
+    self.y += vector.y
+    return self
+  end
+
+  #Helper function to draw snake body
+  def draw! 🎮, 📺, color
+    translate 📺.solids, 🎮.⛓, [self.x * 🎮.⚖️ + 🎮.🛶 / 2, self.y * 🎮.⚖️ + 🎮.🛶 / 2, 🎮.⚖️ - 🎮.🛶, 🎮.⚖️ - 🎮.🛶, color]
+  end
+
+  #This is where it all started, I was trying to find  good way to multiply a map by a number, * is already used so is **
+  #I kept trying different combinations of symbols, when suddenly...
+  def 😀 value
+    self.map {|d| d * value}
+  end
+end
+
+#Draw stuff with an offset
+def translate output_collection, ⛓, what
+  what.x += ⛓.x
+  what.y += ⛓.y
+  output_collection << what
+end
+
+BLUE = [33, 150, 243]
+RED = [244, 67, 54]
+GOLD = [255, 193, 7]
+LAST = 0
+
+def tick args
+  defaults args.state
+  render args.state, args.outputs
+  input args.state, args.inputs
+  update args.state
+end
+
+def update 🎮
+  #Update every 10 frames
+  if 🎮.tick_count.mod_zero? 10
+    #Add new snake body piece at head's location
+    🎮.🐍 << [*🎮.🤖]
+    #Assign Next Direction to Direction
+    🎮.🚗 = *🎮.🚦
+
+    #Trim the snake a bit if its longer than current size
+    if 🎮.🐍.length > 🎮.🛒
+      🎮.🐍 = 🎮.🐍[-🎮.🛒..-1]
+    end
+
+    #Move the head in the Direction
+    🎮.🤖.move! 🎮.🚗
+
+    #If Head is outside the playing field, or inside snake's body restart game
+    if 🎮.🤖.x < 0 || 🎮.🤖.x >= 🎮.🗺.x || 🎮.🤖.y < 0 || 🎮.🤖.y >= 🎮.🗺.y || 🎮.🚗 != [0, 0] && 🎮.🐍.any? {|s| s == 🎮.🤖}
+      LAST = 🎮.💰
+      🎮.as_hash.clear
+      return
+    end
+
+    #If head lands on food add size and score
+    if 🎮.🤖 == 🎮.🍎
+      🎮.🛒 += 1
+      🎮.💰 += (🎮.🛒 * 0.8).floor.to_i + 5
+      spawn_🍎 🎮
+      puts 🎮.🍎
+    end
+  end
+
+  #Every second remove 1 point
+  if 🎮.💰 > 0 && 🎮.tick_count.mod_zero?(60)
+    🎮.💰 -= 1
+  end
+end
+
+def spawn_🍎 🎮
+  #Food
+  🎮.🍎 ||= [*🎮.🤖]
+  #Randomly spawns food inside the playing field, keep doing this if the food keeps landing on the snake's body
+  while 🎮.🐍.any? {|s| s == 🎮.🍎} || 🎮.🍎 == 🎮.🤖 do
+    🎮.🍎 = [rand(🎮.🗺.x), rand(🎮.🗺.y)]
+  end
+end
+
+def render 🎮, 📺
+  #Paint the background black
+  📺.solids << [0, 0, 1280, 720, 0, 0, 0, 255]
+  #Draw a border for the playing field
+  translate 📺.borders, 🎮.⛓, [0, 0, 🎮.🗺.x * 🎮.⚖️, 🎮.🗺.y * 🎮.⚖️, 255, 255, 255]
+
+  #Draw the snake's body
+  🎮.🐍.map do |🐍| 🐍.draw! 🎮, 📺, BLUE end
+  #Draw the head
+  🎮.🤖.draw! 🎮, 📺, BLUE
+  #Draw the food
+  🎮.🍎.draw! 🎮, 📺, RED
+
+  #Draw current score
+  translate 📺.labels, 🎮.⛓, [5, 715, "Score: #{🎮.💰}", GOLD]
+  #Draw your last score, if any
+  translate 📺.labels, 🎮.⛓, [[*🎮.🤖.😀(🎮.⚖️)].move!([0, 🎮.⚖️ * 2]), "Your Last score is #{LAST}", 0, 1, GOLD] unless LAST == 0 || 🎮.🚗 != [0, 0]
+  #Draw starting message, only if Direction is 0
+  translate 📺.labels, 🎮.⛓, [🎮.🤖.😀(🎮.⚖️), "Press any Arrow key to start", 0, 1, GOLD] unless 🎮.🚗 != [0, 0]
+end
+
+def input 🎮, 🕹
+  #Left and Right keyboard input, only change if X direction is 0
+  if 🕹.keyboard.key_held.left && 🎮.🚗.x == 0
+    🎮.🚦 = [-1, 0]
+  elsif 🕹.keyboard.key_held.right && 🎮.🚗.x == 0
+    🎮.🚦 = [1, 0]
+  end
+
+  #Up and Down keyboard input, only change if Y direction is 0
+  if 🕹.keyboard.key_held.up && 🎮.🚗.y == 0
+    🎮.🚦 = [0, 1]
+  elsif 🕹.keyboard.key_held.down && 🎮.🚗.y == 0
+    🎮.🚦 = [0, -1]
+  end
+end
+
+def defaults 🎮
+  #Playing field size
+  🎮.🗺 ||= [20, 20]
+  #Scale for drawing, screen height / Field height
+  🎮.⚖️ ||= 720 / 🎮.🗺.y
+  #Offset, offset all rendering to the center of the screen
+  🎮.⛓ ||= [(1280 - 720).fdiv(2), 0]
+  #Padding, make the snake body slightly smaller than the scale
+  🎮.🛶 ||= (🎮.⚖️ * 0.2).to_i
+  #Snake Size
+  🎮.🛒 ||= 3
+  #Snake head, the only part we are actually controlling
+  🎮.🤖 ||= [🎮.🗺.x / 2, 🎮.🗺.y / 2]
+  #Snake body map, follows the head
+  🎮.🐍 ||= []
+  #Direction the head moves to
+  🎮.🚗 ||= [0, 0]
+  #Next_Direction, during input check only change this variable and then when game updates asign this to Direction
+  🎮.🚦 ||= [*🎮.🚗]
+  #Your score
+  🎮.💰 ||= 0
+  #Spawns Food randomly
+  spawn_🍎(🎮) unless 🎮.🍎?
+end
+
+</pre>
+<h1 id='--99_genre_arcade/solar_system/app/main.rb'>99_genre_arcade/solar_system/app/main.rb</h1>
+<pre># Focused tutorial video: https://s3.amazonaws.com/s3.dragonruby.org/dragonruby-nddnug-workshop.mp4
+# Workshop/Presentation which provides motivation for creating a game engine: https://www.youtube.com/watch?v=S3CFce1arC8
+
+def defaults args
+  args.outputs.background_color = [0, 0, 0]
+  args.state.x ||= 640
+  args.state.y ||= 360
+  args.state.stars ||= 100.map do
+    [1280 * rand, 720 * rand, rand.fdiv(10), 255 * rand, 255 * rand, 255 * rand]
+  end
+
+  args.state.sun ||= args.state.new_entity(:sun) do |s|
+    s.s = 100
+    s.path = 'sprites/sun.png'
+  end
+
+  args.state.planets = [
+    [:mercury,   65,  5,          88],
+    [:venus,    100, 10,         225],
+    [:earth,    120, 10,         365],
+    [:mars,     140,  8,         687],
+    [:jupiter,  280, 30, 365 *  11.8],
+    [:saturn,   350, 20, 365 *  29.5],
+    [:uranus,   400, 15, 365 *    84],
+    [:neptune,  440, 15, 365 * 164.8],
+    [:pluto,    480,  5, 365 * 247.8],
+  ].map do |name, distance, size, year_in_days|
+    args.state.new_entity(name) do |p|
+      p.path = "sprites/#{name}.png"
+      p.distance = distance * 0.7
+      p.s = size * 0.7
+      p.year_in_days = year_in_days
+    end
+  end
+
+  args.state.ship ||= args.state.new_entity(:ship) do |s|
+    s.x = 1280 * rand
+    s.y = 720 * rand
+    s.angle = 0
+  end
+end
+
+def to_sprite args, entity
+  x = 0
+  y = 0
+
+  if entity.year_in_days
+    day = args.state.tick_count
+    day_in_year = day % entity.year_in_days
+    entity.random_start_day ||= day_in_year * rand
+    percentage_of_year = day_in_year.fdiv(entity.year_in_days)
+    angle = 365 * percentage_of_year
+    x = angle.vector_x(entity.distance)
+    y = angle.vector_y(entity.distance)
+  end
+
+  [640 + x - entity.s.half, 360 + y - entity.s.half, entity.s, entity.s, entity.path]
+end
+
+def render args
+  args.outputs.solids << [0, 0, 1280, 720]
+
+  args.outputs.sprites << args.state.stars.map do |x, y, _, r, g, b|
+    [x, y, 10, 10, 'sprites/star.png', 0, 100, r, g, b]
+  end
+
+  args.outputs.sprites << to_sprite(args, args.state.sun)
+  args.outputs.sprites << args.state.planets.map { |p| to_sprite args, p }
+  args.outputs.sprites << [args.state.ship.x, args.state.ship.y, 20, 20, 'sprites/ship.png', args.state.ship.angle]
+end
+
+def calc args
+  args.state.stars = args.state.stars.map do |x, y, speed, r, g, b|
+    x += speed
+    y += speed
+    x = 0 if x > 1280
+    y = 0 if y > 720
+    [x, y, speed, r, g, b]
+  end
+
+  if args.state.tick_count == 0
+    args.outputs.sounds << 'sounds/bg.ogg'
+  end
+end
+
+def process_inputs args
+  if args.inputs.keyboard.left || args.inputs.controller_one.key_held.left
+    args.state.ship.angle += 1
+  elsif args.inputs.keyboard.right || args.inputs.controller_one.key_held.right
+    args.state.ship.angle -= 1
+  end
+
+  if args.inputs.keyboard.up || args.inputs.controller_one.key_held.a
+    args.state.ship.x += args.state.ship.angle.x_vector
+    args.state.ship.y += args.state.ship.angle.y_vector
+  end
+end
+
+def tick args
+  defaults args
+  render args
+  calc args
+  process_inputs args
+end
+
+def r
+  $gtk.reset
+end
+
+</pre>
+<h1 id='--99_genre_crafting/craft_game_starting_point/app/main.rb'>99_genre_crafting/craft_game_starting_point/app/main.rb</h1>
+<pre># ==================================================
+# A NOTE TO JAM CRAFT PARTICIPANTS:
+# The comments and code in here are just as small piece of DragonRuby's capabilities.
+# Be sure to check out the rest of the sample apps. Start with README.txt and go from there!
+# ==================================================
+
+# def tick args is the entry point into your game. This function is called at
+# a fixed update time of 60hz (60 fps).
+def tick args
+  # The defaults function intitializes the game.
+  defaults args
+
+  # After the game is initialized, render it.
+  render args
+
+  # After rendering the player should be able to respond to input.
+  input args
+
+  # After responding to input, the game performs any additional calculations.
+  calc args
+end
+
+def defaults args
+  # hide the mouse cursor for this game, we are going to render our own cursor
+  if args.state.tick_count == 0
+    args.gtk.hide_cursor
+  end
+
+  args.state.click_ripples ||= []
+
+  # everything is on a 1280x720 virtual canvas, so you can
+  # hardcode locations
+
+  # define the borders for where the inventory is located
+  # args.state is a data structure that accepts any arbitrary parameters
+  # so you can create an object graph without having to create any classes.
+
+  # Bottom left is 0, 0. Top right is 1280, 720.
+  # The inventory area is at the top of the screen
+  # the number 80 is the size of all the sprites, so that is what is being
+  # used to decide the with and height
+  args.state.sprite_size = 80
+
+  args.state.inventory_border.w  = args.state.sprite_size * 10
+  args.state.inventory_border.h  = args.state.sprite_size * 3
+  args.state.inventory_border.x  = 10
+  args.state.inventory_border.y  = 710 - args.state.inventory_border.h
+
+  # define the borders for where the crafting area is located
+  # the crafting area is below the inventory area
+  # the number 80 is the size of all the sprites, so that is what is being
+  # used to decide the with and height
+  args.state.craft_border.x =  10
+  args.state.craft_border.y = 220
+  args.state.craft_border.w = args.state.sprite_size * 3
+  args.state.craft_border.h = args.state.sprite_size * 3
+
+  # define the area where results are located
+  # the crafting result is to the right of the craft area
+  args.state.result_border.x =  10 + args.state.sprite_size * 3 + args.state.sprite_size
+  args.state.result_border.y = 220 + args.state.sprite_size
+  args.state.result_border.w = args.state.sprite_size
+  args.state.result_border.h = args.state.sprite_size
+
+  # initialize items for the first time if they are nil
+  # you start with 15 wood, 1 chest, and 5 plank
+  # Ruby has built in syntax for dictionaries (they look a lot like json objects).
+  # Ruby also has a special type called a Symbol denoted with a : followed by a word.
+  # Symbols are nice because they remove the need for magic strings.
+  if !args.state.items
+    args.state.items = [
+      {
+        id: :wood, # :wood is a Symbol, this is better than using "wood" for the id
+        quantity: 15,
+        path: 'sprites/wood.png',
+        location: :inventory,
+        ordinal_x: 0, ordinal_y: 0
+      },
+      {
+        id: :chest,
+        quantity: 1,
+        path: 'sprites/chest.png',
+        location: :inventory,
+        ordinal_x: 1, ordinal_y: 0
+      },
+      {
+        id: :plank,
+        quantity: 5,
+        path: 'sprites/plank.png',
+        location: :inventory,
+        ordinal_x: 2, ordinal_y: 0
+      },
+    ]
+
+    # after initializing the oridinal positions, derive the pixel
+    # locations assuming that the width and height are 80
+    args.state.items.each { |item| set_inventory_position args, item }
+  end
+
+  # define all the oridinal positions of the inventory slots
+  if !args.state.inventory_area
+    args.state.inventory_area = [
+      { ordinal_x: 0,  ordinal_y: 0 },
+      { ordinal_x: 1,  ordinal_y: 0 },
+      { ordinal_x: 2,  ordinal_y: 0 },
+      { ordinal_x: 3,  ordinal_y: 0 },
+      { ordinal_x: 4,  ordinal_y: 0 },
+      { ordinal_x: 5,  ordinal_y: 0 },
+      { ordinal_x: 6,  ordinal_y: 0 },
+      { ordinal_x: 7,  ordinal_y: 0 },
+      { ordinal_x: 8,  ordinal_y: 0 },
+      { ordinal_x: 9,  ordinal_y: 0 },
+      { ordinal_x: 0,  ordinal_y: 1 },
+      { ordinal_x: 1,  ordinal_y: 1 },
+      { ordinal_x: 2,  ordinal_y: 1 },
+      { ordinal_x: 3,  ordinal_y: 1 },
+      { ordinal_x: 4,  ordinal_y: 1 },
+      { ordinal_x: 5,  ordinal_y: 1 },
+      { ordinal_x: 6,  ordinal_y: 1 },
+      { ordinal_x: 7,  ordinal_y: 1 },
+      { ordinal_x: 8,  ordinal_y: 1 },
+      { ordinal_x: 9,  ordinal_y: 1 },
+      { ordinal_x: 0,  ordinal_y: 2 },
+      { ordinal_x: 1,  ordinal_y: 2 },
+      { ordinal_x: 2,  ordinal_y: 2 },
+      { ordinal_x: 3,  ordinal_y: 2 },
+      { ordinal_x: 4,  ordinal_y: 2 },
+      { ordinal_x: 5,  ordinal_y: 2 },
+      { ordinal_x: 6,  ordinal_y: 2 },
+      { ordinal_x: 7,  ordinal_y: 2 },
+      { ordinal_x: 8,  ordinal_y: 2 },
+      { ordinal_x: 9,  ordinal_y: 2 },
+    ]
+
+    # after initializing the oridinal positions, derive the pixel
+    # locations assuming that the width and height are 80
+    args.state.inventory_area.each { |i| set_inventory_position args, i }
+
+    # if you want to see the result you can use the Ruby function called "puts".
+    # Uncomment this line to see the value.
+    # puts args.state.inventory_area
+
+    # You can see all things written via puts in DragonRuby's Console, or under logs/log.txt.
+    # To bring up DragonRuby's Console, press the ~ key within the game.
+  end
+
+  # define all the oridinal positions of the craft slots
+  if !args.state.craft_area
+    args.state.craft_area = [
+      { ordinal_x: 0, ordinal_y: 0 },
+      { ordinal_x: 0, ordinal_y: 1 },
+      { ordinal_x: 0, ordinal_y: 2 },
+      { ordinal_x: 1, ordinal_y: 0 },
+      { ordinal_x: 1, ordinal_y: 1 },
+      { ordinal_x: 1, ordinal_y: 2 },
+      { ordinal_x: 2, ordinal_y: 0 },
+      { ordinal_x: 2, ordinal_y: 1 },
+      { ordinal_x: 2, ordinal_y: 2 },
+    ]
+
+    # after initializing the oridinal positions, derive the pixel
+    # locations assuming that the width and height are 80
+    args.state.craft_area.each { |c| set_craft_position args, c }
+  end
+end
+
+
+def render args
+  # for the results area, create a sprite that show its boundaries
+  args.outputs.primitives << { x: args.state.result_border.x,
+                               y: args.state.result_border.y,
+                               w: args.state.result_border.w,
+                               h: args.state.result_border.h,
+                               path: 'sprites/border-black.png' }
+
+  # for each inventory spot, create a sprite
+  # args.outputs.primitives is how DragonRuby performs a render.
+  # Adding a single hash or multiple hashes to this array will tell
+  # DragonRuby to render those primitives on that frame.
+
+  # The .map function on Array is used instead of any kind of looping.
+  # .map returns a new object for every object within an Array.
+  args.outputs.primitives << args.state.inventory_area.map do |a|
+    { x: a.x, y: a.y, w: a.w, h: a.h, path: 'sprites/border-black.png' }
+  end
+
+  # for each craft spot, create a sprite
+  args.outputs.primitives << args.state.craft_area.map do |a|
+    { x: a.x, y: a.y, w: a.w, h: a.h, path: 'sprites/border-black.png' }
+  end
+
+  # after the borders have been rendered, render the
+  # items within those slots (and allow for highlighting)
+  # if an item isn't currently being held
+  allow_inventory_highlighting = !args.state.held_item
+
+  # go through each item and render them
+  # use Array's find_all method to remove any items that are currently being held
+  args.state.items.find_all { |item| item[:location] != :held }.map do |item|
+    # if an item is currently being held, don't render it in it's spot within the
+    # inventory or craft area (this is handled via the find_all method).
+
+    # the item_prefab returns a hash containing all the visual components of an item.
+    # the main sprite, the black background, the quantity text, and a hover indication
+    # if the mouse is currently hovering over the item.
+    args.outputs.primitives << item_prefab(args, item, allow_inventory_highlighting, args.inputs.mouse)
+  end
+
+  # The last thing we want to render is the item currently being held.
+  args.outputs.primitives << item_prefab(args, args.state.held_item, allow_inventory_highlighting, args.inputs.mouse)
+
+  args.outputs.primitives << args.state.click_ripples
+
+  # render a mouse cursor since we have the OS cursor hidden
+  args.outputs.primitives << { x: args.inputs.mouse.x - 5, y: args.inputs.mouse.y - 5, w: 10, h: 10, path: 'sprites/circle-gray.png', a: 128 }
+end
+
+# Alrighty! This is where all the fun happens
+def input args
+  # if the mouse is clicked and not item is currently being held
+  # args.state.held_item is nil when the game starts.
+  # If the player clicks, the property args.inputs.mouse.click will
+  # be a non nil value, we don't want to process any of the code here
+  # if the mouse hasn't been clicked
+  return if !args.inputs.mouse.click
+
+  # if a click occurred, add a ripple to the ripple queue
+  args.state.click_ripples << { x: args.inputs.mouse.x - 5, y: args.inputs.mouse.y - 5, w: 10, h: 10, path: 'sprites/circle-gray.png', a: 128 }
+
+  # if the mouse has been clicked, and no item is currently held...
+  if !args.state.held_item
+    # see if any of the items intersect the pointer using the inside_rect? method
+    # the find method will either return the first object that returns true
+    # for the match clause, or it'll return nil if nothing matches the match clause
+    found = args.state.items.find do |item|
+      # for each item in args.state.items, run the following boolean check
+      args.inputs.mouse.click.point.inside_rect?(item)
+    end
+
+    # if an item intersects the mouse pointer, then set the item's location to :held and
+    # set args.state.held_item to the item for later reference
+    if found
+      args.state.held_item = found
+      found[:location] = :held
+    end
+
+  # if the mouse is clicked and an item is currently beign held....
+  elsif args.state.held_item
+    # determine if a slot within the craft area was clicked
+    craft_area = args.state.craft_area.find { |a| args.inputs.mouse.click.point.inside_rect? a }
+
+    # also determine if a slot within the inventory area was clicked
+    inventory_area = args.state.inventory_area.find { |a| args.inputs.mouse.click.point.inside_rect? a }
+
+    # if the click was within a craft area
+    if craft_area
+      # check to see if an item is already there and ignore the click if an item is found
+      # item_at_craft_slot is a helper method that returns an item or nil for a given oridinal
+      # position
+      item_already_there = item_at_craft_slot args, craft_area[:ordinal_x], craft_area[:ordinal_y]
+
+      # if an item *doesn't* exist in the craft area
+      if !item_already_there
+        # if the quantity they are currently holding is greater than 1
+        if args.state.held_item[:quantity] > 1
+          # remove one item (creating a seperate item of the same type), and place it
+          # at the oridinal position and location of the craft area
+          # the .merge method on Hash creates a new Hash, but updates any values
+          # passed as arguments to merge
+          new_item = args.state.held_item.merge(quantity: 1,
+                                                location: :craft,
+                                                ordinal_x: craft_area[:ordinal_x],
+                                                ordinal_y: craft_area[:ordinal_y])
+
+          # after the item is crated, place it into the args.state.items collection
+          args.state.items << new_item
+
+          # then subtract one from the held item
+          args.state.held_item[:quantity] -= 1
+
+        # if the craft area is available and there is only one item being held
+        elsif args.state.held_item[:quantity] == 1
+          # instead of creating any new items just set the location of the held item
+          # to the oridinal position of the craft area, and then nil out the
+          # held item state so that a new item can be picked up
+          args.state.held_item[:location] = :craft
+          args.state.held_item[:ordinal_x] = craft_area[:ordinal_x]
+          args.state.held_item[:ordinal_y] = craft_area[:ordinal_y]
+          args.state.held_item = nil
+        end
+      end
+
+    # if the selected area is an inventory area (as opposed to within the craft area)
+    elsif inventory_area
+
+      # check to see if there is already an item in that inventory slot
+      # the item_at_inventory_slot helper method returns an item or nil
+      item_already_there = item_at_inventory_slot args, inventory_area[:ordinal_x], inventory_area[:ordinal_y]
+
+      # if there is already an item there, and the item types/id match
+      if item_already_there && item_already_there[:id] == args.state.held_item[:id]
+        # then merge the item quantities
+        held_quantity = args.state.held_item[:quantity]
+        item_already_there[:quantity] += held_quantity
+
+        # remove the item being held from the items collection (since it's quantity is now 0)
+        args.state.items.reject! { |i| i[:location] == :held }
+
+        # nil out the held_item so a new item can be picked up
+        args.state.held_item = nil
+
+      # if there currently isn't an item there, then put the held item in the slot
+      elsif !item_already_there
+        args.state.held_item[:location] = :inventory
+        args.state.held_item[:ordinal_x] = inventory_area[:ordinal_x]
+        args.state.held_item[:ordinal_y] = inventory_area[:ordinal_y]
+
+        # nil out the held_item so a new item can be picked up
+        args.state.held_item = nil
+      end
+    end
+  end
+end
+
+# the calc method is executed after input
+def calc args
+  # make sure that the real position of the inventory
+  # items are updated every frame to ensure that they
+  # are placed correctly given their location and oridinal positions
+  # instead of using .map, here we use .each (since we are not returning a new item and just updating the items in place)
+  args.state.items.each do |item|
+    # based on the location of the item, invoke the correct pixel conversion method
+    if item[:location] == :inventory
+      set_inventory_position args, item
+    elsif item[:location] == :craft
+      set_craft_position args, item
+    elsif item[:location] == :held
+      # if the item is held, center the item around the mouse pointer
+      args.state.held_item.x = args.inputs.mouse.x - args.state.held_item.w.half
+      args.state.held_item.y = args.inputs.mouse.y - args.state.held_item.h.half
+    end
+  end
+
+  # for each hash/sprite in the click ripples queue,
+  # expand its size by 20 percent and decrease its alpha
+  # by 10.
+  args.state.click_ripples.each do |ripple|
+    delta_w = ripple.w * 1.2 - ripple.w
+    delta_h = ripple.h * 1.2 - ripple.h
+    ripple.x -= delta_w.half
+    ripple.y -= delta_h.half
+    ripple.w += delta_w
+    ripple.h += delta_h
+    ripple.a -= 10
+  end
+
+  # remove any items from the collection where the alpha value is less than equal to
+  # zero using the reject! method (reject with an exclamation point at the end changes the
+  # array value in place, while reject without the exclamation point returns a new array).
+  args.state.click_ripples.reject! { |ripple| ripple.a <= 0 }
+end
+
+# helper function for finding an item at a craft slot
+def item_at_craft_slot args, ordinal_x, ordinal_y
+  args.state.items.find { |i| i[:location] == :craft && i[:ordinal_x] == ordinal_x && i[:ordinal_y] == ordinal_y }
+end
+
+# helper function for finding an item at an inventory slot
+def item_at_inventory_slot args, ordinal_x, ordinal_y
+  args.state.items.find { |i| i[:location] == :inventory && i[:ordinal_x] == ordinal_x && i[:ordinal_y] == ordinal_y }
+end
+
+# helper function that creates a visual representation of an item
+def item_prefab args, item, should_highlight, mouse
+  return nil unless item
+
+  overlay = nil
+
+  x = item.x
+  y = item.y
+  w = item.w
+  h = item.h
+
+  if should_highlight && mouse.point.inside_rect?(item)
+    overlay = { x: x, y: y, w: w, h: h, path: "sprites/square-blue.png", a: 130, }
+  end
+
+  [
+    # sprites are hashes with a path property, this is the main sprite
+    { x: x,      y: y, w: args.state.sprite_size, h: args.state.sprite_size, path: item[:path], },
+
+    # this represents the black area in the bottom right corner of the main sprite so that the
+    # quantity is visible
+    { x: x + 55, y: y, w: 25, h: 25, path: "sprites/square-black.png", }, # sprites are hashes with a path property
+
+    # labels are hashes with a text property
+    { x: x + 56, y: y + 22, text: "#{item[:quantity]}", r: 255, g: 255, b: 255, },
+
+    # this is the mouse overlay, if the overlay isn't applicable, then this value will be nil (nil values will not be rendered)
+    overlay
+  ]
+end
+
+# helper function for deriving the position of an item within inventory
+def set_inventory_position args, item
+  item.x = args.state.inventory_border.x + item[:ordinal_x] * 80
+  item.y = (args.state.inventory_border.y + args.state.inventory_border.h - 80) - item[:ordinal_y] * 80
+  item.w = 80
+  item.h = 80
+end
+
+# helper function for deriving the position of an item within the craft area
+def set_craft_position args, item
+  item.x = args.state.craft_border.x + item[:ordinal_x] * 80
+  item.y = (args.state.craft_border.y + args.state.inventory_border.h - 80) - item[:ordinal_y] * 80
+  item.w = 80
+  item.h = 80
+end
+
+# Any lines outside of a function will be executed when the file is reloaded.
+# So every time you save main.rb, the game will be reset.
+# Comment out the line below if you don't want this to happen.
+$gtk.reset
+
+</pre>
+<h1 id='--99_genre_dev_tools/animation_creator_starting_point/app/main.rb'>99_genre_dev_tools/animation_creator_starting_point/app/main.rb</h1>
+<pre>class OneBitLowrezPaint
+  attr_gtk
+
+  def tick
+    outputs.background_color = [0, 0, 0]
+    defaults
+    render_instructions
+    render_canvas
+    render_buttons_frame_selection
+    render_animation_frame_thumbnails
+    render_animation
+    input_mouse_click
+    input_keyboard
+    calc_auto_export
+    calc_buttons_frame_selection
+    calc_animation_frames
+    process_queue_create_sprite
+    process_queue_reset_sprite
+    process_queue_update_rt_animation_frame
+  end
+
+  def defaults
+    state.animation_frames_per_second = 12
+    queues.create_sprite ||= []
+    queues.reset_sprite ||= []
+    queues.update_rt_animation_frame ||= []
+
+    if !state.animation_frames
+      state.animation_frames ||= []
+      add_animation_frame_to_end
+    end
+
+    state.last_mouse_down ||= 0
+    state.last_mouse_up   ||= 0
+
+    state.buttons_frame_selection.left = 10
+    state.buttons_frame_selection.top  = grid.top - 10
+    state.buttons_frame_selection.size = 20
+
+    defaults_canvas_sprite
+
+    state.edit_mode ||= :drawing
+  end
+
+  def defaults_canvas_sprite
+    rt_canvas.size   = 16
+    rt_canvas.zoom   = 30
+    rt_canvas.width  = rt_canvas.size * rt_canvas.zoom
+    rt_canvas.height = rt_canvas.size * rt_canvas.zoom
+    rt_canvas.sprite = { x: 0,
+                         y: 0,
+                         w: rt_canvas.width,
+                         h: rt_canvas.height,
+                         path: :rt_canvas }.center_inside_rect(x: 0, y: 0, w: 640, h: 720)
+
+    return unless state.tick_count == 1
+
+    outputs[:rt_canvas].width      = rt_canvas.width
+    outputs[:rt_canvas].height     = rt_canvas.height
+    outputs[:rt_canvas].sprites   << (rt_canvas.size + 1).map_with_index do |x|
+      (rt_canvas.size + 1).map_with_index do |y|
+        path = 'sprites/square-white.png'
+        path = 'sprites/square-blue.png' if x == 7 || x == 8
+        { x: x * rt_canvas.zoom,
+          y: y * rt_canvas.zoom,
+          w: rt_canvas.zoom,
+          h: rt_canvas.zoom,
+          path: path,
+          a: 50 }
+      end
+    end
+  end
+
+  def render_instructions
+    instructions = <<-S
+* Instructions:
+- All data is stored in the ~canvas~ directory.
+- Hold ~d~ to set the edit mode to erase.
+- Release ~d~ to set the edit mode drawing.
+- Press ~a~ to added a frame to the end.
+- Press ~b~ to select the previous frame.
+- Press ~f~ to select the next frame.
+- Press ~c~ to copy a frame.
+- Press ~v~ to paste a copied frame into the selected frame.
+- Press ~x~ to delete the currently selected frame.
+- Press ~w~ to save the canvas and export all sprites.
+- Press ~l~ to load the canvas.
+S
+
+    instructions.strip.each_line.with_index do |l, i|
+      outputs.labels << { x: 840, y: 500 - (i * 20), text: "#{l}",
+                          r: 180, g: 180, b: 180, size_enum: -3 }
+    end
+  end
+
+  def render_canvas
+    return if state.tick_count.zero?
+    outputs.sprites << rt_canvas.sprite
+  end
+
+  def render_buttons_frame_selection
+    args.outputs.primitives << state.buttons_frame_selection.items.map_with_index do |b, i|
+      label = { x: b.x + state.buttons_frame_selection.size.half,
+                y: b.y,
+                text: "#{i + 1}", r: 180, g: 180, b: 180,
+                size_enum: -4, alignment_enum: 1 }.label
+
+      selection_border = b.merge(r: 40, g: 40, b: 40).border
+
+      if i == state.animation_frames_selected_index
+        selection_border = b.merge(r: 40, g: 230, b: 200).border
+      end
+
+      [selection_border, label]
+    end
+  end
+
+  def render_animation_frame_thumbnails
+    return if state.tick_count.zero?
+
+    outputs[:current_animation_frame].width   = rt_canvas.size
+    outputs[:current_animation_frame].height  = rt_canvas.size
+    outputs[:current_animation_frame].solids <<  selected_animation_frame[:pixels].map_with_index do |f, i|
+      { x: f.x,
+        y: f.y,
+        w: 1,
+        h: 1, r: 255, g: 255, b: 255 }
+    end
+
+    outputs.sprites << rt_canvas.sprite.merge(path: :current_animation_frame)
+
+    state.animation_frames.map_with_index do |animation_frame, animation_frame_index|
+      outputs.sprites << state.buttons_frame_selection[:items][animation_frame_index][:inner_rect]
+                              .merge(path: animation_frame[:rt_name])
+    end
+  end
+
+  def render_animation
+    sprite_index = 0.frame_index count: state.animation_frames.length,
+                                 hold_for: 60 / state.animation_frames_per_second,
+                                 repeat: true
+
+    args.outputs.sprites << { x: 700 - 8,
+                              y: 120,
+                              w: 16,
+                              h: 16,
+                              path: (sprite_path sprite_index) }
+
+    args.outputs.sprites << { x: 700 - 16,
+                              y: 230,
+                              w: 32,
+                              h: 32,
+                              path: (sprite_path sprite_index) }
+
+    args.outputs.sprites << { x: 700 - 32,
+                              y: 360,
+                              w: 64,
+                              h: 64,
+                              path: (sprite_path sprite_index) }
+
+    args.outputs.sprites << { x: 700 - 64,
+                              y: 520,
+                              w: 128,
+                              h: 128,
+                              path: (sprite_path sprite_index) }
+  end
+
+  def input_mouse_click
+    if inputs.mouse.up
+      state.last_mouse_up = state.tick_count
+    elsif inputs.mouse.moved && user_is_editing?
+      edit_current_animation_frame inputs.mouse.point
+    end
+
+    return unless inputs.mouse.click
+
+    clicked_frame_button = state.buttons_frame_selection.items.find do |b|
+      inputs.mouse.point.inside_rect? b
+    end
+
+    if (clicked_frame_button)
+      state.animation_frames_selected_index = clicked_frame_button[:index]
+    end
+
+    if (inputs.mouse.point.inside_rect? rt_canvas.sprite)
+      state.last_mouse_down = state.tick_count
+      edit_current_animation_frame inputs.mouse.point
+    end
+  end
+
+  def input_keyboard
+    # w to save
+    if inputs.keyboard.key_down.w
+      t = Time.now
+      state.save_description = "Time: #{t} (#{t.to_i})"
+      gtk.serialize_state 'canvas/state.txt', state
+      gtk.serialize_state "tmp/canvas_backups/#{t.to_i}/state.txt", state
+      animation_frames.each_with_index do |animation_frame, i|
+        queues.update_rt_animation_frame << { index: i,
+                                              at: state.tick_count + i,
+                                              queue_sprite_creation: true }
+        queues.create_sprite << { index: i,
+                                  at: state.tick_count + animation_frames.length + i,
+                                  path_override: "tmp/canvas_backups/#{t.to_i}/sprite-#{i}.png" }
+      end
+      gtk.notify! "Canvas saved."
+    end
+
+    # l to load
+    if inputs.keyboard.key_down.l
+      args.state = gtk.deserialize_state 'canvas/state.txt'
+      animation_frames.each_with_index do |a, i|
+        queues.update_rt_animation_frame << { index: i,
+                                              at: state.tick_count + i,
+                                              queue_sprite_creation: true }
+      end
+      gtk.notify! "Canvas loaded."
+    end
+
+    # d to go into delete mode, release to paint
+    if inputs.keyboard.key_held.d
+      state.edit_mode = :erasing
+      gtk.notify! "Erasing." if inputs.keyboard.key_held.d == (state.tick_count - 1)
+    elsif inputs.keyboard.key_up.d
+      state.edit_mode = :drawing
+      gtk.notify! "Drawing."
+    end
+
+    # a to add a frame to the end
+    if inputs.keyboard.key_down.a
+      queues.create_sprite << { index: state.animation_frames_selected_index,
+                                at: state.tick_count }
+      queues.create_sprite << { index: state.animation_frames_selected_index + 1,
+                                at: state.tick_count }
+      add_animation_frame_to_end
+      gtk.notify! "Frame added to end."
+    end
+
+    # c or t to copy
+    if (inputs.keyboard.key_down.c || inputs.keyboard.key_down.t)
+      state.clipboard = [selected_animation_frame[:pixels]].flatten
+      gtk.notify! "Current frame copied."
+    end
+
+    # v or q to paste
+    if (inputs.keyboard.key_down.v || inputs.keyboard.key_down.q) && state.clipboard
+      selected_animation_frame[:pixels] = [state.clipboard].flatten
+      queues.update_rt_animation_frame << { index: state.animation_frames_selected_index,
+                                            at: state.tick_count,
+                                            queue_sprite_creation: true }
+      gtk.notify! "Pasted."
+    end
+
+    # f to go forward/next frame
+    if (inputs.keyboard.key_down.f)
+      if (state.animation_frames_selected_index == (state.animation_frames.length - 1))
+        state.animation_frames_selected_index = 0
+      else
+        state.animation_frames_selected_index += 1
+      end
+      gtk.notify! "Next frame."
+    end
+
+    # b to go back/previous frame
+    if (inputs.keyboard.key_down.b)
+      if (state.animation_frames_selected_index == 0)
+        state.animation_frames_selected_index = state.animation_frames.length - 1
+      else
+        state.animation_frames_selected_index -= 1
+      end
+      gtk.notify! "Previous frame."
+    end
+
+    # x to delete frame
+    if (inputs.keyboard.key_down.x) && animation_frames.length > 1
+      state.clipboard = selected_animation_frame[:pixels]
+      state.animation_frames = animation_frames.find_all { |v| v[:index] != state.animation_frames_selected_index }
+      if state.animation_frames_selected_index >= state.animation_frames.length
+        state.animation_frames_selected_index = state.animation_frames.length - 1
+      end
+      gtk.notify! "Frame deleted."
+    end
+  end
+
+  def calc_auto_export
+    return if user_is_editing?
+    return if state.last_mouse_up.elapsed_time != 30
+    # auto export current animation frame if there is no editing for 30 ticks
+    queues.create_sprite << { index: state.animation_frames_selected_index,
+                              at: state.tick_count }
+  end
+
+  def calc_buttons_frame_selection
+    state.buttons_frame_selection.items = animation_frames.length.map_with_index do |i|
+      { x: state.buttons_frame_selection.left + i * state.buttons_frame_selection.size,
+        y: state.buttons_frame_selection.top - state.buttons_frame_selection.size,
+        inner_rect: {
+          x: (state.buttons_frame_selection.left + 2) + i * state.buttons_frame_selection.size,
+          y: (state.buttons_frame_selection.top - state.buttons_frame_selection.size + 2),
+          w: 16,
+          h: 16,
+        },
+        w: state.buttons_frame_selection.size,
+        h: state.buttons_frame_selection.size,
+        index: i }
+    end
+  end
+
+  def calc_animation_frames
+    animation_frames.each_with_index do |animation_frame, i|
+      animation_frame[:index] = i
+      animation_frame[:rt_name] = "animation_frame_#{i}"
+    end
+  end
+
+  def process_queue_create_sprite
+    sprites_to_create = queues.create_sprite
+                              .find_all { |h| h[:at].elapsed? }
+
+    queues.create_sprite = queues.create_sprite - sprites_to_create
+
+    sprites_to_create.each do |h|
+      export_animation_frame h[:index], h[:path_override]
+    end
+  end
+
+  def process_queue_reset_sprite
+    sprites_to_reset = queues.reset_sprite
+                             .find_all { |h| h[:at].elapsed? }
+
+    queues.reset_sprite -= sprites_to_reset
+
+    sprites_to_reset.each { |h| gtk.reset_sprite (sprite_path h[:index]) }
+  end
+
+  def process_queue_update_rt_animation_frame
+    animation_frames_to_update = queues.update_rt_animation_frame
+                                       .find_all { |h| h[:at].elapsed? }
+
+    queues.update_rt_animation_frame -= animation_frames_to_update
+
+    animation_frames_to_update.each do |h|
+      update_animation_frame_render_target animation_frames[h[:index]]
+
+      if h[:queue_sprite_creation]
+        queues.create_sprite << { index: h[:index],
+                                  at: state.tick_count + 1 }
+      end
+    end
+  end
+
+  def update_animation_frame_render_target animation_frame
+    return if !animation_frame
+
+    outputs[animation_frame[:rt_name]].width   = state.rt_canvas.size
+    outputs[animation_frame[:rt_name]].height  = state.rt_canvas.size
+    outputs[animation_frame[:rt_name]].solids << animation_frame[:pixels].map do |f|
+      { x: f.x,
+        y: f.y,
+        w: 1,
+        h: 1, r: 255, g: 255, b: 255 }
+    end
+  end
+
+  def animation_frames
+    state.animation_frames
+  end
+
+  def add_animation_frame_to_end
+    animation_frames << {
+      index: animation_frames.length,
+      pixels: [],
+      rt_name: "animation_frame_#{animation_frames.length}"
+    }
+
+    state.animation_frames_selected_index = (animation_frames.length - 1)
+    queues.update_rt_animation_frame << { index: state.animation_frames_selected_index,
+                                          at: state.tick_count,
+                                          queue_sprite_creation: true }
+  end
+
+  def sprite_path i
+    "canvas/sprite-#{i}.png"
+  end
+
+  def export_animation_frame i, path_override = nil
+    return if !state.animation_frames[i]
+
+    outputs.screenshots << state.buttons_frame_selection
+                                .items[i][:inner_rect]
+                                .merge(path: path_override || (sprite_path i))
+
+    outputs.screenshots << state.buttons_frame_selection
+                                .items[i][:inner_rect]
+                                .merge(path: "tmp/sprite_backups/#{Time.now.to_i}-sprite-#{i}.png")
+
+    queues.reset_sprite << { index: i, at: state.tick_count }
+  end
+
+  def selected_animation_frame
+    state.animation_frames[state.animation_frames_selected_index]
+  end
+
+  def edit_current_animation_frame point
+    draw_area_point = (to_draw_area point)
+    if state.edit_mode == :drawing && (!selected_animation_frame[:pixels].include? draw_area_point)
+      selected_animation_frame[:pixels] << draw_area_point
+      queues.update_rt_animation_frame << { index: state.animation_frames_selected_index,
+                                            at: state.tick_count,
+                                            queue_sprite_creation: !user_is_editing? }
+    elsif state.edit_mode == :erasing && (selected_animation_frame[:pixels].include? draw_area_point)
+      selected_animation_frame[:pixels] = selected_animation_frame[:pixels].reject { |p| p == draw_area_point }
+      queues.update_rt_animation_frame << { index: state.animation_frames_selected_index,
+                                            at: state.tick_count,
+                                            queue_sprite_creation: !user_is_editing? }
+    end
+  end
+
+  def user_is_editing?
+    state.last_mouse_down > state.last_mouse_up
+  end
+
+  def to_draw_area point
+    x, y = point
+    x -= rt_canvas.sprite.x
+    y -= rt_canvas.sprite.y
+    { x: x.idiv(rt_canvas.zoom),
+      y: y.idiv(rt_canvas.zoom) }
+  end
+
+  def rt_canvas
+    state.rt_canvas ||= state.new_entity(:rt_canvas)
+  end
+
+  def queues
+    state.queues ||= state.new_entity(:queues)
+  end
+end
+
+$game = OneBitLowrezPaint.new
+
+def tick args
+  $game.args = args
+  $game.tick
+end
+
+# $gtk.reset
+
+</pre>
+<h1 id='--99_genre_dev_tools/tile_editor_starting_point/app/main.rb'>99_genre_dev_tools/tile_editor_starting_point/app/main.rb</h1>
+<pre>=begin
+
+ APIs listing that haven't been encountered in previous sample apps:
+
+ - to_s: Returns a string representation of an object.
+   For example, if we had
+   500.to_s
+   the string "500" would be returned.
+   Similar to to_i, which returns an integer representation of an object.
+
+ - Ceil: Returns an integer number greater than or equal to the original
+   with no decimal.
+
+ Reminders:
+
+ - ARRAY#inside_rect?: Returns true or false depending on if the point is inside a rect.
+
+ - args.outputs.labels: An array. The values generate a label.
+   The parameters are [X, Y, TEXT, SIZE, ALIGNMENT, RED, GREEN, BLUE, ALPHA, FONT STYLE]
+   For more information about labels, go to mygame/documentation/02-labels.md.
+
+ - args.outputs.sprites: An array. The values generate a sprite.
+   The parameters are [X, Y, WIDTH, HEIGHT, IMAGE PATH]
+   For more information about sprites, go to mygame/documentation/05-sprites.md.
+
+ - args.outputs.solids: An array. The values generate a solid.
+   The parameters are [X, Y, WIDTH, HEIGHT, RED, GREEN, BLUE]
+   For more information about solids, go to mygame/documentation/03-solids-and-borders.md.
+
+ - args.outputs.lines: An array. The values generate a line.
+   The parameters are [X1, Y1, X2, Y2, RED, GREEN, BLUE]
+   For more information about lines, go to mygame/documentation/04-lines.md.
+
+ - args.state.new_entity: Used when we want to create a new object, like a sprite or button.
+   In this sample app, new_entity is used to create a new button that clears the grid.
+   (Remember, you can use state to define ANY property and it will be retained across frames.)
+
+=end
+
+# This sample app shows an empty grid that the user can paint in. There are different image tiles that
+# the user can use to fill the grid, and the "Clear" button can be pressed to clear the grid boxes.
+
+class TileEditor
+  attr_accessor :inputs, :state, :outputs, :grid, :args
+
+  # Runs all the methods necessary for the game to function properly.
+  def tick
+    defaults
+    render
+    check_click
+    draw_buttons
+  end
+
+  # Sets default values
+  # Initialization only happens in the first frame
+  # NOTE: The values of some of these variables may seem confusingly large at first.
+  # The gridSize is 1600 but it seems a lot smaller on the screen, for example.
+  # But keep in mind that by using the "W", "A", "S", and "D" keys, you can
+  # move the grid's view in all four directions for more grid spaces.
+  def defaults
+    state.tileCords      ||= []
+    state.tileQuantity   ||= 6
+    state.tileSize       ||= 50
+    state.tileSelected   ||= 1
+    state.tempX          ||= 50
+    state.tempY          ||= 500
+    state.speed          ||= 4
+    state.centerX        ||= 4000
+    state.centerY        ||= 4000
+    state.originalCenter ||= [state.centerX, state.centerY]
+    state.gridSize       ||= 1600
+    state.lineQuantity   ||= 50
+    state.increment      ||= state.gridSize / state.lineQuantity
+    state.gridX          ||= []
+    state.gridY          ||= []
+    state.filled_squares ||= []
+    state.grid_border    ||= [390, 140, 500, 500]
+
+    get_grid unless state.tempX == 0 # calls get_grid in the first frame only
+    determineTileCords unless state.tempX == 0 # calls determineTileCords in first frame
+    state.tempX = 0 # sets tempX to 0; the two methods aren't called again
+  end
+
+  # Calculates the placement of lines or separators in the grid
+  def get_grid
+    curr_x = state.centerX - (state.gridSize / 2) # starts at left of grid
+    deltaX = state.gridSize / state.lineQuantity # finds distance to place vertical lines evenly through width of grid
+    (state.lineQuantity + 2).times do
+      state.gridX << curr_x # adds curr_x to gridX collection
+      curr_x += deltaX # increment curr_x by the distance between vertical lines
+    end
+
+    curr_y = state.centerY - (state.gridSize / 2) # starts at bottom of grid
+    deltaY = state.gridSize / state.lineQuantity # finds distance to place horizontal lines evenly through height of grid
+    (state.lineQuantity + 2).times do
+      state.gridY << curr_y # adds curr_y to gridY collection
+      curr_y += deltaY # increments curr_y to distance between horizontal lines
+    end
+  end
+
+  # Determines coordinate positions of patterned tiles (on the left side of the grid)
+  def determineTileCords
+    state.tempCounter ||= 1 # initializes tempCounter to 1
+    state.tileQuantity.times do # there are 6 different kinds of tiles
+      state.tileCords += [[state.tempX, state.tempY, state.tempCounter]] # adds tile definition to collection
+      state.tempX += 75 # increments tempX to put horizontal space between the patterned tiles
+      state.tempCounter += 1 # increments tempCounter
+      if state.tempX > 200 # if tempX exceeds 200 pixels
+        state.tempX = 50 # a new row of patterned tiles begins
+        state.tempY -= 75 # the new row is 75 pixels lower than the previous row
+      end
+    end
+  end
+
+  # Outputs objects (grid, tiles, etc) onto the screen
+  def render
+    outputs.sprites << state.tileCords.map do # outputs tileCords collection using images in sprites folder
+      |x, y, order|
+      [x, y, state.tileSize, state.tileSize, 'sprites/image' + order.to_s + ".png"]
+    end
+    outputs.solids << [0, 0, 1280, 720, 255, 255, 255] # outputs white background
+    add_grid # outputs grid
+    print_title # outputs title and current tile pattern
+  end
+
+  # Creates a grid by outputting vertical and horizontal grid lines onto the screen.
+  # Outputs sprites for the filled_squares collection onto the screen.
+  def add_grid
+
+    # Outputs the grid's border.
+    outputs.borders << state.grid_border
+    temp = 0
+
+    # Before looking at the code that outputs the vertical and horizontal lines in the
+    # grid, take note of the fact that:
+    # grid_border[1] refers to the border's bottom line (running horizontally),
+    # grid_border[2] refers to the border's top line (running (horizontally),
+    # grid_border[0] refers to the border's left line (running vertically),
+    # and grid_border[3] refers to the border's right line (running vertically).
+
+    #           [2]
+    #       ----------
+    #       |        |
+    # [0]   |        | [3]
+    #       |        |
+    #       ----------
+    #           [1]
+
+    # Calculates the positions and outputs the x grid lines in the color gray.
+    state.gridX.map do # perform an action on all elements of the gridX collection
+      |x|
+      temp += 1 # increment temp
+
+      # if x's value is greater than (or equal to) the x value of the border's left side
+      # and less than (or equal to) the x value of the border's right side
+      if x >= state.centerX - (state.grid_border[2] / 2) && x <= state.centerX + (state.grid_border[2] / 2)
+        delta = state.centerX - 640
+        # vertical lines have the same starting and ending x positions
+        # starting y and ending y positions lead from the bottom of the border to the top of the border
+        outputs.lines << [x - delta, state.grid_border[1], x - delta, state.grid_border[1] + state.grid_border[2], 150, 150, 150] # sets definition of vertical line and outputs it
+      end
+    end
+    temp = 0
+
+    # Calculates the positions and outputs the y grid lines in the color gray.
+    state.gridY.map do # perform an action on all elements of the gridY collection
+      |y|
+      temp += 1 # increment temp
+
+      # if y's value is greater than (or equal to) the y value of the border's bottom side
+      # and less than (or equal to) the y value of the border's top side
+      if y >= state.centerY - (state.grid_border[3] / 2) && y <= state.centerY + (state.grid_border[3] / 2)
+        delta = state.centerY - 393
+        # horizontal lines have the same starting and ending y positions
+        # starting x and ending x positions lead from the left side of the border to the right side of the border
+        outputs.lines << [state.grid_border[0], y - delta, state.grid_border[0] + state.grid_border[3], y - delta, 150, 150, 150] # sets definition of horizontal line and outputs it
+      end
+    end
+
+    # Sets values and outputs sprites for the filled_squares collection.
+    state.filled_squares.map do # perform an action on every element of the filled_squares collection
+      |x, y, w, h, sprite|
+        # if x's value is greater than (or equal to) the x value of 17 pixels to the left of the border's left side
+        # and less than (or equal to) the x value of the border's right side
+        # and y's value is greater than (or equal to) the y value of the border's bottom side
+        # and less than (or equal to) the y value of 25 pixels above the border's top side
+        # NOTE: The allowance of 17 pixels and 25 pixels is due to the fact that a grid box may be slightly cut off or
+        # not entirely visible in the grid's view (until it is moved using "W", "A", "S", "D")
+        if x >= state.centerX - (state.grid_border[2] / 2) - 17 && x <= state.centerX + (state.grid_border[2] / 2) &&
+           y >= state.centerY - (state.grid_border[3] / 2) && y <= state.centerY + (state.grid_border[3] / 2) + 25
+          # calculations done to place sprites in grid spaces that are meant to filled in
+          # mess around with the x and y values and see how the sprite placement changes
+          outputs.sprites << [x - state.centerX + 630, y - state.centerY + 360, w, h, sprite]
+        end
+      end
+
+      # outputs a white solid along the left side of the grid (change the color and you'll be able to see it against the white background)
+      # state.increment subtracted in x parameter because solid's position is denoted by bottom left corner
+      # state.increment subtracted in y parameter to avoid covering the title label
+      outputs.primitives << [state.grid_border[0] - state.increment,
+                             state.grid_border[1] - state.increment, state.increment, state.grid_border[3] + (state.increment * 2),
+                             255, 255, 255].solid
+
+      # outputs a white solid along the right side of the grid
+      # state.increment subtracted from y parameter to avoid covering title label
+      outputs.primitives << [state.grid_border[0] + state.grid_border[2],
+                             state.grid_border[1] - state.increment, state.increment, state.grid_border[3] + (state.increment * 2),
+                             255, 255, 255].solid
+
+      # outputs a white solid along the bottom of the grid
+      # state.increment subtracted from y parameter to avoid covering last row of grid boxes
+      outputs.primitives << [state.grid_border[0] - state.increment, state.grid_border[1] - state.increment,
+                             state.grid_border[2] + (2 * state.increment), state.increment, 255, 255, 255].solid
+
+      # outputs a white solid along the top of the grid
+      outputs.primitives << [state.grid_border[0] - state.increment, state.grid_border[1] + state.grid_border[3],
+                             state.grid_border[2] + (2 * state.increment), state.increment, 255, 255, 255].solid
+
+  end
+
+  # Outputs title and current tile pattern
+  def print_title
+    outputs.labels << [640, 700, 'Mouse to Place Tile, WASD to Move Around', 7, 1] # title label
+    outputs.lines << horizontal_separator(660, 0, 1280) # outputs horizontal separator
+    outputs.labels << [1050, 500, 'Current:', 3, 1] # outputs Current label
+    outputs.sprites << [1110, 474, state.tileSize / 2, state.tileSize / 2, 'sprites/image' + state.tileSelected.to_s + ".png"] # outputs sprite of current tile pattern using images in sprites folder; output is half the size of a tile
+  end
+
+  # Sets the starting position, ending position, and color for the horizontal separator.
+  def horizontal_separator y, x, x2
+    [x, y, x2, y, 150, 150, 150] # definition of separator; horizontal line means same starting/ending y
+  end
+
+  # Checks if the mouse is being clicked or dragged
+  def check_click
+    if inputs.keyboard.key_down.r # if the "r" key is pressed down
+      $dragon.reset
+    end
+
+    if inputs.mouse.down #is mouse up or down?
+      state.mouse_held = true
+      if inputs.mouse.position.x < state.grid_border[0] # if mouse's x position is inside the grid's borders
+        state.tileCords.map do # perform action on all elements of tileCords collection
+          |x, y, order|
+          # if mouse's x position is greater than (or equal to) the starting x position of a tile
+          # and the mouse's x position is also less than (or equal to) the ending x position of that tile,
+          # and the mouse's y position is greater than (or equal to) the starting y position of that tile,
+          # and the mouse's y position is also less than (or equal to) the ending y position of that tile,
+          # (BASICALLY, IF THE MOUSE'S POSITION IS WITHIN THE STARTING AND ENDING POSITIONS OF A TILE)
+          if inputs.mouse.position.x >= x && inputs.mouse.position.x <= x + state.tileSize &&
+             inputs.mouse.position.y >= y && inputs.mouse.position.y <= y + state.tileSize
+            state.tileSelected = order # that tile is selected
+          end
+        end
+      end
+    elsif inputs.mouse.up # otherwise, if the mouse is in the "up" state
+      state.mouse_held = false # mouse is not held down or dragged
+      state.mouse_dragging = false
+    end
+
+    if state.mouse_held &&    # mouse needs to be down
+       !inputs.mouse.click &&     # must not be first click
+       ((inputs.mouse.previous_click.point.x - inputs.mouse.position.x).abs > 15 ||
+        (inputs.mouse.previous_click.point.y - inputs.mouse.position.y).abs > 15) # Need to move 15 pixels before "drag"
+      state.mouse_dragging = true
+    end
+
+    # if mouse is clicked inside grid's border, search_lines method is called with click input type
+    if ((inputs.mouse.click) && (inputs.mouse.click.point.inside_rect? state.grid_border))
+      search_lines(inputs.mouse.click.point, :click)
+
+    # if mouse is dragged inside grid's border, search_lines method is called with drag input type
+    elsif ((state.mouse_dragging) && (inputs.mouse.position.inside_rect? state.grid_border))
+      search_lines(inputs.mouse.position, :drag)
+    end
+
+    # Changes grid's position on screen by moving it up, down, left, or right.
+
+    # centerX is incremented by speed if the "d" key is pressed and if that sum is less than
+    # the original left side of the center plus half the grid, minus half the top border of grid.
+    # MOVES GRID RIGHT (increasing x)
+    state.centerX += state.speed if inputs.keyboard.key_held.d &&
+                                    (state.centerX + state.speed) < state.originalCenter[0] + (state.gridSize / 2) - (state.grid_border[2] / 2)
+    # centerX is decremented by speed if the "a" key is pressed and if that difference is greater than
+    # the original left side of the center minus half the grid, plus half the top border of grid.
+    # MOVES GRID LEFT (decreasing x)
+    state.centerX -= state.speed if inputs.keyboard.key_held.a &&
+                                    (state.centerX - state.speed) > state.originalCenter[0] - (state.gridSize / 2) + (state.grid_border[2] / 2)
+    # centerY is incremented by speed if the "w" key is pressed and if that sum is less than
+    # the original bottom of the center plus half the grid, minus half the right border of grid.
+    # MOVES GRID UP (increasing y)
+    state.centerY += state.speed if inputs.keyboard.key_held.w &&
+                                    (state.centerY + state.speed) < state.originalCenter[1] + (state.gridSize / 2) - (state.grid_border[3] / 2)
+    # centerY is decremented by speed if the "s" key is pressed and if the difference is greater than
+    # the original bottom of the center minus half the grid, plus half the right border of grid.
+    # MOVES GRID DOWN (decreasing y)
+    state.centerY -= state.speed if inputs.keyboard.key_held.s &&
+                                    (state.centerY - state.speed) > state.originalCenter[1] - (state.gridSize / 2) + (state.grid_border[3] / 2)
+  end
+
+  # Performs calculations on the gridX and gridY collections, and sets values.
+  # Sets the definition of a grid box, including the image that it is filled with.
+  def search_lines (point, input_type)
+    point.x += state.centerX - 630 # increments x and y
+    point.y += state.centerY - 360
+    findX = 0
+    findY = 0
+    increment = state.gridSize / state.lineQuantity # divides grid by number of separators
+
+    state.gridX.map do # perform an action on every element of collection
+      |x|
+      # findX increments x by 10 if point.x is less than that sum and findX is currently 0
+      findX = x + 10 if point.x < (x + 10) && findX == 0
+    end
+
+    state.gridY.map do
+      |y|
+      # findY is set to y if point.y is less than that value and findY is currently 0
+      findY = y if point.y < (y) && findY == 0
+    end
+    # position of a box is denoted by bottom left corner, which is why the increment is being subtracted
+    grid_box = [findX - (increment.ceil), findY - (increment.ceil), increment.ceil, increment.ceil,
+                "sprites/image" + state.tileSelected.to_s + ".png"] # sets sprite definition
+
+    if input_type == :click # if user clicks their mouse
+      if state.filled_squares.include? grid_box # if grid box is already filled in
+        state.filled_squares.delete grid_box # box is cleared and removed from filled_squares
+      else
+        state.filled_squares << grid_box # otherwise, box is filled in and added to filled_squares
+      end
+    elsif input_type == :drag # if user drags mouse
+      unless state.filled_squares.include? grid_box # unless grid box dragged over is already filled in
+        state.filled_squares << grid_box # box is filled in and added to filled_squares
+      end
+    end
+  end
+
+  # Creates a "Clear" button using labels and borders.
+  def draw_buttons
+    x, y, w, h = 390, 50, 240, 50
+    state.clear_button        ||= state.new_entity(:button_with_fade)
+
+    # x and y positions are set to display "Clear" label in center of the button
+    # Try changing first two parameters to simply x, y and see what happens to the text placement
+    state.clear_button.label  ||= [x + w.half, y + h.half + 10, "Clear", 0, 1]
+    state.clear_button.border ||= [x, y, w, h] # definition of button's border
+
+    # If the mouse is clicked inside the borders of the clear button
+    if inputs.mouse.click && inputs.mouse.click.point.inside_rect?(state.clear_button.border)
+      state.clear_button.clicked_at = inputs.mouse.click.created_at # value is frame of mouse click
+      state.filled_squares.clear # filled squares collection is emptied (squares are cleared)
+      inputs.mouse.previous_click = nil # no previous click
+    end
+
+    outputs.labels << state.clear_button.label # outputs clear button
+    outputs.borders << state.clear_button.border
+
+    # When the clear button is clicked, the color of the button changes
+    # and the transparency changes, as well. If you change the time from
+    # 0.25.seconds to 1.25.seconds or more, the change will last longer.
+    if state.clear_button.clicked_at
+      outputs.solids << [x, y, w, h, 0, 180, 80, 255 * state.clear_button.clicked_at.ease(0.25.seconds, :flip)]
+    end
+  end
+end
+
+$tile_editor = TileEditor.new
+
+def tick args
+  $tile_editor.inputs = args.inputs
+  $tile_editor.grid = args.grid
+  $tile_editor.args = args
+  $tile_editor.outputs = args.outputs
+  $tile_editor.state = args.state
+  $tile_editor.tick
+  tick_instructions args, "Roll your own tile editor. CLICK to select a sprite. CLICK in grid to place sprite. WASD to move around."
+end
+
+def tick_instructions args, text, y = 715
+  return if args.state.key_event_occurred
+  if args.inputs.mouse.click ||
+     args.inputs.keyboard.directional_vector ||
+     args.inputs.keyboard.key_down.enter ||
+     args.inputs.keyboard.key_down.escape
+    args.state.key_event_occurred = true
+  end
+
+  args.outputs.debug << [0, y - 50, 1280, 60].solid
+  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
+  args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
+end
+
+</pre>
+<h1 id='--99_genre_lowrez/resolution_64x64/app/lowrez.rb'>99_genre_lowrez/resolution_64x64/app/lowrez.rb</h1>
+<pre># Emulation of a 64x64 canvas. Don't change this file unless you know what you're doing :-)
+# Head over to main.rb and study the code there.
+
+LOWREZ_SIZE            = 64
+LOWREZ_ZOOM            = 10
+LOWREZ_ZOOMED_SIZE     = LOWREZ_SIZE * LOWREZ_ZOOM
+LOWREZ_X_OFFSET        = (1280 - LOWREZ_ZOOMED_SIZE).half
+LOWREZ_Y_OFFSET        = ( 720 - LOWREZ_ZOOMED_SIZE).half
+
+LOWREZ_FONT_XL         = -1
+LOWREZ_FONT_XL_HEIGHT  = 20
+
+LOWREZ_FONT_LG         = -3.5
+LOWREZ_FONT_LG_HEIGHT  = 15
+
+LOWREZ_FONT_MD         = -6
+LOWREZ_FONT_MD_HEIGHT  = 10
+
+LOWREZ_FONT_SM         = -8.5
+LOWREZ_FONT_SM_HEIGHT  = 5
+
+LOWREZ_FONT_PATH       = 'fonts/lowrez.ttf'
+
+
+class LowrezOutputs
+  attr_accessor :width, :height
+
+  def initialize args
+    @args = args
+    @background_color ||= [0, 0, 0]
+    @args.outputs.background_color = @background_color
+  end
+
+  def background_color
+    @background_color ||= [0, 0, 0]
+  end
+
+  def background_color= opts
+    @background_color = opts
+    @args.outputs.background_color = @background_color
+
+    outputs_lowrez.solids << [0, 0, LOWREZ_SIZE, LOWREZ_SIZE, @background_color]
+  end
+
+  def outputs_lowrez
+    return @args.outputs if @args.state.tick_count <= 0
+    return @args.outputs[:lowrez]
+  end
+
+  def solids
+    outputs_lowrez.solids
+  end
+
+  def borders
+    outputs_lowrez.borders
+  end
+
+  def sprites
+    outputs_lowrez.sprites
+  end
+
+  def labels
+    outputs_lowrez.labels
+  end
+
+  def default_label
+    {
+      x: 0,
+      y: 63,
+      text: "",
+      size_enum: LOWREZ_FONT_SM,
+      alignment_enum: 0,
+      r: 0,
+      g: 0,
+      b: 0,
+      a: 255,
+      font: LOWREZ_FONT_PATH
+    }
+  end
+
+  def lines
+    outputs_lowrez.lines
+  end
+
+  def primitives
+    outputs_lowrez.primitives
+  end
+
+  def click
+    return nil unless @args.inputs.mouse.click
+    mouse
+  end
+
+  def mouse_click
+    click
+  end
+
+  def mouse_down
+    @args.inputs.mouse.down
+  end
+
+  def mouse_up
+    @args.inputs.mouse.up
+  end
+
+  def mouse
+    [
+      ((@args.inputs.mouse.x - LOWREZ_X_OFFSET).idiv(LOWREZ_ZOOM)),
+      ((@args.inputs.mouse.y - LOWREZ_Y_OFFSET).idiv(LOWREZ_ZOOM))
+    ]
+  end
+
+  def mouse_position
+    mouse
+  end
+
+  def keyboard
+    @args.inputs.keyboard
+  end
+end
+
+class GTK::Args
+  def init_lowrez
+    return if @lowrez
+    @lowrez = LowrezOutputs.new self
+  end
+
+  def lowrez
+    @lowrez
+  end
+end
+
+module GTK
+  class Runtime
+    alias_method :__original_tick_core__, :tick_core unless Runtime.instance_methods.include?(:__original_tick_core__)
+
+    def tick_core
+      @args.init_lowrez
+      __original_tick_core__
+
+      return if @args.state.tick_count <= 0
+
+      @args.render_target(:lowrez)
+           .labels
+           .each do |l|
+        l.y  += 1
+      end
+
+      @args.render_target(:lowrez)
+           .lines
+           .each do |l|
+        l.y  += 1
+        l.y2 += 1
+        l.y2 += 1 if l.y1 != l.y2
+        l.x2 += 1 if l.x1 != l.x2
+      end
+
+      @args.outputs
+           .sprites << { x: 320,
+                         y: 40,
+                         w: 640,
+                         h: 640,
+                         source_x: 0,
+                         source_y: 0,
+                         source_w: 64,
+                         source_h: 64,
+                         path: :lowrez }
+    end
+  end
+end
+
+</pre>
+<h1 id='--99_genre_lowrez/resolution_64x64/app/main.rb'>99_genre_lowrez/resolution_64x64/app/main.rb</h1>
+<pre>require 'app/lowrez.rb'
+
+def tick args
+  # How to set the background color
+  args.lowrez.background_color = [255, 255, 255]
+
+  # ==== HELLO WORLD ======================================================
+  # Steps to get started:
+  # 1. ~def tick args~ is the entry point for your game.
+  # 2. There are quite a few code samples below, remove the "##"
+  #    before each line and save the file to see the changes.
+  # 3. 0,  0 is in bottom left and 63, 63 is in top right corner.
+  # 4. Be sure to come to the discord channel if you need
+  #    more help: [[http://discord.dragonruby.org]].
+
+  # Commenting and uncommenting code:
+  # - Add a "#" infront of lines to comment out code
+  # - Remove the "#" infront of lines to comment out code
+
+  # Invoke the hello_world subroutine/method
+  hello_world args # <---- add a "#" to the beginning of the line to stop running this subroutine/method.
+  # =======================================================================
+
+
+  # ==== HOW TO RENDER A LABEL ============================================
+  # Uncomment the line below to invoke the how_to_render_a_label subroutine/method.
+  # Note: The method is defined in this file with the signature ~def how_to_render_a_label args~
+  #       Scroll down to the method to see the details.
+
+  # Remove the "#" at the beginning of the line below
+  # how_to_render_a_label args # <---- remove the "#" at the begging of this line to run the method
+  # =======================================================================
+
+
+  # ==== HOW TO RENDER A FILLED SQUARE (SOLID) ============================
+  # Remove the "#" at the beginning of the line below
+  # how_to_render_solids args
+  # =======================================================================
+
+
+  # ==== HOW TO RENDER AN UNFILLED SQUARE (BORDER) ========================
+  # Remove the "#" at the beginning of the line below
+  # how_to_render_borders args
+  # =======================================================================
+
+
+  # ==== HOW TO RENDER A LINE =============================================
+  # Remove the "#" at the beginning of the line below
+  # how_to_render_lines args
+  # =======================================================================
+
+
+  # == HOW TO RENDER A SPRITE =============================================
+  # Remove the "#" at the beginning of the line below
+  # how_to_render_sprites args
+  # =======================================================================
+
+
+  # ==== HOW TO MOVE A SPRITE BASED OFF OF USER INPUT =====================
+  # Remove the "#" at the beginning of the line below
+  # how_to_move_a_sprite args
+  # =======================================================================
+
+
+  # ==== HOW TO ANIMATE A SPRITE (SEPERATE PNGS) ==========================
+  # Remove the "#" at the beginning of the line below
+  # how_to_animate_a_sprite args
+  # =======================================================================
+
+
+  # ==== HOW TO ANIMATE A SPRITE (SPRITE SHEET) ===========================
+  # Remove the "#" at the beginning of the line below
+  # how_to_animate_a_sprite_sheet args
+  # =======================================================================
+
+
+  # ==== HOW TO DETERMINE COLLISION =============================================
+  # Remove the "#" at the beginning of the line below
+  # how_to_determine_collision args
+  # =======================================================================
+
+
+  # ==== HOW TO CREATE BUTTONS ==================================================
+  # Remove the "#" at the beginning of the line below
+  # how_to_create_buttons args
+  # =======================================================================
+
+
+  # ==== The line below renders a debug grid, mouse information, and current tick
+  render_debug args
+end
+
+def hello_world args
+  args.lowrez.solids  << { x: 0, y: 64, w: 10, h: 10, r: 255 }
+
+  args.lowrez.labels  << {
+    x: 32,
+    y: 63,
+    text: "lowrezjam 2020",
+    size_enum: LOWREZ_FONT_SM,
+    alignment_enum: 1,
+    r: 0,
+    g: 0,
+    b: 0,
+    a: 255,
+    font: LOWREZ_FONT_PATH
+  }
+
+  args.lowrez.sprites << {
+    x: 32 - 10,
+    y: 32 - 10,
+    w: 20,
+    h: 20,
+    path: 'sprites/lowrez-ship-blue.png',
+    a: args.state.tick_count % 255,
+    angle: args.state.tick_count % 360
+  }
+end
+
+
+# =======================================================================
+# ==== HOW TO RENDER A LABEL ============================================
+# =======================================================================
+def how_to_render_a_label args
+  # NOTE: Text is aligned from the TOP LEFT corner
+
+  # Render an EXTRA LARGE/XL label (remove the "#" in front of each line below)
+  args.lowrez.labels << { x: 0, y: 57, text: "Hello World",
+                         size_enum: LOWREZ_FONT_XL,
+                         r: 0, g: 0, b: 0, a: 255,
+                         font: LOWREZ_FONT_PATH }
+
+  # Render a LARGE/LG label (remove the "#" in front of each line below)
+  args.lowrez.labels << { x: 0, y: 36, text: "Hello World",
+                          size_enum: LOWREZ_FONT_LG,
+                          r: 0, g: 0, b: 0, a: 255,
+                          font: LOWREZ_FONT_PATH }
+
+  # Render a MEDIUM/MD label (remove the "#" in front of each line below)
+  args.lowrez.labels << { x: 0, y: 20, text: "Hello World",
+                          size_enum: LOWREZ_FONT_MD,
+                          r: 0, g: 0, b: 0, a: 255,
+                          font: LOWREZ_FONT_PATH }
+
+  # Render a SMALL/SM label (remove the "#" in front of each line below)
+  args.lowrez.labels << { x: 0, y: 9, text: "Hello World",
+                          size_enum: LOWREZ_FONT_SM,
+                          r: 0, g: 0, b: 0, a: 255,
+                          font: LOWREZ_FONT_PATH }
+
+  # You are provided args.lowrez.default_label which returns a Hash that you
+  # can ~merge~ properties with
+  # Example 1
+  args.lowrez.labels << args.lowrez
+                            .default_label
+                            .merge(text: "Default")
+
+  # Example 2
+  args.lowrez.labels << args.lowrez
+                            .default_label
+                            .merge(x: 31,
+                                   text: "Default",
+                                   r: 128,
+                                   g: 128,
+                                   b: 128)
+end
+
+## # =============================================================================
+## # ==== HOW TO RENDER FILLED SQUARES (SOLIDS) ==================================
+## # =============================================================================
+def how_to_render_solids args
+  # Render a red square at 0, 0 with a width and height of 1
+  args.lowrez.solids << { x: 0, y: 0, w: 1, h: 1, r: 255, g: 0, b: 0, a: 255 }
+
+  # Render a red square at 1, 1 with a width and height of 2
+  args.lowrez.solids << { x: 1, y: 1, w: 2, h: 2, r: 255, g: 0, b: 0, a: 255 }
+
+  # Render a red square at 3, 3 with a width and height of 3
+  args.lowrez.solids << { x: 3, y: 3, w: 3, h: 3, r: 255, g: 0, b: 0 }
+
+  # Render a red square at 6, 6 with a width and height of 4
+  args.lowrez.solids << { x: 6, y: 6, w: 4, h: 4, r: 255, g: 0, b: 0 }
+end
+
+## # =============================================================================
+## # ==== HOW TO RENDER UNFILLED SQUARES (BORDERS) ===============================
+## # =============================================================================
+def how_to_render_borders args
+  # Render a red square at 0, 0 with a width and height of 3
+  args.lowrez.borders << { x: 0, y: 0, w: 3, h: 3, r: 255, g: 0, b: 0, a: 255 }
+
+  # Render a red square at 3, 3 with a width and height of 3
+  args.lowrez.borders << { x: 3, y: 3, w: 4, h: 4, r: 255, g: 0, b: 0, a: 255 }
+
+  # Render a red square at 5, 5 with a width and height of 4
+  args.lowrez.borders << { x: 7, y: 7, w: 5, h: 5, r: 255, g: 0, b: 0, a: 255 }
+end
+
+## # =============================================================================
+## # ==== HOW TO RENDER A LINE ===================================================
+## # =============================================================================
+def how_to_render_lines args
+  # Render a horizontal line at the bottom
+  args.lowrez.lines << { x: 0, y: 0, x2: 63, y2:  0, r: 255 }
+
+  # Render a vertical line at the left
+  args.lowrez.lines << { x: 0, y: 0, x2:  0, y2: 63, r: 255 }
+
+  # Render a diagonal line starting from the bottom left and going to the top right
+  args.lowrez.lines << { x: 0, y: 0, x2: 63, y2: 63, r: 255 }
+end
+
+## # =============================================================================
+## # == HOW TO RENDER A SPRITE ===================================================
+## # =============================================================================
+def how_to_render_sprites args
+  # Loop 10 times and create 10 sprites in 10 positions
+  # Render a sprite at the bottom left with a width and height of 5 and a path of 'sprites/lowrez-ship-blue.png'
+  10.times do |i|
+    args.lowrez.sprites << {
+      x: i * 5,
+      y: i * 5,
+      w: 5,
+      h: 5,
+      path: 'sprites/lowrez-ship-blue.png'
+    }
+  end
+
+  # Given an array of positions create sprites
+  positions = [
+    { x: 10, y: 42 },
+    { x: 15, y: 45 },
+    { x: 22, y: 33 },
+  ]
+
+  positions.each do |position|
+    # use Ruby's ~Hash#merge~ function to create a sprite
+    args.lowrez.sprites << position.merge(path: 'sprites/lowrez-ship-red.png',
+                                          w: 5,
+                                          h: 5)
+  end
+end
+
+## # =============================================================================
+## # ==== HOW TO ANIMATE A SPRITE (SEPERATE PNGS) ==========================
+## # =============================================================================
+def how_to_animate_a_sprite args
+  # STEP 1: Define when you want the animation to start. The animation in this case will start in 3 seconds
+  start_animation_on_tick = 180
+
+  # STEP 2: Get the frame_index given the start tick.
+  sprite_index = start_animation_on_tick.frame_index count: 7,     # how many sprites?
+                                                     hold_for: 4,  # how long to hold each sprite?
+                                                     repeat: true  # should it repeat?
+
+  # STEP 3: frame_index will return nil if the frame hasn't arrived yet
+  if sprite_index
+    # if the sprite_index is populated, use it to determine the sprite path and render it
+    sprite_path  = "sprites/explosion-#{sprite_index}.png"
+    args.lowrez.sprites << { x: 0, y: 0, w: 64, h: 64, path: sprite_path }
+  else
+    # if the sprite_index is nil, render a countdown instead
+    countdown_in_seconds = ((start_animation_on_tick - args.state.tick_count) / 60).round(1)
+
+    args.lowrez.labels  << args.lowrez
+                               .default_label
+                               .merge(x: 32,
+                                      y: 32,
+                                      text: "Count Down: #{countdown_in_seconds}",
+                                      alignment_enum: 1)
+  end
+
+  # render the current tick and the resolved sprite index
+  args.lowrez.labels  << args.lowrez
+                               .default_label
+                               .merge(x: 0,
+                                      y: 11,
+                                      text: "Tick: #{args.state.tick_count}")
+  args.lowrez.labels  << args.lowrez
+                               .default_label
+                               .merge(x: 0,
+                                      y: 5,
+                                      text: "sprite_index: #{sprite_index}")
+end
+
+## # =============================================================================
+## # ==== HOW TO ANIMATE A SPRITE (SPRITE SHEET) =================================
+## # =============================================================================
+def how_to_animate_a_sprite_sheet args
+  # STEP 1: Define when you want the animation to start. The animation in this case will start in 3 seconds
+  start_animation_on_tick = 180
+
+  # STEP 2: Get the frame_index given the start tick.
+  sprite_index = start_animation_on_tick.frame_index count: 7,     # how many sprites?
+                                                     hold_for: 4,  # how long to hold each sprite?
+                                                     repeat: true  # should it repeat?
+
+  # STEP 3: frame_index will return nil if the frame hasn't arrived yet
+  if sprite_index
+    # if the sprite_index is populated, use it to determine the source rectangle and render it
+    args.lowrez.sprites << {
+      x: 0,
+      y: 0,
+      w: 64,
+      h: 64,
+      path:  "sprites/explosion-sheet.png",
+      source_x: 32 * sprite_index,
+      source_y: 0,
+      source_w: 32,
+      source_h: 32
+    }
+  else
+    # if the sprite_index is nil, render a countdown instead
+    countdown_in_seconds = ((start_animation_on_tick - args.state.tick_count) / 60).round(1)
+
+    args.lowrez.labels  << args.lowrez
+                               .default_label
+                               .merge(x: 32,
+                                      y: 32,
+                                      text: "Count Down: #{countdown_in_seconds}",
+                                      alignment_enum: 1)
+  end
+
+  # render the current tick and the resolved sprite index
+  args.lowrez.labels  << args.lowrez
+                               .default_label
+                               .merge(x: 0,
+                                      y: 11,
+                                      text: "tick: #{args.state.tick_count}")
+  args.lowrez.labels  << args.lowrez
+                               .default_label
+                               .merge(x: 0,
+                                      y: 5,
+                                      text: "sprite_index: #{sprite_index}")
+end
+
+## # =============================================================================
+## # ==== HOW TO STORE STATE, ACCEPT INPUT, AND RENDER SPRITE BASED OFF OF STATE =
+## # =============================================================================
+def how_to_move_a_sprite args
+  args.lowrez.labels << args.lowrez
+                            .default_label
+                            .merge(x: 32,
+                                   y: 62, text: "Use Arrow Keys",
+                                   alignment_enum: 1)
+
+  args.lowrez.labels << args.lowrez
+                            .default_label
+                            .merge(x: 32,
+                                   y: 56, text: "Use WASD",
+                                   alignment_enum: 1)
+
+  args.lowrez.labels << args.lowrez
+                            .default_label
+                            .merge(x: 32,
+                                   y: 50, text: "Or Click",
+                                   alignment_enum: 1)
+
+  # set the initial values for x and y using ||= ("or equal operator")
+  args.state.ship.x ||= 0
+  args.state.ship.y ||= 0
+
+  # if a mouse click occurs, update the ship's x and y to be the location of the click
+  if args.lowrez.mouse_click
+    args.state.ship.x = args.lowrez.mouse_click.x
+    args.state.ship.y = args.lowrez.mouse_click.y
+  end
+
+  # if a or left arrow is pressed/held, decrement the ships x position
+  if args.lowrez.keyboard.left
+    args.state.ship.x -= 1
+  end
+
+  # if d or right arrow is pressed/held, increment the ships x position
+  if args.lowrez.keyboard.right
+    args.state.ship.x += 1
+  end
+
+  # if s or down arrow is pressed/held, decrement the ships y position
+  if args.lowrez.keyboard.down
+    args.state.ship.y -= 1
+  end
+
+  # if w or up arrow is pressed/held, increment the ships y position
+  if args.lowrez.keyboard.up
+    args.state.ship.y += 1
+  end
+
+  # render the sprite to the screen using the position stored in args.state.ship
+  args.lowrez.sprites << {
+    x: args.state.ship.x,
+    y: args.state.ship.y,
+    w: 5,
+    h: 5,
+    path: 'sprites/lowrez-ship-blue.png',
+    # parameters beyond this point are optional
+    angle: 0, # Note: rotation angle is denoted in degrees NOT radians
+    r: 255,
+    g: 255,
+    b: 255,
+    a: 255
+  }
+end
+
+# =======================================================================
+# ==== HOW TO DETERMINE COLLISION =======================================
+# =======================================================================
+def how_to_determine_collision args
+  # Render the instructions
+  args.lowrez.labels << args.lowrez
+                            .default_label
+                            .merge(x: 32,
+                                   y: 62, text: "Click Anywhere",
+                                   alignment_enum: 1)
+
+  # if a mouse click occurs:
+  # - set ship_one if it isn't set
+  # - set ship_two if it isn't set
+  # - otherwise reset ship one and ship two
+  if args.lowrez.mouse_click
+    # is ship_one set?
+    if !args.state.ship_one
+      args.state.ship_one = { x: args.lowrez.mouse_click.x - 10,
+                              y: args.lowrez.mouse_click.y - 10,
+                              w: 20,
+                              h: 20 }
+    # is ship_one set?
+    elsif !args.state.ship_two
+      args.state.ship_two = { x: args.lowrez.mouse_click.x - 10,
+                              y: args.lowrez.mouse_click.y - 10,
+                              w: 20,
+                              h: 20 }
+    # should we reset?
+    else
+      args.state.ship_one = nil
+      args.state.ship_two = nil
+    end
+  end
+
+  # render ship one if it's set
+  if args.state.ship_one
+    # use Ruby's .merge method which is available on ~Hash~ to set the sprite and alpha
+    # render ship one
+    args.lowrez.sprites << args.state.ship_one.merge(path: 'sprites/lowrez-ship-blue.png', a: 100)
+  end
+
+  if args.state.ship_two
+    # use Ruby's .merge method which is available on ~Hash~ to set the sprite and alpha
+    # render ship two
+    args.lowrez.sprites << args.state.ship_two.merge(path: 'sprites/lowrez-ship-red.png', a: 100)
+  end
+
+  # if both ship one and ship two are set, then determine collision
+  if args.state.ship_one && args.state.ship_two
+    # collision is determined using the intersect_rect? method
+    if args.state.ship_one.intersect_rect? args.state.ship_two
+      # if collision occurred, render the words collision!
+      args.lowrez.labels << args.lowrez
+                            .default_label
+                            .merge(x: 31,
+                                   y: 5,
+                                   text: "Collision!",
+                                   alignment_enum: 1)
+    else
+      # if collision occurred, render the words no collision.
+      args.lowrez.labels << args.lowrez
+                            .default_label
+                            .merge(x: 31,
+                                   y: 5,
+                                   text: "No Collision.",
+                                   alignment_enum: 1)
+    end
+  else
+    # if both ship one and ship two aren't set, then render --
+      args.lowrez.labels << args.lowrez
+                            .default_label
+                            .merge(x: 31,
+                                   y: 6,
+                                   text: "--",
+                                   alignment_enum: 1)
+  end
+end
+
+## # =============================================================================
+## # ==== HOW TO CREATE BUTTONS ==================================================
+## # =============================================================================
+def how_to_create_buttons args
+  # Define a button style
+  args.state.button_style = { w: 62, h: 10, r: 80, g: 80, b: 80 }
+  args.state.label_style  = { r: 80, g: 80, b: 80 }
+
+  # Render instructions
+  args.state.button_message ||= "Press a Button!"
+  args.lowrez.labels << args.lowrez
+                            .default_label
+                            .merge(args.state.label_style)
+                            .merge(x: 32,
+                                   y: 62,
+                                   text: args.state.button_message,
+                                   alignment_enum: 1)
+
+
+  # Creates button one using a border and a label
+  args.state.button_one_border = args.state.button_style.merge( x: 1, y: 32)
+  args.lowrez.borders << args.state.button_one_border
+  args.lowrez.labels  << args.lowrez
+                             .default_label
+                             .merge(args.state.label_style)
+                             .merge(x: args.state.button_one_border.x + 2,
+                                    y: args.state.button_one_border.y + LOWREZ_FONT_SM_HEIGHT + 2,
+                                    text: "Button One")
+
+  # Creates button two using a border and a label
+  args.state.button_two_border = args.state.button_style.merge( x: 1, y: 20)
+
+  args.lowrez.borders << args.state.button_two_border
+  args.lowrez.labels << args.lowrez
+                            .default_label
+                            .merge(args.state.label_style)
+                            .merge(x: args.state.button_two_border.x + 2,
+                                   y: args.state.button_two_border.y + LOWREZ_FONT_SM_HEIGHT + 2,
+                                   text: "Button Two")
+
+  # Initialize the state variable that tracks which button was clicked to "" (empty stringI
+  args.state.last_button_clicked ||= "--"
+
+  # If a click occurs, check to see if either button one, or button two was clicked
+  # using the inside_rect? method of the mouse
+  # set args.state.last_button_clicked accordingly
+  if args.lowrez.mouse_click
+    if args.lowrez.mouse_click.inside_rect? args.state.button_one_border
+      args.state.last_button_clicked = "One Clicked!"
+    elsif args.lowrez.mouse_click.inside_rect? args.state.button_two_border
+      args.state.last_button_clicked = "Two Clicked!"
+    else
+      args.state.last_button_clicked = "--"
+    end
+  end
+
+  # Render the current value of args.state.last_button_clicked
+  args.lowrez.labels << args.lowrez
+                             .default_label
+                             .merge(args.state.label_style)
+                             .merge(x: 32,
+                                    y: 5,
+                                    text: args.state.last_button_clicked,
+                                    alignment_enum: 1)
+end
+
+
+def render_debug args
+  if !args.state.grid_rendered
+    65.map_with_index do |i|
+      args.outputs.static_debug << {
+        x:  LOWREZ_X_OFFSET,
+        y:  LOWREZ_Y_OFFSET + (i * 10),
+        x2: LOWREZ_X_OFFSET + LOWREZ_ZOOMED_SIZE,
+        y2: LOWREZ_Y_OFFSET + (i * 10),
+        r: 128,
+        g: 128,
+        b: 128,
+        a: 80
+      }.line
+
+      args.outputs.static_debug << {
+        x:  LOWREZ_X_OFFSET + (i * 10),
+        y:  LOWREZ_Y_OFFSET,
+        x2: LOWREZ_X_OFFSET + (i * 10),
+        y2: LOWREZ_Y_OFFSET + LOWREZ_ZOOMED_SIZE,
+        r: 128,
+        g: 128,
+        b: 128,
+        a: 80
+      }.line
+    end
+  end
+
+  args.state.grid_rendered = true
+
+  args.state.last_click ||= 0
+  args.state.last_up    ||= 0
+  args.state.last_click   = args.state.tick_count if args.lowrez.mouse_down # you can also use args.lowrez.click
+  args.state.last_up      = args.state.tick_count if args.lowrez.mouse_up
+  args.state.label_style  = { size_enum: -1.5 }
+
+  args.state.watch_list = [
+    "args.state.tick_count is:       #{args.state.tick_count}",
+    "args.lowrez.mouse_position is:  #{args.lowrez.mouse_position.x}, #{args.lowrez.mouse_position.y}",
+    "args.lowrez.mouse_down tick:    #{args.state.last_click || "never"}",
+    "args.lowrez.mouse_up tick:      #{args.state.last_up || "false"}",
+  ]
+
+  args.outputs.debug << args.state
+                            .watch_list
+                            .map_with_index do |text, i|
+    {
+      x: 5,
+      y: 720 - (i * 20),
+      text: text,
+      size_enum: -1.5
+    }.label
+  end
+
+  args.outputs.debug << {
+    x: 640,
+    y:  25,
+    text: "INFO: dev mode is currently enabled. Comment out the invocation of ~render_debug~ within the ~tick~ method to hide the debug layer.",
+    size_enum: -0.5,
+    alignment_enum: 1
+  }.label
+end
+
+$gtk.reset
+
+</pre>
+<h1 id='--99_genre_narrative_rpg/choose_your_own_adventure/app/decision.rb'>99_genre_narrative_rpg/choose_your_own_adventure/app/decision.rb</h1>
+<pre># Hey there! Welcome to Four Decisions. Here is how you
+# create your decision tree. Remove =being and =end from the text to
+# enable the game (just save the file). Change stuff and see what happens!
+
+def game
+  {
+    starting_decision: :stormy_night,
+    decisions: {
+      stormy_night: {
+        description: 'It was a dark and stormy night. (storyline located in decision.rb)',
+        option_one: {
+          description: 'Go to sleep.',
+          decision: :nap
+        },
+        option_two: {
+          description: 'Watch a movie.',
+          decision: :movie
+        },
+        option_three: {
+          description: 'Go outside.',
+          decision: :go_outside
+        },
+        option_four: {
+          description: 'Get a snack.',
+          decision: :get_a_snack
+        }
+      },
+      nap: {
+        description: 'You took a nap. The end.',
+        option_one: {
+          description: 'Start over.',
+          decision: :stormy_night
+        }
+      }
+    }
+  }
+end
+
+</pre>
+<h1 id='--99_genre_narrative_rpg/choose_your_own_adventure/app/main.rb'>99_genre_narrative_rpg/choose_your_own_adventure/app/main.rb</h1>
+<pre>=begin
+
+ Reminders:
+
+ - Hashes: Collection of unique keys and their corresponding values. The values can be found
+   using their keys.
+
+   In this sample app, the decisions needed for the game are stored in a hash. In fact, the
+   decision.rb file contains hashes inside of other hashes!
+
+   Each option is a key in the first hash, but also contains a hash (description and
+   decision being its keys) as its value.
+   Go into the decision.rb file and take a look before diving into the code below.
+
+ - args.outputs.labels: An array. The values generate a label.
+   The parameters are [X, Y, TEXT, SIZE, ALIGNMENT, RED, GREEN, BLUE, ALPHA, FONT STYLE]
+   For more information about labels, go to mygame/documentation/02-labels.md.
+
+ - args.keyboard.key_down.KEY: Determines if a key is in the down state or pressed down.
+   For more information about the keyboard, go to mygame/documentation/06-keyboard.md.
+
+ - String interpolation: uses #{} syntax; everything between the #{ and the } is evaluated
+   as Ruby code, and the placeholder is replaced with its corresponding value or result.
+
+=end
+
+# This sample app provides users with a story and multiple decisions that they can choose to make.
+# Users can make a decision using their keyboard, and the story will move forward based on user choices.
+
+# The decisions available to users are stored in the decision.rb file.
+# We must have access to it for the game to function properly.
+GAME_FILE = 'app/decision.rb' # found in app folder
+
+require GAME_FILE # require used to load another file, import class/method definitions
+
+# Instructions are given using labels to users if they have not yet set up their story in the decision.rb file.
+# Otherwise, the game is run.
+def tick args
+  if !args.state.loaded && !respond_to?(:game) # if game is not loaded and not responding to game symbol's method
+    args.labels << [640, 370, 'Hey there! Welcome to Four Decisions.', 0, 1] # a welcome label is shown
+    args.labels << [640, 340, 'Go to the file called decision.rb and tell me your story.', 0, 1]
+  elsif respond_to?(:game) # otherwise, if responds to game
+    args.state.loaded = true
+    tick_game args # calls tick_game method, runs game
+  end
+
+  if args.state.tick_count.mod_zero? 60 # update every 60 frames
+    t = args.gtk.ffi_file.mtime GAME_FILE # mtime returns modification time for named file
+    if t != args.state.mtime
+      args.state.mtime = t
+      require GAME_FILE # require used to load file
+      args.state.game_definition = nil # game definition and decision are empty
+      args.state.decision_id = nil
+    end
+  end
+end
+
+# Runs methods needed for game to function properly
+# Creates a rectangular border around the screen
+def tick_game args
+  defaults args
+  args.borders << args.grid.rect
+  render_decision args
+  process_inputs args
+end
+
+# Sets default values and uses decision.rb file to define game and decision_id
+# variable using the starting decision
+def defaults args
+  args.state.game_definition ||= game
+  args.state.decision_id ||= args.state.game_definition[:starting_decision]
+end
+
+# Outputs the possible decision descriptions the user can choose onto the screen
+# as well as what key to press on their keyboard to make their decision
+def render_decision args
+  decision = current_decision args
+  # text is either the value of decision's description key or warning that no description exists
+  args.labels << [640, 360, decision[:description] || "No definition found for #{args.state.decision_id}. Please update decision.rb.", 0, 1] # uses string interpolation
+
+  # All decisions are stored in a hash
+  # The descriptions output onto the screen are the values for the description keys of the hash.
+  if decision[:option_one]
+    args.labels << [10, 360, decision[:option_one][:description], 0, 0] # option one's description label
+    args.labels << [10, 335, "(Press 'left' on the keyboard to select this decision)", -5, 0] # label of what key to press to select the decision
+  end
+
+  if decision[:option_two]
+    args.labels << [1270, 360, decision[:option_two][:description], 0, 2] # option two's description
+    args.labels << [1270, 335, "(Press 'right' on the keyboard to select this decision)", -5, 2]
+  end
+
+  if decision[:option_three]
+    args.labels << [640, 45, decision[:option_three][:description], 0, 1] # option three's description
+    args.labels << [640, 20, "(Press 'down' on the keyboard to select this decision)", -5, 1]
+  end
+
+  if decision[:option_four]
+    args.labels << [640, 700, decision[:option_four][:description], 0, 1] # option four's description
+    args.labels << [640, 675, "(Press 'up' on the keyboard to select this decision)", -5, 1]
+  end
+end
+
+# Uses keyboard input from the user to make a decision
+# Assigns the decision as the value of the decision_id variable
+def process_inputs args
+  decision = current_decision args # calls current_decision method
+
+  if args.keyboard.key_down.left! && decision[:option_one] # if left key pressed and option one exists
+    args.state.decision_id = decision[:option_one][:decision] # value of option one's decision hash key is set to decision_id
+  end
+
+  if args.keyboard.key_down.right! && decision[:option_two] # if right key pressed and option two exists
+    args.state.decision_id = decision[:option_two][:decision] # value of option two's decision hash key is set to decision_id
+  end
+
+  if args.keyboard.key_down.down! && decision[:option_three] # if down key pressed and option three exists
+    args.state.decision_id = decision[:option_three][:decision] # value of option three's decision hash key is set to decision_id
+  end
+
+  if args.keyboard.key_down.up! && decision[:option_four] # if up key pressed and option four exists
+    args.state.decision_id = decision[:option_four][:decision] # value of option four's decision hash key is set to decision_id
+  end
+end
+
+# Uses decision_id's value to keep track of current decision being made
+def current_decision args
+  args.state.game_definition[:decisions][args.state.decision_id] || {} # either has value or is empty
+end
+
+# Resets the game.
+$gtk.reset
+
+</pre>
+<h1 id='--99_genre_narrative_rpg/return_of_serenity/app/lowrez_simulator.rb'>99_genre_narrative_rpg/return_of_serenity/app/lowrez_simulator.rb</h1>
+<pre>###################################################################################
+# YOU CAN PLAY AROUND WITH THE CODE BELOW, BUT USE CAUTION AS THIS IS WHAT EMULATES
+# THE 64x64 CANVAS.
+###################################################################################
+
+TINY_RESOLUTION       = 64
+TINY_SCALE            = 720.fdiv(TINY_RESOLUTION + 5)
+CENTER_OFFSET         = 10
+EMULATED_FONT_SIZE    = 20
+EMULATED_FONT_X_ZERO  = 0
+EMULATED_FONT_Y_ZERO  = 46
+
+def tick args
+  sprites = []
+  labels = []
+  borders = []
+  solids = []
+  mouse = emulate_lowrez_mouse args
+  args.state.show_gridlines = false
+  lowrez_tick args, sprites, labels, borders, solids, mouse
+  render_gridlines_if_needed args
+  render_mouse_crosshairs args, mouse
+  emulate_lowrez_scene args, sprites, labels, borders, solids, mouse
+end
+
+def emulate_lowrez_mouse args
+  args.state.new_entity_strict(:lowrez_mouse) do |m|
+    m.x = args.mouse.x.idiv(TINY_SCALE) - CENTER_OFFSET.idiv(TINY_SCALE) - 1
+    m.y = args.mouse.y.idiv(TINY_SCALE)
+    if args.mouse.click
+      m.click = [
+        args.mouse.click.point.x.idiv(TINY_SCALE) - CENTER_OFFSET.idiv(TINY_SCALE) - 1,
+        args.mouse.click.point.y.idiv(TINY_SCALE)
+      ]
+      m.down = m.click
+    else
+      m.click = nil
+      m.down = nil
+    end
+
+    if args.mouse.up
+      m.up = [
+        args.mouse.up.point.x.idiv(TINY_SCALE) - CENTER_OFFSET.idiv(TINY_SCALE) - 1,
+        args.mouse.up.point.y.idiv(TINY_SCALE)
+      ]
+    else
+      m.up = nil
+    end
+  end
+end
+
+def render_mouse_crosshairs args, mouse
+  return unless args.state.show_gridlines
+  args.labels << [10, 25, "mouse: #{mouse.x} #{mouse.y}", 255, 255, 255]
+end
+
+def emulate_lowrez_scene args, sprites, labels, borders, solids, mouse
+  args.render_target(:lowrez).solids  << [0, 0, 1280, 720]
+  args.render_target(:lowrez).sprites << sprites
+  args.render_target(:lowrez).borders << borders
+  args.render_target(:lowrez).solids  << solids
+  args.outputs.primitives << labels.map do |l|
+    as_label = l.label
+    l.text.each_char.each_with_index.map do |char, i|
+      [CENTER_OFFSET + EMULATED_FONT_X_ZERO + (as_label.x * TINY_SCALE) + i * 5 * TINY_SCALE,
+       EMULATED_FONT_Y_ZERO + (as_label.y * TINY_SCALE), char,
+       EMULATED_FONT_SIZE, 0, as_label.r, as_label.g, as_label.b, as_label.a, 'fonts/dragonruby-gtk-4x4.ttf'].label
+    end
+  end
+
+  args.sprites    << [CENTER_OFFSET, 0, 1280 * TINY_SCALE, 720 * TINY_SCALE, :lowrez]
+end
+
+def render_gridlines_if_needed args
+  if args.state.show_gridlines && args.static_lines.length == 0
+    args.static_lines << 65.times.map do |i|
+      [
+        [CENTER_OFFSET + i * TINY_SCALE + 1,  0,
+         CENTER_OFFSET + i * TINY_SCALE + 1,  720,                128, 128, 128],
+        [CENTER_OFFSET + i * TINY_SCALE,      0,
+         CENTER_OFFSET + i * TINY_SCALE,      720,                128, 128, 128],
+        [CENTER_OFFSET,                       0 + i * TINY_SCALE,
+         CENTER_OFFSET + 720,                 0 + i * TINY_SCALE, 128, 128, 128],
+        [CENTER_OFFSET,                       1 + i * TINY_SCALE,
+         CENTER_OFFSET + 720,                 1 + i * TINY_SCALE, 128, 128, 128]
+      ]
+    end
+  elsif !args.state.show_gridlines
+    args.static_lines.clear
+  end
+end
+
+</pre>
+<h1 id='--99_genre_narrative_rpg/return_of_serenity/app/main.rb'>99_genre_narrative_rpg/return_of_serenity/app/main.rb</h1>
+<pre>require 'app/require.rb'
+
+def defaults args
+  args.outputs.background_color = [0, 0, 0]
+  args.state.last_story_line_text ||= ""
+  args.state.scene_history ||= []
+  args.state.storyline_history ||= []
+  args.state.word_delay ||= 8
+  if args.state.tick_count == 0
+    args.gtk.stop_music
+    args.outputs.sounds << 'sounds/static-loop.ogg'
+  end
+
+  if args.state.storyline_history[-1] && args.state.storyline_queue_empty_at
+    lines = args.state
+                .storyline_history[-1]
+                .gsub("-", "")
+                .gsub("~", "")
+                .wrapped_lines(55)
+
+    args.outputs.labels << multiple_lines(args, 690, 10 + lines.length * 25, lines, 0, 0)
+  elsif !args.state.is_storyline_dialog_active
+    args.outputs.labels << multiple_lines(args, 690, 55, "Use the arrow keys on your keyboard to move around. The GREEN boxes are important.".wrapped_lines(50))
+  end
+
+  return if args.state.current_scene
+  set_scene(args, day_one_beginning(args))
+end
+
+def inputs_move_player args
+  if args.state.scene_changed_at.elapsed_time > 5
+    if args.keyboard.down  || args.keyboard.s || args.keyboard.j
+      args.state.player.y -= 0.25
+    elsif args.keyboard.up || args.keyboard.w || args.keyboard.k
+      args.state.player.y += 0.25
+    end
+
+    if args.keyboard.left     || args.keyboard.a  || args.keyboard.h
+      args.state.player.x -= 0.25
+    elsif args.keyboard.right || args.keyboard.d  || args.keyboard.l
+      args.state.player.x += 0.25
+    end
+
+    args.state.player.y = 60 if args.state.player.y > 63
+    args.state.player.y =  0 if args.state.player.y < -3
+    args.state.player.x = 60 if args.state.player.x > 63
+    args.state.player.x =  0 if args.state.player.x < -3
+  end
+end
+
+def null_or_empty? ary
+  return true unless ary
+  return true if ary.length == 0
+  return false
+end
+
+def calc_storyline_hotspot args
+  hotspots = args.state.storylines.find_all do |hs|
+    args.state.player.inside_rect?(hs.shift_rect(-2, 0))
+  end
+
+  if !null_or_empty?(hotspots) && !args.state.inside_storyline_hotspot
+    _, _, _, _, storyline = hotspots.first
+    queue_storyline_text(args, storyline)
+    args.state.inside_storyline_hotspot = true
+  elsif null_or_empty?(hotspots)
+    args.state.inside_storyline_hotspot = false
+  end
+end
+
+def calc_scenes args
+  hotspots = args.state.scenes.find_all do |hs|
+    args.state.player.inside_rect?(hs.shift_rect(-2, 0))
+  end
+
+  if !null_or_empty?(hotspots) && !args.state.inside_scene_hotspot
+    _, _, _, _, scene_method_or_hash = hotspots.first
+    if scene_method_or_hash.is_a? Symbol
+      set_scene(args, send(scene_method_or_hash, args))
+      args.state.last_hotspot_scene = scene_method_or_hash
+      args.state.scene_history << scene_method_or_hash
+    else
+      set_scene(args, scene_method_or_hash)
+    end
+    args.state.inside_scene_hotspot = true
+  elsif null_or_empty?(hotspots)
+    args.state.inside_scene_hotspot = false
+  end
+end
+
+def null_or_whitespace? word
+  return true if !word
+  return true if word.strip.length == 0
+  return false
+end
+
+def calc_storyline_presentation args
+  return unless args.state.tick_count > args.state.next_storyline
+  return unless args.state.scene_storyline_queue
+  next_storyline = args.state.scene_storyline_queue.shift
+  if null_or_whitespace? next_storyline
+    args.state.storyline_queue_empty_at ||= args.state.tick_count
+    args.state.is_storyline_dialog_active = false
+    return
+  end
+  args.state.storyline_to_show = next_storyline
+  args.state.is_storyline_dialog_active = true
+  args.state.storyline_queue_empty_at = nil
+  if next_storyline.end_with?(".") || next_storyline.end_with?("!") || next_storyline.end_with?("?") || next_storyline.end_with?("\"")
+    args.state.next_storyline += 60
+  elsif next_storyline.end_with?(",")
+    args.state.next_storyline += 50
+  elsif next_storyline.end_with?(":")
+    args.state.next_storyline += 60
+  else
+    default_word_delay = 13 + args.state.word_delay - 8
+    if next_storyline.gsub("-", "").gsub("~", "").length <= 4
+      default_word_delay = 11 + args.state.word_delay - 8
+    end
+    number_of_syllabals = next_storyline.length - next_storyline.gsub("-", "").length
+    args.state.next_storyline += default_word_delay + number_of_syllabals * (args.state.word_delay + 1)
+  end
+end
+
+def inputs_reload_current_scene args
+  return
+  if args.inputs.keyboard.key_down.r!
+    reload_current_scene
+  end
+end
+
+def inputs_dismiss_current_storyline args
+  if args.inputs.keyboard.key_down.x!
+    args.state.scene_storyline_queue.clear
+  end
+end
+
+def inputs_restart_game args
+  if args.inputs.keyboard.exclamation_point
+    args.gtk.reset_state
+  end
+end
+
+def inputs_change_word_delay args
+  if args.inputs.keyboard.key_down.plus || args.inputs.keyboard.key_down.equal_sign
+    args.state.word_delay -= 2
+    if args.state.word_delay < 0
+      args.state.word_delay = 0
+      # queue_storyline_text args, "Text speed at MAXIMUM. Geez, how fast do you read?"
+    else
+      # queue_storyline_text args, "Text speed INCREASED."
+    end
+  end
+
+  if args.inputs.keyboard.key_down.hyphen || args.inputs.keyboard.key_down.underscore
+    args.state.word_delay += 2
+    # queue_storyline_text args, "Text speed DECREASED."
+  end
+end
+
+def multiple_lines args, x, y, texts, size = 0, minimum_alpha = nil
+  texts.each_with_index.map do |t, i|
+    [x, y - i * (25 + size * 2), t, size, 0, 255, 255, 255, adornments_alpha(args, 255, minimum_alpha)]
+  end
+end
+
+def lowrez_tick args, lowrez_sprites, lowrez_labels, lowrez_borders, lowrez_solids, lowrez_mouse
+  # args.state.show_gridlines = true
+  defaults args
+  render_current_scene args, lowrez_sprites, lowrez_labels, lowrez_solids
+  lowrez_solids << [0, 0, 64, 64, 0, 0, 0]
+  calc_storyline_presentation args
+  calc_scenes args
+  calc_storyline_hotspot args
+  inputs_move_player args
+  inputs_print_mouse_rect args, lowrez_mouse
+  inputs_reload_current_scene args
+  inputs_dismiss_current_storyline args
+  inputs_change_word_delay args
+  inputs_restart_game args
+  if !args.state.storyline_queue_empty_at
+    args.outputs.labels << multiple_lines(args, 690, 80,
+                                          ["Press \"X\" on the keyboard to dismiss dialog.",
+                                           "Press \"+\" on the keyboard to INCREASE text speed.",
+                                           "Press \"-\" on the keyboard to DECREASE text speed."], 0, 255)
+  end
+end
+
+def inputs_print_mouse_rect args, lowrez_mouse
+  if lowrez_mouse.click
+    if args.state.previous_mouse_click
+      dx = lowrez_mouse.click.x - args.state.previous_mouse_click.x
+      dy = lowrez_mouse.click.y - args.state.previous_mouse_click.y
+      x, y, w, h = args.state.previous_mouse_click.x, args.state.previous_mouse_click.y, dx, dy
+
+      if dx < 0 && dx < 0
+        x = x + w
+        w = w.abs
+        y = y + h
+        h = h.abs
+      end
+
+      w += 1
+      h += 1
+
+      puts [x, y, w, h]
+      args.state.previous_mouse_click = nil
+    else
+      args.state.previous_mouse_click = lowrez_mouse.click
+      square_x, square_y = lowrez_mouse.click
+      puts [square_x, square_y]
+      8.map_with_index do |i|
+        puts [square_x - i + 1, square_y - i + 1, i + 1, i + 1]
+      end
+    end
+
+  end
+end
+
+def try_centering! word
+  word ||= ""
+  just_word = word.gsub("-", "").gsub(",", "").gsub(".", "").gsub("'", "").gsub('""', "\"-\"")
+  return word if just_word.strip.length == 0
+  return word if just_word.include? "~"
+  return "~#{word}" if just_word.length <= 2
+  if just_word.length.mod_zero? 2
+    center_index = just_word.length.idiv(2) - 1
+  else
+    center_index = (just_word.length - 1).idiv(2)
+  end
+  return "#{word[0..center_index - 1]}~#{word[center_index]}#{word[center_index + 1..-1]}"
+end
+
+def queue_storyline args, scene
+  queue_storyline_text args, scene[:storyline]
+end
+
+def queue_storyline_text args, text
+  args.state.last_story_line_text = text
+  args.state.storyline_history << text if text
+  words = (text || "").split(" ")
+  words = words.map { |w| try_centering! w }
+  args.state.scene_storyline_queue = words
+  if args.state.scene_storyline_queue.length != 0
+    args.state.scene_storyline_queue.unshift "~$--"
+    args.state.storyline_to_show = "~."
+  else
+    args.state.storyline_to_show = ""
+  end
+  args.state.scene_storyline_queue << ""
+  args.state.next_storyline = args.state.tick_count
+end
+
+def set_scene args, scene
+  args.state.current_scene = scene
+  args.state.background = scene[:background] ||  'sprites/todo.png'
+  args.state.scene_fade = scene[:fade] || 0
+  args.state.scenes = (scene[:scenes] || []).reject { |s| !s }
+  args.state.scene_render_override = scene[:render_override]
+  args.state.storylines = (scene[:storylines] || []).reject { |s| !s }
+  args.state.scene_changed_at = args.state.tick_count
+  if scene[:player]
+    args.state.player = scene[:player]
+  end
+  args.state.inside_scene_hotspot = false
+  args.state.inside_storyline_hotspot = false
+  queue_storyline args, scene
+end
+
+def replay_storyline_rect
+  [26, -1, 7, 4]
+end
+
+def labels_for_word word
+  left_side_of_word = ""
+  center_letter = ""
+  right_side_of_word = ""
+
+  if word[0] == "~"
+    left_side_of_word = ""
+    center_letter = word[1]
+    right_side_of_word = word[2..-1]
+  elsif word.length > 0
+    left_side_of_word, right_side_of_word = word.split("~")
+    center_letter = right_side_of_word[0]
+    right_side_of_word = right_side_of_word[1..-1]
+  end
+
+  right_side_of_word = right_side_of_word.gsub("-", "")
+
+  {
+    left:   [29 - left_side_of_word.length * 4 - 1 * left_side_of_word.length, 2, left_side_of_word],
+    center: [29, 2, center_letter, 255, 0, 0],
+    right:  [34, 2, right_side_of_word]
+  }
+end
+
+def render_scenes args, lowrez_sprites
+  lowrez_sprites << args.state.scenes.flat_map do |hs|
+    hotspot_square args, hs.x, hs.y, hs.w, hs.h
+  end
+end
+
+def render_storylines args, lowrez_sprites
+  lowrez_sprites << args.state.storylines.flat_map do |hs|
+    hotspot_square args, hs.x, hs.y, hs.w, hs.h
+  end
+end
+
+def adornments_alpha args, target_alpha = nil, minimum_alpha = nil
+  return (minimum_alpha || 80) unless args.state.storyline_queue_empty_at
+  target_alpha ||= 255
+  target_alpha * args.state.storyline_queue_empty_at.ease(60)
+end
+
+def hotspot_square args, x, y, w, h
+  if w >= 3 && h >= 3
+    [
+      [x + w.idiv(2) + 1, y, w.idiv(2), h, 'sprites/label-background.png', 0, adornments_alpha(args, 50), 23, 23, 23],
+      [x, y, w.idiv(2), h, 'sprites/label-background.png', 0, adornments_alpha(args, 100), 223, 223, 223],
+      [x + 1, y + 1, w - 2, h - 2, 'sprites/label-background.png', 0, adornments_alpha(args, 200), 40, 140, 40],
+    ]
+  else
+    [
+      [x, y, w, h, 'sprites/label-background.png', 0, adornments_alpha(args, 200), 0, 140, 0],
+    ]
+  end
+end
+
+def render_storyline_dialog args, lowrez_labels, lowrez_sprites
+  return unless args.state.is_storyline_dialog_active
+  return unless args.state.storyline_to_show
+  labels = labels_for_word args.state.storyline_to_show
+  if true # high rez version
+    scale = 8.88
+    offset = 45
+    size = 25
+    args.outputs.labels << [offset + labels[:left].x.-(1) * scale,
+                            labels[:left].y * TINY_SCALE + 55,
+                            labels[:left].text, size, 0, 0, 0, 0, 255,
+                            'fonts/manaspc.ttf']
+    center_text = labels[:center].text
+    center_text = "|" if center_text == "$"
+    args.outputs.labels << [offset + labels[:center].x * scale,
+                            labels[:center].y * TINY_SCALE + 55,
+                            center_text, size, 0, 255, 0, 0, 255,
+                            'fonts/manaspc.ttf']
+    args.outputs.labels << [offset + labels[:right].x * scale,
+                            labels[:right].y * TINY_SCALE + 55,
+                            labels[:right].text, size, 0, 0, 0, 0, 255,
+                            'fonts/manaspc.ttf']
+  else
+    lowrez_labels << labels[:left]
+    lowrez_labels << labels[:center]
+    lowrez_labels << labels[:right]
+  end
+  args.state.is_storyline_dialog_active = true
+  render_player args, lowrez_sprites
+  lowrez_sprites <<  [0, 0, 64, 8, 'sprites/label-background.png']
+end
+
+def render_player args, lowrez_sprites
+  lowrez_sprites << player_md_down(args, *args.state.player)
+end
+
+def render_adornments args, lowrez_sprites
+  render_scenes args, lowrez_sprites
+  render_storylines args, lowrez_sprites
+  return if args.state.is_storyline_dialog_active
+  lowrez_sprites << player_md_down(args, *args.state.player)
+end
+
+def global_alpha_percentage args, max_alpha = 255
+  return 255 unless args.state.scene_changed_at
+  return 255 unless args.state.scene_fade
+  return 255 unless args.state.scene_fade > 0
+  return max_alpha * args.state.scene_changed_at.ease(args.state.scene_fade)
+end
+
+def render_current_scene args, lowrez_sprites, lowrez_labels, lowrez_solids
+  lowrez_sprites << [0, 0, 64, 64, args.state.background, 0, (global_alpha_percentage args)]
+  if args.state.scene_render_override
+    send args.state.scene_render_override, args, lowrez_sprites, lowrez_labels, lowrez_solids
+  end
+  storyline_to_show = args.state.storyline_to_show || ""
+  render_adornments args, lowrez_sprites
+  render_storyline_dialog args, lowrez_labels, lowrez_sprites
+
+  if args.state.background == 'sprites/tribute-game-over.png'
+    lowrez_sprites << [0, 0, 64, 11, 'sprites/label-background.png', 0, adornments_alpha(args, 200), 0, 0, 0]
+    lowrez_labels << [9, 6, 'Return of', 255, 255, 255]
+    lowrez_labels << [9, 1, ' Serenity', 255, 255, 255]
+    if !args.state.ended
+      args.gtk.stop_music
+      args.outputs.sounds << 'sounds/music-loop.ogg'
+      args.state.ended = true
+    end
+  end
+end
+
+def player_md_right args, x, y
+  [x, y, 4, 11, 'sprites/player-right.png', 0, (global_alpha_percentage args)]
+end
+
+def player_md_left args, x, y
+  [x, y, 4, 11, 'sprites/player-left.png', 0, (global_alpha_percentage args)]
+end
+
+def player_md_up args, x, y
+  [x, y, 4, 11, 'sprites/player-up.png', 0, (global_alpha_percentage args)]
+end
+
+def player_md_down args, x, y
+  [x, y, 4, 11, 'sprites/player-down.png', 0, (global_alpha_percentage args)]
+end
+
+def player_sm args, x, y
+  [x, y, 3, 7, 'sprites/player-zoomed-out.png', 0, (global_alpha_percentage args)]
+end
+
+def player_xs args, x, y
+  [x, y, 1, 4, 'sprites/player-zoomed-out.png', 0, (global_alpha_percentage args)]
+end
+
+</pre>
+<h1 id='--99_genre_narrative_rpg/return_of_serenity/app/repl.rb'>99_genre_narrative_rpg/return_of_serenity/app/repl.rb</h1>
+<pre>puts $gtk.args.state.current_scene
+
+</pre>
+<h1 id='--99_genre_narrative_rpg/return_of_serenity/app/require.rb'>99_genre_narrative_rpg/return_of_serenity/app/require.rb</h1>
+<pre>require 'app/lowrez_simulator.rb'
+require 'app/storyline_day_one.rb'
+require 'app/storyline_blinking_light.rb'
+require 'app/storyline_serenity_introduction.rb'
+require 'app/storyline_speed_of_light.rb'
+require 'app/storyline_serenity_alive.rb'
+require 'app/storyline_serenity_bio.rb'
+require 'app/storyline_anka.rb'
+require 'app/storyline_final_message.rb'
+require 'app/storyline_final_decision.rb'
+require 'app/storyline.rb'
+
+</pre>
+<h1 id='--99_genre_narrative_rpg/return_of_serenity/app/storyline.rb'>99_genre_narrative_rpg/return_of_serenity/app/storyline.rb</h1>
+<pre>def hotspot_top
+  [4, 61, 56, 3]
+end
+
+def hotspot_bottom
+  [4, 0, 56, 3]
+end
+
+def hotspot_top_right
+  [62, 35, 3, 25]
+end
+
+def hotspot_bottom_right
+  [62, 0, 3, 25]
+end
+
+def storyline_history_include? args, text
+  args.state.storyline_history.any? { |s| s.gsub("-", "").gsub(" ", "").include? text.gsub("-", "").gsub(" ", "") }
+end
+
+def blinking_light_side_of_home_render args, lowrez_sprites, lowrez_labels, lowrez_solids
+  lowrez_sprites << [48, 44, 5, 5, 'sprites/square.png', 0,  50 * (args.state.tick_count % 50).fdiv(50), 0, 255, 0]
+  lowrez_sprites << [49, 45, 3, 3, 'sprites/square.png', 0, 100 * (args.state.tick_count % 50).fdiv(50), 0, 255, 0]
+  lowrez_sprites << [50, 46, 1, 1, 'sprites/square.png', 0, 255 * (args.state.tick_count % 50).fdiv(50), 0, 255, 0]
+end
+
+def blinking_light_mountain_pass_render args, lowrez_sprites, lowrez_labels, lowrez_solids
+  lowrez_sprites << [18, 47, 5, 5, 'sprites/square.png', 0,  50 * (args.state.tick_count % 50).fdiv(50), 0, 255, 0]
+  lowrez_sprites << [19, 48, 3, 3, 'sprites/square.png', 0, 100 * (args.state.tick_count % 50).fdiv(50), 0, 255, 0]
+  lowrez_sprites << [20, 49, 1, 1, 'sprites/square.png', 0, 255 * (args.state.tick_count % 50).fdiv(50), 0, 255, 0]
+end
+
+def blinking_light_path_to_observatory_render args, lowrez_sprites, lowrez_labels, lowrez_solids
+  lowrez_sprites << [0, 26, 5, 5, 'sprites/square.png', 0,  50 * (args.state.tick_count % 50).fdiv(50), 0, 255, 0]
+  lowrez_sprites << [1, 27, 3, 3, 'sprites/square.png', 0, 100 * (args.state.tick_count % 50).fdiv(50), 0, 255, 0]
+  lowrez_sprites << [2, 28, 1, 1, 'sprites/square.png', 0, 255 * (args.state.tick_count % 50).fdiv(50), 0, 255, 0]
+end
+
+def blinking_light_observatory_render args, lowrez_sprites, lowrez_labels, lowrez_solids
+  lowrez_sprites << [23, 59, 5, 5, 'sprites/square.png', 0,  50 * (args.state.tick_count % 50).fdiv(50), 0, 255, 0]
+  lowrez_sprites << [24, 60, 3, 3, 'sprites/square.png', 0, 100 * (args.state.tick_count % 50).fdiv(50), 0, 255, 0]
+  lowrez_sprites << [25, 61, 1, 1, 'sprites/square.png', 0, 255 * (args.state.tick_count % 50).fdiv(50), 0, 255, 0]
+end
+
+def blinking_light_inside_observatory_render args, lowrez_sprites, lowrez_labels, lowrez_solids
+  lowrez_sprites << [30, 30, 5, 5, 'sprites/square.png', 0,  50 * (args.state.tick_count % 50).fdiv(50), 0, 255, 0]
+  lowrez_sprites << [31, 31, 3, 3, 'sprites/square.png', 0, 100 * (args.state.tick_count % 50).fdiv(50), 0, 255, 0]
+  lowrez_sprites << [32, 32, 1, 1, 'sprites/square.png', 0, 255 * (args.state.tick_count % 50).fdiv(50), 0, 255, 0]
+end
+
+def decision_graph context_message, context_action, context_result_one, context_result_two, context_result_three = [], context_result_four = []
+  result_one_scene, result_one_label, result_one_text = context_result_one
+  result_two_scene, result_two_label, result_two_text = context_result_two
+  result_three_scene, result_three_label, result_three_text = context_result_three
+  result_four_scene, result_four_label, result_four_text = context_result_four
+
+  top_level_hash = {
+    background: 'sprites/decision.png',
+    fade: 60,
+    player: [20, 36],
+    storylines: [ ],
+    scenes: [ ]
+  }
+
+  confirmation_result_one_hash = {
+    background: 'sprites/decision.png',
+    scenes: [ ],
+    storylines: [ ]
+  }
+
+  confirmation_result_two_hash = {
+    background: 'sprites/decision.png',
+    scenes: [ ],
+    storylines: [ ]
+  }
+
+  confirmation_result_three_hash = {
+    background: 'sprites/decision.png',
+    scenes: [ ],
+    storylines: [ ]
+  }
+
+  confirmation_result_four_hash = {
+    background: 'sprites/decision.png',
+    scenes: [ ],
+    storylines: [ ]
+  }
+
+  top_level_hash[:storylines] << [ 5, 35, 4, 4, context_message]
+  top_level_hash[:storylines] << [20, 35, 4, 4, context_action]
+
+  confirmation_result_one_hash[:scenes]       << [20, 35, 4, 4, top_level_hash]
+  confirmation_result_one_hash[:scenes]       << [60, 50, 4, 4, result_one_scene]
+  confirmation_result_one_hash[:storylines]   << [40, 50, 4, 4, "#{result_one_label}: \"#{result_one_text}\""]
+  confirmation_result_one_hash[:scenes]       << [40, 40, 4, 4, confirmation_result_four_hash] if result_four_scene
+  confirmation_result_one_hash[:scenes]       << [40, 30, 4, 4, confirmation_result_three_hash] if result_three_scene
+  confirmation_result_one_hash[:scenes]       << [40, 20, 4, 4, confirmation_result_two_hash]
+
+  confirmation_result_two_hash[:scenes]       << [20, 35, 4, 4, top_level_hash]
+  confirmation_result_two_hash[:scenes]       << [40, 50, 4, 4, confirmation_result_one_hash]
+  confirmation_result_two_hash[:scenes]       << [40, 40, 4, 4, confirmation_result_four_hash] if result_four_scene
+  confirmation_result_two_hash[:scenes]       << [40, 30, 4, 4, confirmation_result_three_hash] if result_three_scene
+  confirmation_result_two_hash[:scenes]       << [60, 20, 4, 4, result_two_scene]
+  confirmation_result_two_hash[:storylines]   << [40, 20, 4, 4, "#{result_two_label}: \"#{result_two_text}\""]
+
+  confirmation_result_three_hash[:scenes]     << [20, 35, 4, 4, top_level_hash]
+  confirmation_result_three_hash[:scenes]     << [40, 50, 4, 4, confirmation_result_one_hash]
+  confirmation_result_three_hash[:scenes]     << [40, 40, 4, 4, confirmation_result_four_hash]
+  confirmation_result_three_hash[:scenes]     << [60, 30, 4, 4, result_three_scene]
+  confirmation_result_three_hash[:storylines] << [40, 30, 4, 4, "#{result_three_label}: \"#{result_three_text}\""]
+  confirmation_result_three_hash[:scenes]     << [40, 20, 4, 4, confirmation_result_two_hash]
+
+  confirmation_result_four_hash[:scenes]      << [20, 35, 4, 4, top_level_hash]
+  confirmation_result_four_hash[:scenes]      << [40, 50, 4, 4, confirmation_result_one_hash]
+  confirmation_result_four_hash[:scenes]      << [60, 40, 4, 4, result_four_scene]
+  confirmation_result_four_hash[:storylines]  << [40, 40, 4, 4, "#{result_four_label}: \"#{result_four_text}\""]
+  confirmation_result_four_hash[:scenes]      << [40, 30, 4, 4, confirmation_result_three_hash]
+  confirmation_result_four_hash[:scenes]      << [40, 20, 4, 4, confirmation_result_two_hash]
+
+  top_level_hash[:scenes]     << [40, 50, 4, 4, confirmation_result_one_hash]
+  top_level_hash[:scenes]     << [40, 40, 4, 4, confirmation_result_four_hash] if result_four_scene
+  top_level_hash[:scenes]     << [40, 30, 4, 4, confirmation_result_three_hash] if result_three_scene
+  top_level_hash[:scenes]     << [40, 20, 4, 4, confirmation_result_two_hash]
+
+  top_level_hash
+end
+
+def ship_control_hotspot offset_x, offset_y, a, b, c, d
+  results = []
+  results << [ 6 + offset_x, 0 + offset_y, 4, 4, a]  if a
+  results << [ 1 + offset_x, 5 + offset_y, 4, 4, b]  if b
+  results << [ 6 + offset_x, 5 + offset_y, 4, 4, c]  if c
+  results << [ 11 + offset_x, 5 + offset_y, 4, 4, d] if d
+  results
+end
+
+def reload_current_scene
+  if $gtk.args.state.last_hotspot_scene
+    set_scene $gtk.args, send($gtk.args.state.last_hotspot_scene, $gtk.args)
+    tick $gtk.args
+  elsif respond_to? :set_scene
+    set_scene $gtk.args, (replied_to_serenity_alive_firmly $gtk.args)
+    tick $gtk.args
+  end
+  $gtk.console.close
+end
+
+</pre>
+<h1 id='--99_genre_narrative_rpg/return_of_serenity/app/storyline_anka.rb'>99_genre_narrative_rpg/return_of_serenity/app/storyline_anka.rb</h1>
+<pre>def anka_inside_room args
+  {
+    background: 'sprites/inside-home.png',
+    player: [34, 35],
+    storylines: [
+      [34, 34, 4, 4, "Ahhhh!!! Oh god, it was just- a nightmare."],
+    ],
+    scenes: [
+      [32, -1, 8, 3, :anka_observatory]
+    ]
+  }
+end
+
+def anka_observatory args
+  {
+    background: 'sprites/inside-observatory.png',
+    fade: 60,
+    player: [51, 12],
+    storylines: [
+      [50, 10, 4, 4,   "Breathe, Hiro. Just see what's there... everything--- will- be okay."]
+    ],
+    scenes: [
+      [30, 18, 5, 12, :anka_inside_mainframe]
+    ],
+    render_override: :blinking_light_inside_observatory_render
+  }
+end
+
+def anka_inside_mainframe args
+  {
+    player: [32, 4],
+    background: 'sprites/mainframe.png',
+    fade: 60,
+    storylines: [
+      [22, 45, 17, 4, (anka_last_reply args)],
+      [45, 45,  4, 4, (anka_current_reply args)],
+    ],
+    scenes: [
+      [*hotspot_top_right, :reply_to_anka]
+    ]
+  }
+end
+
+def reply_to_anka args
+  decision_graph anka_current_reply(args),
+                 "Matthew's-- wife is doing-- well. What's-- even-- better-- is that he's-- a dad, and he didn't-- even-- know it. Should- I- leave- out the part about-- the crew- being-- in hibernation-- for 20-- years? They- should- enter-- statis-- on a high- note... Right?",
+                 [:replied_with_whole_truth, "Whole-- Truth--", anka_reply_whole_truth],
+                 [:replied_with_half_truth, "Half-- Truth--", anka_reply_half_truth]
+end
+
+def anka_last_reply args
+  if args.state.scene_history.include? :replied_to_serenity_alive_firmly
+    return "Buffer--: #{serenity_alive_firm_reply.quote}"
+  else
+    return "Buffer--: #{serenity_alive_sugarcoated_reply.quote}"
+  end
+end
+
+def anka_reply_whole_truth
+  "Matthew's wife is doing-- very-- well. In fact, she was pregnant. Matthew-- is a dad. He has a son. But, I need- all-- of-- you-- to brace-- yourselves. You've-- been in statis-- for 20 years. A lot has changed. Most of Earth's-- population--- didn't-- survive. Tell- Matthew-- that I'm-- sorry he didn't-- get to see- his- son grow- up."
+end
+
+def anka_reply_half_truth
+  "Matthew's--- wife- is doing-- very-- well. In fact, she was pregnant. Matthew is a dad! It's a boy! Tell- Matthew-- congrats-- for me. Hope-- to see- all of you- soon."
+end
+
+def replied_with_whole_truth args
+  {
+    background: 'sprites/inside-observatory.png',
+    fade: 60,
+    player: [32, 21],
+    scenes: [[60, 0, 4, 32, :replied_to_anka_back_home]],
+    storylines: [
+      [30, 18, 5, 12, "Buffer-- has been set to: #{anka_reply_whole_truth.quote}"],
+      [30, 10, 5, 4, "I- hope- I- did the right- thing- by laying-- it all- out- there."],
+    ]
+  }
+end
+
+def replied_with_half_truth args
+  {
+    background: 'sprites/inside-observatory.png',
+    fade: 60,
+    player: [32, 21],
+    scenes: [[60, 0, 4, 32, :replied_to_anka_back_home]],
+    storylines: [
+      [30, 18, 5, 12, "Buffer-- has been set to: #{anka_reply_half_truth.quote}"],
+      [30, 10, 5, 4, "I- hope- I- did the right- thing- by not giving-- them- the whole- truth."],
+    ]
+  }
+end
+
+def anka_current_reply args
+  if args.state.scene_history.include? :replied_to_serenity_alive_firmly
+    return "Hello. This is, Aanka. Sasha-- is still- trying-- to gather-- her wits about-- her, given- the gravity--- of your- last- reply. Thank- you- for being-- honest, and thank- you- for the help- with the ship- diagnostics. I was able-- to retrieve-- all of the navigation--- information---- after-- the battery--- swap. We- are ready-- to head back to Earth. Before-- we go- back- into-- statis, Matthew--- wanted-- to know- how his- wife- is doing. Please- reply-- as soon- as you can. He's-- not going-- to get- into-- the statis-- chamber-- until-- he knows- his wife is okay."
+  else
+    return "Hello. This is, Aanka. Thank- you for the help- with the ship's-- diagnostics. I was able-- to retrieve-- all of the navigation--- information--- after-- the battery-- swap. I- know-- that- you didn't-- tell- the whole truth- about-- how far we are from- Earth. Don't-- worry. I understand-- why you did it. We- are ready-- to head back to Earth. Before-- we go- back- into-- statis, Matthew--- wanted-- to know- how his- wife- is doing. Please- reply-- as soon- as you can. He's-- not going-- to get- into-- the statis-- chamber-- until-- he knows- his wife is okay."
+  end
+end
+
+def replied_to_anka_back_home args
+  if args.state.scene_history.include? :replied_with_whole_truth
+    return {
+      fade: 60,
+      background: 'sprites/inside-home.png',
+      player: [34, 4],
+      storylines: [
+        [34, 4, 4, 4, "I- hope-- this pit in my stomach-- is gone-- by tomorrow---."],
+      ],
+      scenes: [
+        [30, 38, 12, 13, :final_message_sad],
+      ]
+    }
+  else
+    return {
+      fade: 60,
+      background: 'sprites/inside-home.png',
+      player: [34, 4],
+      storylines: [
+        [34, 4, 4, 4, "I- get the feeling-- I'm going-- to sleep real well tonight--."],
+      ],
+      scenes: [
+        [30, 38, 12, 13, :final_message_happy],
+      ]
+    }
+  end
+end
+
+</pre>
+<h1 id='--99_genre_narrative_rpg/return_of_serenity/app/storyline_blinking_light.rb'>99_genre_narrative_rpg/return_of_serenity/app/storyline_blinking_light.rb</h1>
+<pre>def the_blinking_light args
+  {
+    fade: 60,
+    background: 'sprites/side-of-home.png',
+    player: [16, 13],
+    scenes: [
+      [52, 24, 11, 5, :blinking_light_mountain_pass],
+    ],
+    render_override: :blinking_light_side_of_home_render
+  }
+end
+
+def blinking_light_mountain_pass args
+  {
+    background: 'sprites/mountain-pass-zoomed-out.png',
+    player: [4, 4],
+    scenes: [
+      [18, 47, 5, 5, :blinking_light_path_to_observatory]
+    ],
+    render_override: :blinking_light_mountain_pass_render
+  }
+end
+
+def blinking_light_path_to_observatory args
+  {
+    background: 'sprites/path-to-observatory.png',
+    player: [60, 4],
+    scenes: [
+      [0, 26, 5, 5, :blinking_light_observatory]
+    ],
+    render_override: :blinking_light_path_to_observatory_render
+  }
+end
+
+def blinking_light_observatory args
+  {
+    background: 'sprites/observatory.png',
+    player: [60, 2],
+    scenes: [
+      [28, 39, 4, 10, :blinking_light_inside_observatory]
+    ],
+    render_override: :blinking_light_observatory_render
+  }
+end
+
+def blinking_light_inside_observatory args
+  {
+    background: 'sprites/inside-observatory.png',
+    player: [60, 2],
+    storylines: [
+      [50, 2, 4, 8,   "That's weird. I thought- this- mainframe-- was broken--."]
+    ],
+    scenes: [
+      [30, 18, 5, 12, :blinking_light_inside_mainframe]
+    ],
+    render_override: :blinking_light_inside_observatory_render
+  }
+end
+
+def blinking_light_inside_mainframe args
+  {
+    background: 'sprites/mainframe.png',
+    fade: 60,
+    player: [30, 4],
+    scenes: [
+      [62, 32, 4, 32, :reply_to_introduction]
+    ],
+    storylines: [
+      [43, 43,  8, 8, "\"Mission-- control--, your- main- comm-- channels-- seem-- to be down. My apologies-- for- using-- this low- level-- exploit--. What's-- going-- on down there? We are ready-- for reentry--.\" Message--- Timestamp---: 4- hours-- 23--- minutes-- ago--."],
+      [30, 30,  4, 4, "There's-- a low- level-- message-- here... NANI.T.F?"],
+      [14, 10, 24, 4, "Oh interesting---. This transistor--- needed-- to be activated--- for the- mainframe-- to work."],
+      [14, 20, 24, 4, "What the heck activated--- this thing- though?"]
+    ]
+  }
+end
+
+</pre>
+<h1 id='--99_genre_narrative_rpg/return_of_serenity/app/storyline_day_one.rb'>99_genre_narrative_rpg/return_of_serenity/app/storyline_day_one.rb</h1>
+<pre>def day_one_beginning args
+  {
+    background: 'sprites/side-of-home.png',
+    player: [16, 13],
+    scenes: [
+      [0, 0, 64, 2, :day_one_infront_of_home],
+    ],
+    storylines: [
+      [35, 10, 6, 6,  "Man. Hard to believe- that today- is the 20th--- anniversary-- of The Impact."]
+    ]
+  }
+end
+
+def day_one_infront_of_home args
+  {
+    background: 'sprites/front-of-home.png',
+    player: [56, 23],
+    scenes: [
+      [43, 34, 10, 16, :day_one_home],
+      [62, 0,  3, 40, :day_one_beginning],
+      [0, 4, 3, 20, :day_one_ceremony]
+    ],
+    storylines: [
+      [40, 20, 4, 4, "It looks like everyone- is already- at the rememberance-- ceremony."],
+    ]
+  }
+end
+
+def day_one_home args
+  {
+    background: 'sprites/inside-home.png',
+    player: [34, 3],
+    scenes: [
+      [28, 0, 12, 2, :day_one_infront_of_home]
+    ],
+    storylines: [
+      [
+        38, 4, 4, 4, "My mansion- in all its glory! Okay yea, it's just a shipping- container-. Apparently-, it's nothing- like the luxuries- of the 2040's. But it's- all we have- in- this day and age. And it'll suffice."
+      ],
+      [
+        28, 7, 4, 7,
+        "Ahhh. My reading- couch. It's so comfortable--."
+      ],
+      [
+        38, 21, 4, 4,
+        "I'm- lucky- to have a computer--. I'm- one of the few people- with- the skills to put this- thing to good use."
+      ],
+      [
+        45, 37, 4, 8,
+        "This corner- of my home- is always- warmer-. It's cause of the ref~lected-- light- from the solar-- panels--, just on the other- side- of this wall. It's hard- to believe- there was o~nce-- an unlimited- amount- of electricity--."
+      ],
+      [
+        32, 40, 8, 10,
+        "This isn't- a good time- to sleep. I- should probably- head to the ceremony-."
+      ],
+      [
+        25, 21, 5, 12,
+        "Fifteen-- years- of computer-- science-- notes, neatly-- organized. Compiler--- Theory--, Linear--- Algebra---, Game-- Development---... Every-- subject-- imaginable--."
+      ]
+    ]
+  }
+end
+
+def day_one_ceremony args
+  {
+    background: 'sprites/tribute.png',
+    player: [57, 21],
+    scenes: [
+      [62, 0, 2, 40, :day_one_infront_of_home],
+      [0, 24, 2, 40, :day_one_infront_of_library]
+    ],
+    storylines: [
+      [53, 12, 3,  8,  "It's- been twenty- years since The Impact. Twenty- years, since Halley's-- Comet-- set Earth's- blue- sky on fire."],
+      [45, 12, 3,  8,  "The space mission- sent to prevent- Earth's- total- destruction--, was a success. Only- 99.9%------ of the world's- population-- died-- that day. Hey, it's- better-- than 100%---- of humanity-- dying."],
+      [20, 12, 23, 4, "The monument--- reads:---- Here- stands- the tribute-- to Space- Mission-- Serenity--- and- its- crew. You- have- given-- humanity--- a second-- chance."],
+      [15, 12, 3,  8, "Rest- in- peace--- Matthew----, Sasha----, Aanka----"],
+    ]
+  }
+end
+
+def day_one_infront_of_library args
+  {
+    background: 'sprites/outside-library.png',
+    player: [57, 21],
+    scenes: [
+      [62, 0, 2, 40, :day_one_ceremony],
+      [49, 39, 6, 9, :day_one_library]
+    ],
+    storylines: [
+      [50, 20, 4, 8,  "Shipping- containers-- as far- as the eye- can see. It's- rather- beautiful-- if you ask me. Even- though-- this- view- represents-- all- that's-- left- of humanity-."]
+    ]
+  }
+end
+
+def day_one_library args
+  {
+    background: 'sprites/library.png',
+    player: [27, 4],
+    scenes: [
+      [0, 0, 64, 2, :end_day_one_infront_of_library]
+    ],
+    storylines: [
+      [28, 22, 8, 4,  "I grew- up- in this library. I've- read every- book- here. My favorites-- were- of course-- anything- computer-- related."],
+      [6, 32, 10, 6, "My favorite-- area--- of the library. The Science-- Section."]
+    ]
+  }
+end
+
+def end_day_one_infront_of_library args
+  {
+    background: 'sprites/outside-library.png',
+    player: [51, 33],
+    scenes: [
+      [49, 39, 6, 9, :day_one_library],
+      [62, 0, 2, 40, :end_day_one_monument],
+    ],
+    storylines: [
+      [50, 27, 4, 4, "It's getting late. Better get some sleep."]
+    ]
+  }
+end
+
+def end_day_one_monument args
+  {
+    background: 'sprites/tribute.png',
+    player: [2, 36],
+    scenes: [
+      [62, 0, 2, 40, :end_day_one_infront_of_home],
+    ],
+    storylines: [
+      [50, 27, 4, 4, "It's getting late. Better get some sleep."],
+    ]
+  }
+end
+
+def end_day_one_infront_of_home args
+  {
+    background: 'sprites/front-of-home.png',
+    player: [1, 17],
+    scenes: [
+      [43, 34, 10, 16, :end_day_one_home],
+    ],
+    storylines: [
+      [20, 10, 4, 4, "It's getting late. Better get some sleep."],
+    ]
+  }
+end
+
+def end_day_one_home args
+  {
+    background: 'sprites/inside-home.png',
+    player: [34, 3],
+    scenes: [
+      [32, 40, 8, 10, :end_day_one_dream],
+    ],
+    storylines: [
+      [38, 4, 4, 4, "It's getting late. Better get some sleep."],
+    ]
+  }
+end
+
+def end_day_one_dream args
+  {
+    background: 'sprites/dream.png',
+    fade: 60,
+    player: [4, 4],
+    scenes: [
+      [62, 0, 2, 64, :explaining_the_special_power]
+    ],
+    storylines: [
+      [10, 10, 4, 4, "Why- does this- moment-- always- haunt- my dreams?"],
+      [20, 10, 4, 4, "This kid- reads these computer--- science--- books- nonstop-. What's- wrong with him?"],
+      [30, 10, 4, 4, "There- is nothing-- wrong- with him. This behavior-- should be encouraged---! In fact-, I think- he's- special---. Have- you seen- him use- a computer---? It's-- almost-- as if he can- speak-- to it."]
+    ]
+  }
+end
+
+def explaining_the_special_power args
+  {
+    fade: 60,
+    background: 'sprites/inside-home.png',
+    player: [32, 30],
+    scenes: [
+      [
+        38, 21, 4, 4, :explaining_the_special_power_inside_computer
+      ],
+    ]
+  }
+end
+
+def explaining_the_special_power_inside_computer args
+  {
+    background: 'sprites/pc.png',
+    fade: 60,
+    player: [34, 4],
+    scenes: [
+      [0, 62, 64, 3, :the_blinking_light]
+    ],
+    storylines: [
+      [14, 20, 24, 4, "So... I have a special-- power--. I don't-- need a mouse-, keyboard--, or even-- a monitor--- to control-- a computer--."],
+      [14, 25, 24, 4, "I only-- pretend-- to use peripherals---, so as not- to freak- anyone--- out."],
+      [14, 30, 24, 4, "Inside-- this silicon--- Universe---, is the only-- place I- feel- at peace."],
+      [14, 35, 24, 4, "It's-- the only-- place where I don't-- feel alone."]
+    ]
+  }
+end
+
+</pre>
+<h1 id='--99_genre_narrative_rpg/return_of_serenity/app/storyline_final_decision.rb'>99_genre_narrative_rpg/return_of_serenity/app/storyline_final_decision.rb</h1>
+<pre>def final_decision_side_of_home args
+  {
+    fade: 120,
+    background: 'sprites/side-of-home.png',
+    player: [16, 13],
+    scenes: [
+      [52, 24, 11, 5, :final_decision_mountain_pass],
+    ],
+    render_override: :blinking_light_side_of_home_render,
+    storylines: [
+      [28, 13, 8, 4,  "Man. Hard to believe- that today- is the 21st--- anniversary-- of The Impact. Serenity--- will- be- home- soon."]
+    ]
+  }
+end
+
+def final_decision_mountain_pass args
+  {
+    background: 'sprites/mountain-pass-zoomed-out.png',
+    player: [4, 4],
+    scenes: [
+      [18, 47, 5, 5, :final_decision_path_to_observatory]
+    ],
+    render_override: :blinking_light_mountain_pass_render
+  }
+end
+
+def final_decision_path_to_observatory args
+  {
+    background: 'sprites/path-to-observatory.png',
+    player: [60, 4],
+    scenes: [
+      [0, 26, 5, 5, :final_decision_observatory]
+    ],
+    render_override: :blinking_light_path_to_observatory_render
+  }
+end
+
+def final_decision_observatory args
+  {
+    background: 'sprites/observatory.png',
+    player: [60, 2],
+    scenes: [
+      [28, 39, 4, 10, :final_decision_inside_observatory]
+    ],
+    render_override: :blinking_light_observatory_render
+  }
+end
+
+def final_decision_inside_observatory args
+  {
+    background: 'sprites/inside-observatory.png',
+    player: [60, 2],
+    storylines: [],
+    scenes: [
+      [30, 18, 5, 12, :final_decision_inside_mainframe]
+    ],
+    render_override: :blinking_light_inside_observatory_render
+  }
+end
+
+def final_decision_inside_mainframe args
+  {
+    player: [32, 4],
+    background: 'sprites/mainframe.png',
+    storylines: [],
+    scenes: [
+      [*hotspot_top, :final_decision_ship_status],
+    ]
+  }
+end
+
+def final_decision_ship_status args
+  {
+    background: 'sprites/serenity.png',
+    fade: 60,
+    player: [30, 10],
+    scenes: [
+      [*hotspot_top_right, :final_decision]
+    ],
+    storylines: [
+      [30,  8, 4, 4, "????"],
+      *final_decision_ship_status_shared(args)
+    ]
+  }
+end
+
+def final_decision args
+  decision_graph  "Stasis-- Chambers--: UNDERPOWERED, Life- forms-- will be terminated---- unless-- equilibrium----- is reached.",
+                  "I CAN'T DO THIS... But... If-- I-- don't--- bring-- the- chambers--- to- equilibrium-----, they all die...",
+                  [:final_decision_game_over_noone, "Kill--- Everyone---", "DO--- NOTHING?"],
+                  [:final_decision_game_over_matthew, "Kill--- Sasha---", "KILL--- SASHA?"],
+                  [:final_decision_game_over_anka, "Kill--- Aanka---", "KILL--- AANKA?"],
+                  [:final_decision_game_over_sasha, "Kill--- Matthew---", "KILL--- MATTHEW?"]
+end
+
+def final_decision_game_over_noone args
+  {
+    background: 'sprites/tribute-game-over.png',
+    player: [53, 14],
+    fade: 600
+  }
+end
+
+def final_decision_game_over_matthew args
+  {
+    background: 'sprites/tribute-game-over.png',
+    player: [53, 14],
+    fade: 600
+  }
+end
+
+def final_decision_game_over_anka args
+  {
+    background: 'sprites/tribute-game-over.png',
+    player: [53, 14],
+    fade: 600
+  }
+end
+
+def final_decision_game_over_sasha args
+  {
+    background: 'sprites/tribute-game-over.png',
+    player: [53, 14],
+    fade: 600
+  }
+end
+
+def final_decision_ship_status_shared args
+  [
+    *ship_control_hotspot(24, 22,
+                           "Stasis-- Chambers--: UNDERPOWERED, Life- forms-- will be terminated---- unless-- equilibrium----- is reached. WHAT?! NO!",
+                           "Matthew's--- Chamber--: UNDER-- THREAT-- OF-- TERMINATION. WHAT?! NO!",
+                           "Aanka's--- Chamber--: UNDER-- THREAT-- OF-- TERMINATION.  WHAT?! NO!",
+                           "Sasha's--- Chamber--: UNDER-- THREAT-- OF-- TERMINATION. WHAT?! NO!"),
+  ]
+end
+
+</pre>
+<h1 id='--99_genre_narrative_rpg/return_of_serenity/app/storyline_final_message.rb'>99_genre_narrative_rpg/return_of_serenity/app/storyline_final_message.rb</h1>
+<pre>def final_message_sad args
+  {
+    fade: 60,
+    background: 'sprites/inside-home.png',
+    player: [34, 35],
+    storylines: [
+      [34, 34, 4, 4, "Another-- sleepless-- night..."],
+    ],
+    scenes: [
+      [32, -1, 8, 3, :final_message_observatory]
+    ]
+  }
+end
+
+def final_message_happy args
+  {
+    fade: 60,
+    background: 'sprites/inside-home.png',
+    player: [34, 35],
+    storylines: [
+      [34, 34, 4, 4, "Oh man, I slept like rock!"],
+    ],
+    scenes: [
+      [32, -1, 8, 3, :final_message_observatory]
+    ]
+  }
+end
+
+def final_message_side_of_home args
+  {
+    fade: 60,
+    background: 'sprites/side-of-home.png',
+    player: [16, 13],
+    scenes: [
+      [52, 24, 11, 5, :final_message_mountain_pass],
+    ],
+    render_override: :blinking_light_side_of_home_render
+  }
+end
+
+def final_message_mountain_pass args
+  {
+    background: 'sprites/mountain-pass-zoomed-out.png',
+    player: [4, 4],
+    scenes: [
+      [18, 47, 5, 5, :final_message_path_to_observatory],
+    ],
+    storylines: [
+      [18, 13, 5, 5, "Hnnnnnnnggg. My legs-- are still sore- from yesterday."]
+    ],
+    render_override: :blinking_light_mountain_pass_render
+  }
+end
+
+def final_message_path_to_observatory args
+  {
+    background: 'sprites/path-to-observatory.png',
+    player: [60, 4],
+    scenes: [
+      [0, 26, 5, 5, :final_message_observatory]
+    ],
+    storylines: [
+      [22, 20, 10, 10, "This spot--, on the mountain, right here, it's-- perfect. This- is where- I'll-- yeet-- the person-- who is playing-- this- prank- on me."]
+    ],
+    render_override: :blinking_light_path_to_observatory_render
+  }
+end
+
+def final_message_observatory args
+  if args.state.scene_history.include? :replied_with_whole_truth
+    return {
+      background: 'sprites/inside-observatory.png',
+      fade: 60,
+      player: [51, 12],
+      storylines: [
+        [50, 10, 4, 4, "Here-- we- go..."]
+      ],
+      scenes: [
+        [30, 18, 5, 12, :final_message_inside_mainframe]
+      ],
+      render_override: :blinking_light_inside_observatory_render
+    }
+  else
+    return {
+      background: 'sprites/inside-observatory.png',
+      fade: 60,
+      player: [51, 12],
+      storylines: [
+        [50, 10, 4, 4, "I feel like I'm-- walking-- on sunshine!"]
+      ],
+      scenes: [
+        [30, 18, 5, 12, :final_message_inside_mainframe]
+      ],
+      render_override: :blinking_light_inside_observatory_render
+    }
+  end
+end
+
+def final_message_inside_mainframe args
+  {
+    player: [32, 4],
+    background: 'sprites/mainframe.png',
+    fade: 60,
+    scenes: [[45, 45,  4, 4, :final_message_check_ship_status]]
+  }
+end
+
+def final_message_check_ship_status args
+  {
+    background: 'sprites/mainframe.png',
+    storylines: [
+      [45, 45, 4, 4, (final_message_current args)],
+    ],
+    scenes: [
+      [*hotspot_top, :final_message_ship_status],
+    ]
+  }
+end
+
+def final_message_ship_status args
+  {
+    background: 'sprites/serenity.png',
+    fade: 60,
+    player: [30, 10],
+    scenes: [
+      [30, 50, 4, 4, :final_message_ship_status_reviewed]
+    ],
+    storylines: [
+      [30,  8, 4, 4, "Let me make- sure- everything--- looks good. It'll-- give me peace- of mind."],
+      *final_message_ship_status_shared(args)
+    ]
+  }
+end
+
+def final_message_ship_status_reviewed args
+  {
+    background: 'sprites/serenity.png',
+    fade: 60,
+    scenes: [
+      [*hotspot_bottom, :final_message_summary]
+    ],
+    storylines: [
+      [0, 62, 62, 3, "Whew. Everyone-- is in their- chambers. The engines-- are roaring-- and Serenity-- is coming-- home."],
+    ]
+  }
+end
+
+def final_message_ship_status_shared args
+  [
+    *ship_control_hotspot( 0, 50,
+                           "Stasis-- Chambers--: Online, All chambers-- are powered. Battery--- Allocation---: 3--- of-- 3--.",
+                           "Matthew's--- Chamber--: OCCUPIED----",
+                           "Aanka's--- Chamber--: OCCUPIED----",
+                           "Sasha's--- Chamber--: OCCUPIED----"),
+    *ship_control_hotspot(12, 35,
+                          "Life- Support--: Not-- Needed---",
+                          "O2--- Production---: OFF---",
+                          "CO2--- Scrubbers---: OFF---",
+                          "H2O--- Production---: OFF---"),
+    *ship_control_hotspot(24, 20,
+                          "Navigation: Offline---",
+                          "Sensor: OFF---",
+                          "Heads- Up- Display: DAMAGED---",
+                          "Arithmetic--- Unit: DAMAGED----"),
+    *ship_control_hotspot(36, 35,
+                          "COMM: Underpowered----",
+                          "Text: ON---",
+                          "Audio: SEGFAULT---",
+                          "Video: DAMAGED---"),
+    *ship_control_hotspot(48, 50,
+                          "Engine: Online, Coordinates--- Set- for Earth. Battery--- Allocation---: 3--- of-- 3---",
+                          "Engine I: ON---",
+                          "Engine II: ON---",
+                          "Engine III: ON---")
+  ]
+end
+
+def final_message_last_reply args
+  if args.state.scene_history.include? :replied_with_whole_truth
+    return "Buffer--: #{anka_reply_whole_truth.quote}"
+  else
+    return "Buffer--: #{anka_reply_half_truth.quote}"
+  end
+end
+
+def final_message_current args
+  if args.state.scene_history.include? :replied_with_whole_truth
+    return "Hey... It's-- me Sasha. Aanka-- is trying-- her best to comfort-- Matthew. This- is the first- time- I've-- ever-- seen-- Matthew-- cry. We'll-- probably-- be in stasis-- by the time you get this message--. Thank- you- again-- for all your help. I look forward-- to meeting-- you in person."
+  else
+    return "Hey! It's-- me Sasha! LOL! Aanka-- and Matthew-- are dancing-- around-- like- goofballs--! They- are both- so adorable! Only-- this- tiny-- little-- genius-- can make-- a battle-- hardened-- general--- put- on a tiara-- and dance- around-- like a fairy-- princess-- XD------ Anyways, we are heading-- back into-- the chambers--. I hope our welcome-- home- parade-- has fireworks!"
+  end
+end
+
+def final_message_summary args
+  if args.state.scene_history.include? :replied_with_whole_truth
+    return {
+      background: 'sprites/inside-observatory.png',
+      fade: 60,
+      player: [31, 11],
+      scenes: [[60, 0, 4, 32, :final_decision_side_of_home]],
+      storylines: [
+        [30, 10, 5, 4, "I can't-- imagine-- what they are feeling-- right now. But at least- they- know everything---, and we can- concentrate-- on rebuilding--- this world-- right- off the bat. I can't-- wait to see the future-- they'll-- help- build."],
+      ]
+    }
+  else
+    return {
+      background: 'sprites/inside-observatory.png',
+      fade: 60,
+      player: [31, 11],
+      scenes: [[60, 0, 4, 32, :final_decision_side_of_home]],
+      storylines: [
+        [30, 10, 5, 4, "They all sounded-- so happy. I know- they'll-- be in for a tough- dose- of reality--- when they- arrive. But- at least- they'll-- be around-- all- of us. We'll-- help them- cope."],
+      ]
+    }
+  end
+end
+
+</pre>
+<h1 id='--99_genre_narrative_rpg/return_of_serenity/app/storyline_serenity_alive.rb'>99_genre_narrative_rpg/return_of_serenity/app/storyline_serenity_alive.rb</h1>
+<pre>def serenity_alive_side_of_home args
+  {
+    fade: 60,
+    background: 'sprites/side-of-home.png',
+    player: [16, 13],
+    scenes: [
+      [52, 24, 11, 5, :serenity_alive_mountain_pass],
+    ],
+    render_override: :blinking_light_side_of_home_render
+  }
+end
+
+def serenity_alive_mountain_pass args
+  {
+    background: 'sprites/mountain-pass-zoomed-out.png',
+    player: [4, 4],
+    scenes: [
+      [18, 47, 5, 5, :serenity_alive_path_to_observatory],
+    ],
+    storylines: [
+      [18, 13, 5, 5, "Hnnnnnnnggg. My legs-- are still sore- from yesterday."]
+    ],
+    render_override: :blinking_light_mountain_pass_render
+  }
+end
+
+def serenity_alive_path_to_observatory args
+  {
+    background: 'sprites/path-to-observatory.png',
+    player: [60, 4],
+    scenes: [
+      [0, 26, 5, 5, :serenity_alive_observatory]
+    ],
+    storylines: [
+      [22, 20, 10, 10, "This spot--, on the mountain, right here, it's-- perfect. This- is where- I'll-- yeet-- the person-- who is playing-- this- prank- on me."]
+    ],
+    render_override: :blinking_light_path_to_observatory_render
+  }
+end
+
+def serenity_alive_observatory args
+  {
+    background: 'sprites/observatory.png',
+    player: [60, 2],
+    scenes: [
+      [28, 39, 4, 10, :serenity_alive_inside_observatory]
+    ],
+    render_override: :blinking_light_observatory_render
+  }
+end
+
+def serenity_alive_inside_observatory args
+  {
+    background: 'sprites/inside-observatory.png',
+    player: [60, 2],
+    storylines: [],
+    scenes: [
+      [30, 18, 5, 12, :serenity_alive_inside_mainframe]
+    ],
+    render_override: :blinking_light_inside_observatory_render
+  }
+end
+
+def serenity_alive_inside_mainframe args
+  {
+    background: 'sprites/mainframe.png',
+    fade: 60,
+    player: [30, 4],
+    scenes: [
+      [*hotspot_top, :serenity_alive_ship_status],
+    ],
+    storylines: [
+      [22, 45, 17, 4, (serenity_alive_last_reply args)],
+      [45, 45,  4, 4, (serenity_alive_current_message args)],
+    ]
+  }
+end
+
+def serenity_alive_ship_status args
+  {
+    background: 'sprites/serenity.png',
+    fade: 60,
+    player: [30, 10],
+    scenes: [
+      [30, 50, 4, 4, :serenity_alive_ship_status_reviewed]
+    ],
+    storylines: [
+      [30,  8, 4, 4, "Serenity? THE--- Mission-- Serenity?! How is that possible? They- are supposed-- to be dead."],
+      [30, 10, 4, 4, "I... can't-- believe-- it. I- can access-- Serenity's-- computer? I- guess my \"superpower----\" isn't limited-- by proximity-- to- a machine--."],
+      *serenity_alive_shared_ship_status(args)
+    ]
+  }
+end
+
+def serenity_alive_ship_status_reviewed args
+  {
+    background: 'sprites/serenity.png',
+    fade: 60,
+    scenes: [
+      [*hotspot_bottom, :serenity_alive_time_to_reply]
+    ],
+    storylines: [
+      [0, 62, 62, 3, "Okay. Reviewing-- everything--, it looks- like- I- can- take- the batteries--- from the Stasis--- Chambers--- and- Engine--- to keep- the crew-- alive-- and-- their-- location--- pinpointed---."],
+    ]
+  }
+end
+
+def serenity_alive_time_to_reply args
+  decision_graph serenity_alive_current_message(args),
+                  "Okay... time to deliver the bad news...",
+                  [:replied_to_serenity_alive_firmly, "Firm-- Reply", serenity_alive_firm_reply],
+                  [:replied_to_serenity_alive_kindly, "Sugar-- Coated---- Reply", serenity_alive_sugarcoated_reply]
+end
+
+def serenity_alive_shared_ship_status args
+  [
+    *ship_control_hotspot( 0, 50,
+                           "Stasis-- Chambers--: Online, All chambers-- are powered. Battery--- Allocation---: 3--- of-- 3--, Hmmm. They don't-- need this to be powered-- right- now. Everyone-- is awake.",
+                           nil,
+                           nil,
+                           nil),
+    *ship_control_hotspot(12, 35,
+                          "Life- Support--: Offline, Unable--- to- Sustain-- Life. Battery--- Allocation---: 0--- of-- 3---, Okay. That is definitely---- not a good thing.",
+                          nil,
+                          nil,
+                          nil),
+    *ship_control_hotspot(24, 20,
+                          "Navigation: Offline, Unable--- to- Calculate--- Location. Battery--- Allocation---: 0--- of-- 3---, Whelp. No wonder-- Sasha-- can't-- get- any-- readings. Their- Navigation--- is completely--- offline.",
+                          nil,
+                          nil,
+                          nil),
+    *ship_control_hotspot(36, 35,
+                          "COMM: Underpowered----, Limited--- to- Text-- Based-- COMM. Battery--- Allocation---: 1--- of-- 3---, It's-- lucky- that- their- COMM---- system was able to survive-- twenty-- years--. Just- barely-- it seems.",
+                          nil,
+                          nil,
+                          nil),
+    *ship_control_hotspot(48, 50,
+                          "Engine: Online, Full- Control-- Available. Battery--- Allocation---: 3--- of-- 3---, Hmmm. No point of having an engine-- online--, if you don't- know- where you're-- going.",
+                          nil,
+                          nil,
+                          nil)
+  ]
+end
+
+def serenity_alive_firm_reply
+  "Serenity, you are at a distance-- farther-- than- Neptune. All- of the ship's-- systems-- are failing. Please- move the batteries---- from- the Stasis-- Chambers-- over- to- Life-- Support--. I also-- need- you to move-- the batteries---- from- the Engines--- to your Navigation---- System."
+end
+
+def serenity_alive_sugarcoated_reply
+  "So... you- are- a teeny--- tiny--- bit--- farther-- from Earth- than you think. And you have a teeny--- tiny--- problem-- with your ship. Please-- move the batteries--- from the Stasis--- Chambers--- over to Life--- Support---. I also need you to move the batteries--- from the Engines--- to your- Navigation--- System. Don't-- worry-- Sasha. I'll-- get y'all-- home."
+end
+
+def replied_to_serenity_alive_firmly args
+  {
+    background: 'sprites/inside-observatory.png',
+    fade: 60,
+    player: [32, 21],
+    scenes: [
+      [*hotspot_bottom_right, :serenity_alive_path_from_observatory]
+    ],
+    storylines: [
+      [30, 18, 5, 12, "Buffer-- has been set to: #{serenity_alive_firm_reply.quote}"],
+      *serenity_alive_reply_completed_shared_hotspots(args),
+    ]
+  }
+end
+
+def replied_to_serenity_alive_kindly args
+  {
+    background: 'sprites/inside-observatory.png',
+    fade: 60,
+    player: [32, 21],
+    scenes: [
+      [*hotspot_bottom_right, :serenity_alive_path_from_observatory]
+    ],
+    storylines: [
+      [30, 18, 5, 12, "Buffer-- has been set to: #{serenity_alive_sugarcoated_reply.quote}"],
+      *serenity_alive_reply_completed_shared_hotspots(args),
+    ]
+  }
+end
+
+def serenity_alive_path_from_observatory args
+  {
+    fade: 60,
+    background: 'sprites/path-to-observatory.png',
+    player: [4, 21],
+    scenes: [
+      [*hotspot_bottom_right, :serenity_bio_infront_of_home]
+    ],
+    storylines: [
+      [22, 20, 10, 10, "I'm not sure what's-- worse. Waiting-- for Sasha's-- reply. Or jumping-- off- from- right- here."]
+    ]
+  }
+end
+
+def serenity_alive_reply_completed_shared_hotspots args
+  [
+    [30, 10, 5, 4, "I guess it wasn't-- a joke- after-- all."],
+    [40, 10, 5, 4, "I barely-- remember--- the- history----- of the crew."],
+    [50, 10, 5, 4, "It probably--- wouldn't-- hurt- to- refresh-- my memory--."]
+  ]
+end
+
+def serenity_alive_last_reply args
+  if args.state.scene_history.include? :replied_to_introduction_seriously
+    return "Buffer--: \"Hello, Who- is sending-- this message--?\""
+  else
+    return "Buffer--: \"New- phone. Who dis?\""
+  end
+end
+
+def serenity_alive_current_message args
+  if args.state.scene_history.include? :replied_to_introduction_seriously
+    "This- is Sasha. The Serenity--- crew-- is out of hibernation---- and ready-- for Earth reentry--. But, it seems like we are having-- trouble-- with our Navigation---- systems. Please advise.".quote
+  else
+    "LOL! Thanks for the laugh. I needed that. This- is Sasha. The Serenity--- crew-- is out of hibernation---- and ready-- for Earth reentry--. But, it seems like we are having-- trouble-- with our Navigation---- systems. Can you help me out- babe?".quote
+  end
+end
+
+</pre>
+<h1 id='--99_genre_narrative_rpg/return_of_serenity/app/storyline_serenity_bio.rb'>99_genre_narrative_rpg/return_of_serenity/app/storyline_serenity_bio.rb</h1>
+<pre>def serenity_bio_infront_of_home args
+  {
+    fade: 60,
+    background: 'sprites/front-of-home.png',
+    player: [54, 23],
+    scenes: [
+      [44, 34, 8, 14, :serenity_bio_inside_home],
+      [0, 3, 3, 22, :serenity_bio_library]
+    ]
+  }
+end
+
+def serenity_bio_inside_home args
+  {
+    background: 'sprites/inside-home.png',
+    player: [34, 4],
+    storylines: [
+      [34, 4, 4, 4, "I'm--- completely--- exhausted."],
+    ],
+    scenes: [
+      [30, 38, 12, 13, :serenity_bio_restless_sleep],
+      [32, 0, 8, 3, :serenity_bio_infront_of_home],
+    ]
+  }
+end
+
+def serenity_bio_restless_sleep args
+  {
+    fade: 60,
+    background: 'sprites/inside-home.png',
+    storylines: [
+      [32, 38, 10, 13, "I can't-- seem to sleep. I know nothing-- about the- crew-. Maybe- I- should- go read- up- on- them."],
+    ],
+    scenes: [
+      [32, 0, 8, 3, :serenity_bio_infront_of_home],
+    ]
+  }
+end
+
+def serenity_bio_library args
+  {
+    background: 'sprites/library.png',
+    fade: 60,
+    player: [30, 7],
+    scenes: [
+      [21, 35, 3, 18, :serenity_bio_book]
+    ]
+  }
+end
+
+def serenity_bio_book args
+  {
+    background: 'sprites/book.png',
+    fade: 60,
+    player: [6, 52],
+    storylines: [
+      [ 4, 50, 56, 4, "The Title-- Reads: Never-- Forget-- Mission-- Serenity---"],
+
+      [ 4, 38,  8, 8, "Name: Matthew--- R. Sex: Male--- Age-- at-- Departure: 36-----"],
+      [14, 38, 46, 8, "Tribute-- Text: Matthew graduated-- Magna-- Cum-- Laude-- from MIT--- with-- a- PHD---- in Aero-- Nautical--- Engineering. He was immensely--- competitive, and had an insatiable---- thirst- for aerial-- battle. From the age of twenty, he remained-- undefeated--- in the Israeli-- Air- Force- \"Blue Flag\" combat-- exercises. By the age of 29--- he had already-- risen through- the ranks, and became-- the Lieutenant--- General--- of Lufwaffe. Matthew-- volenteered-- to- pilot-- Mission-- Serenity. To- this day, his wife- and son- are pillars-- of strength- for us. Rest- in Peace- Matthew, we are sorry-- that- news of the pregancy-- never-- reached- you. Please forgive us."],
+
+      [4,  26,  8, 8, "Name: Aanka--- P. Sex: Female--- Age-- at-- Departure: 9-----"],
+      [14, 26, 46, 8, "Tribute-- Text: Aanka--- gratuated--- Magna-- Cum- Laude-- from MIT, at- the- age- of eight, with a- PHD---- in Astro-- Physics. Her-- IQ--- was over 390, the highest-- ever- recorded--- IQ-- in- human-- history. She changed- the landscape-- of Physics-- with her efforts- in- unravelling--- the mysteries--- of- Dark- Matter--. Anka discovered-- the threat- of Halley's-- Comet-- collision--- with Earth. She spear headed-- the global-- effort-- for Misson-- Serenity. Her- multilingual--- address-- to- the world-- brought- us all hope."],
+
+      [4,  14,  8, 8, "Name: Sasha--- N. Sex: Female--- Age-- at-- Departure: 29-----"],
+      [14, 14, 46, 8, "Tribute-- Text: Sasha gratuated-- Magna-- Cum- Laude-- from MIT--- with-- a- PHD---- in Computer---- Science----. She-- was-- brilliant--, strong- willed--, and-- a-- stunningly--- beautiful--- woman---. Sasha---- is- the- creator--- of the world's--- first- Ruby--- Quantum-- Machine---. After-- much- critical--- acclaim--, the Quantum-- Computer-- was placed in MIT's---- Museam-- next- to- Richard--- G. and Thomas--- K.'s---- Lisp-- Machine---. Her- engineering--- skills-- were-- paramount--- for Mission--- Serenity's--- success. Humanity-- misses-- you-- dearly,-- Sasha--. Life-- shines-- a dimmer-- light-- now- that- your- angelic- voice-- can never- be heard- again."],
+    ],
+    scenes: [
+      [*hotspot_bottom, :serenity_bio_finally_to_bed]
+    ]
+  }
+end
+
+def serenity_bio_finally_to_bed args
+  {
+    fade: 60,
+    background: 'sprites/inside-home.png',
+    player: [35, 3],
+    storylines: [
+      [34, 4, 4, 4, "Maybe-- I'll-- be able-- to sleep- now..."],
+    ],
+    scenes: [
+      [32, 38, 10, 13, :bad_dream],
+    ]
+  }
+end
+
+def bad_dream args
+  {
+    fade: 120,
+    background: 'sprites/inside-home.png',
+    player: [34, 35],
+    storylines: [
+      [34, 34, 4, 4, "Man. I did not- sleep- well- at all..."],
+    ],
+    scenes: [
+      [32, -1, 8, 3, :bad_dream_observatory]
+    ]
+  }
+end
+
+def bad_dream_observatory args
+  {
+    background: 'sprites/inside-observatory.png',
+    fade: 120,
+    player: [51, 12],
+    storylines: [
+      [50, 10, 4, 4,   "Breathe, Hiro. Just see what's there... everything--- will- be okay."]
+    ],
+    scenes: [
+      [30, 18, 5, 12, :bad_dream_inside_mainframe]
+    ],
+    render_override: :blinking_light_inside_observatory_render
+  }
+end
+
+def bad_dream_inside_mainframe args
+  {
+    player: [32, 4],
+    background: 'sprites/mainframe.png',
+    fade: 120,
+    storylines: [
+      [22, 45, 17, 4, (bad_dream_last_reply args)],
+    ],
+    scenes: [
+      [45, 45,  4, 4, :bad_dream_everyone_dead],
+    ]
+  }
+end
+
+def bad_dream_everyone_dead args
+  {
+    background: 'sprites/mainframe.png',
+    storylines: [
+      [22, 45, 17, 4, (bad_dream_last_reply args)],
+      [45, 45,  4, 4, "Hi-- Hiro. This is Sasha. By the time- you get this- message, chances-- are we will- already-- be- dead. The batteries--- got- damaged-- during-- removal. And- we don't-- have enough-- power-- for Life-- Support. The air-- is- already--- starting-- to taste- bad. It... would- have been- nice... to go- on a date--- with- you-- when-- I- got- back- to Earth. Anyways, good-- bye-- Hiro-- XOXOXO----"],
+      [22,  5, 17, 4, "Meh. Whatever, I didn't-- want to save them anyways. What- a pain- in my ass."],
+    ],
+    scenes: [
+      [*hotspot_bottom, :anka_inside_room]
+    ]
+  }
+end
+
+def bad_dream_last_reply args
+  if args.state.scene_history.include? :replied_to_serenity_alive_firmly
+    return "Buffer--: #{serenity_alive_firm_reply.quote}"
+  else
+    return "Buffer--: #{serenity_alive_sugarcoated_reply.quote}"
+  end
+end
+
+</pre>
+<h1 id='--99_genre_narrative_rpg/return_of_serenity/app/storyline_serenity_introduction.rb'>99_genre_narrative_rpg/return_of_serenity/app/storyline_serenity_introduction.rb</h1>
+<pre># decision_graph "Message from Sasha",
+#                "I should reply.",
+#                [:replied_to_introduction_seriously,  "Reply Seriously", "Who is this?"],
+# [:replied_to_introduction_humorously, "Reply Humorously", "New phone who dis?"]
+def reply_to_introduction args
+  decision_graph  "\"Mission-- control--, your- main- comm-- channels-- seem-- to be down. My apologies-- for- using-- this low- level-- exploit--. What's-- going-- on down there? We are ready-- for reentry--.\" Message--- Timestamp---: 4- hours-- 23--- minutes-- ago--.",
+                  "Whoever-- pulled- off this exploit-- knows their stuff. I should reply--.",
+                  [:replied_to_introduction_seriously,  "Serious Reply",  "Hello, Who- is sending-- this message--?"],
+                  [:replied_to_introduction_humorously, "Humorous Reply", "New phone, who dis?"]
+end
+
+def replied_to_introduction_seriously args
+  {
+    background: 'sprites/inside-observatory.png',
+    fade: 60,
+    player: [32, 21],
+    scenes: [
+      *replied_to_introduction_shared_scenes(args)
+    ],
+    storylines: [
+      [30, 18, 5, 12, "Buffer-- has been set to: \"Hello, Who- is sending-- this message--?\""],
+      *replied_to_introduction_shared_storylines(args)
+    ]
+  }
+end
+
+def replied_to_introduction_humorously args
+  {
+    background: 'sprites/inside-observatory.png',
+    fade: 60,
+    player: [32, 21],
+    scenes: [
+      *replied_to_introduction_shared_scenes(args)
+    ],
+    storylines: [
+      [30, 18, 5, 12, "Buffer-- has been set to: \"New- phone. Who dis?\""],
+      *replied_to_introduction_shared_storylines(args)
+    ]
+  }
+end
+
+def replied_to_introduction_shared_storylines args
+  [
+    [30, 10, 5, 4, "It's-- going-- to take a while-- for this reply-- to make it's-- way back."],
+    [40, 10, 5, 4, "4- hours-- to send a message-- at light speed?! How far away-- is the sender--?"],
+    [50, 10, 5, 4, "I know- I've-- read about-- light- speed- travel-- before--. Maybe-- the library--- still has that- poster."]
+  ]
+end
+
+def replied_to_introduction_shared_scenes args
+  [[60, 0, 4, 32, :replied_to_introduction_observatory]]
+end
+
+def replied_to_introduction_observatory args
+  {
+    background: 'sprites/observatory.png',
+    player: [28, 39],
+    scenes: [
+      [60, 0, 4, 32, :replied_to_introduction_path_to_observatory]
+    ]
+  }
+end
+
+def replied_to_introduction_path_to_observatory args
+  {
+    background: 'sprites/path-to-observatory.png',
+    player: [0, 26],
+    scenes: [
+      [60, 0, 4, 20, :replied_to_introduction_mountain_pass]
+    ],
+  }
+end
+
+def replied_to_introduction_mountain_pass args
+  {
+    background: 'sprites/mountain-pass-zoomed-out.png',
+    player: [21, 48],
+    scenes: [
+      [0, 0, 15, 4, :replied_to_introduction_side_of_home]
+    ],
+    storylines: [
+      [15, 28, 5, 3, "At least I'm-- getting-- my- exercise-- in- for- today--."]
+    ]
+  }
+end
+
+def replied_to_introduction_side_of_home args
+  {
+    background: 'sprites/side-of-home.png',
+    player: [58, 29],
+    scenes: [
+      [2, 0, 61, 2, :speed_of_light_front_of_home]
+    ],
+  }
+end
+
+</pre>
+<h1 id='--99_genre_narrative_rpg/return_of_serenity/app/storyline_speed_of_light.rb'>99_genre_narrative_rpg/return_of_serenity/app/storyline_speed_of_light.rb</h1>
+<pre>def speed_of_light_front_of_home args
+  {
+    background: 'sprites/front-of-home.png',
+    player: [54, 23],
+    scenes: [
+      [44, 34, 8, 14, :speed_of_light_inside_home],
+      [0, 3, 3, 22, :speed_of_light_outside_library]
+    ]
+  }
+end
+
+def speed_of_light_inside_home args
+  {
+    background: 'sprites/inside-home.png',
+    player: [35, 4],
+    storylines: [
+      [30, 38, 12, 13, "Can't- sleep right now. I have to- find- out- why- it took- over-- 4- hours-- to receive-- that message."]
+    ],
+    scenes: [
+      [32, 0, 8, 3, :speed_of_light_front_of_home],
+    ]
+  }
+end
+
+def speed_of_light_outside_library args
+  {
+    background: 'sprites/outside-library.png',
+    player: [55, 19],
+    scenes: [
+      [49, 39, 6, 10, :speed_of_light_library],
+      [61, 11, 3, 20, :speed_of_light_front_of_home]
+    ]
+  }
+end
+
+def speed_of_light_library args
+  {
+    background: 'sprites/library.png',
+    player: [30, 7],
+    scenes: [
+      [3, 50, 10, 3, :speed_of_light_celestial_bodies_diagram]
+    ]
+  }
+end
+
+def speed_of_light_celestial_bodies_diagram args
+  {
+    background: 'sprites/planets.png',
+    fade: 60,
+    player: [30, 3],
+    scenes: [
+      [56 - 2, 10, 5, 5, :speed_of_light_distance_discovered]
+    ],
+    storylines: [
+      [30, 2, 4, 4, "Here- it is! This is a diagram--- of the solar-- system--. It was printed-- over-- fifty-- years- ago. Geez-- that's-- old."],
+
+      [ 0 - 2, 10, 5, 5, "The label- reads: Sun. The length- of the Astronomical-------- Unit-- (AU), is the distance-- from the Sun- to the Earth. Which is about 150--- million--- kilometers----."],
+      [ 7 - 2, 10, 5, 5, "The label- reads: Mercury. Distance from Sun: 0.39AU------------ or- 3----- light-- minutes--."],
+      [14 - 2, 10, 5, 5, "The label- reads: Venus. Distance from Sun: 0.72AU------------ or- 6----- light-- minutes--."],
+      [21 - 2, 10, 5, 5, "The label- reads: Earth. Distance from Sun: 1.00AU------------ or- 8----- light-- minutes--."],
+      [28 - 2, 10, 5, 5, "The label- reads: Mars. Distance from Sun: 1.52AU------------ or- 12----- light-- minutes--."],
+      [35 - 2, 10, 5, 5, "The label- reads: Jupiter. Distance from Sun: 5.20AU------------ or- 45----- light-- minutes--."],
+      [42 - 2, 10, 5, 5, "The label- reads: Saturn. Distance from Sun: 9.53AU------------ or- 79----- light-- minutes--."],
+      [49 - 2, 10, 5, 5, "The label- reads: Uranus. Distance from Sun: 19.81AU------------ or- 159----- light-- minutes--."],
+      # [56 - 2, 15, 4, 4, "The label- reads: Neptune. Distance from Sun: 30.05AU------------ or- 4.1----- light-- hours--."],
+      [63 - 2, 10, 5, 5, "The label- reads: Pluto. Wait. WTF? Pluto-- isn't-- a planet."],
+    ]
+  }
+end
+
+def speed_of_light_distance_discovered args
+  {
+    background: 'sprites/planets.png',
+    scenes: [
+      [13, 0, 44, 3, :speed_of_light_end_of_day]
+    ],
+    storylines: [
+      [ 0 - 2, 10, 5, 5, "The label- reads: Sun. The length- of the Astronomical-------- Unit-- (AU), is the distance-- from the Sun- to the Earth. Which is about 150--- million--- kilometers----."],
+      [ 7 - 2, 10, 5, 5, "The label- reads: Mercury. Distance from Sun: 0.39AU------------ or- 3----- light-- minutes--."],
+      [14 - 2, 10, 5, 5, "The label- reads: Venus. Distance from Sun: 0.72AU------------ or- 6----- light-- minutes--."],
+      [21 - 2, 10, 5, 5, "The label- reads: Earth. Distance from Sun: 1.00AU------------ or- 8----- light-- minutes--."],
+      [28 - 2, 10, 5, 5, "The label- reads: Mars. Distance from Sun: 1.52AU------------ or- 12----- light-- minutes--."],
+      [35 - 2, 10, 5, 5, "The label- reads: Jupiter. Distance from Sun: 5.20AU------------ or- 45----- light-- minutes--."],
+      [42 - 2, 10, 5, 5, "The label- reads: Saturn. Distance from Sun: 9.53AU------------ or- 79----- light-- minutes--."],
+      [49 - 2, 10, 5, 5, "The label- reads: Uranus. Distance from Sun: 19.81AU------------ or- 159----- light-- minutes--."],
+      [56 - 2, 10, 5, 5, "The label- reads: Neptune. Distance from Sun: 30.05AU------------ or- 4.1----- light-- hours--. What?! The message--- I received-- was from a source-- farther-- than-- Neptune?!"],
+      [63 - 2, 10, 5, 5, "The label- reads: Pluto. Dista- Wait... Pluto-- isn't-- a planet. People-- thought- Pluto-- was a planet-- back- then?--"],
+    ]
+  }
+end
+
+def speed_of_light_end_of_day args
+  {
+    fade: 60,
+    background: 'sprites/inside-home.png',
+    player: [35, 0],
+    storylines: [
+      [35, 10, 4, 4, "Wonder-- what the reply-- will be. Who- the hell is contacting--- me from beyond-- Neptune? This- has to be some- kind- of- joke."]
+    ],
+    scenes: [
+      [31, 38, 10, 12, :serenity_alive_side_of_home]
+    ]
+  }
+end
+
+</pre>
+<h1 id='--99_genre_platformer/clepto_frog/app/main.rb'>99_genre_platformer/clepto_frog/app/main.rb</h1>
+<pre>MAP_FILE_PATH = 'app/map.txt'
+
+require 'app/map.rb'
+
+class CleptoFrog
+  attr_gtk
+
+  def render_ending
+    state.game_over_at ||= state.tick_count
+
+    outputs.labels << [640, 700, "Clepto Frog", 4, 1]
+
+    if state.tick_count >= (state.game_over_at + 120)
+      outputs.labels << [640, 620, "\"I... I.... don't believe it.\" - New Guy",
+                         4, 1, 0, 0, 0, 255 * (state.game_over_at + 120).ease(60)]
+    end
+
+    if state.tick_count >= (state.game_over_at + 240)
+      outputs.labels << [640, 580, "\"He actually stole all the mugs?\" - New Guy",
+                         4, 1, 0, 0, 0, 255 * (state.game_over_at + 240).ease(60)]
+    end
+
+    if state.tick_count >= (state.game_over_at + 360)
+      outputs.labels << [640, 540, "\"Kind of feel bad STARTING HIM WITH NOTHING again.\" - New Guy",
+                         4, 1, 0, 0, 0, 255 * (state.game_over_at + 360).ease(60)]
+    end
+
+    outputs.sprites << [640 - 50, 360 - 50, 100, 100,
+                        "sprites/square-green.png"]
+
+    outputs.labels << [640, 300, "Current Time: #{"%.2f" % state.stuff_time}", 4, 1]
+    outputs.labels << [640, 270, "Best Time: #{"%.2f" % state.stuff_best_time}", 4, 1]
+
+    if state.tick_count >= (state.game_over_at + 550)
+      restart_game
+    end
+  end
+
+  def restart_game
+    state.world = nil
+    state.x = nil
+    state.y = nil
+    state.dx = nil
+    state.dy = nil
+    state.stuff_score = 0
+    state.stuff_time = 0
+    state.intro_tick_count = nil
+    defaults
+    state.game_start_at = state.tick_count
+    state.scene = :game
+    state.game_over_at = nil
+  end
+
+  def render_intro
+    outputs.labels << [640, 700, "Clepto Frog", 4, 1]
+    if state.tick_count >= 120
+      outputs.labels << [640, 620, "\"Uh... your office has a pet frog?\" - New Guy",
+                         4, 1, 0, 0, 0, 255 * 120.ease(60)]
+    end
+
+    if state.tick_count >= 240
+      outputs.labels << [640, 580, "\"Yep! His name is Clepto.\" - Jim",
+                         4, 1, 0, 0, 0, 255 * 240.ease(60)]
+    end
+
+    if state.tick_count >= 360
+      outputs.labels << [640, 540, "\"Uh...\" - New Guy",
+                         4, 1, 0, 0, 0, 255 * 360.ease(60)]
+    end
+
+    if state.tick_count >= 480
+      outputs.labels << [640, 500, "\"He steals mugs while we're away...\" - Jim",
+                         4, 1, 0, 0, 0, 255 * 480.ease(60)]
+    end
+
+    if state.tick_count >= 600
+      outputs.labels << [640, 460, "\"It's not a big deal, we take them back in the morning.\" - Jim",
+                         4, 1, 0, 0, 0, 255 * 600.ease(60)]
+    end
+
+    outputs.sprites << [640 - 50, 360 - 50, 100, 100,
+                        "sprites/square-green.png"]
+
+    if state.tick_count == 800
+      state.scene = :game
+      state.game_start_at = state.tick_count
+    end
+  end
+
+  def tick
+    defaults
+    if state.scene == :intro && state.tick_count <= 800
+      render_intro
+    elsif state.scene == :ending
+      render_ending
+    else
+      render
+    end
+    calc
+    process_inputs
+  end
+
+  def defaults
+    state.scene ||= :intro
+    state.stuff_score     ||= 0
+    state.stuff_time      ||= 0
+    state.stuff_best_time ||= nil
+    state.camera_x ||= 0
+    state.camera_y ||= 0
+    state.target_camera_scale ||= 1
+    state.camera_scale ||= 1
+    state.tongue_length          ||= 100
+    state.dev_action             ||= :collision_mode
+    state.action                 ||= :aiming
+    state.tongue_angle           ||= 90
+    state.tile_size                = 64
+    state.gravity                  = -0.1
+    state.air                      = -0.01
+    state.player_width             = 60
+    state.player_height            = 60
+    state.collision_tolerance      = 0.0
+    state.previous_tile_size     ||= state.tile_size
+    state.x                      ||= 2400
+    state.y                      ||= 200
+    state.dy                     ||= 0
+    state.dx                     ||= 0
+    attempt_load_world_from_file
+    state.world_lookup           ||= { }
+    state.world_collision_rects  ||= []
+    state.mode                   ||= :creating
+    state.select_menu            ||= [0, 720, 1280, 720]
+    state.sprite_quantity        ||= 20
+    state.sprite_coords          ||= []
+    state.banner_coords          ||= [640, 680 + 720]
+    state.sprite_selected        ||= 1
+    state.map_saved_at           ||= 0
+    state.intro_tick_count       ||= state.tick_count
+    if state.sprite_coords == []
+      count = 1
+      temp_x = 165
+      temp_y = 500 + 720
+      state.sprite_quantity.times do
+        state.sprite_coords += [[temp_x, temp_y, count]]
+        temp_x += 100
+        count += 1
+        if temp_x > 1280 - (165 + 50)
+          temp_x = 165
+          temp_y -= 75
+        end
+      end
+    end
+  end
+
+  def start_of_tongue x = nil, y = nil
+    x ||= state.x
+    y ||= state.y
+    [
+      x + state.player_width.half,
+      y + state.player_height.half
+    ]
+  end
+
+  def stage_definition
+    outputs.sprites << [vx(0), vy(0), vw(10000), vw(5875), 'sprites/level-map.png']
+  end
+
+  def render
+    stage_definition
+    start_of_tongue_render = [vx(start_of_tongue.x), vy(start_of_tongue.y)]
+    end_of_tongue_render = [vx(end_of_tongue.x), vy(end_of_tongue.y)]
+
+    if state.anchor_point
+      anchor_point_render = [vx(state.anchor_point.x), vy(state.anchor_point.y)]
+      outputs.sprites << { x: start_of_tongue_render.x,
+                           y: start_of_tongue_render.y,
+                           w: vw(2),
+                           h: args.geometry.distance(start_of_tongue_render, anchor_point_render),
+                           path:  'sprites/square-pink.png',
+                           angle_anchor_y: 0,
+                           angle: state.tongue_angle - 90 }
+    else
+      outputs.sprites << { x: vx(start_of_tongue.x),
+                           y: vy(start_of_tongue.y),
+                           w: vw(2),
+                           h: vh(state.tongue_length),
+                           path:  'sprites/square-pink.png',
+                           angle_anchor_y: 0,
+                           angle: state.tongue_angle - 90 }
+    end
+
+    outputs.sprites << state.objects.map { |o| [vx(o.x), vy(o.y), vw(o.w), vh(o.h), o.path] }
+
+    if state.god_mode
+      # SHOW HIDE COLLISIONS
+      outputs.sprites << state.world.map do |x, y, w, h|
+        x = vx(x)
+        y = vy(y)
+        if x > -80 && x < 1280 && y > -80 && y < 720
+          {
+            x: x,
+            y: y,
+            w: vw(w || state.tile_size),
+            h: vh(h || state.tile_size),
+            path: 'sprites/square-gray.png',
+            a: 128
+          }
+        end
+      end
+    end
+
+    render_player
+    outputs.sprites << [vx(2315), vy(45), vw(569), vh(402), 'sprites/square-blue.png', 0, 40]
+
+    # Label in top left of the screen
+    outputs.primitives << [20, 640, 180, 70, 255, 255, 255, 128].solid
+    outputs.primitives << [30, 700, "Stuff: #{state.stuff_score} of #{$mugs.count}", 1].label
+    outputs.primitives << [30, 670, "Time: #{"%.2f" % state.stuff_time}", 1].label
+
+    if state.god_mode
+      if state.map_saved_at > 0 && state.map_saved_at.elapsed_time < 120
+        outputs.primitives << [920, 670, 'Map has been exported!', 1, 0, 50, 100, 50].label
+      end
+
+
+      # Creates sprite following mouse to help indicate which sprite you have selected
+      outputs.primitives << [inputs.mouse.position.x, inputs.mouse.position.y,
+                             state.tile_size, state.tile_size, 'sprites/square-indigo.png', 0, 100].sprite
+    end
+
+    render_mini_map
+    outputs.primitives << [0, 0, 1280, 720, 255, 255, 255, 255 * state.game_start_at.ease(60, :flip)].solid
+  end
+
+  def render_mini_map
+    x, y = 1170, 10
+    outputs.primitives << [x, y, 100, 58, 0, 0, 0, 200].solid
+    outputs.primitives << [x + args.state.x.fdiv(100) - 1, y + args.state.y.fdiv(100) - 1, 2, 2, 0, 255, 0].solid
+    t_start = start_of_tongue
+    t_end = end_of_tongue
+    outputs.primitives << [
+      x + t_start.x.fdiv(100), y + t_start.y.fdiv(100),
+      x + t_end.x.fdiv(100), y + t_end.y.fdiv(100),
+      255, 255, 255
+    ].line
+
+    state.objects.each do |o|
+      outputs.primitives << [x + o.x.fdiv(100) - 1, y + o.y.fdiv(100) - 1, 2, 2, 200, 200, 0].solid
+    end
+  end
+
+  def calc_camera percentage_override = nil
+    percentage = percentage_override || (0.2 * state.camera_scale)
+    target_scale = state.target_camera_scale
+    distance_scale = target_scale - state.camera_scale
+    state.camera_scale += distance_scale * percentage
+
+    target_x = state.x * state.target_camera_scale
+    target_y = state.y * state.target_camera_scale
+
+    distance_x = target_x - (state.camera_x + 640)
+    distance_y = target_y - (state.camera_y + 360)
+    state.camera_x += distance_x * percentage if distance_x.abs > 1
+    state.camera_y += distance_y * percentage if distance_y.abs > 1
+    state.camera_x = 0 if state.camera_x < 0
+    state.camera_y = 0 if state.camera_y < 0
+  end
+
+  def vx x
+     (x * state.camera_scale) - state.camera_x
+  end
+
+  def vy y
+    (y * state.camera_scale) - state.camera_y
+  end
+
+  def vw w
+    w * state.camera_scale
+  end
+
+  def vh h
+    h * state.camera_scale
+  end
+
+  def calc
+    calc_camera
+    calc_world_lookup
+    calc_player
+    calc_on_floor
+    calc_score
+  end
+
+  def set_camera_scale v = nil
+    return if v < 0.1
+    state.target_camera_scale = v
+  end
+
+  def process_inputs_god_mode
+    return unless state.god_mode
+
+    if inputs.keyboard.key_down.equal_sign || (inputs.keyboard.equal_sign && state.tick_count.mod_zero?(10))
+      set_camera_scale state.camera_scale + 0.1
+    elsif inputs.keyboard.key_down.hyphen || (inputs.keyboard.hyphen && state.tick_count.mod_zero?(10))
+      set_camera_scale state.camera_scale - 0.1
+    elsif inputs.keyboard.eight || inputs.keyboard.zero
+      set_camera_scale 1
+    end
+
+    if input_up?
+      state.y += 10
+      state.dy = 0
+    elsif input_down?
+      state.y -= 10
+      state.dy = 0
+    end
+
+    if input_left?
+      state.x -= 10
+      state.dx = 0
+    elsif input_right?
+      state.x += 10
+      state.dx = 0
+    end
+  end
+
+  def process_inputs
+    if state.scene == :game
+      process_inputs_player_movement
+      process_inputs_god_mode
+    elsif state.scene == :intro
+      if args.inputs.keyboard.key_down.enter || args.inputs.keyboard.key_down.space
+        if Kernel.tick_count < 600
+          Kernel.tick_count = 600
+        end
+      end
+    end
+  end
+
+  def input_up?
+    inputs.keyboard.w || inputs.keyboard.up || inputs.keyboard.k
+  end
+
+  def input_up_released?
+    inputs.keyboard.key_up.w ||
+    inputs.keyboard.key_up.up ||
+    inputs.keyboard.key_up.k
+  end
+
+  def input_down?
+    inputs.keyboard.s || inputs.keyboard.down || inputs.keyboard.j
+  end
+
+  def input_down_released?
+    inputs.keyboard.key_up.s ||
+    inputs.keyboard.key_up.down ||
+    inputs.keyboard.key_up.j
+  end
+
+  def input_left?
+    inputs.keyboard.a || inputs.keyboard.left || inputs.keyboard.h
+  end
+
+  def input_right?
+    inputs.keyboard.d || inputs.keyboard.right || inputs.keyboard.l
+  end
+
+  def set_object path, w, h
+    state.object = path
+    state.object_w = w
+    state.object_h = h
+  end
+
+  def collision_mode
+    state.dev_action = :collision_mode
+  end
+
+  def process_inputs_player_movement
+    if inputs.keyboard.key_down.g
+      state.god_mode = !state.god_mode
+      puts state.god_mode
+    end
+
+    if inputs.keyboard.key_down.u && state.dev_action == :collision_mode
+      state.world = state.world[0..-2]
+      state.world_lookup = {}
+    end
+
+    if inputs.keyboard.key_down.space && !state.anchor_point
+      state.tongue_length = 0
+      state.action = :shooting
+      outputs.sounds << 'sounds/shooting.wav'
+    elsif inputs.keyboard.key_down.space
+      state.action = :aiming
+      state.anchor_point  = nil
+      state.tongue_length = 100
+    end
+
+    if state.anchor_point
+      if input_up?
+        if state.tongue_length >= 105
+          state.tongue_length -= 5
+          state.dy += 0.8
+        end
+      elsif input_down?
+        state.tongue_length += 5
+        state.dy -= 0.8
+      end
+
+      if input_left? && state.dx > 1
+        state.dx *= 0.98
+      elsif input_left? && state.dx < -1
+        state.dx *= 1.03
+      elsif input_left? && !state.on_floor
+        state.dx -= 3
+      elsif input_right? && state.dx > 1
+        state.dx *= 1.03
+      elsif input_right? && state.dx < -1
+        state.dx *= 0.98
+      elsif input_right? && !state.on_floor
+        state.dx += 3
+      end
+    else
+      if input_left?
+        state.tongue_angle += 1.5
+        state.tongue_angle = state.tongue_angle
+      elsif input_right?
+        state.tongue_angle -= 1.5
+        state.tongue_angle = state.tongue_angle
+      end
+    end
+  end
+
+  def add_floors
+    # floors
+    state.world += [
+      [0,       0, 10000, 40],
+      [0,    1670, 3250, 60],
+      [6691, 1653, 3290, 60],
+      [1521, 3792, 7370, 60],
+      [0, 5137, 3290, 60]
+    ]
+  end
+
+  def attempt_load_world_from_file
+    return if state.world
+    # exported_world = gtk.read_file(MAP_FILE_PATH)
+    state.world = []
+    state.objects = []
+
+    if $collisions
+      $collisions.map do |x, y, w, h|
+        state.world << [x, y, w, h]
+      end
+
+      add_floors
+    # elsif exported_world
+    #   exported_world.each_line.map do |l|
+    #     tokens = l.strip.split(',')
+    #     x    = tokens[0].to_i
+    #     y    = tokens[1].to_i
+    #     type = tokens[2].to_i
+    #     if type == 1
+    #       state.world << [x, y, state.tile_size, state.tile_size]
+    #     elsif type == 2
+    #       w, h, path = tokens[3..-1]
+    #       state.objects << [x, y, w.to_i, h.to_i, path]
+    #     end
+    #   end
+
+    #   add_floors
+    end
+
+    if $mugs
+      $mugs.map do |x, y, w, h, path|
+        state.objects << [x, y, w, h, path]
+      end
+    end
+  end
+
+  def calc_world_lookup
+    if state.tile_size != state.previous_tile_size
+      state.previous_tile_size = state.tile_size
+      state.world_lookup = {}
+    end
+
+    return if state.world_lookup.keys.length > 0
+    return unless state.world.length > 0
+
+    # Searches through the world and finds the cordinates that exist
+    state.world_lookup = {}
+    state.world.each do |x, y, w, h|
+      state.world_lookup[[x, y, w || state.tile_size, h || state.tile_size]] = true
+    end
+
+    # Assigns collision rects for every sprite drawn
+    state.world_collision_rects =
+      state.world_lookup
+           .keys
+           .map do |x, y, w, h|
+             s = state.tile_size
+             w ||= s
+             h ||= s
+             {
+               args:       [x, y, w, h],
+               left_right: [x,     y + 4, w,     h - 6],
+               top:        [x + 4, y + 6, w - 8, h - 6],
+               bottom:     [x + 1, y - 1, w - 2, h - 8],
+             }
+           end
+
+  end
+
+  def calc_pendulum
+    return if !state.anchor_point
+    target_x = state.anchor_point.x - start_of_tongue.x
+    target_y = state.anchor_point.y -
+               state.tongue_length - 5 - 20 - state.player_height
+
+    diff_y = state.y - target_y
+
+    if target_x > 0
+      state.dx += 0.6
+    elsif target_x < 0
+      state.dx -= 0.6
+    end
+
+    if diff_y > 0
+      state.dy -= 0.1
+    elsif diff_y < 0
+      state.dy += 0.1
+    end
+
+    state.dx *= 0.99
+
+    if state.dy.abs < 2
+      state.dy *= 0.8
+    else
+      state.dy *= 0.90
+    end
+
+    if state.tongue_length && state.y
+      state.dy += state.tongue_angle.vector_y state.tongue_length.fdiv(1000)
+    end
+  end
+
+  def calc_tongue_angle
+    return unless state.anchor_point
+    state.tongue_angle = args.geometry.angle_from state.anchor_point, start_of_tongue
+    state.tongue_length = args.geometry.distance(start_of_tongue, state.anchor_point)
+    state.tongue_length = state.tongue_length.greater(100)
+  end
+
+  def player_from_end_of_tongue
+    p = state.tongue_angle.vector(state.tongue_length)
+    derived_start = [state.anchor_point.x - p.x, state.anchor_point.y - p.y]
+    derived_start.x -= state.player_width.half
+    derived_start.y -= state.player_height.half
+    derived_start
+  end
+
+  def end_of_tongue
+    p = state.tongue_angle.vector(state.tongue_length)
+    [start_of_tongue.x + p.x, start_of_tongue.y + p.y]
+  end
+
+  def calc_shooting
+    return unless state.action == :shooting
+    state.tongue_length += 30
+    potential_anchor = end_of_tongue
+    if potential_anchor.x <= 0
+      state.anchor_point = potential_anchor
+      state.action = :anchored
+      outputs.sounds << 'sounds/attached.wav'
+    elsif potential_anchor.x >= 10000
+      state.anchor_point = potential_anchor
+      state.action = :anchored
+      outputs.sounds << 'sounds/attached.wav'
+    elsif potential_anchor.y <= 0
+      state.anchor_point = potential_anchor
+      state.action = :anchored
+      outputs.sounds << 'sounds/attached.wav'
+    elsif potential_anchor.y >= 5875
+      state.anchor_point = potential_anchor
+      state.action = :anchored
+      outputs.sounds << 'sounds/attached.wav'
+    else
+      anchor_rect = [potential_anchor.x - 5, potential_anchor.y - 5, 10, 10]
+      collision = state.world_collision_rects.find_all do |v|
+        [v[:args].x, v[:args].y, v[:args].w, v[:args].h].intersect_rect?(anchor_rect)
+      end.first
+      if collision
+        state.anchor_point = potential_anchor
+        state.action = :anchored
+      outputs.sounds << 'sounds/attached.wav'
+      end
+    end
+  end
+
+  def calc_player
+    calc_shooting
+    if !state.god_mode
+      state.dy += state.gravity  # Since acceleration is the change in velocity, the change in y (dy) increases every frame
+      state.dx += state.dx * state.air
+    end
+    calc_pendulum
+    calc_box_collision
+    calc_edge_collision
+    if !state.god_mode
+      state.y  += state.dy
+      state.x  += state.dx
+    end
+    calc_tongue_angle
+  end
+
+  def calc_box_collision
+    return unless state.world_lookup.keys.length > 0
+    collision_floor
+    collision_left
+    collision_right
+    collision_ceiling
+  end
+
+  def calc_edge_collision
+    # Ensures that player doesn't fall below the map
+    if next_y < 0 && state.dy < 0
+      state.y = 0
+      state.dy = state.dy.abs * 0.8
+      state.collision_on_y = true
+    # Ensures player doesn't go insanely high
+    elsif next_y > 5875 - state.tile_size && state.dy > 0
+      state.y = 5875 - state.tile_size
+      state.dy = state.dy.abs * 0.8 * -1
+      state.collision_on_y = true
+    end
+
+    # Ensures that player remains in the horizontal range its supposed to
+    if state.x >= 10000 - state.tile_size && state.dx > 0
+      state.x = 10000 - state.tile_size
+      state.dx = state.dx.abs * 0.8 * -1
+      state.collision_on_x = true
+    elsif state.x <= 0 && state.dx < 0
+      state.x = 0
+      state.dx = state.dx.abs * 0.8
+      state.collision_on_x = true
+    end
+  end
+
+  def next_y
+    state.y + state.dy
+  end
+
+  def next_x
+    if state.dx < 0
+      return (state.x + state.dx) - (state.tile_size - state.player_width)
+    else
+      return (state.x + state.dx) + (state.tile_size - state.player_width)
+    end
+  end
+
+  def collision_floor
+    return unless state.dy <= 0
+
+    player_rect = [state.x, next_y, state.tile_size, state.tile_size]
+
+    # Runs through all the sprites on the field and determines if the player hits the bottom of sprite (hence "-0.1" above)
+    floor_collisions = state.world_collision_rects
+                         .find_all { |r| r[:top].intersect_rect?(player_rect, state.collision_tolerance) }
+                         .first
+
+    return unless floor_collisions
+    state.y = floor_collisions[:top].top
+    state.dy = state.dy.abs * 0.8
+  end
+
+  def collision_left
+    return unless state.dx < 0
+    player_rect = [next_x, state.y, state.tile_size, state.tile_size]
+
+    # Runs through all the sprites on the field and determines if the player hits the left side of sprite (hence "-0.1" above)
+    left_side_collisions = state.world_collision_rects
+                             .find_all { |r| r[:left_right].intersect_rect?(player_rect, state.collision_tolerance) }
+                             .first
+
+    return unless left_side_collisions
+    state.x = left_side_collisions[:left_right].right
+    state.dx = state.dy.abs * 0.8
+    state.collision_on_x = true
+  end
+
+  def collision_right
+    return unless state.dx > 0
+
+    player_rect = [next_x, state.y, state.tile_size, state.tile_size]
+    # Runs through all the sprites on the field and determines if the player hits the right side of sprite (hence "-0.1" above)
+    right_side_collisions = state.world_collision_rects
+                              .find_all { |r| r[:left_right].intersect_rect?(player_rect, state.collision_tolerance) }
+                              .first
+
+    return unless right_side_collisions
+    state.x = right_side_collisions[:left_right].left - state.tile_size
+    state.dx = state.dx.abs * 0.8 * -1
+    state.collision_on_x = true
+  end
+
+  def collision_ceiling
+    return unless state.dy > 0
+
+    player_rect = [state.x, next_y, state.player_width, state.player_height]
+
+    # Runs through all the sprites on the field and determines if the player hits the ceiling of sprite (hence "+0.1" above)
+    ceil_collisions = state.world_collision_rects
+                        .find_all { |r| r[:bottom].intersect_rect?(player_rect, state.collision_tolerance) }
+                        .first
+
+    return unless ceil_collisions
+    state.y = ceil_collisions[:bottom].y - state.tile_size
+    state.dy = state.dy.abs * 0.8 * -1
+    state.collision_on_y = true
+  end
+
+  def to_coord point
+    # Integer divides (idiv) point.x to turn into grid
+    # Then, you can just multiply each integer by state.tile_size
+    # later and huzzah. Grid coordinates
+    [point.x.idiv(state.tile_size), point.y.idiv(state.tile_size)]
+  end
+
+  def export_map
+    export_string = state.world.map do |x, y|
+      "#{x},#{y},1"
+    end
+    export_string += state.objects.map do |x, y, w, h, path|
+      "#{x},#{y},2,#{w},#{h},#{path}"
+    end
+    gtk.write_file(MAP_FILE_PATH, export_string.join("\n"))
+    state.map_saved_at = state.tick_count
+  end
+
+  def inputs_export_stage
+  end
+
+  def calc_score
+    return unless state.scene == :game
+    player = [state.x, state.y, state.player_width, state.player_height]
+    collected = state.objects.find_all { |s| s.intersect_rect? player }
+    state.stuff_score += collected.length
+    if collected.length > 0
+      outputs.sounds << 'sounds/collectable.wav'
+    end
+    state.objects = state.objects.reject { |s| collected.include? s }
+    state.stuff_time += 0.01
+    if state.objects.length == 0
+      if !state.stuff_best_time || state.stuff_time < state.stuff_best_time
+        state.stuff_best_time = state.stuff_time
+      end
+      state.game_over_at = nil
+      state.scene = :ending
+    end
+  end
+
+  def calc_on_floor
+    if state.action == :anchored
+      state.on_floor = false
+      state.on_floor_debounce = 30
+    else
+      state.on_floor_debounce ||= 30
+
+      if state.dy.round != 0
+        state.on_floor_debounce = 30
+        state.on_floor = false
+      else
+        state.on_floor_debounce -= 1
+      end
+
+      if state.on_floor_debounce <= 0
+        state.on_floor_debounce = 0
+        state.on_floor = true
+      end
+    end
+  end
+
+  def render_player
+    path = "sprites/square-green.png"
+    angle = 0
+    # outputs.labels << [vx(state.x), vy(state.y) - 30, "dy: #{state.dy.round}"]
+    if state.action == :idle
+      # outputs.labels << [vx(state.x), vy(state.y), "IDLE"]
+      path = "sprites/square-green.png"
+    elsif state.action == :aiming && !state.on_floor
+      # outputs.labels << [vx(state.x), vy(state.y), "AIMING AIR BORN"]
+      angle = state.tongue_angle - 90
+      path = "sprites/square-green.png"
+    elsif state.action == :aiming # ON THE GROUND
+      # outputs.labels << [vx(state.x), vy(state.y), "AIMING GROUND"]
+      path = "sprites/square-green.png"
+    elsif state.action == :shooting && !state.on_floor
+      # outputs.labels << [vx(state.x), vy(state.y), "SHOOTING AIR BORN"]
+      path = "sprites/square-green.png"
+      angle = state.tongue_angle - 90
+    elsif state.action == :shooting
+      # outputs.labels << [vx(state.x), vy(state.y), "SHOOTING ON GROUND"]
+      path = "sprites/square-green.png"
+    elsif state.action == :anchored
+      # outputs.labels << [vx(state.x), vy(state.y), "SWINGING"]
+      angle = state.tongue_angle - 90
+      path = "sprites/square-green.png"
+    end
+
+    outputs.sprites << [vx(state.x),
+                        vy(state.y),
+                        vw(state.player_width),
+                        vh(state.player_height),
+                        path,
+                        angle]
+  end
+
+  def render_player_old
+    # Player
+    if state.action == :aiming
+      path = 'sprites\frg\idle\frog_idle.png'
+      if state.dx > 2
+	  #directional right sprite was here but i needa redo it
+        path = 'sprites\frg\anchor\frog-anchor-0.png'
+      #directional left sprite was here but i needa redo it
+	  elsif state.dx < -2
+        path = 'sprites\frg\anchor\frog-anchor-0.png'
+      end
+      outputs.sprites << [vx(state.x),
+                          vy(state.y),
+                          vw(state.player_width),
+                          vh(state.player_height),
+                          path,
+                          (state.tongue_angle - 90)]
+    elsif state.action == :anchored || state.action == :shooting
+      outputs.sprites << [vx(state.x),
+                          vy(state.y),
+                          vw(state.player_width),
+                          vw(state.player_height),
+                          'sprites/animations_povfrog/frog_bwah_up.png',
+                          (state.tongue_angle - 90)]
+    end
+  end
+end
+
+
+$game = CleptoFrog.new
+
+def tick args
+  if args.state.scene == :game
+    tick_instructions args, "SPACE to SHOOT and RELEASE tongue. LEFT, RIGHT to SWING and BUILD momentum. MINIMAP in bottom right corner.", 360
+  end
+  $game.args = args
+  $game.tick
+end
+
+def tick_instructions args, text, y = 715
+  return if args.state.key_event_occurred
+  if args.inputs.keyboard.directional_vector || args.inputs.keyboard.key_down.space
+    args.state.key_event_occurred = true
+  end
+
+  args.outputs.debug << [0, y - 50, 1280, 60].solid
+  args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
+  args.outputs.debug << [640, y - 25, "(SPACE to dismiss instructions)" , -2, 1, 255, 255, 255].label
+end
+
+</pre>
+<h1 id='--99_genre_platformer/clepto_frog/app/map.rb'>99_genre_platformer/clepto_frog/app/map.rb</h1>
+<pre>$collisions = [
+  [326, 463, 64, 64],
+  [274, 462, 64, 64],
+  [326, 413, 64, 64],
+  [275, 412, 64, 64],
+  [124, 651, 64, 64],
+  [72, 651, 64, 64],
+  [124, 600, 64, 64],
+  [69, 599, 64, 64],
+  [501, 997, 64, 64],
+  [476, 995, 64, 64],
+  [3224, 2057, 64, 64],
+  [3224, 1994, 64, 64],
+  [3225, 1932, 64, 64],
+  [3225, 1870, 64, 64],
+  [3226, 1806, 64, 64],
+  [3224, 1744, 64, 64],
+  [3225, 1689, 64, 64],
+  [3226, 1660, 64, 64],
+  [3161, 1658, 64, 64],
+  [3097, 1660, 64, 64],
+  [3033, 1658, 64, 64],
+  [2969, 1658, 64, 64],
+  [2904, 1658, 64, 64],
+  [2839, 1657, 64, 64],
+  [2773, 1657, 64, 64],
+  [2709, 1658, 64, 64],
+  [2643, 1657, 64, 64],
+  [2577, 1657, 64, 64],
+  [2509, 1658, 64, 64],
+  [2440, 1658, 64, 64],
+  [2371, 1658, 64, 64],
+  [2301, 1659, 64, 64],
+  [2230, 1659, 64, 64],
+  [2159, 1659, 64, 64],
+  [2092, 1660, 64, 64],
+  [2025, 1661, 64, 64],
+  [1958, 1660, 64, 64],
+  [1888, 1659, 64, 64],
+  [1817, 1657, 64, 64],
+  [1745, 1656, 64, 64],
+  [1673, 1658, 64, 64],
+  [1605, 1660, 64, 64],
+  [1536, 1658, 64, 64],
+  [1465, 1660, 64, 64],
+  [1386, 1960, 64, 64],
+  [1384, 1908, 64, 64],
+  [1387, 1862, 64, 64],
+  [1326, 1863, 64, 64],
+  [1302, 1862, 64, 64],
+  [1119, 1906, 64, 64],
+  [1057, 1905, 64, 64],
+  [994, 1905, 64, 64],
+  [937, 1904, 64, 64],
+  [896, 1904, 64, 64],
+  [1001, 1845, 64, 64],
+  [1003, 1780, 64, 64],
+  [1003, 1718, 64, 64],
+  [692, 1958, 64, 64],
+  [691, 1900, 64, 64],
+  [774, 1861, 64, 64],
+  [712, 1861, 64, 64],
+  [691, 1863, 64, 64],
+  [325, 2133, 64, 64],
+  [275, 2134, 64, 64],
+  [326, 2082, 64, 64],
+  [275, 2082, 64, 64],
+  [124, 2321, 64, 64],
+  [71, 2320, 64, 64],
+  [123, 2267, 64, 64],
+  [71, 2268, 64, 64],
+  [2354, 1859, 64, 64],
+  [2292, 1859, 64, 64],
+  [2231, 1857, 64, 64],
+  [2198, 1858, 64, 64],
+  [2353, 1802, 64, 64],
+  [2296, 1798, 64, 64],
+  [2233, 1797, 64, 64],
+  [2200, 1797, 64, 64],
+  [2352, 1742, 64, 64],
+  [2288, 1741, 64, 64],
+  [2230, 1743, 64, 64],
+  [2196, 1743, 64, 64],
+  [1736, 460, 64, 64],
+  [1735, 400, 64, 64],
+  [1736, 339, 64, 64],
+  [1736, 275, 64, 64],
+  [1738, 210, 64, 64],
+  [1735, 145, 64, 64],
+  [1735, 87, 64, 64],
+  [1736, 51, 64, 64],
+  [539, 289, 64, 64],
+  [541, 228, 64, 64],
+  [626, 191, 64, 64],
+  [572, 192, 64, 64],
+  [540, 193, 64, 64],
+  [965, 233, 64, 64],
+  [904, 234, 64, 64],
+  [840, 234, 64, 64],
+  [779, 234, 64, 64],
+  [745, 236, 64, 64],
+  [851, 169, 64, 64],
+  [849, 108, 64, 64],
+  [852, 50, 64, 64],
+  [1237, 289, 64, 64],
+  [1236, 228, 64, 64],
+  [1238, 197, 64, 64],
+  [1181, 192, 64, 64],
+  [1152, 192, 64, 64],
+  [1443, 605, 64, 64],
+  [1419, 606, 64, 64],
+  [1069, 925, 64, 64],
+  [1068, 902, 64, 64],
+  [1024, 927, 64, 64],
+  [1017, 897, 64, 64],
+  [963, 926, 64, 64],
+  [958, 898, 64, 64],
+  [911, 928, 64, 64],
+  [911, 896, 64, 64],
+  [2132, 803, 64, 64],
+  [2081, 803, 64, 64],
+  [2131, 752, 64, 64],
+  [2077, 751, 64, 64],
+  [2615, 649, 64, 64],
+  [2564, 651, 64, 64],
+  [2533, 650, 64, 64],
+  [2027, 156, 64, 64],
+  [1968, 155, 64, 64],
+  [1907, 153, 64, 64],
+  [1873, 155, 64, 64],
+  [2025, 95, 64, 64],
+  [1953, 98, 64, 64],
+  [1894, 100, 64, 64],
+  [1870, 100, 64, 64],
+  [2029, 45, 64, 64],
+  [1971, 48, 64, 64],
+  [1915, 47, 64, 64],
+  [1873, 47, 64, 64],
+  [3956, 288, 64, 64],
+  [3954, 234, 64, 64],
+  [4042, 190, 64, 64],
+  [3990, 190, 64, 64],
+  [3958, 195, 64, 64],
+  [3422, 709, 64, 64],
+  [3425, 686, 64, 64],
+  [3368, 709, 64, 64],
+  [3364, 683, 64, 64],
+  [3312, 711, 64, 64],
+  [3307, 684, 64, 64],
+  [3266, 712, 64, 64],
+  [3269, 681, 64, 64],
+  [4384, 236, 64, 64],
+  [4320, 234, 64, 64],
+  [4257, 235, 64, 64],
+  [4192, 234, 64, 64],
+  [4162, 234, 64, 64],
+  [4269, 171, 64, 64],
+  [4267, 111, 64, 64],
+  [4266, 52, 64, 64],
+  [4580, 458, 64, 64],
+  [4582, 396, 64, 64],
+  [4582, 335, 64, 64],
+  [4581, 275, 64, 64],
+  [4581, 215, 64, 64],
+  [4581, 152, 64, 64],
+  [4582, 89, 64, 64],
+  [4583, 51, 64, 64],
+  [4810, 289, 64, 64],
+  [4810, 227, 64, 64],
+  [4895, 189, 64, 64],
+  [4844, 191, 64, 64],
+  [4809, 191, 64, 64],
+  [5235, 233, 64, 64],
+  [5176, 232, 64, 64],
+  [5118, 230, 64, 64],
+  [5060, 232, 64, 64],
+  [5015, 237, 64, 64],
+  [5123, 171, 64, 64],
+  [5123, 114, 64, 64],
+  [5121, 51, 64, 64],
+  [5523, 461, 64, 64],
+  [5123, 42, 64, 64],
+  [5525, 401, 64, 64],
+  [5525, 340, 64, 64],
+  [5526, 273, 64, 64],
+  [5527, 211, 64, 64],
+  [5525, 150, 64, 64],
+  [5527, 84, 64, 64],
+  [5524, 44, 64, 64],
+  [5861, 288, 64, 64],
+  [5861, 229, 64, 64],
+  [5945, 193, 64, 64],
+  [5904, 193, 64, 64],
+  [5856, 194, 64, 64],
+  [6542, 234, 64, 64],
+  [6478, 235, 64, 64],
+  [6413, 238, 64, 64],
+  [6348, 235, 64, 64],
+  [6285, 236, 64, 64],
+  [6222, 235, 64, 64],
+  [6160, 235, 64, 64],
+  [6097, 236, 64, 64],
+  [6069, 237, 64, 64],
+  [6321, 174, 64, 64],
+  [6318, 111, 64, 64],
+  [6320, 49, 64, 64],
+  [6753, 291, 64, 64],
+  [6752, 227, 64, 64],
+  [6753, 192, 64, 64],
+  [6692, 191, 64, 64],
+  [6668, 193, 64, 64],
+  [6336, 604, 64, 64],
+  [6309, 603, 64, 64],
+  [7264, 461, 64, 64],
+  [7264, 395, 64, 64],
+  [7264, 333, 64, 64],
+  [7264, 270, 64, 64],
+  [7265, 207, 64, 64],
+  [7266, 138, 64, 64],
+  [7264, 78, 64, 64],
+  [7266, 48, 64, 64],
+  [7582, 149, 64, 64],
+  [7524, 147, 64, 64],
+  [7461, 146, 64, 64],
+  [7425, 148, 64, 64],
+  [7580, 86, 64, 64],
+  [7582, 41, 64, 64],
+  [7519, 41, 64, 64],
+  [7460, 40, 64, 64],
+  [7427, 96, 64, 64],
+  [7427, 41, 64, 64],
+  [8060, 288, 64, 64],
+  [8059, 226, 64, 64],
+  [8145, 194, 64, 64],
+  [8081, 194, 64, 64],
+  [8058, 195, 64, 64],
+  [8485, 234, 64, 64],
+  [8422, 235, 64, 64],
+  [8360, 235, 64, 64],
+  [8296, 235, 64, 64],
+  [8266, 237, 64, 64],
+  [8371, 173, 64, 64],
+  [8370, 117, 64, 64],
+  [8372, 59, 64, 64],
+  [8372, 51, 64, 64],
+  [9147, 192, 64, 64],
+  [9063, 287, 64, 64],
+  [9064, 225, 64, 64],
+  [9085, 193, 64, 64],
+  [9063, 194, 64, 64],
+  [9492, 234, 64, 64],
+  [9428, 234, 64, 64],
+  [9365, 235, 64, 64],
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+  [2332, 379, 64, 64],
+  [2315, 379, 64, 64],
+  [2334, 316, 64, 64],
+  [2315, 317, 64, 64],
+  [2332, 254, 64, 64],
+  [2314, 254, 64, 64],
+  [2335, 192, 64, 64],
+  [2311, 192, 64, 64],
+  [2846, 142, 64, 64],
+  [2784, 140, 64, 64],
+  [2846, 79, 64, 64],
+  [2847, 41, 64, 64],
+  [2783, 80, 64, 64],
+  [2790, 39, 64, 64],
+  [2727, 41, 64, 64],
+  [2665, 43, 64, 64],
+  [2605, 43, 64, 64],
+  [2543, 44, 64, 64],
+  [2480, 45, 64, 64],
+  [2419, 45, 64, 64],
+  [2357, 44, 64, 64],
+  [2313, 129, 64, 64],
+  [2313, 70, 64, 64],
+  [2314, 40, 64, 64],
+  [2517, 2385, 64, 64],
+  [2452, 2385, 64, 64],
+  [2390, 2386, 64, 64],
+  [2328, 2386, 64, 64],
+  [2264, 2386, 64, 64],
+  [2200, 2386, 64, 64],
+  [2137, 2387, 64, 64],
+  [2071, 2385, 64, 64],
+  [2016, 2389, 64, 64],
+  [2517, 2341, 64, 64],
+  [2518, 2316, 64, 64],
+  [2456, 2316, 64, 64],
+  [2393, 2316, 64, 64],
+  [2328, 2317, 64, 64],
+  [2264, 2316, 64, 64],
+  [2207, 2318, 64, 64],
+  [2144, 2317, 64, 64],
+  [2081, 2316, 64, 64],
+  [2015, 2342, 64, 64],
+  [2016, 2315, 64, 64],
+  [869, 3709, 64, 64],
+  [819, 3710, 64, 64],
+  [869, 3658, 64, 64],
+  [820, 3658, 64, 64],
+  [0, 0, 64, 64],
+  [0, 1670, 64, 64],
+  [6691, 1653, 64, 64],
+  [1521, 3792, 64, 64],
+  [0, 5137, 64, 64],
+  [3898, 2400, 64, 64],
+  [3835, 2400, 64, 64],
+  [3771, 2400, 64, 64],
+  [3708, 2401, 64, 64],
+  [3646, 2401, 64, 64],
+  [3587, 2401, 64, 64],
+  [3530, 2401, 64, 64],
+  [3897, 2340, 64, 64],
+  [3897, 2295, 64, 64],
+  [3834, 2296, 64, 64],
+  [3773, 2295, 64, 64],
+  [3710, 2296, 64, 64],
+  [3656, 2295, 64, 64],
+  [3593, 2294, 64, 64],
+  [3527, 2339, 64, 64],
+  [3531, 2293, 64, 64],
+  [4152, 2903, 64, 64],
+  [4155, 2858, 64, 64],
+  [3942, 1306, 64, 64],
+  [3942, 1279, 64, 64],
+  [3879, 1306, 64, 64],
+  [3881, 1278, 64, 64],
+  [3819, 1305, 64, 64],
+  [3819, 1277, 64, 64],
+  [3756, 1306, 64, 64],
+  [3756, 1277, 64, 64],
+  [3694, 1306, 64, 64],
+  [3695, 1277, 64, 64],
+  [3631, 1306, 64, 64],
+  [3632, 1278, 64, 64],
+  [3565, 1306, 64, 64],
+  [3567, 1279, 64, 64],
+  [4432, 1165, 64, 64],
+  [4408, 1163, 64, 64],
+  [5123, 1003, 64, 64],
+  [5065, 1002, 64, 64],
+  [5042, 1002, 64, 64],
+  [6020, 1780, 64, 64],
+  [6020, 1756, 64, 64],
+  [5959, 1780, 64, 64],
+  [5959, 1752, 64, 64],
+  [5897, 1779, 64, 64],
+  [5899, 1752, 64, 64],
+  [5836, 1779, 64, 64],
+  [5836, 1751, 64, 64],
+  [5776, 1780, 64, 64],
+  [5776, 1754, 64, 64],
+  [5717, 1780, 64, 64],
+  [5716, 1752, 64, 64],
+  [5658, 1781, 64, 64],
+  [5658, 1755, 64, 64],
+  [5640, 1781, 64, 64],
+  [5640, 1754, 64, 64],
+  [5832, 2095, 64, 64],
+  [5782, 2093, 64, 64],
+  [5832, 2044, 64, 64],
+  [5777, 2043, 64, 64],
+  [4847, 2577, 64, 64],
+  [4795, 2577, 64, 64],
+  [4846, 2526, 64, 64],
+  [4794, 2526, 64, 64],
+  [8390, 923, 64, 64],
+  [8363, 922, 64, 64],
+  [7585, 1084, 64, 64],
+  [7582, 1058, 64, 64],
+  [7525, 1084, 64, 64],
+  [7524, 1056, 64, 64],
+  [7478, 1085, 64, 64],
+  [7476, 1055, 64, 64],
+  [7421, 1086, 64, 64],
+  [7421, 1052, 64, 64],
+  [7362, 1085, 64, 64],
+  [7361, 1053, 64, 64],
+  [7307, 1087, 64, 64],
+  [7307, 1054, 64, 64],
+  [7258, 1086, 64, 64],
+  [7255, 1058, 64, 64],
+  [7203, 1083, 64, 64],
+  [7203, 1055, 64, 64],
+  [7161, 1085, 64, 64],
+  [7158, 1057, 64, 64],
+  [7100, 1083, 64, 64],
+  [7099, 1058, 64, 64],
+  [7038, 1082, 64, 64],
+  [7038, 1058, 64, 64],
+  [6982, 1083, 64, 64],
+  [6984, 1057, 64, 64],
+  [0, 0, 64, 64],
+  [0, 1670, 64, 64],
+  [6691, 1653, 64, 64],
+  [1521, 3792, 64, 64],
+  [0, 5137, 64, 64],
+  [0, 0, 64, 64],
+  [0, 1670, 64, 64],
+  [6691, 1653, 64, 64],
+  [1521, 3792, 64, 64],
+  [0, 5137, 64, 64],
+  [0, 0, 64, 64],
+  [0, 1670, 64, 64],
+  [6691, 1653, 64, 64],
+  [1521, 3792, 64, 64],
+  [0, 5137, 64, 64],
+  [8346, 424, 64, 64],
+  [8407, 376, 64, 64],
+  [8375, 386, 64, 64],
+  [8407, 347, 64, 64],
+  [8388, 343, 64, 64],
+  [8320, 423, 64, 64],
+  [8319, 363, 64, 64],
+  [8368, 303, 64, 64],
+  [8359, 303, 64, 64],
+  [8318, 330, 64, 64],
+  [9369, 425, 64, 64],
+  [9340, 425, 64, 64],
+  [9431, 376, 64, 64],
+  [9414, 382, 64, 64],
+  [9387, 391, 64, 64],
+  [9431, 349, 64, 64],
+  [9412, 344, 64, 64],
+  [9392, 305, 64, 64],
+  [9339, 365, 64, 64],
+  [9341, 333, 64, 64],
+  [9384, 301, 64, 64],
+  [7673, 1896, 64, 64],
+  [7642, 1834, 64, 64],
+  [7646, 1901, 64, 64],
+  [4500, 4054, 64, 64],
+  [4476, 4055, 64, 64],
+  [4459, 3997, 64, 64],
+  [76, 5215, 64, 64],
+  [39, 5217, 64, 64],
+]
+
+$mugs = [
+  [85, 87, 39, 43, "sprites/square-orange.png"],
+  [958, 1967, 39, 43, "sprites/square-orange.png"],
+  [2537, 1734, 39, 43, "sprites/square-orange.png"],
+  [3755, 2464, 39, 43, "sprites/square-orange.png"],
+  [1548, 3273, 39, 43, "sprites/square-orange.png"],
+  [2050, 220, 39, 43, "sprites/square-orange.png"],
+  [854, 297, 39, 43, "sprites/square-orange.png"],
+  [343, 526, 39, 43, "sprites/square-orange.png"],
+  [3454, 772, 39, 43, "sprites/square-orange.png"],
+  [5041, 298, 39, 43, "sprites/square-orange.png"],
+  [6089, 300, 39, 43, "sprites/square-orange.png"],
+  [6518, 295, 39, 43, "sprites/square-orange.png"],
+  [7661, 47, 39, 43, "sprites/square-orange.png"],
+  [9392, 1125, 39, 43, "sprites/square-orange.png"],
+  [7298, 1152, 39, 43, "sprites/square-orange.png"],
+  [5816, 1843, 39, 43, "sprites/square-orange.png"],
+  [876, 3772, 39, 43, "sprites/square-orange.png"],
+  [1029, 4667, 39, 43, "sprites/square-orange.png"],
+  [823, 5324, 39, 43, "sprites/square-orange.png"],
+  [3251, 5220, 39, 43, "sprites/square-orange.png"],
+  [4747, 5282, 39, 43, "sprites/square-orange.png"],
+  [9325, 5178, 39, 43, "sprites/square-orange.png"],
+  [9635, 4298, 39, 43, "sprites/square-orange.png"],
+  [7837, 4127, 39, 43, "sprites/square-orange.png"],
+  [8651, 1971, 39, 43, "sprites/square-orange.png"],
+  [6892, 2031, 39, 43, "sprites/square-orange.png"],
+  [4626, 3882, 39, 43, "sprites/square-orange.png"],
+  [4024, 4554, 39, 43, "sprites/square-orange.png"],
+  [3925, 3337, 39, 43, "sprites/square-orange.png"],
+  [5064, 1064, 39, 43, "sprites/square-orange.png"]
+]
+
+</pre>
+<h1 id='--99_genre_platformer/gorillas_basic/app/main.rb'>99_genre_platformer/gorillas_basic/app/main.rb</h1>
+<pre>class YouSoBasicGorillas
+  attr_accessor :outputs, :grid, :state, :inputs
+
+  def tick
+    defaults
+    render
+    calc
+    process_inputs
+  end
+
+  def defaults
+    outputs.background_color = [33, 32, 87]
+    state.building_spacing       = 1
+    state.building_room_spacing  = 15
+    state.building_room_width    = 10
+    state.building_room_height   = 15
+    state.building_heights       = [4, 4, 6, 8, 15, 20, 18]
+    state.building_room_sizes    = [5, 4, 6, 7]
+    state.gravity                = 0.25
+    state.first_strike         ||= :player_1
+    state.buildings            ||= []
+    state.holes                ||= []
+    state.player_1_score       ||= 0
+    state.player_2_score       ||= 0
+    state.wind                 ||= 0
+  end
+
+  def render
+    render_stage
+    render_value_insertion
+    render_gorillas
+    render_holes
+    render_banana
+    render_game_over
+    render_score
+    render_wind
+  end
+
+  def render_score
+    outputs.primitives << [0, 0, 1280, 31, fancy_white].solid
+    outputs.primitives << [1, 1, 1279, 29].solid
+    outputs.labels << [  10, 25, "Score: #{state.player_1_score}", 0, 0, fancy_white]
+    outputs.labels << [1270, 25, "Score: #{state.player_2_score}", 0, 2, fancy_white]
+  end
+
+  def render_wind
+    outputs.primitives << [640, 12, state.wind * 500 + state.wind * 10 * rand, 4, 35, 136, 162].solid
+    outputs.lines     <<  [640, 30, 640, 0, fancy_white]
+  end
+
+  def render_game_over
+    return unless state.over
+    outputs.primitives << [grid.rect, 0, 0, 0, 200].solid
+    outputs.primitives << [640, 370, "Game Over!!", 5, 1, fancy_white].label
+    if state.winner == :player_1
+      outputs.primitives << [640, 340, "Player 1 Wins!!", 5, 1, fancy_white].label
+    else
+      outputs.primitives << [640, 340, "Player 2 Wins!!", 5, 1, fancy_white].label
+    end
+  end
+
+  def render_stage
+    return unless state.stage_generated
+    return if state.stage_rendered
+
+    outputs.static_solids << [grid.rect, 33, 32, 87]
+    outputs.static_solids << state.buildings.map(&:solids)
+    state.stage_rendered = true
+  end
+
+  def render_gorilla gorilla, id
+    return unless gorilla
+    if state.banana && state.banana.owner == gorilla
+      animation_index  = state.banana.created_at.frame_index(3, 5, false)
+    end
+    if !animation_index
+      outputs.sprites << [gorilla.solid, "sprites/#{id}-idle.png"]
+    else
+      outputs.sprites << [gorilla.solid, "sprites/#{id}-#{animation_index}.png"]
+    end
+  end
+
+  def render_gorillas
+    render_gorilla state.player_1, :left
+    render_gorilla state.player_2, :right
+  end
+
+  def render_value_insertion
+    return if state.banana
+    return if state.over
+
+    if    state.current_turn == :player_1_angle
+      outputs.labels << [  10, 710, "Angle:    #{state.player_1_angle}_",    fancy_white]
+    elsif state.current_turn == :player_1_velocity
+      outputs.labels << [  10, 710, "Angle:    #{state.player_1_angle}",     fancy_white]
+      outputs.labels << [  10, 690, "Velocity: #{state.player_1_velocity}_", fancy_white]
+    elsif state.current_turn == :player_2_angle
+      outputs.labels << [1120, 710, "Angle:    #{state.player_2_angle}_",    fancy_white]
+    elsif state.current_turn == :player_2_velocity
+      outputs.labels << [1120, 710, "Angle:    #{state.player_2_angle}",     fancy_white]
+      outputs.labels << [1120, 690, "Velocity: #{state.player_2_velocity}_", fancy_white]
+    end
+  end
+
+  def render_banana
+    return unless state.banana
+    rotation = state.tick_count.%(360) * 20
+    rotation *= -1 if state.banana.dx > 0
+    outputs.sprites << [state.banana.x, state.banana.y, 15, 15, 'sprites/banana.png', rotation]
+  end
+
+  def render_holes
+    outputs.sprites << state.holes.map do |s|
+      animation_index = s.created_at.frame_index(7, 3, false)
+      if animation_index
+        [s.sprite, [s.sprite.rect, "sprites/explosion#{animation_index}.png" ]]
+      else
+        s.sprite
+      end
+    end
+  end
+
+  def calc
+    calc_generate_stage
+    calc_current_turn
+    calc_banana
+  end
+
+  def calc_current_turn
+    return if state.current_turn
+
+    state.current_turn = :player_1_angle
+    state.current_turn = :player_2_angle if state.first_strike == :player_2
+  end
+
+  def calc_generate_stage
+    return if state.stage_generated
+
+    state.buildings << building_prefab(state.building_spacing + -20, *random_building_size)
+    8.numbers.inject(state.buildings) do |buildings, i|
+      buildings <<
+        building_prefab(state.building_spacing +
+                        state.buildings.last.right,
+                        *random_building_size)
+    end
+
+    building_two = state.buildings[1]
+    state.player_1 = new_player(building_two.x + building_two.w.fdiv(2),
+                               building_two.h)
+
+    building_nine = state.buildings[-3]
+    state.player_2 = new_player(building_nine.x + building_nine.w.fdiv(2),
+                               building_nine.h)
+    state.stage_generated = true
+    state.wind = 1.randomize(:ratio, :sign)
+  end
+
+  def new_player x, y
+    state.new_entity(:gorilla) do |p|
+      p.x = x - 25
+      p.y = y
+      p.solid = [p.x, p.y, 50, 50]
+    end
+  end
+
+  def calc_banana
+    return unless state.banana
+
+    state.banana.x  += state.banana.dx
+    state.banana.dx += state.wind.fdiv(50)
+    state.banana.y  += state.banana.dy
+    state.banana.dy -= state.gravity
+    banana_collision = [state.banana.x, state.banana.y, 10, 10]
+
+    if state.player_1 && banana_collision.intersect_rect?(state.player_1.solid)
+      state.over = true
+      if state.banana.owner == state.player_2
+        state.winner = :player_2
+      else
+        state.winner = :player_1
+      end
+
+      state.player_2_score += 1
+    elsif state.player_2 && banana_collision.intersect_rect?(state.player_2.solid)
+      state.over = true
+      if state.banana.owner == state.player_2
+        state.winner = :player_1
+      else
+        state.winner = :player_2
+      end
+      state.player_1_score += 1
+    end
+
+    if state.over
+      place_hole
+      return
+    end
+
+    return if state.holes.any? do |h|
+      h.sprite.scale_rect(0.8, 0.5, 0.5).intersect_rect? [state.banana.x, state.banana.y, 10, 10]
+    end
+
+    return unless state.banana.y < 0 || state.buildings.any? do |b|
+      b.rect.intersect_rect? [state.banana.x, state.banana.y, 1, 1]
+    end
+
+    place_hole
+  end
+
+  def place_hole
+    return unless state.banana
+
+    state.holes << state.new_entity(:banana) do |b|
+      b.sprite = [state.banana.x - 20, state.banana.y - 20, 40, 40, 'sprites/hole.png']
+    end
+
+    state.banana = nil
+  end
+
+  def process_inputs_main
+    return if state.banana
+    return if state.over
+
+    if inputs.keyboard.key_down.enter
+      input_execute_turn
+    elsif inputs.keyboard.key_down.backspace
+      state.as_hash[state.current_turn] ||= ""
+      state.as_hash[state.current_turn]   = state.as_hash[state.current_turn][0..-2]
+    elsif inputs.keyboard.key_down.char
+      state.as_hash[state.current_turn] ||= ""
+      state.as_hash[state.current_turn]  += inputs.keyboard.key_down.char
+    end
+  end
+
+  def process_inputs_game_over
+    return unless state.over
+    return unless inputs.keyboard.key_down.truthy_keys.any?
+    state.over = false
+    outputs.static_solids.clear
+    state.buildings.clear
+    state.holes.clear
+    state.stage_generated = false
+    state.stage_rendered = false
+    if state.first_strike == :player_1
+      state.first_strike = :player_2
+    else
+      state.first_strike = :player_1
+    end
+  end
+
+  def process_inputs
+    process_inputs_main
+    process_inputs_game_over
+  end
+
+  def input_execute_turn
+    return if state.banana
+
+    if state.current_turn == :player_1_angle && parse_or_clear!(:player_1_angle)
+      state.current_turn = :player_1_velocity
+    elsif state.current_turn == :player_1_velocity && parse_or_clear!(:player_1_velocity)
+      state.current_turn = :player_2_angle
+      state.banana =
+        new_banana(state.player_1,
+                   state.player_1.x + 25,
+                   state.player_1.y + 60,
+                   state.player_1_angle,
+                   state.player_1_velocity)
+    elsif state.current_turn == :player_2_angle && parse_or_clear!(:player_2_angle)
+      state.current_turn = :player_2_velocity
+    elsif state.current_turn == :player_2_velocity && parse_or_clear!(:player_2_velocity)
+      state.current_turn = :player_1_angle
+      state.banana =
+        new_banana(state.player_2,
+                   state.player_2.x + 25,
+                   state.player_2.y + 60,
+                   180 - state.player_2_angle,
+                   state.player_2_velocity)
+    end
+
+    if state.banana
+      state.player_1_angle = nil
+      state.player_1_velocity = nil
+      state.player_2_angle = nil
+      state.player_2_velocity = nil
+    end
+  end
+
+  def random_building_size
+    [state.building_heights.sample, state.building_room_sizes.sample]
+  end
+
+  def int? v
+    v.to_i.to_s == v.to_s
+  end
+
+  def random_building_color
+    [[ 99,   0, 107],
+     [ 35,  64, 124],
+     [ 35, 136, 162],
+     ].sample
+  end
+
+  def random_window_color
+    [[ 88,  62, 104],
+     [253, 224, 187]].sample
+  end
+
+  def windows_for_building starting_x, floors, rooms
+    floors.-(1).combinations(rooms - 1).map do |floor, room|
+      [starting_x +
+       state.building_room_width.*(room) +
+       state.building_room_spacing.*(room + 1),
+       state.building_room_height.*(floor) +
+       state.building_room_spacing.*(floor + 1),
+       state.building_room_width,
+       state.building_room_height,
+       random_window_color]
+    end
+  end
+
+  def building_prefab starting_x, floors, rooms
+    state.new_entity(:building) do |b|
+      b.x      = starting_x
+      b.y      = 0
+      b.w      = state.building_room_width.*(rooms) +
+                 state.building_room_spacing.*(rooms + 1)
+      b.h      = state.building_room_height.*(floors) +
+                 state.building_room_spacing.*(floors + 1)
+      b.right  = b.x + b.w
+      b.rect   = [b.x, b.y, b.w, b.h]
+      b.solids = [[b.x - 1, b.y, b.w + 2, b.h + 1, fancy_white],
+                  [b.x, b.y, b.w, b.h, random_building_color],
+                  windows_for_building(b.x, floors, rooms)]
+    end
+  end
+
+  def parse_or_clear! game_prop
+    if int? state.as_hash[game_prop]
+      state.as_hash[game_prop] = state.as_hash[game_prop].to_i
+      return true
+    end
+
+    state.as_hash[game_prop] = nil
+    return false
+  end
+
+  def new_banana owner, x, y, angle, velocity
+    state.new_entity(:banana) do |b|
+      b.owner     = owner
+      b.x         = x
+      b.y         = y
+      b.angle     = angle % 360
+      b.velocity  = velocity / 5
+      b.dx        = b.angle.vector_x(b.velocity)
+      b.dy        = b.angle.vector_y(b.velocity)
+    end
+  end
+
+  def fancy_white
+    [253, 252, 253]
+  end
+end
+
+$you_so_basic_gorillas = YouSoBasicGorillas.new
+
+def tick args
+  $you_so_basic_gorillas.outputs = args.outputs
+  $you_so_basic_gorillas.grid    = args.grid
+  $you_so_basic_gorillas.state    = args.state
+  $you_so_basic_gorillas.inputs  = args.inputs
+  $you_so_basic_gorillas.tick
+end
+
+</pre>
+<h1 id='--99_genre_platformer/gorillas_basic/app/repl.rb'>99_genre_platformer/gorillas_basic/app/repl.rb</h1>
+<pre>begin
+  if $gtk.args.state.current_turn == :player_1_angle
+    $gtk.args.state.player_1_angle = "#{60 + 10.randomize(:ratio).to_i}"
+    $you_so_basic_gorillas.input_execute_turn
+    $gtk.args.state.player_1_velocity = "#{30 + 20.randomize(:ratio).to_i}"
+    $you_so_basic_gorillas.input_execute_turn
+  elsif $gtk.args.state.current_turn == :player_2_angle
+    $gtk.args.state.player_2_angle = "#{60 + 10.randomize(:ratio).to_i}"
+    $you_so_basic_gorillas.input_execute_turn
+    $gtk.args.state.player_2_velocity = "#{30 + 20.randomize(:ratio).to_i}"
+    $you_so_basic_gorillas.input_execute_turn
+  else
+    $you_so_basic_gorillas.input_execute_turn
+  end
+rescue Exception => e
+  puts e
+end
+
+</pre>
+<h1 id='--99_genre_platformer/gorillas_basic/app/tests.rb'>99_genre_platformer/gorillas_basic/app/tests.rb</h1>
+<pre>$gtk.reset 100
+$gtk.supress_framerate_warning = true
+$gtk.require 'app/tests/building_generation_tests.rb'
+$gtk.tests.start
+
+</pre>
+<h1 id='--99_genre_platformer/gorillas_basic/app/tests/building_generation_tests.rb'>99_genre_platformer/gorillas_basic/app/tests/building_generation_tests.rb</h1>
+<pre>def test_solids args, assert
+  game = YouSoBasicGorillas.new
+  game.outputs = args.outputs
+  game.grid = args.grid
+  game.state = args.state
+  game.inputs = args.inputs
+  game.tick
+  assert.true! args.state.stage_generated, "stage wasn't generated but it should have been"
+  game.tick
+  assert.true! args.outputs.static_solids.length > 0, "stage wasn't rendered"
+  number_of_building_components = (args.state.buildings.map { |b| 2 + b.solids[2].length }.inject do |sum, v| (sum || 0) + v end)
+  the_only_background = 1
+  static_solids = args.outputs.static_solids.length
+  assert.true! static_solids == the_only_background.+(number_of_building_components), "not all parts of the buildings and background were rendered"
+end
+
+</pre>
+<h1 id='--99_genre_platformer/the_little_probe/app/main.rb'>99_genre_platformer/the_little_probe/app/main.rb</h1>
+<pre>class FallingCircle
+  attr_gtk
+
+  def tick
+    fiddle
+    defaults
+    render
+    input
+    calc
+  end
+
+  def fiddle
+    state.gravity     = -0.02
+    circle.radius     = 15
+    circle.elasticity = 0.4
+    camera.follow_speed = 0.4 * 0.4
+  end
+
+  def render
+    render_stage_editor
+    render_debug
+    render_game
+  end
+
+  def defaults
+    if state.tick_count == 0
+      outputs.sounds << "sounds/bg.ogg"
+    end
+
+    state.storyline ||= [
+      { text: "<- -> to aim, hold space to charge",                            distance_gate: 0 },
+      { text: "the little probe - by @amirrajan, made with DragonRuby Game Toolkit", distance_gate: 0 },
+      { text: "mission control, this is sasha. landing on europa successful.", distance_gate: 0 },
+      { text: "operation \"find earth 2.0\", initiated at 8-29-2036 14:00.",   distance_gate: 0 },
+      { text: "jupiter's sure is beautiful...",   distance_gate: 4000 },
+      { text: "hmm, it seems there's some kind of anomoly in the sky",   distance_gate: 7000 },
+      { text: "dancing lights, i'll call them whisps.",   distance_gate: 8000 },
+      { text: "#todo... look i ran out of time -_-",   distance_gate: 9000 },
+      { text: "there's never enough time",   distance_gate: 9000 },
+      { text: "the game jam was fun though ^_^",   distance_gate: 10000 },
+    ]
+
+    load_level force: args.state.tick_count == 0
+    state.line_mode            ||= :terrain
+
+    state.sound_index          ||= 1
+    circle.potential_lift      ||= 0
+    circle.angle               ||= 90
+    circle.check_point_at      ||= -1000
+    circle.game_over_at        ||= -1000
+    circle.x                   ||= -485
+    circle.y                   ||= 12226
+    circle.check_point_x       ||= circle.x
+    circle.check_point_y       ||= circle.y
+    circle.dy                  ||= 0
+    circle.dx                  ||= 0
+    circle.previous_dy         ||= 0
+    circle.previous_dx         ||= 0
+    circle.angle               ||= 0
+    circle.after_images        ||= []
+    circle.terrains_to_monitor ||= {}
+    circle.impact_history      ||= []
+
+    camera.x                   ||= 0
+    camera.y                   ||= 0
+    camera.target_x            ||= 0
+    camera.target_y            ||= 0
+    state.snaps                ||= { }
+    state.snap_number            = 10
+
+    args.state.storyline_x ||= -1000
+    args.state.storyline_y ||= -1000
+  end
+
+  def render_game
+    outputs.background_color = [0, 0, 0]
+    outputs.sprites << [-circle.x + 1100,
+                        -circle.y - 100,
+                        2416 * 4,
+                        3574 * 4,
+                        'sprites/jupiter.png']
+    outputs.sprites << [-circle.x,
+                        -circle.y,
+                        2416 * 4,
+                        3574 * 4,
+                        'sprites/level.png']
+    outputs.sprites << state.whisp_queue
+    render_aiming_retical
+    render_circle
+    render_notification
+  end
+
+  def render_notification
+    toast_length = 500
+    if circle.game_over_at.elapsed_time < toast_length
+      label_text = "..."
+    elsif circle.check_point_at.elapsed_time > toast_length
+      args.state.current_storyline = nil
+      return
+    end
+    if circle.check_point_at &&
+       circle.check_point_at.elapsed_time == 1 &&
+       !args.state.current_storyline
+       if args.state.storyline.length > 0 && args.state.distance_traveled > args.state.storyline[0][:distance_gate]
+         args.state.current_storyline = args.state.storyline.shift[:text]
+         args.state.distance_traveled ||= 0
+         args.state.storyline_x = circle.x
+         args.state.storyline_y = circle.y
+       end
+      return unless args.state.current_storyline
+    end
+    label_text = args.state.current_storyline
+    return unless label_text
+    x = circle.x + camera.x
+    y = circle.y + camera.y - 40
+    w = 900
+    h = 30
+    outputs.primitives << [x - w.idiv(2), y - h, w, h, 255, 255, 255, 255].solid
+    outputs.primitives << [x - w.idiv(2), y - h, w, h, 0, 0, 0, 255].border
+    outputs.labels << [x, y - 4, label_text, 1, 1, 0, 0, 0, 255]
+  end
+
+  def render_aiming_retical
+    outputs.sprites << [state.camera.x + circle.x + circle.angle.vector_x(circle.potential_lift * 10) - 5,
+                        state.camera.y + circle.y + circle.angle.vector_y(circle.potential_lift * 10) - 5,
+                        10, 10, 'sprites/circle-orange.png']
+    outputs.sprites << [state.camera.x + circle.x + circle.angle.vector_x(circle.radius * 3) - 5,
+                        state.camera.y + circle.y + circle.angle.vector_y(circle.radius * 3) - 5,
+                        10, 10, 'sprites/circle-orange.png', 0, 128]
+    if rand > 0.9
+      outputs.sprites << [state.camera.x + circle.x + circle.angle.vector_x(circle.radius * 3) - 5,
+                          state.camera.y + circle.y + circle.angle.vector_y(circle.radius * 3) - 5,
+                          10, 10, 'sprites/circle-white.png', 0, 128]
+    end
+  end
+
+  def render_circle
+    outputs.sprites << circle.after_images.map do |ai|
+      ai.merge(x: ai.x + state.camera.x - circle.radius,
+               y: ai.y + state.camera.y - circle.radius,
+               w: circle.radius * 2,
+               h: circle.radius * 2,
+               path: 'sprites/circle-white.png')
+    end
+
+    outputs.sprites << [(circle.x - circle.radius) + state.camera.x,
+                        (circle.y - circle.radius) + state.camera.y,
+                        circle.radius * 2,
+                        circle.radius * 2,
+                        'sprites/probe.png']
+  end
+
+  def render_debug
+    return unless state.debug_mode
+
+    outputs.labels << [10, 30, state.line_mode, 0, 0, 0, 0, 0]
+    outputs.labels << [12, 32, state.line_mode, 0, 0, 255, 255, 255]
+
+    args.outputs.lines << trajectory(circle).line.to_hash.tap do |h|
+      h[:x] += state.camera.x
+      h[:y] += state.camera.y
+      h[:x2] += state.camera.x
+      h[:y2] += state.camera.y
+    end
+
+    outputs.primitives << state.terrain.find_all do |t|
+      circle.x.between?(t.x - 640, t.x2 + 640) || circle.y.between?(t.y - 360, t.y2 + 360)
+    end.map do |t|
+      [
+        t.line.associate(r: 0, g: 255, b: 0) do |h|
+          h.x  += state.camera.x
+          h.y  += state.camera.y
+          h.x2 += state.camera.x
+          h.y2 += state.camera.y
+          if circle.rect.intersect_rect? t[:rect]
+            h[:r] = 255
+            h[:g] = 0
+          end
+          h
+        end,
+        t[:rect].border.associate(r: 255, g: 0, b: 0) do |h|
+          h.x += state.camera.x
+          h.y += state.camera.y
+          h.b = 255 if line_near_rect? circle.rect, t
+          h
+        end
+      ]
+    end
+
+    outputs.primitives << state.lava.find_all do |t|
+      circle.x.between?(t.x - 640, t.x2 + 640) || circle.y.between?(t.y - 360, t.y2 + 360)
+    end.map do |t|
+      [
+        t.line.associate(r: 0, g: 0, b: 255) do |h|
+          h.x  += state.camera.x
+          h.y  += state.camera.y
+          h.x2 += state.camera.x
+          h.y2 += state.camera.y
+          if circle.rect.intersect_rect? t[:rect]
+            h[:r] = 255
+            h[:b] = 0
+          end
+          h
+        end,
+        t[:rect].border.associate(r: 255, g: 0, b: 0) do |h|
+          h.x += state.camera.x
+          h.y += state.camera.y
+          h.b = 255 if line_near_rect? circle.rect, t
+          h
+        end
+      ]
+    end
+
+    if state.god_mode
+      border = circle.rect.merge(x: circle.rect.x + state.camera.x,
+                                 y: circle.rect.y + state.camera.y,
+                                 g: 255)
+    else
+      border = circle.rect.merge(x: circle.rect.x + state.camera.x,
+                                 y: circle.rect.y + state.camera.y,
+                                 b: 255)
+    end
+
+    outputs.borders << border
+
+    overlapping ||= {}
+
+    circle.impact_history.each do |h|
+      label_mod = 300
+      x = (h[:body][:x].-(150).idiv(label_mod)) * label_mod + camera.x
+      y = (h[:body][:y].+(150).idiv(label_mod)) * label_mod + camera.y
+      10.times do
+        if overlapping[x] && overlapping[x][y]
+          y -= 52
+        else
+          break
+        end
+      end
+
+      overlapping[x] ||= {}
+      overlapping[x][y] ||= true
+      outputs.primitives << [x, y - 25, 300, 50, 0, 0, 0, 128].solid
+      outputs.labels << [x + 10, y + 24, "dy: %.2f" % h[:body][:new_dy], -2, 0, 255, 255, 255]
+      outputs.labels << [x + 10, y +  9, "dx: %.2f" % h[:body][:new_dx], -2, 0, 255, 255, 255]
+      outputs.labels << [x + 10, y -  5, " ?: #{h[:body][:new_reason]}", -2, 0, 255, 255, 255]
+
+      outputs.labels << [x + 100, y + 24, "angle: %.2f" % h[:impact][:angle], -2, 0, 255, 255, 255]
+      outputs.labels << [x + 100, y + 9, "m(l): %.2f" % h[:terrain][:slope], -2, 0, 255, 255, 255]
+      outputs.labels << [x + 100, y - 5, "m(c): %.2f" % h[:body][:slope], -2, 0, 255, 255, 255]
+
+      outputs.labels << [x + 200, y + 24, "ray: #{h[:impact][:ray]}", -2, 0, 255, 255, 255]
+      outputs.labels << [x + 200, y +  9, "nxt: #{h[:impact][:ray_next]}", -2, 0, 255, 255, 255]
+      outputs.labels << [x + 200, y -  5, "typ: #{h[:impact][:type]}", -2, 0, 255, 255, 255]
+    end
+
+    if circle.floor
+      outputs.labels << [circle.x + camera.x + 30, circle.y + camera.y + 100, "point: #{circle.floor_point.slice(:x, :y).values}", -2, 0]
+      outputs.labels << [circle.x + camera.x + 31, circle.y + camera.y + 101, "point: #{circle.floor_point.slice(:x, :y).values}", -2, 0, 255, 255, 255]
+      outputs.labels << [circle.x + camera.x + 30, circle.y + camera.y +  85, "circle: #{circle.hash.slice(:x, :y).values}", -2, 0]
+      outputs.labels << [circle.x + camera.x + 31, circle.y + camera.y +  86, "circle: #{circle.hash.slice(:x, :y).values}", -2, 0, 255, 255, 255]
+      outputs.labels << [circle.x + camera.x + 30, circle.y + camera.y +  70, "rel: #{circle.floor_relative_x} #{circle.floor_relative_y}", -2, 0]
+      outputs.labels << [circle.x + camera.x + 31, circle.y + camera.y +  71, "rel: #{circle.floor_relative_x} #{circle.floor_relative_y}", -2, 0, 255, 255, 255]
+    end
+  end
+
+  def render_stage_editor
+    return unless state.god_mode
+    return unless state.point_one
+    args.lines << [state.point_one, inputs.mouse.point, 0, 255, 255]
+  end
+
+  def trajectory body
+    [body.x + body.dx,
+     body.y + body.dy,
+     body.x + body.dx * 1000,
+     body.y + body.dy * 1000,
+     0, 255, 255]
+  end
+
+  def lengthen_line line, num
+    line = normalize_line(line)
+    slope = geometry.line_slope(line, replace_infinity: 10).abs
+    if slope < 2
+      [line.x - num, line.y, line.x2 + num, line.y2].line.to_hash
+    else
+      [line.x, line.y, line.x2, line.y2].line.to_hash
+    end
+  end
+
+  def normalize_line line
+    if line.x > line.x2
+      x  = line.x2
+      y  = line.y2
+      x2 = line.x
+      y2 = line.y
+    else
+      x  = line.x
+      y  = line.y
+      x2 = line.x2
+      y2 = line.y2
+    end
+    [x, y, x2, y2]
+  end
+
+  def rect_for_line line
+    if line.x > line.x2
+      x  = line.x2
+      y  = line.y2
+      x2 = line.x
+      y2 = line.y
+    else
+      x  = line.x
+      y  = line.y
+      x2 = line.x2
+      y2 = line.y2
+    end
+
+    w = x2 - x
+    h = y2 - y
+
+    if h < 0
+      y += h
+      h = h.abs
+    end
+
+    if w < circle.radius
+      x -= circle.radius
+      w = circle.radius * 2
+    end
+
+    if h < circle.radius
+      y -= circle.radius
+      h = circle.radius * 2
+    end
+
+    { x: x, y: y, w: w, h: h }
+  end
+
+  def snap_to_grid x, y, snaps
+    snap_number = 10
+    x = x.to_i
+    y = y.to_i
+
+    x_floor = x.idiv(snap_number) * snap_number
+    x_mod   = x % snap_number
+    x_ceil  = (x.idiv(snap_number) + 1) * snap_number
+
+    y_floor = y.idiv(snap_number) * snap_number
+    y_mod   = y % snap_number
+    y_ceil  = (y.idiv(snap_number) + 1) * snap_number
+
+    if snaps[x_floor]
+      x_result = x_floor
+    elsif snaps[x_ceil]
+      x_result = x_ceil
+    elsif x_mod < snap_number.idiv(2)
+      x_result = x_floor
+    else
+      x_result = x_ceil
+    end
+
+    snaps[x_result] ||= {}
+
+    if snaps[x_result][y_floor]
+      y_result = y_floor
+    elsif snaps[x_result][y_ceil]
+      y_result = y_ceil
+    elsif y_mod < snap_number.idiv(2)
+      y_result = y_floor
+    else
+      y_result = y_ceil
+    end
+
+    snaps[x_result][y_result] = true
+    return [x_result, y_result]
+
+  end
+
+  def snap_line line
+    x, y, x2, y2 = line
+  end
+
+  def string_to_line s
+    x, y, x2, y2 = s.split(',').map(&:to_f)
+
+    if x > x2
+      x2, x = x, x2
+      y2, y = y, y2
+    end
+
+    x, y = snap_to_grid x, y, state.snaps
+    x2, y2 = snap_to_grid x2, y2, state.snaps
+    [x, y, x2, y2].line.to_hash
+  end
+
+  def load_lines file
+    data = gtk.read_file(file) || ""
+    data.each_line
+        .reject { |l| l.strip.length == 0 }
+        .map { |l| string_to_line l }
+        .map { |h| h.merge(rect: rect_for_line(h))  }
+  end
+
+  def load_terrain
+    load_lines 'level.txt'
+  end
+
+  def load_lava
+    load_lines 'level_lava.txt'
+  end
+
+  def load_level force: false
+    if force
+      state.snaps = {}
+      state.terrain = load_terrain
+      state.lava = load_lava
+    else
+      state.terrain ||= load_terrain
+      state.lava ||= load_lava
+    end
+  end
+
+  def save_lines lines, file
+    s = lines.map do |l|
+      "#{l.x1},#{l.y1},#{l.x2},#{l.y2}"
+    end.join("\n")
+    gtk.write_file(file, s)
+  end
+
+  def save_level
+    save_lines(state.terrain, 'level.txt')
+    save_lines(state.lava, 'level_lava.txt')
+    load_level force: true
+  end
+
+  def line_near_rect? rect, terrain
+    geometry.intersect_rect?(rect, terrain[:rect])
+  end
+
+  def point_within_line? point, line
+    return false if !point
+    return false if !line
+    return true
+  end
+
+  def calc_impacts x, dx, y, dy, radius
+    results = { }
+    results[:x] = x
+    results[:y] = y
+    results[:dx] = x
+    results[:dy] = y
+    results[:point] = { x: x, y: y }
+    results[:rect] = { x: x - radius, y: y - radius, w: radius * 2, h: radius * 2 }
+    results[:trajectory] = trajectory(results)
+    results[:impacts] = terrain.find_all { |t| line_near_rect? results[:rect], t }.map do |t|
+      {
+        terrain: t,
+        point: geometry.line_intersect(results[:trajectory], t),
+        type: :terrain
+      }
+    end.reject { |t| !point_within_line? t[:point], t[:terrain] }
+
+    results[:impacts] += lava.find_all { |t| line_near_rect? results[:rect], t }.map do |t|
+      {
+        terrain: t,
+        point: geometry.line_intersect(results[:trajectory], t),
+        type: :lava
+      }
+    end.reject { |t| !point_within_line? t[:point], t[:terrain] }
+
+    results
+  end
+
+  def calc_potential_impacts
+    impact_results = calc_impacts circle.x, circle.dx, circle.y, circle.dy, circle.radius
+    circle.rect = impact_results[:rect]
+    circle.trajectory = impact_results[:trajectory]
+    circle.impacts = impact_results[:impacts]
+  end
+
+  def calc_terrains_to_monitor
+    circle.impact = nil
+    circle.impacts.each do |i|
+      circle.terrains_to_monitor[i[:terrain]] ||= {
+        ray_start: geometry.ray_test(circle, i[:terrain]),
+      }
+
+      circle.terrains_to_monitor[i[:terrain]][:ray_current] = geometry.ray_test(circle, i[:terrain])
+      if circle.terrains_to_monitor[i[:terrain]][:ray_start] != circle.terrains_to_monitor[i[:terrain]][:ray_current]
+        if circle.x.between?(i[:terrain].x, i[:terrain].x2) || circle.y.between?(i[:terrain].y, i[:terrain].y2)
+          circle.impact = i
+          circle.ray_current = circle.terrains_to_monitor[i[:terrain]][:ray_current]
+        end
+      end
+    end
+  end
+
+  def impact_result body, impact
+    infinity_alias = 1000
+    r = {
+      body: {},
+      terrain: {},
+      impact: {}
+    }
+
+    r[:body][:line] = body.trajectory.dup
+    r[:body][:slope] = geometry.line_slope(body.trajectory, replace_infinity: infinity_alias)
+    r[:body][:slope_sign] = r[:body][:slope].sign
+    r[:body][:x] = body.x
+    r[:body][:y] = body.y
+    r[:body][:dy] = body.dy
+    r[:body][:dx] = body.dx
+
+    r[:terrain][:line] = impact[:terrain].dup
+    r[:terrain][:slope] = geometry.line_slope(impact[:terrain], replace_infinity: infinity_alias)
+    r[:terrain][:slope_sign] = r[:terrain][:slope].sign
+
+    r[:impact][:angle] = geometry.angle_between_lines(body.trajectory, impact[:terrain], replace_infinity: infinity_alias)
+    r[:impact][:point] = { x: impact[:point].x, y: impact[:point].y }
+    r[:impact][:same_slope_sign] = r[:body][:slope_sign] == r[:terrain][:slope_sign]
+    r[:impact][:ray] = body.ray_current
+    r[:body][:new_on_floor] = body.on_floor
+    r[:body][:new_floor] = r[:terrain][:line]
+
+    if r[:impact][:angle].abs < 90 && r[:terrain][:slope].abs < 3
+      play_sound
+      r[:body][:new_dy] = r[:body][:dy] * circle.elasticity * -1
+      r[:body][:new_dx] = r[:body][:dx] * circle.elasticity
+      r[:impact][:type] = :horizontal
+      r[:body][:new_reason] = "-"
+    elsif r[:impact][:angle].abs < 90 && r[:terrain][:slope].abs > 3
+      play_sound
+      r[:body][:new_dy] = r[:body][:dy] * 1.1
+      r[:body][:new_dx] = r[:body][:dx] * -circle.elasticity
+      r[:impact][:type] = :vertical
+      r[:body][:new_reason] = "|"
+    else
+      play_sound
+      r[:body][:new_dx] = r[:body][:dx] * -circle.elasticity
+      r[:body][:new_dy] = r[:body][:dy] * -circle.elasticity
+      r[:impact][:type] = :slanted
+      r[:body][:new_reason] = "/"
+    end
+
+    r[:impact][:energy] = r[:body][:new_dx].abs + r[:body][:new_dy].abs
+
+    if r[:impact][:energy] <= 0.3 && r[:terrain][:slope].abs < 4
+      r[:body][:new_dx] = 0
+      r[:body][:new_dy] = 0
+      r[:impact][:energy] = 0
+      r[:body][:new_on_floor] = true
+      r[:body][:new_floor] = r[:terrain][:line]
+      r[:body][:new_reason] = "0"
+    end
+
+    r[:impact][:ray_next] = geometry.ray_test({ x: r[:body][:x] - (r[:body][:dx] * 1.1) + r[:body][:new_dx],
+                                                y: r[:body][:y] - (r[:body][:dy] * 1.1) + r[:body][:new_dy] + state.gravity },
+                                              r[:terrain][:line])
+
+    if r[:impact][:ray_next] == r[:impact][:ray]
+      r[:body][:new_dx] *= -1
+      r[:body][:new_dy] *= -1
+      r[:body][:new_reason] = "clip"
+    end
+
+    r
+  end
+
+  def game_over!
+    circle.x = circle.check_point_x
+    circle.y = circle.check_point_y
+    circle.dx = 0
+    circle.dy = 0
+    circle.game_over_at = state.tick_count
+  end
+
+  def not_game_over!
+    impact_history_entry = impact_result circle, circle.impact
+    circle.impact_history << impact_history_entry
+    circle.x -= circle.dx * 1.1
+    circle.y -= circle.dy * 1.1
+    circle.dx = impact_history_entry[:body][:new_dx]
+    circle.dy = impact_history_entry[:body][:new_dy]
+    circle.on_floor = impact_history_entry[:body][:new_on_floor]
+
+    if circle.on_floor
+      circle.check_point_at = state.tick_count
+      circle.check_point_x = circle.x
+      circle.check_point_y = circle.y
+    end
+
+    circle.previous_floor = circle.floor || {}
+    circle.floor = impact_history_entry[:body][:new_floor] || {}
+    circle.floor_point = impact_history_entry[:impact][:point]
+    if circle.floor.slice(:x, :y, :x2, :y2) != circle.previous_floor.slice(:x, :y, :x2, :y2)
+      new_relative_x = if circle.dx > 0
+                         :right
+                       elsif circle.dx < 0
+                         :left
+                       else
+                         nil
+                       end
+
+      new_relative_y = if circle.dy > 0
+                         :above
+                       elsif circle.dy < 0
+                         :below
+                       else
+                         nil
+                       end
+
+      circle.floor_relative_x = new_relative_x
+      circle.floor_relative_y = new_relative_y
+    end
+
+    circle.impact = nil
+    circle.terrains_to_monitor.clear
+  end
+
+  def calc_physics
+    if args.state.god_mode
+      calc_potential_impacts
+      calc_terrains_to_monitor
+      return
+    end
+
+    if circle.y < -700
+      game_over
+      return
+    end
+
+    return if state.game_over
+    return if circle.on_floor
+    circle.previous_dy = circle.dy
+    circle.previous_dx = circle.dx
+    circle.x  += circle.dx
+    circle.y  += circle.dy
+    args.state.distance_traveled ||= 0
+    args.state.distance_traveled += circle.dx.abs + circle.dy.abs
+    circle.dy += state.gravity
+    calc_potential_impacts
+    calc_terrains_to_monitor
+    return unless circle.impact
+    if circle.impact && circle.impact[:type] == :lava
+      game_over!
+    else
+      not_game_over!
+    end
+  end
+
+  def input_god_mode
+    state.debug_mode = !state.debug_mode if inputs.keyboard.key_down.forward_slash
+
+    # toggle god mode
+    if inputs.keyboard.key_down.g
+      state.god_mode = !state.god_mode
+      state.potential_lift = 0
+      circle.floor = nil
+      circle.floor_point = nil
+      circle.floor_relative_x = nil
+      circle.floor_relative_y = nil
+      circle.impact = nil
+      circle.terrains_to_monitor.clear
+      return
+    end
+
+    return unless state.god_mode
+
+    circle.x = circle.x.to_i
+    circle.y = circle.y.to_i
+
+    # move god circle
+    if inputs.keyboard.left || inputs.keyboard.a
+      circle.x -= 20
+    elsif inputs.keyboard.right || inputs.keyboard.d || inputs.keyboard.f
+      circle.x += 20
+    end
+
+    if inputs.keyboard.up || inputs.keyboard.w
+      circle.y += 20
+    elsif inputs.keyboard.down || inputs.keyboard.s
+      circle.y -= 20
+    end
+
+    # delete terrain
+    if inputs.keyboard.key_down.x
+      calc_terrains_to_monitor
+      state.terrain = state.terrain.reject do |t|
+        t[:rect].intersect_rect? circle.rect
+      end
+
+      state.lava = state.lava.reject do |t|
+        t[:rect].intersect_rect? circle.rect
+      end
+
+      calc_potential_impacts
+      save_level
+    end
+
+    # change terrain type
+    if inputs.keyboard.key_down.l
+      if state.line_mode == :terrain
+        state.line_mode = :lava
+      else
+        state.line_mode = :terrain
+      end
+    end
+
+    if inputs.mouse.click && !state.point_one
+      state.point_one = inputs.mouse.click.point
+    elsif inputs.mouse.click && state.point_one
+      l = [*state.point_one, *inputs.mouse.click.point]
+      l = [l.x  - state.camera.x,
+           l.y  - state.camera.y,
+           l.x2 - state.camera.x,
+           l.y2 - state.camera.y].line.to_hash
+      l[:rect] = rect_for_line l
+      if state.line_mode == :terrain
+        state.terrain << l
+      else
+        state.lava << l
+      end
+      save_level
+      next_x = inputs.mouse.click.point.x - 640
+      next_y = inputs.mouse.click.point.y - 360
+      circle.x += next_x
+      circle.y += next_y
+      state.point_one = nil
+    elsif inputs.keyboard.one
+      state.point_one = [circle.x + camera.x, circle.y+ camera.y]
+    end
+
+    # cancel chain lines
+    if inputs.keyboard.key_down.nine || inputs.keyboard.key_down.escape || inputs.keyboard.key_up.six || inputs.keyboard.key_up.one
+      state.point_one = nil
+    end
+  end
+
+  def play_sound
+    return if state.sound_debounce > 0
+    state.sound_debounce = 5
+    outputs.sounds << "sounds/03#{"%02d" % state.sound_index}.wav"
+    state.sound_index += 1
+    if state.sound_index > 21
+      state.sound_index = 1
+    end
+  end
+
+  def input_game
+    if inputs.keyboard.down || inputs.keyboard.space
+      circle.potential_lift += 0.03
+      circle.potential_lift = circle.potential_lift.lesser(10)
+    elsif inputs.keyboard.key_up.down || inputs.keyboard.key_up.space
+      play_sound
+      circle.dy += circle.angle.vector_y circle.potential_lift
+      circle.dx += circle.angle.vector_x circle.potential_lift
+
+      if circle.on_floor
+        if circle.floor_relative_y == :above
+          circle.y += circle.potential_lift.abs * 2
+        elsif circle.floor_relative_y == :below
+          circle.y -= circle.potential_lift.abs * 2
+        end
+      end
+
+      circle.on_floor = false
+      circle.potential_lift = 0
+      circle.terrains_to_monitor.clear
+      circle.impact_history.clear
+      circle.impact = nil
+      calc_physics
+    end
+
+    # aim probe
+    if inputs.keyboard.right || inputs.keyboard.a
+      circle.angle -= 2
+    elsif inputs.keyboard.left || inputs.keyboard.d
+      circle.angle += 2
+    end
+  end
+
+  def input
+    input_god_mode
+    input_game
+  end
+
+  def calc_camera
+    state.camera.target_x = 640 - circle.x
+    state.camera.target_y = 360 - circle.y
+    xdiff = state.camera.target_x - state.camera.x
+    ydiff = state.camera.target_y - state.camera.y
+    state.camera.x += xdiff * camera.follow_speed
+    state.camera.y += ydiff * camera.follow_speed
+  end
+
+  def calc
+    state.sound_debounce ||= 0
+    state.sound_debounce -= 1
+    state.sound_debounce = 0 if state.sound_debounce < 0
+    if state.god_mode
+      circle.dy *= 0.1
+      circle.dx *= 0.1
+    end
+    calc_camera
+    state.whisp_queue ||= []
+    if state.tick_count.mod_zero?(4)
+      state.whisp_queue << {
+        x: -300,
+        y: 1400 * rand,
+        speed: 2.randomize(:ratio) + 3,
+        w: 20,
+        h: 20, path: 'sprites/whisp.png',
+        a: 0,
+        created_at: state.tick_count,
+        angle: 0,
+        r: 100,
+        g: 128 + 128 * rand,
+        b: 128 + 128 * rand
+      }
+    end
+
+    state.whisp_queue.each do |w|
+      w.x += w[:speed] * 2
+      w.x -= circle.dx * 0.3
+      w.y -= w[:speed]
+      w.y -= circle.dy * 0.3
+      w.angle += w[:speed]
+      w.a = w[:created_at].ease(30) * 255
+    end
+
+    state.whisp_queue = state.whisp_queue.reject { |w| w[:x] > 1280 }
+
+    if state.tick_count.mod_zero?(2) && (circle.dx != 0 || circle.dy != 0)
+      circle.after_images << {
+        x: circle.x,
+        y: circle.y,
+        w: circle.radius,
+        h: circle.radius,
+        a: 255,
+        created_at: state.tick_count
+      }
+    end
+
+    circle.after_images.each do |ai|
+      ai.a = ai[:created_at].ease(10, :flip) * 255
+    end
+
+    circle.after_images = circle.after_images.reject { |ai| ai[:created_at].elapsed_time > 10 }
+    calc_physics
+  end
+
+  def circle
+    state.circle
+  end
+
+  def camera
+    state.camera
+  end
+
+  def terrain
+    state.terrain
+  end
+
+  def lava
+    state.lava
+  end
+end
+
+# $gtk.reset
+
+def tick args
+  args.outputs.background_color = [0, 0, 0]
+  if args.inputs.keyboard.r
+    args.gtk.reset
+    return
+  end
+  # uncomment the line below to slow down the game so you
+  # can see each tick as it passes
+  # args.gtk.slowmo! 30
+  $game ||= FallingCircle.new
+  $game.args = args
+  $game.tick
+end
+
+def reset
+  $game = nil
+end
+
+</pre>
+<h1 id='--99_genre_roguelike/roguelike_line_of_sight/app/constants.rb'>99_genre_roguelike/roguelike_line_of_sight/app/constants.rb</h1>
+<pre>SHOW_LEGEND = true
+SOURCE_TILE_SIZE = 16
+DESTINATION_TILE_SIZE = 16
+TILE_SHEET_SIZE = 256
+TILE_R = 0
+TILE_G = 0
+TILE_B = 0
+TILE_A = 255
+
+</pre>
+<h1 id='--99_genre_roguelike/roguelike_line_of_sight/app/legend.rb'>99_genre_roguelike/roguelike_line_of_sight/app/legend.rb</h1>
+<pre>def tick_legend args
+  return unless SHOW_LEGEND
+
+  legend_padding = 16
+  legend_x = 1280 - TILE_SHEET_SIZE - legend_padding
+  legend_y =  720 - TILE_SHEET_SIZE - legend_padding
+  tile_sheet_sprite = [legend_x,
+                       legend_y,
+                       TILE_SHEET_SIZE,
+                       TILE_SHEET_SIZE,
+                       'sprites/simple-mood-16x16.png', 0,
+                       TILE_A,
+                       TILE_R,
+                       TILE_G,
+                       TILE_B]
+
+  if args.inputs.mouse.point.inside_rect? tile_sheet_sprite
+    mouse_row = args.inputs.mouse.point.y.idiv(SOURCE_TILE_SIZE)
+    tile_row = 15 - (mouse_row - legend_y.idiv(SOURCE_TILE_SIZE))
+
+    mouse_col = args.inputs.mouse.point.x.idiv(SOURCE_TILE_SIZE)
+    tile_col = (mouse_col - legend_x.idiv(SOURCE_TILE_SIZE))
+
+    args.outputs.primitives << [legend_x - legend_padding * 2,
+                                mouse_row * SOURCE_TILE_SIZE, 256 + legend_padding * 2, 16, 128, 128, 128, 64].solid
+
+    args.outputs.primitives << [mouse_col * SOURCE_TILE_SIZE,
+                                legend_y - legend_padding * 2, 16, 256 + legend_padding * 2, 128, 128, 128, 64].solid
+
+    sprite_key = sprite_lookup.find { |k, v| v == [tile_row, tile_col] }
+    if sprite_key
+      member_name, _ = sprite_key
+      member_name = member_name_as_code member_name
+      args.outputs.labels << [660, 70, "# CODE SAMPLE (place in the tick_game method located in main.rb)", -1, 0]
+      args.outputs.labels << [660, 50, "#                                    GRID_X, GRID_Y, TILE_KEY", -1, 0]
+      args.outputs.labels << [660, 30, "args.outputs.sprites << tile_in_game(     5,      6, #{member_name}    )", -1, 0]
+    else
+      args.outputs.labels << [660, 50, "Tile [#{tile_row}, #{tile_col}] not found. Add a key and value to app/sprite_lookup.rb:", -1, 0]
+      args.outputs.labels << [660, 30, "{ \"some_string\" => [#{tile_row}, #{tile_col}] } OR { some_symbol: [#{tile_row}, #{tile_col}] }.", -1, 0]
+    end
+
+  end
+
+  # render the sprite in the top right with a padding to the top and right so it's
+  # not flush against the edge
+  args.outputs.sprites << tile_sheet_sprite
+
+  # carefully place some ascii arrows to show the legend labels
+  args.outputs.labels  <<  [895, 707, "ROW --->"]
+  args.outputs.labels  <<  [943, 412, "       ^"]
+  args.outputs.labels  <<  [943, 412, "       |"]
+  args.outputs.labels  <<  [943, 394, "COL ---+"]
+
+  # use the tile sheet to print out row and column numbers
+  args.outputs.sprites << 16.map_with_index do |i|
+    sprite_key = i % 10
+    [
+      tile(1280 - TILE_SHEET_SIZE - legend_padding * 2 - SOURCE_TILE_SIZE,
+            720 - legend_padding * 2 - (SOURCE_TILE_SIZE * i),
+            sprite(sprite_key)),
+      tile(1280 - TILE_SHEET_SIZE - SOURCE_TILE_SIZE + (SOURCE_TILE_SIZE * i),
+            720 - TILE_SHEET_SIZE - legend_padding * 3, sprite(sprite_key))
+    ]
+  end
+end
+
+</pre>
+<h1 id='--99_genre_roguelike/roguelike_line_of_sight/app/main.rb'>99_genre_roguelike/roguelike_line_of_sight/app/main.rb</h1>
+<pre>require 'app/constants.rb'
+require 'app/sprite_lookup.rb'
+require 'app/legend.rb'
+
+def tick args
+  tick_game args
+  tick_legend args
+end
+
+def tick_game args
+  # setup the grid
+  args.state.grid.padding = 104
+  args.state.grid.size = 512
+
+  # set up your game
+  # initialize the game/game defaults. ||= means that you only initialize it if
+  # the value isn't alread initialized
+  args.state.player.x ||= 0
+  args.state.player.y ||= 0
+
+  args.state.enemies ||= [
+    { x: 10, y: 10, type: :goblin, tile_key: :G },
+    { x: 15, y: 30, type: :rat,    tile_key: :R }
+  ]
+
+  args.state.info_message ||= "Use arrow keys to move around."
+
+  # handle keyboard input
+  # keyboard input (arrow keys to move player)
+  new_player_x = args.state.player.x
+  new_player_y = args.state.player.y
+  player_direction = ""
+  player_moved = false
+  if args.inputs.keyboard.key_down.up
+    new_player_y += 1
+    player_direction = "north"
+    player_moved = true
+  elsif args.inputs.keyboard.key_down.down
+    new_player_y -= 1
+    player_direction = "south"
+    player_moved = true
+  elsif args.inputs.keyboard.key_down.right
+    new_player_x += 1
+    player_direction = "east"
+    player_moved = true
+  elsif args.inputs.keyboard.key_down.left
+    new_player_x -= 1
+    player_direction = "west"
+    player_moved = true
+  end
+
+  #handle game logic
+  # determine if there is an enemy on that square,
+  # if so, don't let the player move there
+  if player_moved
+    found_enemy = args.state.enemies.find do |e|
+      e[:x] == new_player_x && e[:y] == new_player_y
+    end
+
+    if !found_enemy
+      args.state.player.x = new_player_x
+      args.state.player.y = new_player_y
+      args.state.info_message = "You moved #{player_direction}."
+    else
+      args.state.info_message = "You cannot move into a square an enemy occupies."
+    end
+  end
+
+  args.outputs.sprites << tile_in_game(args.state.player.x,
+                                       args.state.player.y, '@')
+
+  # render game
+  # render enemies at locations
+  args.outputs.sprites << args.state.enemies.map do |e|
+    tile_in_game(e[:x], e[:y], e[:tile_key])
+  end
+
+  # render the border
+  border_x = args.state.grid.padding - DESTINATION_TILE_SIZE
+  border_y = args.state.grid.padding - DESTINATION_TILE_SIZE
+  border_size = args.state.grid.size + DESTINATION_TILE_SIZE * 2
+
+  args.outputs.borders << [border_x,
+                           border_y,
+                           border_size,
+                           border_size]
+
+  # render label stuff
+  args.outputs.labels << [border_x, border_y - 10, "Current player location is: #{args.state.player.x}, #{args.state.player.y}"]
+  args.outputs.labels << [border_x, border_y + 25 + border_size, args.state.info_message]
+end
+
+def tile_in_game x, y, tile_key
+  tile($gtk.args.state.grid.padding + x * DESTINATION_TILE_SIZE,
+       $gtk.args.state.grid.padding + y * DESTINATION_TILE_SIZE,
+       tile_key)
+end
+
+</pre>
+<h1 id='--99_genre_roguelike/roguelike_line_of_sight/app/sprite_lookup.rb'>99_genre_roguelike/roguelike_line_of_sight/app/sprite_lookup.rb</h1>
+<pre>def sprite_lookup
+  {
+    0 => [3, 0],
+    1 => [3, 1],
+    2 => [3, 2],
+    3 => [3, 3],
+    4 => [3, 4],
+    5 => [3, 5],
+    6 => [3, 6],
+    7 => [3, 7],
+    8 => [3, 8],
+    9 => [3, 9],
+    '@' => [4, 0],
+    A: [ 4,  1],
+    B: [ 4,  2],
+    C: [ 4,  3],
+    D: [ 4,  4],
+    E: [ 4,  5],
+    F: [ 4,  6],
+    G: [ 4,  7],
+    H: [ 4,  8],
+    I: [ 4,  9],
+    J: [ 4, 10],
+    K: [ 4, 11],
+    L: [ 4, 12],
+    M: [ 4, 13],
+    N: [ 4, 14],
+    O: [ 4, 15],
+    P: [ 5,  0],
+    Q: [ 5,  1],
+    R: [ 5,  2],
+    S: [ 5,  3],
+    T: [ 5,  4],
+    U: [ 5,  5],
+    V: [ 5,  6],
+    W: [ 5,  7],
+    X: [ 5,  8],
+    Y: [ 5,  9],
+    Z: [ 5, 10],
+    a: [ 6,  1],
+    b: [ 6,  2],
+    c: [ 6,  3],
+    d: [ 6,  4],
+    e: [ 6,  5],
+    f: [ 6,  6],
+    g: [ 6,  7],
+    h: [ 6,  8],
+    i: [ 6,  9],
+    j: [ 6, 10],
+    k: [ 6, 11],
+    l: [ 6, 12],
+    m: [ 6, 13],
+    n: [ 6, 14],
+    o: [ 6, 15],
+    p: [ 7,  0],
+    q: [ 7,  1],
+    r: [ 7,  2],
+    s: [ 7,  3],
+    t: [ 7,  4],
+    u: [ 7,  5],
+    v: [ 7,  6],
+    w: [ 7,  7],
+    x: [ 7,  8],
+    y: [ 7,  9],
+    z: [ 7, 10],
+    '|' => [ 7, 12]
+  }
+end
+
+def sprite key
+  $gtk.args.state.reserved.sprite_lookup[key]
+end
+
+def member_name_as_code raw_member_name
+  if raw_member_name.is_a? Symbol
+    ":#{raw_member_name}"
+  elsif raw_member_name.is_a? String
+    "'#{raw_member_name}'"
+  elsif raw_member_name.is_a? Fixnum
+    "#{raw_member_name}"
+  else
+    "UNKNOWN: #{raw_member_name}"
+  end
+end
+
+def tile x, y, tile_row_column_or_key
+  tile_extended x, y, DESTINATION_TILE_SIZE, DESTINATION_TILE_SIZE, TILE_R, TILE_G, TILE_B, TILE_A, tile_row_column_or_key
+end
+
+def tile_extended x, y, w, h, r, g, b, a, tile_row_column_or_key
+  row_or_key, column = tile_row_column_or_key
+  if !column
+    row, column = sprite row_or_key
+  else
+    row, column = row_or_key, column
+  end
+
+  if !row
+    member_name = member_name_as_code tile_row_column_or_key
+    raise "Unabled to find a sprite for #{member_name}. Make sure the value exists in app/sprite_lookup.rb."
+  end
+
+  # Sprite provided by Rogue Yun
+  # http://www.bay12forums.com/smf/index.php?topic=144897.0
+  # License: Public Domain
+
+  {
+    x: x,
+    y: y,
+    w: w,
+    h: h,
+    tile_x: column * 16,
+    tile_y: (row * 16),
+    tile_w: 16,
+    tile_h: 16,
+    r: r,
+    g: g,
+    b: b,
+    a: a,
+    path: 'sprites/simple-mood-16x16.png'
+  }
+end
+
+$gtk.args.state.reserved.sprite_lookup = sprite_lookup
+
+</pre>
+<h1 id='--99_genre_roguelike/roguelike_starting_point/app/main.rb'>99_genre_roguelike/roguelike_starting_point/app/main.rb</h1>
+<pre>=begin
+
+ APIs listing that haven't been encountered in previous sample apps:
+
+ - lambda: A way to define a block and its parameters with special syntax.
+   For example, the syntax of lambda looks like this:
+   my_lambda = -> { puts "This is my lambda" }
+
+ Reminders:
+ - args.outputs.labels: An array. The values generate a label.
+   The parameters are [X, Y, TEXT, SIZE, ALIGNMENT, RED, GREEN, BLUE, ALPHA, FONT STYLE]
+   For more information about labels, go to mygame/documentation/02-labels.
+
+ - ARRAY#inside_rect?: Returns whether or not the point is inside a rect.
+
+ - product: Returns an array of all combinations of elements from all arrays.
+
+ - find: Finds all elements of a collection that meet requirements.
+
+ - abs: Returns the absolute value.
+
+=end
+
+# This sample app allows the player to move around in the dungeon, which becomes more or less visible
+# depending on the player's location, and also has enemies.
+
+class Game
+  attr_accessor :args, :state, :inputs, :outputs, :grid
+
+  # Calls all the methods needed for the game to run properly.
+  def tick
+    defaults
+    render_canvas
+    render_dungeon
+    render_player
+    render_enemies
+    print_cell_coordinates
+    calc_canvas
+    input_move
+    input_click_map
+  end
+
+  # Sets default values and initializes variables
+  def defaults
+    outputs.background_color = [0, 0, 0] # black background
+
+    # Initializes empty canvas, dungeon, and enemies collections.
+    state.canvas   ||= []
+    state.dungeon  ||= []
+    state.enemies  ||= []
+
+    # If state.area doesn't have value, load_area_one and derive_dungeon_from_area methods are called
+    if !state.area
+      load_area_one
+      derive_dungeon_from_area
+
+      # Changing these values will change the position of player
+      state.x = 7
+      state.y = 5
+
+      # Creates new enemies, sets their values, and adds them to the enemies collection.
+      state.enemies << state.new_entity(:enemy) do |e| # declares each enemy as new entity
+        e.x           = 13 # position
+        e.y           = 5
+        e.previous_hp = 3
+        e.hp          = 3
+        e.max_hp      = 3
+        e.is_dead     = false # the enemy is alive
+      end
+
+      update_line_of_sight # updates line of sight by adding newly visible cells
+    end
+  end
+
+  # Adds elements into the state.area collection
+  # The dungeon is derived using the coordinates of this collection
+  def load_area_one
+    state.area ||= []
+    state.area << [8, 6]
+    state.area << [7, 6]
+    state.area << [7, 7]
+    state.area << [8, 9]
+    state.area << [7, 8]
+    state.area << [7, 9]
+    state.area << [6, 4]
+    state.area << [7, 3]
+    state.area << [7, 4]
+    state.area << [6, 5]
+    state.area << [7, 5]
+    state.area << [8, 5]
+    state.area << [8, 4]
+    state.area << [1, 1]
+    state.area << [0, 1]
+    state.area << [0, 2]
+    state.area << [1, 2]
+    state.area << [2, 2]
+    state.area << [2, 1]
+    state.area << [2, 3]
+    state.area << [1, 3]
+    state.area << [1, 4]
+    state.area << [2, 4]
+    state.area << [2, 5]
+    state.area << [1, 5]
+    state.area << [2, 6]
+    state.area << [3, 6]
+    state.area << [4, 6]
+    state.area << [4, 7]
+    state.area << [4, 8]
+    state.area << [5, 8]
+    state.area << [5, 9]
+    state.area << [6, 9]
+    state.area << [7, 10]
+    state.area << [7, 11]
+    state.area << [7, 12]
+    state.area << [7, 12]
+    state.area << [7, 13]
+    state.area << [8, 13]
+    state.area << [9, 13]
+    state.area << [10, 13]
+    state.area << [11, 13]
+    state.area << [12, 13]
+    state.area << [12, 12]
+    state.area << [8, 12]
+    state.area << [9, 12]
+    state.area << [10, 12]
+    state.area << [11, 12]
+    state.area << [12, 11]
+    state.area << [13, 11]
+    state.area << [13, 10]
+    state.area << [13, 9]
+    state.area << [13, 8]
+    state.area << [13, 7]
+    state.area << [13, 6]
+    state.area << [12, 6]
+    state.area << [14, 6]
+    state.area << [14, 5]
+    state.area << [13, 5]
+    state.area << [12, 5]
+    state.area << [12, 4]
+    state.area << [13, 4]
+    state.area << [14, 4]
+    state.area << [1, 6]
+    state.area << [6, 6]
+  end
+
+  # Starts with an empty dungeon collection, and adds dungeon cells into it.
+  def derive_dungeon_from_area
+    state.dungeon = [] # starts as empty collection
+
+    state.area.each do |a| # for each element of the area collection
+      state.dungeon << state.new_entity(:dungeon_cell) do |d| # declares each dungeon cell as new entity
+        d.x = a.x # dungeon cell position using coordinates from area
+        d.y = a.y
+        d.is_visible = false # cell is not visible
+        d.alpha = 0 # not transparent at all
+        d.border = [left_margin   + a.x * grid_size,
+                    bottom_margin + a.y * grid_size,
+                    grid_size,
+                    grid_size,
+                    *blue,
+                    255] # sets border definition for dungeon cell
+        d # returns dungeon cell
+      end
+    end
+  end
+
+  def left_margin
+    40  # sets left margin
+  end
+
+  def bottom_margin
+    60 # sets bottom margin
+  end
+
+  def grid_size
+    40 # sets size of grid square
+  end
+
+  # Updates the line of sight by calling the thick_line_of_sight method and
+  # adding dungeon cells to the newly_visible collection
+  def update_line_of_sight
+    variations = [-1, 0, 1]
+    # creates collection of newly visible dungeon cells
+    newly_visible = variations.product(variations).flat_map do |rise, run| # combo of all elements
+      thick_line_of_sight state.x, state.y, rise, run, 15, # calls thick_line_of_sight method
+                          lambda { |x, y| dungeon_cell_exists? x, y } # checks whether or not cell exists
+    end.uniq# removes duplicates
+
+    state.dungeon.each do |d| # perform action on each element of dungeons collection
+      d.is_visible = newly_visible.find { |v| v.x == d.x && v.y == d.y } # finds match inside newly_visible collection
+    end
+  end
+
+  #Returns a boolean value
+  def dungeon_cell_exists? x, y
+    # Finds cell coordinates inside dungeon collection to determine if dungeon cell exists
+    state.dungeon.find { |d| d.x == x && d.y == y }
+  end
+
+  # Calls line_of_sight method to add elements to result collection
+  def thick_line_of_sight start_x, start_y, rise, run, distance, cell_exists_lambda
+    result = []
+    result += line_of_sight start_x, start_y, rise, run, distance, cell_exists_lambda
+    result += line_of_sight start_x - 1, start_y, rise, run, distance, cell_exists_lambda # one left
+    result += line_of_sight start_x + 1, start_y, rise, run, distance, cell_exists_lambda # one right
+    result
+  end
+
+  # Adds points to the result collection to create the player's line of sight
+  def line_of_sight start_x, start_y, rise, run, distance, cell_exists_lambda
+    result = [] # starts as empty collection
+    points = points_on_line start_x, start_y, rise, run, distance # calls points_on_line method
+    points.each do |p| # for each point in collection
+      if cell_exists_lambda.call(p.x, p.y) # if the cell exists
+        result << p # add it to result collection
+      else # if cell does not exist
+        return result # return result collection as it is
+      end
+    end
+
+    result # return result collection
+  end
+
+  # Finds the coordinates of the points on the line by performing calculations
+  def points_on_line start_x, start_y, rise, run, distance
+    distance.times.map do |i| # perform an action
+      [start_x + run * i, start_y + rise * i] # definition of point
+    end
+  end
+
+  def render_canvas
+    return
+    outputs.borders << state.canvas.map do |c| # on each element of canvas collection
+      c.border # outputs border
+    end
+  end
+
+  # Outputs the dungeon cells.
+  def render_dungeon
+    outputs.solids << [0, 0, grid.w, grid.h] # outputs black background for grid
+
+    # Sets the alpha value (opacity) for each dungeon cell and calls the cell_border method.
+    outputs.borders << state.dungeon.map do |d| # for each element in dungeon collection
+      d.alpha += if d.is_visible # if cell is visible
+                 255.fdiv(30) # increment opacity (transparency)
+               else # if cell is not visible
+                 255.fdiv(600) * -1 # decrease opacity
+               end
+      d.alpha = d.alpha.cap_min_max(0, 255)
+      cell_border d.x, d.y, [*blue, d.alpha] # sets blue border using alpha value
+    end.reject_nil
+  end
+
+  # Sets definition of a cell border using the parameters
+  def cell_border x, y, color = nil
+    [left_margin   + x * grid_size,
+    bottom_margin + y * grid_size,
+    grid_size,
+    grid_size,
+    *color]
+  end
+
+  # Sets the values for the player and outputs it as a label
+  def render_player
+    outputs.labels << [grid_x(state.x) + 20, # positions "@" text in center of grid square
+                     grid_y(state.y) + 35,
+                     "@", # player is represented by a white "@" character
+                     1, 1, *white]
+  end
+
+  def grid_x x
+    left_margin + x * grid_size # positions horizontally on grid
+  end
+
+  def grid_y y
+    bottom_margin + y * grid_size # positions vertically on grid
+  end
+
+  # Outputs enemies onto the screen.
+  def render_enemies
+    state.enemies.map do |e| # for each enemy in the collection
+      alpha = 255 # set opacity (full transparency)
+
+      # Outputs an enemy using a label.
+      outputs.labels << [
+                   left_margin + 20 +  e.x * grid_size, # positions enemy's "r" text in center of grid square
+                   bottom_margin + 35 + e.y * grid_size,
+                   "r", # enemy's text
+                   1, 1, *white, alpha]
+
+      # Creates a red border around an enemy.
+      outputs.borders << [grid_x(e.x), grid_y(e.y), grid_size, grid_size, *red]
+    end
+  end
+
+  #White labels are output for the cell coordinates of each element in the dungeon collection.
+  def print_cell_coordinates
+    return unless state.debug
+    state.dungeon.each do |d|
+      outputs.labels << [grid_x(d.x) + 2,
+                         grid_y(d.y) - 2,
+                         "#{d.x},#{d.y}",
+                         -2, 0, *white]
+    end
+  end
+
+  # Adds new elements into the canvas collection and sets their values.
+  def calc_canvas
+    return if state.canvas.length > 0 # return if canvas collection has at least one element
+    15.times do |x| # 15 times perform an action
+      15.times do |y|
+        state.canvas << state.new_entity(:canvas) do |c| # declare canvas element as new entity
+          c.x = x # set position
+          c.y = y
+          c.border = [left_margin   + x * grid_size,
+                      bottom_margin + y * grid_size,
+                      grid_size,
+                      grid_size,
+                      *white, 30] # sets border definition
+        end
+      end
+    end
+  end
+
+  # Updates x and y values of the player, and updates player's line of sight
+  def input_move
+    x, y, x_diff, y_diff = input_target_cell
+
+    return unless dungeon_cell_exists? x, y # player can't move there if a dungeon cell doesn't exist in that location
+    return if enemy_at x, y # player can't move there if there is an enemy in that location
+
+    state.x += x_diff # increments x by x_diff (so player moves left or right)
+    state.y += y_diff # same with y and y_diff ( so player moves up or down)
+    update_line_of_sight # updates visible cells
+  end
+
+  def enemy_at x, y
+    # Finds if coordinates exist in enemies collection and enemy is not dead
+    state.enemies.find { |e| e.x == x && e.y == y && !e.is_dead }
+  end
+
+  #M oves the user based on their keyboard input and sets values for target cell
+  def input_target_cell
+    if inputs.keyboard.key_down.up # if "up" key is in "down" state
+      [state.x, state.y + 1,  0,  1] # user moves up
+    elsif inputs.keyboard.key_down.down # if "down" key is pressed
+      [state.x, state.y - 1,  0, -1] # user moves down
+    elsif inputs.keyboard.key_down.left # if "left" key is pressed
+      [state.x - 1, state.y, -1,  0] # user moves left
+    elsif inputs.keyboard.key_down.right # if "right" key is pressed
+      [state.x + 1, state.y,  1,  0] # user moves right
+    else
+      nil  # otherwise, empty
+    end
+  end
+
+  # Goes through the canvas collection to find if the mouse was clicked inside of the borders of an element.
+  def input_click_map
+    return unless inputs.mouse.click # return unless the mouse is clicked
+    canvas_entry = state.canvas.find do |c| # find element from canvas collection that meets requirements
+      inputs.mouse.click.inside_rect? c.border # find border that mouse was clicked inside of
+    end
+    puts canvas_entry # prints canvas_entry value
+  end
+
+  # Sets the definition of a label using the parameters.
+  def label text, x, y, color = nil
+    color ||= white # color is initialized to white
+    [x, y, text, 1, 1, *color] # sets label definition
+  end
+
+  def green
+    [60, 200, 100] # sets color saturation to shade of green
+  end
+
+  def blue
+    [50, 50, 210] # sets color saturation to shade of blue
+  end
+
+  def white
+    [255, 255, 255] # sets color saturation to white
+  end
+
+  def red
+    [230, 80, 80] # sets color saturation to shade of red
+  end
+
+  def orange
+    [255, 80, 60] # sets color saturation to shade of orange
+  end
+
+  def pink
+    [255, 0, 200] # sets color saturation to shade of pink
+  end
+
+  def gray
+    [75, 75, 75] # sets color saturation to shade of gray
+  end
+
+  # Recolors the border using the parameters.
+  def recolor_border border, r, g, b
+    border[4] = r
+    border[5] = g
+    border[6] = b
+    border
+  end
+
+  # Returns a boolean value.
+  def visible? cell
+    # finds cell's coordinates inside visible_cells collections to determine if cell is visible
+    state.visible_cells.find { |c| c.x == cell.x && c.y == cell.y}
+  end
+
+  # Exports dungeon by printing dungeon cell coordinates
+  def export_dungeon
+    state.dungeon.each do |d| # on each element of dungeon collection
+      puts "state.dungeon << [#{d.x}, #{d.y}]" # prints cell coordinates
+    end
+  end
+
+  def distance_to_cell cell
+    distance_to state.x, cell.x, state.y, cell.y # calls distance_to method
+  end
+
+  def distance_to from_x, x, from_y, y
+    (from_x - x).abs + (from_y - y).abs # finds distance between two cells using coordinates
+  end
+end
+
+$game = Game.new
+
+def tick args
+  $game.args    = args
+  $game.state   = args.state
+  $game.inputs  = args.inputs
+  $game.outputs = args.outputs
+  $game.grid    = args.grid
+  $game.tick
+end
+
+</pre>
+<h1 id='--99_genre_tactical_rpg/hexagonal_grid/app/main.rb'>99_genre_tactical_rpg/hexagonal_grid/app/main.rb</h1>
+<pre>class HexagonTileGame
+  attr_gtk
+
+  def defaults
+    state.tile_scale      = 1.3
+    state.tile_size       = 80
+    state.tile_w          = Math.sqrt(3) * state.tile_size.half
+    state.tile_h          = state.tile_size * 3/4
+    state.tiles_x_count   = 1280.idiv(state.tile_w) - 1
+    state.tiles_y_count   = 720.idiv(state.tile_h) - 1
+    state.world_width_px  = state.tiles_x_count * state.tile_w
+    state.world_height_px = state.tiles_y_count * state.tile_h
+    state.world_x_offset  = (1280 - state.world_width_px).half
+    state.world_y_offset  = (720 - state.world_height_px).half
+    state.tiles         ||= state.tiles_x_count.map_with_ys(state.tiles_y_count) do |ordinal_x, ordinal_y|
+      {
+        ordinal_x: ordinal_x,
+        ordinal_y: ordinal_y,
+        offset_x: (ordinal_y.even?) ?
+                  (state.world_x_offset + state.tile_w.half.half) :
+                  (state.world_x_offset - state.tile_w.half.half),
+        offset_y: state.world_y_offset,
+        w: state.tile_w,
+        h: state.tile_h,
+        type: :blank,
+        path: "sprites/hexagon-gray.png",
+        a: 20
+      }.associate do |h|
+        h.merge(x: h[:offset_x] + h[:ordinal_x] * h[:w],
+                y: h[:offset_y] + h[:ordinal_y] * h[:h]).scale_rect(state.tile_scale)
+      end.associate do |h|
+        h.merge(center: {
+                  x: h[:x] + h[:w].half,
+                  y: h[:y] + h[:h].half
+                }, radius: [h[:w].half, h[:h].half].max)
+      end
+    end
+  end
+
+  def input
+    if inputs.click
+      tile = state.tiles.find { |t| inputs.click.point_inside_circle? t[:center], t[:radius] }
+      if tile
+        tile[:a] = 255
+        tile[:path] = "sprites/hexagon-black.png"
+      end
+    end
+  end
+
+  def tick
+    defaults
+    input
+    render
+  end
+
+  def render
+    outputs.sprites << state.tiles
+  end
+end
+
+$game = HexagonTileGame.new
+
+def tick args
+  $game.args = args
+  $game.tick
+end
+
+$gtk.reset
+
+</pre>
+<h1 id='--99_genre_tactical_rpg/isometric_grid/app/main.rb'>99_genre_tactical_rpg/isometric_grid/app/main.rb</h1>
+<pre>class Isometric
+    attr_accessor :grid, :inputs, :state, :outputs
+
+    def tick
+        defaults
+        render
+        calc
+        process_inputs
+    end
+
+    def defaults
+        state.quantity              ||= 6                                                        #Size of grid
+        state.tileSize              ||= [262 / 2, 194 / 2]                                       #width and heigth of orange tiles
+        state.tileGrid              ||= []                                                       #Holds ordering of tiles
+        state.currentSpriteLocation ||= -1                                                       #Current Sprite hovering location
+        state.tileCords             ||= []                                                       #Physical, rendering cordinates
+        state.initCords             ||= [640 - (state.quantity / 2 * state.tileSize[0]), 330]    #Location of tile (0, 0)
+        state.sideSize              ||= [state.tileSize[0] / 2, 242 / 2]                         #Purple & green cube face size
+        state.mode                  ||= :delete                                                  #Switches between :delete and :insert
+        state.spriteSelection       ||= [['river',    0, 0, 262 / 2, 194 / 2],
+                                         ['mountain', 0, 0, 262 / 2, 245 / 2],
+                                         ['ocean',    0, 0, 262 / 2, 194 / 2]]             #Storage for sprite information
+                                                                                           #['name', deltaX, deltaY, sizeW, sizeH]
+                                                                                           #^delta refers to distance from tile cords
+
+        #Orders tiles based on tile placement and fancy math. Very left: 0,0. Very bottom: quantity-1, 0, etc
+        if state.tileGrid == []
+            tempX = 0
+            tempY = 0
+            tempLeft = false
+            tempRight = false
+            count = 0
+            (state.quantity * state.quantity).times do
+                if tempY == 0
+                    tempLeft = true
+                end
+                if tempX == (state.quantity - 1)
+                    tempRight = true
+                end
+                state.tileGrid.push([tempX, tempY, true, tempLeft, tempRight, count])
+                    #orderX, orderY, exists?, leftSide, rightSide, order
+                tempX += 1
+                if tempX == state.quantity
+                    tempX = 0
+                    tempY += 1
+                end
+                tempLeft = false
+                tempRight = false
+                count += 1
+            end
+        end
+
+        #Calculates physical cordinates for tiles
+        if state.tileCords == []
+            state.tileCords = state.tileGrid.map do
+                |val|
+                x = (state.initCords[0]) + ((val[0] + val[1]) * state.tileSize[0] / 2)
+                y = (state.initCords[1]) + (-1 * val[0] * state.tileSize[1] / 2) + (val[1] * state.tileSize[1] / 2)
+                [x, y, val[2], val[3], val[4], val[5], -1] #-1 represents sprite on top of tile. -1 for now
+            end
+        end
+
+    end
+
+    def render
+        renderBackground
+        renderLeft
+        renderRight
+        renderTiles
+        renderObjects
+        renderLabels
+    end
+
+    def renderBackground
+        outputs.solids << [0, 0, 1280, 720, 0, 0, 0]   #Background color
+    end
+
+    def renderLeft
+        #Shows the pink left cube face
+        outputs.sprites << state.tileCords.map do
+            |val|
+            if val[2] == true && val[3] == true       #Checks if the tile exists and right face needs to be rendered
+                [val[0], val[1] + (state.tileSize[1] / 2) - state.sideSize[1], state.sideSize[0],
+                state.sideSize[1], 'sprites/leftSide.png']
+            end
+        end
+    end
+
+    def renderRight
+        #Shows the green right cube face
+        outputs.sprites << state.tileCords.map do
+            |val|
+            if val[2] == true && val[4] == true        #Checks if it exists & checks if right face needs to be rendered
+                [val[0] + state.tileSize[0] / 2, val[1] + (state.tileSize[1] / 2) - state.sideSize[1], state.sideSize[0],
+                state.sideSize[1], 'sprites/rightSide.png']
+            end
+        end
+    end
+
+    def renderTiles
+        #Shows the tile itself. Important that it's rendered after the two above!
+        outputs.sprites << state.tileCords.map do
+            |val|
+            if val[2] == true     #Chcekcs if tile needs to be rendered
+              if val[5] == state.currentSpriteLocation
+                [val[0], val[1], state.tileSize[0], state.tileSize[1], 'sprites/selectedTile.png']
+              else
+                [val[0], val[1], state.tileSize[0], state.tileSize[1], 'sprites/tile.png']
+              end
+            end
+        end
+    end
+
+    def renderObjects
+        #Renders the sprites on top of the tiles. Order of rendering: top corner to right corner and cascade down until left corner
+        #to bottom corner.
+        a = (state.quantity * state.quantity) - state.quantity
+        iter = 0
+        loop do
+            if state.tileCords[a][2] == true && state.tileCords[a][6] != -1
+                outputs.sprites << [state.tileCords[a][0] + state.spriteSelection[state.tileCords[a][6]][1],
+                                    state.tileCords[a][1] + state.spriteSelection[state.tileCords[a][6]][2],
+                                    state.spriteSelection[state.tileCords[a][6]][3], state.spriteSelection[state.tileCords[a][6]][4],
+                                    'sprites/' + state.spriteSelection[state.tileCords[a][6]][0] + '.png']
+            end
+            iter += 1
+            a    += 1
+            a -= state.quantity * 2 if iter == state.quantity
+            iter = 0                if iter == state.quantity
+            break if a < 0
+        end
+    end
+
+    def renderLabels
+        #Labels
+        outputs.labels << [50, 680, 'Click to delete!',             5, 0, 255, 255, 255, 255] if state.mode == :delete
+        outputs.labels << [50, 640, 'Press 
+    </div>
+  </body>
+</html>
+i
+    </div>
+  </body>
+</html>
+ for insert mode!', 5, 0, 255, 255, 255, 255] if state.mode == :delete
+        outputs.labels << [50, 680, 'Click to insert!',             5, 0, 255, 255, 255, 255] if state.mode == :insert
+        outputs.labels << [50, 640, 'Press 
+    </div>
+  </body>
+</html>
+d
+    </div>
+  </body>
+</html>
+ for delete mode!', 5, 0, 255, 255, 255, 255] if state.mode == :insert
+    end
+
+    def calc
+        calcCurrentHover
+    end
+
+    def calcCurrentHover
+        #This determines what tile the mouse is hovering (or last hovering) over
+        x = inputs.mouse.position.x
+        y = inputs.mouse.position.y
+        m = (state.tileSize[1] / state.tileSize[0])   #slope
+        state.tileCords.map do
+            |val|
+            #Conditions that makes runtime faster. Checks if the mouse click was between tile dimensions (rectangle collision)
+            next unless val[0] < x && x < val[0] + state.tileSize[0]
+            next unless val[1] < y && y < val[1] + state.tileSize[1]
+            next unless val[2] == true
+            tempBool = false
+            if x == val[0] + (state.tileSize[0] / 2)
+                #The height of a diamond is the height of the diamond, so if x equals that exact point, it must be inside the diamond
+                tempBool = true
+            elsif x < state.tileSize[0] / 2 + val[0]
+                #Uses y = (m) * (x - x1) + y1 to determine the y values for the two diamond lines on the left half of diamond
+                tempY1 =      (m * (x - val[0])) + val[1] + (state.tileSize[1] / 2)
+                tempY2 = (-1 * m * (x - val[0])) + val[1] + (state.tileSize[1] / 2)
+                #Checks to see if the mouse click y value is between those temp y values
+                tempBool = true if y < tempY1 && y > tempY2
+            elsif x > state.tileSize[0] / 2 + val[0]
+                #Uses y = (m) * (x - x1) + y1 to determine the y values for the two diamond lines on the right half of diamond
+                tempY1 =      (m * (x - val[0] - (state.tileSize[0] / 2))) + val[1]
+                tempY2 = (-1 * m * (x - val[0] - (state.tileSize[0] / 2))) + val[1] + state.tileSize[1]
+                #Checks to see if the mouse click y value is between those temp y values
+                tempBool = true if y > tempY1 && y < tempY2
+            end
+
+            if tempBool == true
+                state.currentSpriteLocation = val[5]         #Current sprite location set to the order value
+            end
+        end
+    end
+
+    def process_inputs
+        #Makes development much faster and easier
+        if inputs.keyboard.key_up.r
+            $dragon.reset
+        end
+        checkTileSelected
+        switchModes
+    end
+
+    def checkTileSelected
+        if inputs.mouse.down
+            x = inputs.mouse.down.point.x
+            y = inputs.mouse.down.point.y
+            m = (state.tileSize[1] / state.tileSize[0])   #slope
+            state.tileCords.map do
+                |val|
+                #Conditions that makes runtime faster. Checks if the mouse click was between tile dimensions (rectangle collision)
+                next unless val[0] < x && x < val[0] + state.tileSize[0]
+                next unless val[1] < y && y < val[1] + state.tileSize[1]
+                next unless val[2] == true
+                tempBool = false
+                if x == val[0] + (state.tileSize[0] / 2)
+                    #The height of a diamond is the height of the diamond, so if x equals that exact point, it must be inside the diamond
+                    tempBool = true
+                elsif x < state.tileSize[0] / 2 + val[0]
+                    #Uses y = (m) * (x - x1) + y1 to determine the y values for the two diamond lines on the left half of diamond
+                    tempY1 =      (m * (x - val[0])) + val[1] + (state.tileSize[1] / 2)
+                    tempY2 = (-1 * m * (x - val[0])) + val[1] + (state.tileSize[1] / 2)
+                    #Checks to see if the mouse click y value is between those temp y values
+                    tempBool = true if y < tempY1 && y > tempY2
+                elsif x > state.tileSize[0] / 2 + val[0]
+                    #Uses y = (m) * (x - x1) + y1 to determine the y values for the two diamond lines on the right half of diamond
+                    tempY1 =      (m * (x - val[0] - (state.tileSize[0] / 2))) + val[1]
+                    tempY2 = (-1 * m * (x - val[0] - (state.tileSize[0] / 2))) + val[1] + state.tileSize[1]
+                    #Checks to see if the mouse click y value is between those temp y values
+                    tempBool = true if y > tempY1 && y < tempY2
+                end
+
+                if tempBool == true
+                    if state.mode == :delete
+                        val[2] = false
+                        state.tileGrid[val[5]][2]  = false      #Unnecessary because never used again but eh, I like consistency
+                        state.tileCords[val[5]][2] = false      #Ensures that the tile isn't rendered
+                        unless state.tileGrid[val[5]][0] == 0   #If tile is the left most tile in the row, right doesn't get rendered
+                            state.tileGrid[val[5] - 1][4] = true            #Why the order value is amazing
+                            state.tileCords[val[5] - 1][4] = true
+                        end
+                        unless state.tileGrid[val[5]][1] == state.quantity - 1     #Same but left side
+                            state.tileGrid[val[5] + state.quantity][3] = true
+                            state.tileCords[val[5] + state.quantity][3] = true
+                        end
+                    elsif state.mode == :insert
+                        #adds the current sprite value selected to tileCords. (changes from the -1 earlier)
+                        val[6] = rand(state.spriteSelection.length)
+                    end
+                end
+            end
+        end
+    end
+
+    def switchModes
+        #Switches between insert and delete modes
+        if inputs.keyboard.key_up.i && state.mode == :delete
+            state.mode = :insert
+            inputs.keyboard.clear
+        elsif inputs.keyboard.key_up.d && state.mode == :insert
+            state.mode = :delete
+            inputs.keyboard.clear
+        end
+    end
+
+end
+
+$isometric = Isometric.new
+
+def tick args
+    $isometric.grid    = args.grid
+    $isometric.inputs  = args.inputs
+    $isometric.state   = args.state
+    $isometric.outputs = args.outputs
+    $isometric.tick
+end
+
+</pre>
+<h1 id='--99_genre_topdown_rpg/topdown_starting_point/app/main.rb'>99_genre_topdown_rpg/topdown_starting_point/app/main.rb</h1>
+<pre>=begin
+
+ APIs listing that haven't been encountered in previous sample apps:
+
+ - reverse: Returns a new string with the characters from original string in reverse order.
+   For example, the command
+   "dragonruby".reverse
+   would return the string
+   "yburnogard".
+   Reverse is not only limited to strings, but can be applied to arrays and other collections.
+
+ Reminders:
+
+ - ARRAY#intersect_rect?: Returns true or false depending on if two rectangles intersect.
+
+ - args.outputs.labels: An array. The values generate a label.
+   The parameters are [X, Y, TEXT, SIZE, ALIGNMENT, RED, GREEN, BLUE, ALPHA, FONT STYLE]
+   For more information about labels, go to mygame/documentation/02-labels.md.
+
+=end
+
+# This code shows a maze and uses input from the keyboard to move the user around the screen.
+# The objective is to reach the goal.
+
+# Sets values of tile size and player's movement speed
+# Also creates tile or box for player and generates map
+def tick args
+  args.state.tile_size     = 80
+  args.state.player_speed  = 4
+  args.state.player      ||= tile(args, 7, 3, 0, 128, 180)
+  generate_map args
+
+  # Adds walls, goal, and player to args.outputs.solids so they appear on screen
+  args.outputs.solids << args.state.walls
+  args.outputs.solids << args.state.goal
+  args.outputs.solids << args.state.player
+
+  # If player's box intersects with goal, a label is output onto the screen
+  if args.state.player.intersect_rect? args.state.goal
+    args.outputs.labels << [30, 720 - 30, "You're a wizard Harry!!"] # 30 pixels lower than top of screen
+  end
+
+  move_player args, -1,  0 if args.inputs.keyboard.left # x position decreases by 1 if left key is pressed
+  move_player args,  1,  0 if args.inputs.keyboard.right # x position increases by 1 if right key is pressed
+  move_player args,  0,  1 if args.inputs.keyboard.up # y position increases by 1 if up is pressed
+  move_player args,  0, -1 if args.inputs.keyboard.down # y position decreases by 1 if down is pressed
+end
+
+# Sets position, size, and color of the tile
+def tile args, x, y, *color
+  [x * args.state.tile_size, # sets definition for array using method parameters
+   y * args.state.tile_size, # multiplying by tile_size sets x and y to correct position using pixel values
+   args.state.tile_size,
+   args.state.tile_size,
+   *color]
+end
+
+# Creates map by adding tiles to the wall, as well as a goal (that the player needs to reach)
+def generate_map args
+  return if args.state.area
+
+  # Creates the area of the map. There are 9 rows running horizontally across the screen
+  # and 16 columns running vertically on the screen. Any spot with a "1" is not
+  # open for the player to move into (and is green), and any spot with a "0" is available
+  # for the player to move in.
+  args.state.area = [
+    [1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1,],
+    [1, 1, 1, 2, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1,], # the "2" represents the goal
+    [1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1,],
+    [1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1,],
+    [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,],
+    [1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1,],
+    [1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1,],
+    [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,],
+    [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 ],
+  ].reverse # reverses the order of the area collection
+
+  # By reversing the order, the way that the area appears above is how it appears
+  # on the screen in the game. If we did not reverse, the map would appear inverted.
+
+  #The wall starts off with no tiles.
+  args.state.walls = []
+
+  # If v is 1, a green tile is added to args.state.walls.
+  # If v is 2, a black tile is created as the goal.
+  args.state.area.map_2d do |y, x, v|
+    if    v == 1
+      args.state.walls << tile(args, x, y, 0, 255, 0) # green tile
+    elsif v == 2 # notice there is only one "2" above because there is only one single goal
+      args.state.goal   = tile(args, x, y, 0,   0, 0) # black tile
+    end
+  end
+end
+
+# Allows the player to move their box around the screen
+def move_player args, *vector
+  box = args.state.player.shift_rect(vector) # box is able to move at an angle
+
+  # If the player's box hits a wall, it is not able to move further in that direction
+  return if args.state.walls
+                .any_intersect_rect?(box)
+
+  # Player's box is able to move at angles (not just the four general directions) fast
+  args.state.player =
+    args.state.player
+        .shift_rect(vector.x * args.state.player_speed, # if we don't multiply by speed, then
+                    vector.y * args.state.player_speed) # the box will move extremely slow
+end
+
+</pre>
+<h1 id='--./dragon/args.rb'>./dragon/args.rb</h1>
+<pre># coding: utf-8
+# Copyright 2019 DragonRuby LLC
+# MIT License
+# args.rb has been released under MIT (*only this file*).
+
+module GTK
+  # This class is the one you'll interact with the most. It's
+  # constructed by the DragonRuby Runtime and is provided to you on
+  # each tick.
+  class Args
+    include ArgsDeprecated
+    include Serialize
+
+    # Contains information related to input devices and input events.
+    #
+    # @return [Inputs]
+    attr_accessor :inputs
+
+    # Contains the means to interact with output devices such as the screen.
+    #
+    # @return [Outputs]
+    attr_accessor :outputs
+
+    # Contains display size information to assist in positioning things on the screen.
+    #
+    # @return [Grid]
+    attr_accessor :grid
+
+    # Provides access to game play recording facilities within Game Toolkit.
+    #
+    # @return [Recording]
+    attr_accessor :recording
+
+    # Gives you access to geometry related functions.
+    #
+    # @return [Geometry]
+    attr_accessor :geometry
+
+    # This is where you'll put state associated with your video game.
+    #
+    # @return [OpenEntity]
+    attr_accessor :state
+
+    # Gives you access to the top level DragonRuby runtime.
+    #
+    # @return [Runtime]
+    attr_accessor :runtime
+    alias_method :gtk, :runtime
+
+    attr_accessor :passes
+
+    attr_accessor :wizards
+
+    def initialize runtime, recording
+      @inputs = Inputs.new
+      @outputs = Outputs.new args: self
+      @passes = []
+      @state = OpenEntity.new
+      @state.tick_count = -1
+      @runtime = runtime
+      @recording = recording
+      @grid = Grid.new runtime
+      @render_targets = {}
+      @all_tests = []
+      @geometry = GTK::Geometry
+      @wizards = Wizards.new
+    end
+
+
+    # The number of ticks since the start of the game.
+    #
+    # @return [Integer]
+    def tick_count
+      @state.tick_count
+    end
+
+    def tick_count= value
+      @state.tick_count = value
+    end
+
+    def serialize
+      {
+        state: state.as_hash,
+        inputs: inputs.serialize,
+        passes: passes.serialize,
+        outputs: outputs.serialize,
+        grid: grid.serialize
+      }
+    end
+
+    def destructure
+      [grid, inputs, state, outputs, runtime, passes]
+    end
+
+    def clear_render_targets
+      render_targets_clear
+    end
+
+    def render_targets_clear
+      @render_targets = {}
+    end
+
+    def render_targets
+      @render_targets
+    end
+
+    def render_target name
+      name = name.to_s
+      if !@render_targets[name]
+        @render_targets[name] = Outputs.new(args: self, target: name, background_color_override: [255, 255, 255, 0])
+        @passes << @render_targets[name]
+      end
+      @render_targets[name]
+    end
+
+    def solids
+      @outputs.solids
+    end
+
+    def static_solids
+      @outputs.static_solids
+    end
+
+    def sprites
+      @outputs.sprites
+    end
+
+    def static_sprites
+      @outputs.static_sprites
+    end
+
+    def labels
+      @outputs.labels
+    end
+
+    def static_labels
+      @outputs.static_labels
+    end
+
+    def lines
+      @outputs.lines
+    end
+
+    def static_lines
+      @outputs.static_lines
+    end
+
+    def borders
+      @outputs.borders
+    end
+
+    def static_borders
+      @outputs.static_borders
+    end
+
+    def primitives
+      @outputs.primitives
+    end
+
+    def static_primitives
+      @outputs.static_primitives
+    end
+
+    def keyboard
+      @inputs.keyboard
+    end
+
+    def click
+      return nil unless @inputs.mouse.click
+
+      @inputs.mouse.click.point
+    end
+
+    def click_at
+      return nil unless @inputs.mouse.click
+
+      @inputs.mouse.click.created_at
+    end
+
+    def mouse
+      @inputs.mouse
+    end
+
+    # @see Inputs#controller_one
+    # @return (see Inputs#controller_one)
+    def controller_one
+      @inputs.controller_one
+    end
+
+    # @see Inputs#controller_two
+    # @return (see Inputs#controller_two)
+    def controller_two
+      @inputs.controller_two
+    end
+  end
+end
+
+</pre>
+<h1 id='--./dragon/assert.rb'>./dragon/assert.rb</h1>
+<pre># coding: utf-8
+# Copyright 2019 DragonRuby LLC
+# MIT License
+# assert.rb has been released under MIT (*only this file*).
+
+module GTK
+=begin
+This is a tiny assertion api for the unit testing portion of Game Toolkit.
+
+@example
+
+1. Create a file called tests.rb under mygame.
+2. Any method that begins with the word test_ will be considered a test.
+
+def test_this_works args, assert
+  assert.equal! 1, 1
+end
+
+3. To run a test, save the file while the game is running.
+
+@example
+
+To add an assertion open up this class and write:
+
+class Assert
+  def custom_assertion actual, expected, message = nil
+    # this tell Game Toolkit that an assertion was performed (so that the test isn't marked inconclusive).
+    @assertion_performed = true
+
+    # perform your custom logic here and rais an exception to denote a failure.
+
+    raise "Some Error. #{message}."
+  end
+end
+=end
+  class Assert
+    attr :assertion_performed
+
+=begin
+Us this if you are throwing your own exceptions and you want to mark the tests as ran (so that it wont be marked as inconclusive).
+=end
+    def ok!
+      @assertion_performed = true
+    end
+
+=begin
+Assert if a value is a thruthy value. All assert method take an optional final parameter that is the message to display to the user.
+
+@example
+
+def test_does_this_work args, assert
+  some_result = Person.new
+  assert.true! some_result
+  # OR
+  assert.true! some_result, "Person was not created."
+end
+=end
+    def true! value, message = nil
+      @assertion_performed = true
+      if !value
+        message = "#{value} was not truthy.\n#{message}"
+        raise "#{message}"
+      end
+      nil
+    end
+
+=begin
+Assert if a value is a falsey value.
+
+@example
+
+def test_does_this_work args, assert
+  some_result = nil
+  assert.false! some_result
+end
+=end
+    def false! value, message = nil
+      @assertion_performed = true
+      if value
+        message = "#{value} was not falsey.\n#{message}"
+        raise message
+      end
+      nil
+    end
+
+=begin
+Assert if two values are equal.
+
+@example
+
+def test_does_this_work args, assert
+  a = 1
+  b = 1
+  assert.equal! a, b
+end
+=end
+    def equal! actual, expected, message = nil
+      @assertion_performed = true
+      if actual != expected
+        actual_string = "#{actual}#{actual.nil? ? " (nil) " : " " }".strip
+        message = "actual:\n#{actual_string} did not equal\nexpected:\n#{expected}.\n#{message}"
+        raise message
+      end
+      nil
+    end
+
+=begin
+Assert if a value is explicitly nil (not false).
+
+@example
+
+def test_does_this_work args, assert
+  a = nil
+  b = false
+  assert.nil! a # this will pass
+  assert.nil! b # this will throw an exception.
+end
+=end
+    def nil! value, message = nil
+      @assertion_performed = true
+      if !value.nil?
+        message = "#{value} was supposed to be nil, but wasn't.\n#{message}"
+        raise message
+      end
+      nil
+    end
+  end
+end
+
+</pre>
+<h1 id='--./dragon/attr_gtk.rb'>./dragon/attr_gtk.rb</h1>
+<pre># coding: utf-8
+# Copyright 2019 DragonRuby LLC
+# MIT License
+# attr_gtk.rb has been released under MIT (*only this file*).
+
+# @private
+module AttrGTK
+  attr_accessor :args
+
+  def keyboard
+    args.inputs.keyboard
+  end
+
+  def grid
+    args.grid
+  end
+
+  def state
+    args.state
+  end
+
+  def inputs
+    args.inputs
+  end
+
+  def outputs
+    args.outputs
+  end
+
+  def gtk
+    args.gtk
+  end
+
+  def passes
+    args.passes
+  end
+
+  def geometry
+    args.geometry
+  end
+end
+
+</pre>
+<h1 id='--./dragon/attr_sprite.rb'>./dragon/attr_sprite.rb</h1>
+<pre># Copyright 2019 DragonRuby LLC
+# MIT License
+# attr_sprite.rb has been released under MIT (*only this file*).
+
+# @private
+module AttrRect
+  def left
+    @x
+  end
+
+  def right
+    @x + @w
+  end
+
+  def bottom
+    @y
+  end
+
+  def top
+    @y + @h
+  end
+end
+
+module AttrSprite
+  include AttrRect
+  include GTK::Geometry
+
+  attr_accessor :x, :y, :w, :h, :path, :angle, :a, :r, :g, :b, :tile_x,
+                :tile_y, :tile_w, :tile_h, :flip_horizontally,
+                :flip_vertically, :angle_anchor_x, :angle_anchor_y, :id,
+                :source_x, :source_y, :source_w, :source_h
+
+  def primitive_marker
+    :sprite
+  end
+
+  def sprite
+    self
+  end
+
+  def x1
+    @x
+  end
+
+  def x1= value
+    @x = value
+  end
+
+  def y1
+    @y
+  end
+
+  def y1= value
+    @y = value
+  end
+end
+
+</pre>
+<h1 id='--./dragon/console.rb'>./dragon/console.rb</h1>
+<pre># Copyright 2019 DragonRuby LLC
+# MIT License
+# console.rb has been released under MIT (*only this file*).
+
+# Contributors outside of DragonRuby who also hold Copyright:
+# - Kevin Fischer: https://github.com/kfischer-okarin
+
+module GTK
+  class Console
+    attr_accessor :show_reason, :log, :logo, :background_color,
+                  :text_color, :animation_duration,
+                  :max_log_lines, :max_history, :log,
+                  :last_command_errored, :last_command, :error_color, :shown_at,
+                  :header_color, :archived_log, :last_log_lines, :last_log_lines_count,
+                  :suppress_left_arrow_behavior, :command_set_at,
+                  :toast_ids, :bottom,
+                  :font_style, :menu
+
+    def initialize
+      @font_style = FontStyle.new(font: 'font.ttf', size_enum: -1, line_height: 1.1)
+      @menu = Menu.new self
+      @disabled = false
+      @log_offset = 0
+      @visible = false
+      @toast_ids = []
+      @archived_log = []
+      @log = [ 'Console ready.' ]
+      @max_log_lines = 1000  # I guess...?
+      @max_history = 1000  # I guess...?
+      @log_invocation_count = 0
+      @command_history = []
+      @command_history_index = -1
+      @nonhistory_input = ''
+      @logo = 'console-logo.png'
+      @history_fname = 'console_history.txt'
+      @background_color = Color.new [0, 0, 0, 224]
+      @text_color = Color.new [255, 255, 255]
+      @error_color = Color.new [200, 50, 50]
+      @header_color = Color.new [100, 200, 220]
+      @animation_duration = 1.seconds
+      @shown_at = -1
+      load_history
+    end
+
+    def console_text_width
+      @console_text_width ||= ($gtk.logical_width - 20).idiv(font_style.letter_size.x)
+    end
+
+    def save_history
+      $gtk.ffi_file.storefile(@history_fname, @command_history.reverse.join("\n"))
+    end
+
+    def load_history
+      @command_history.clear
+      str = $gtk.ffi_file.loadfile(@history_fname)
+      return if str.nil?  # no history to load.
+
+      str.chomp!("\n")  # Don't let endlines at the end cause extra blank line.
+      str.chomp!("\r")
+      str.each_line { |s|
+        s.chomp!("\n")
+        s.chomp!("\r")
+        if s.length > 0
+          @command_history.unshift s
+          break if @command_history.length >= @max_history
+        end
+      }
+
+      @command_history.uniq!
+    end
+
+    def disable
+      @disabled = true
+    end
+
+    def enable
+      @disabled = false
+    end
+
+    def addsprite obj
+      @log_invocation_count += 1
+      obj[:id] ||= "id_#{obj[:path]}_#{Time.now.to_i}".to_sym
+
+      if @last_line_log_index &&
+         @last_sprite_line.is_a?(Hash) &&
+         @last_sprite_line[:id] == obj[:id]
+
+        @log[@last_line_log_index] = obj
+        return
+      end
+
+      @log << obj
+      @last_line_log_index = @log.length - 1
+      @last_sprite_line = obj
+      nil
+    end
+
+    def add_primitive obj
+      if obj.is_a? Hash
+        addsprite obj
+      else
+        addtext obj
+      end
+      nil
+    end
+
+    def addtext obj
+      @last_log_lines_count ||= 1
+      @log_invocation_count += 1
+
+      str = obj.to_s
+
+      log_lines = []
+
+      str.each_line do |s|
+        s.wrapped_lines(self.console_text_width).each do |l|
+          log_lines << l
+        end
+      end
+
+      if log_lines == @last_log_lines
+        @last_log_lines_count += 1
+        new_log_line_with_count = @last_log_lines.last + " (#{@last_log_lines_count})"
+        if log_lines.length > 1
+          @log = @log[0..-(@log.length - log_lines.length)] + log_lines[0..-2] + [new_log_line_with_count]
+        else
+          @log = @log[0..-2] + [new_log_line_with_count]
+        end
+        return
+      end
+
+      log_lines.each do |l|
+        @log.shift if @log.length > @max_log_lines
+        @log << l
+      end
+
+      @last_log_lines_count = 1
+      @last_log_lines = log_lines
+      nil
+    end
+
+    def ready?
+      visible? && @toggled_at.elapsed?(@animation_duration, Kernel.global_tick_count)
+    end
+
+    def hidden?
+      !@visible
+    end
+
+    def visible?
+      @visible
+    end
+
+    # @gtk
+    def show reason = nil
+      @shown_at = Kernel.global_tick_count
+      @show_reason = reason
+      toggle if hidden?
+    end
+
+    # @gtk
+    def hide
+      if visible?
+        toggle
+        @archived_log += @log
+        if @archived_log.length > @max_log_lines
+          @archived_log = @archived_log.drop(@archived_log.length - @max_log_lines)
+        end
+        @log.clear
+        @show_reason = nil
+        clear_toast
+      end
+    end
+
+    def close
+      hide
+    end
+
+    def clear_toast
+      @toasted_at = nil
+      @toast_duration = 0
+    end
+
+    def toggle
+      @visible = !@visible
+      @toggled_at = Kernel.global_tick_count
+    end
+
+    def currently_toasting?
+      return false if hidden?
+      return false unless @show_reason == :toast
+      return false unless @toasted_at
+      return false if @toasted_at.elapsed?(5.seconds, Kernel.global_tick_count)
+      return true
+    end
+
+    def toast_extended id = nil, duration = nil, *messages
+      if !id.is_a?(Symbol)
+        raise <<-S
+* ERROR:
+args.gtk.console.toast has the following signature:
+
+  def toast id, *messages
+  end
+
+The id property uniquely defines the message and must be
+a symbol.
+
+After that, you can provide all the objects you want to
+look at.
+
+Example:
+
+  args.gtk.console.toast :say_hello,
+                            \"Hello world.\",
+                            args.state.tick_count
+
+Toast messages autohide after 5 seconds.
+
+If you need to look at something for longer, use
+args.gtk.console.perma_toast instead (which you can manually dismiss).
+
+S
+      end
+
+      return if currently_toasting?
+      return if @toast_ids.include? id
+      @toasted_at = Kernel.global_tick_count
+      log_once_info :perma_toast_tip, "Use console.perma_toast to show the toast for longer."
+      dwim_duration = 5.seconds
+      addtext "* toast :#{id}"
+      puts "* TOAST: :#{id}"
+      messages.each do |message|
+        lines = message.to_s.wrapped_lines(self.console_text_width)
+        dwim_duration += lines.length.seconds
+        addtext "** #{message}"
+        puts "** #{message}"
+      end
+      show :toast
+      @toast_duration += duration || dwim_duration
+      @toast_ids << id
+      set_command "$gtk.console.hide"
+    end
+
+    def perma_toast id = nil, messages
+      toast_extended id, 600.seconds, *messages
+    end
+
+    def toast id = nil, *messages
+      toast_extended id, nil, *messages
+    end
+
+    def console_toggle_keys
+      [
+        :backtick!,
+        :tilde!,
+        :superscript_two!,
+        :section_sign!,
+        :ordinal_indicator!,
+        :circumflex!,
+      ]
+    end
+
+    def console_toggle_key_down? args
+      args.inputs.keyboard.key_down.any? console_toggle_keys
+    end
+
+    def eval_the_set_command
+      cmd = current_input_str.strip
+      if cmd.length != 0
+        @log_offset = 0
+        prompt.clear
+
+        @command_history.pop while @command_history.length >= @max_history
+        @command_history.unshift cmd
+        @command_history_index = -1
+        @nonhistory_input = ''
+
+        if cmd == 'quit' || cmd == ':wq' || cmd == ':q!' || cmd == ':q' || cmd == ':wqa'
+          $gtk.request_quit
+        else
+          puts "-> #{cmd}"
+          begin
+            @last_command = cmd
+            Kernel.eval("$results = (#{cmd})")
+            if $results.nil?
+              puts "=> nil"
+            elsif $results == :console_silent_eval
+            else
+              puts "=> #{$results}"
+            end
+            @last_command_errored = false
+          rescue Exception => e
+            string_e = "#{e}"
+            @last_command_errored = true
+            if (string_e.include? "wrong number of arguments")
+              method_name = (string_e.split ":")[0].gsub "'", ""
+              results = Kernel.docs_search method_name
+              if !results.include "* DOCS: No results found."
+                puts results
+                log results
+              end
+            end
+
+            puts "#{e}"
+            log "#{e}"
+          end
+        end
+      end
+    end
+
+    def inputs_scroll_up_full? args
+      return false if @disabled
+      args.inputs.keyboard.key_down.pageup ||
+        (args.inputs.keyboard.key_up.b && args.inputs.keyboard.key_up.control)
+    end
+
+    def scroll_up_full
+      @log_offset += lines_on_one_page
+      @log_offset = @log.size if @log_offset > @log.size
+    end
+
+    def inputs_scroll_up_half? args
+      return false if @disabled
+      args.inputs.keyboard.ctrl_u
+    end
+
+    def scroll_up_half
+      @log_offset += lines_on_one_page.idiv(2)
+      @log_offset = @log.size if @log_offset > @log.size
+    end
+
+    def inputs_scroll_down_full? args
+      return false if @disabled
+      args.inputs.keyboard.key_down.pagedown ||
+        (args.inputs.keyboard.key_up.f && args.inputs.keyboard.key_up.control)
+    end
+
+    def scroll_down_full
+      @log_offset -= lines_on_one_page
+      @log_offset = 0 if @log_offset < 0
+    end
+
+    def inputs_scroll_down_half? args
+      return false if @disabled
+      args.inputs.keyboard.ctrl_d
+    end
+
+    def inputs_clear_command? args
+      return false if @disabled
+      args.inputs.keyboard.escape || args.inputs.keyboard.ctrl_g
+    end
+
+    def scroll_down_half
+      @log_offset -= lines_on_one_page.idiv(2)
+      @log_offset = 0 if @log_offset < 0
+    end
+
+    def mouse_wheel_scroll args
+      @inertia ||= 0
+
+      if args.inputs.mouse.wheel && args.inputs.mouse.wheel.y > 0
+        @inertia = 1
+      elsif args.inputs.mouse.wheel && args.inputs.mouse.wheel.y < 0
+        @inertia = -1
+      end
+
+      if args.inputs.mouse.click
+        @inertia = 0
+      end
+
+      return if @inertia == 0
+
+      if @inertia != 0
+        @inertia = (@inertia * 0.7)
+        if @inertia > 0
+          @log_offset -= 1
+        elsif @inertia < 0
+          @log_offset += 1
+        end
+      end
+
+      if @inertia.abs < 0.01
+        @inertia = 0
+      end
+
+      if @log_offset > @log.size
+        @log_offset = @log.size
+      elsif @log_offset < 0
+        @log_offset = 0
+      end
+    end
+
+    def process_inputs args
+      if console_toggle_key_down? args
+        args.inputs.text.clear
+        toggle
+      end
+
+      return unless visible?
+
+      args.inputs.text.each { |str| prompt << str }
+      args.inputs.text.clear
+      mouse_wheel_scroll args
+
+      @log_offset = 0 if @log_offset < 0
+
+      if args.inputs.keyboard.key_down.enter
+        eval_the_set_command
+      elsif args.inputs.keyboard.key_down.v
+        if args.inputs.keyboard.key_down.control || args.inputs.keyboard.key_down.meta
+          prompt << $gtk.ffi_misc.getclipboard
+        end
+      elsif args.inputs.keyboard.key_down.up
+        if @command_history_index == -1
+          @nonhistory_input = current_input_str
+        end
+        if @command_history_index < (@command_history.length - 1)
+          @command_history_index += 1
+          self.current_input_str = @command_history[@command_history_index].dup
+        end
+      elsif args.inputs.keyboard.key_down.down
+        if @command_history_index == 0
+          @command_history_index = -1
+          self.current_input_str = @nonhistory_input
+          @nonhistory_input = ''
+        elsif @command_history_index > 0
+          @command_history_index -= 1
+          self.current_input_str = @command_history[@command_history_index].dup
+        end
+      elsif inputs_scroll_up_full? args
+        scroll_up_full
+      elsif inputs_scroll_down_full? args
+        scroll_down_full
+      elsif inputs_scroll_up_half? args
+        scroll_up_half
+      elsif inputs_scroll_down_half? args
+        scroll_down_half
+      elsif inputs_clear_command? args
+        prompt.clear
+        @command_history_index = -1
+        @nonhistory_input = ''
+      elsif args.inputs.keyboard.key_down.backspace || args.inputs.keyboard.key_down.delete
+        prompt.backspace
+      elsif args.inputs.keyboard.key_down.tab
+        prompt.autocomplete
+      end
+
+      args.inputs.keyboard.key_down.clear
+      args.inputs.keyboard.key_up.clear
+      args.inputs.keyboard.key_held.clear
+    end
+
+    def write_primitive_and_return_offset(args, left, y, str, archived: false)
+      if str.is_a?(Hash)
+        padding = 10
+        args.outputs.reserved << [left + 10, y + 5, str[:w], str[:h], str[:path]].sprite
+        return str[:h] + padding
+      else
+        write_line args, left, y, str, archived: archived
+        return line_height_px
+      end
+    end
+
+    def write_line(args, left, y, str, archived: false)
+      color = color_for_log_entry(str)
+      color = color.mult_alpha(0.5) if archived
+
+      args.outputs.reserved << font_style.label(x: left.shift_right(10), y: y, text: str, color: color)
+    end
+
+    def should_tick?
+      return false if !@toggled_at
+      return false if slide_progress == 0
+      return false if @disabled
+      return visible?
+    end
+
+    def render args
+      return if !@toggled_at
+      return if slide_progress == 0
+
+      @bottom = top - (h * slide_progress)
+      args.outputs.reserved << [left, @bottom, w, h, *@background_color.mult_alpha(slide_progress)].solid
+      args.outputs.reserved << [right.shift_left(110), @bottom.shift_up(630), 100, 100, @logo, 0, (80.0 * slide_progress).to_i].sprite
+
+      y = @bottom + 2  # just give us a little padding at the bottom.
+      prompt.render args, x: left.shift_right(10), y: y
+      y += line_height_px * 1.5
+      args.outputs.reserved << line(y: y, color: @text_color.mult_alpha(slide_progress))
+      y += line_height_px.to_f / 2.0
+
+      ((@log.size - @log_offset) - 1).downto(0) do |idx|
+        offset_after_write = write_primitive_and_return_offset args, left, y, @log[idx]
+        y += offset_after_write
+        break if y > top
+      end
+
+      # past log separator
+      args.outputs.reserved << line(y: y + line_height_px.half, color: @text_color.mult_alpha(0.25 * slide_progress))
+
+      y += line_height_px
+
+      ((@archived_log.size - @log_offset) - 1).downto(0) do |idx|
+        offset_after_write = write_primitive_and_return_offset args, left, y, @archived_log[idx], archived: true
+        y += offset_after_write
+        break if y > top
+      end
+
+      render_log_offset args
+    end
+
+    def tick_help args
+      tick_help_debounce args
+      alpha_rate = 20
+      @render_help_target_alpha  ||= 255
+      @render_help_current_alpha ||= 255
+      @render_help_target_alpha  += 4 if @render_help_current_alpha == @render_help_target_alpha
+      @render_help_current_alpha = (@render_help_current_alpha.towards @render_help_target_alpha, 20)
+
+      @render_help_target_alpha  = @render_help_target_alpha.clamp(-255, 255)
+      @render_help_current_alpha = @render_help_current_alpha.clamp(-255, 255)
+
+      [
+        "* Prompt Commands:                   ",
+        "You can type any of the following    ",
+        "commands in the command prompt.      ",
+        "** docs: Provides API docs.          ",
+        "** $gtk: Accesses the global runtime.",
+        "* Shortcut Keys:                     ",
+        "** full page up:   ctrl + b          ",
+        "** full page down: ctrl + f          ",
+        "** half page up:   ctrl + u          ",
+        "** half page down: ctrl + d          ",
+        "** clear prompt:   ctrl + g          ",
+        "** up arrow:       next command      ",
+        "** down arrow:     prev command      ",
+      ].each_with_index do |s, i|
+        args.outputs.reserved << [args.grid.right - 10,
+                                  top - 100 - line_height_px * i * 0.8,
+                                  s, -3, 2, 180, 180, 180, (@render_help_current_alpha.clamp 0, 255)].label
+      end
+    end
+
+    def tick_help_debounce args
+      hide_log_alpha = -255
+      if hidden?
+        @render_help_current_alpha = -255
+      end
+
+      if prompt.last_input_str_changed
+        @render_help_target_alpha = hide_log_alpha
+      end
+
+      if args.inputs.mouse.moved
+        @render_help_target_alpha = hide_log_alpha
+      end
+
+      if args.inputs.mouse.wheel
+        @render_help_target_alpha = hide_log_alpha
+      end
+
+      if @render_help_last_log_invocation_count != @log_invocation_count
+        @render_help_target_alpha = hide_log_alpha
+      end
+
+      @render_help_last_log_invocation_count = @log_invocation_count
+    end
+
+    def render_log_offset args
+      return if @log_offset <= 0
+      args.outputs.reserved << font_style.label(
+        x: right.shift_left(5),
+        y: top.shift_down(5 + line_height_px),
+        text: "[#{@log_offset}/#{@log.size}]",
+        color: @text_color,
+        alignment_enum: 2
+      )
+    end
+
+    def include_error_marker? text
+      include_any_words?(text.gsub('OutputsDeprecated', ''), error_markers)
+    end
+
+    def error_markers
+      ["exception", "error", "undefined method", "failed", "syntax", "deprecated"]
+    end
+
+    def include_subdued_markers? text
+      include_any_words? text, subdued_markers
+    end
+
+    def include_any_words? text, words
+      words.any? { |w| text.downcase.include?(w) && !text.downcase.include?(":#{w}") }
+    end
+
+    def subdued_markers
+      ["reloaded", "exported the"]
+    end
+
+    def calc args
+      if visible? &&
+         @show_reason == :toast &&
+         @toasted_at &&
+         @toasted_at.elapsed?(@toast_duration, Kernel.global_tick_count)
+        hide
+      end
+
+      if !$gtk.paused? && visible? && (show_reason == :exception || show_reason == :exception_on_load)
+        hide
+      end
+
+      if $gtk.files_reloaded.length > 0
+        clear_toast
+        @toast_ids.clear
+      end
+    end
+
+    def tick args
+      begin
+        return if @disabled
+        render args
+        process_inputs args
+        return unless should_tick?
+        calc args
+        tick_help args
+        prompt.tick
+        menu.tick args
+      rescue Exception => e
+        begin
+          puts "#{e}"
+          puts "* FATAL: The GTK::Console console threw an unhandled exception and has been reset. You should report this exception (along with reproduction steps) to DragonRuby."
+        rescue
+        end
+        @disabled = true
+        $stdout.puts e
+        $stdout.puts "* FATAL: The GTK::Console console threw an unhandled exception and has been reset. You should report this exception (along with reproduction steps) to DragonRuby."
+      end
+    end
+
+    def set_command_with_history_silent command, histories, show_reason = nil
+      set_command_extended command: command, histories: histories, show_reason: show_reason
+    end
+
+    def defaults_set_command_extended
+      {
+        command: "puts 'Hello World'",
+        histories: [],
+        show_reason: nil,
+        force: false
+      }
+    end
+
+    def set_command_extended opts
+      opts = defaults_set_command_extended.merge opts
+      @command_history.concat opts[:histories]
+      @command_history << opts[:command]  if @command_history[-1] != opts[:command]
+      self.current_input_str = opts[:command] if @command_set_at != Kernel.global_tick_count || opts[:force]
+      @command_set_at = Kernel.global_tick_count
+      @command_history_index = -1
+      save_history
+    end
+
+    def set_command_with_history command, histories, show_reason = nil
+      set_command_with_history_silent command, histories, show_reason
+      show show_reason
+    end
+
+    # @gtk
+    def set_command command, show_reason = nil
+      set_command_silent command, show_reason
+      show show_reason
+    end
+
+    def set_command_silent command, show_reason = nil
+      set_command_with_history_silent command, [], show_reason
+    end
+
+    def set_system_command command, show_reason = nil
+      if $gtk.platform == "Mac OS X"
+        set_command_silent "$gtk.system \"open #{command}\""
+      else
+        set_command_silent "$gtk.system \"start #{command}\""
+      end
+    end
+
+    def system_command
+      if $gtk.platform == "Mac OS X"
+        "open"
+      else
+        "start"
+      end
+    end
+
+    private
+
+    def w
+      $gtk.logical_width
+    end
+
+    def h
+      $gtk.logical_height
+    end
+
+    # methods top; left; right
+    # Forward to grid
+    %i[top left right].each do |method|
+      define_method method do
+        $gtk.args.grid.send(method)
+      end
+    end
+
+    def line_height_px
+      font_style.line_height_px
+    end
+
+    def lines_on_one_page
+      (h - 4).idiv(line_height_px)
+    end
+
+    def line(y:, color:)
+      [left, y, right, y, *color].line
+    end
+
+    def include_row_marker? log_entry
+      log_entry[0] == "|"
+    end
+
+    def include_header_marker? log_entry
+      return false if (log_entry.strip.include? ".rb")
+      (log_entry.start_with? "* ")    ||
+      (log_entry.start_with? "** ")   ||
+      (log_entry.start_with? "*** ")  ||
+      (log_entry.start_with? "**** ")
+    end
+
+    def color_for_log_entry(log_entry)
+      if include_row_marker? log_entry
+        @text_color
+      elsif include_error_marker? log_entry
+        @error_color
+      elsif include_subdued_markers? log_entry
+        @text_color.mult_alpha(0.5)
+      elsif include_header_marker? log_entry
+        @header_color
+      elsif log_entry.start_with?("====")
+        @header_color
+      else
+        @text_color
+      end
+    end
+
+    def prompt
+      @prompt ||= Prompt.new(font_style: font_style, text_color: @text_color, console_text_width: console_text_width)
+    end
+
+    def current_input_str
+      prompt.current_input_str
+    end
+
+    def current_input_str=(str)
+      prompt.current_input_str = str
+    end
+
+    def clear
+      @archived_log.clear
+      @log.clear
+      @prompt.clear
+      :console_silent_eval
+    end
+
+    def slide_progress
+      return 0 if !@toggled_at
+      if visible?
+        @slide_progress = @toggled_at.global_ease(@animation_duration, :flip, :quint, :flip)
+      else
+        @slide_progress = @toggled_at.global_ease(@animation_duration, :flip, :quint)
+      end
+      @slide_progress
+    end
+  end
+end
+
+</pre>
+<h1 id='--./dragon/console_color.rb'>./dragon/console_color.rb</h1>
+<pre># Copyright 2019 DragonRuby LLC
+# MIT License
+# console_color.rb has been released under MIT (*only this file*).
+
+# Contributors outside of DragonRuby who also hold Copyright:
+# - Kevin Fischer: https://github.com/kfischer-okarin
+
+module GTK
+  class Console
+    class Color
+      def initialize(color)
+        @color = color
+        @color << 255 if @color.size == 3
+      end
+
+      def mult_alpha(alpha_modifier)
+        Color.new [@color[0], @color[1], @color[2], (@color[3].to_f * alpha_modifier).to_i]
+      end
+
+      # Support splat operator
+      def to_a
+        @color
+      end
+
+      def to_h
+        { r: @color[0], g: @color[1], b: @color[2], a: @color[3] }
+      end
+    end
+  end
+end
+
+</pre>
+<h1 id='--./dragon/console_font_style.rb'>./dragon/console_font_style.rb</h1>
+<pre># Copyright 2019 DragonRuby LLC
+# MIT License
+# console_font_style.rb has been released under MIT (*only this file*).
+
+# Contributors outside of DragonRuby who also hold Copyright:
+# - Kevin Fischer: https://github.com/kfischer-okarin
+
+module GTK
+  class Console
+    class FontStyle
+      attr_reader :font, :size_enum, :line_height
+
+      def initialize(font:, size_enum:, line_height:)
+        @font = font
+        @size_enum = size_enum
+        @line_height = line_height
+      end
+
+      def letter_size
+        @letter_size ||= $gtk.calcstringbox 'W', size_enum, font
+      end
+
+      def line_height_px
+        @line_height_px ||= letter_size.y * line_height
+      end
+
+      def label(x:, y:, text:, color:, alignment_enum: 0)
+        {
+          x: x,
+          y: y.shift_up(line_height_px),  # !!! FIXME: remove .shift_up(line_height_px) when we fix coordinate origin on labels.
+          text: text,
+          font: font,
+          size_enum: size_enum,
+          alignment_enum: alignment_enum,
+          **color.to_h,
+        }.label
+      end
+    end
+  end
+end
+
+</pre>
+<h1 id='--./dragon/console_menu.rb'>./dragon/console_menu.rb</h1>
+<pre># Copyright 2019 DragonRuby LLC
+# MIT License
+# console_menu.rb has been released under MIT (*only this file*).
+
+module GTK
+  class Console
+    class Menu
+      def initialize console
+        @console = console
+      end
+
+      def record_clicked
+        $recording.start 100
+      end
+
+      def replay_clicked
+        $replay.start 'replay.txt'
+      end
+
+      def reset_clicked
+        $gtk.reset
+      end
+
+      def scroll_up_clicked
+        @console.scroll_up_half
+      end
+
+      def scroll_down_clicked
+        @console.scroll_down_half
+      end
+
+      def show_menu_clicked
+        @menu_shown = :visible
+      end
+
+      def close_clicked
+        @menu_shown = :hidden
+        @console.hide
+      end
+
+      def framerate_diagnostics_clicked
+        $gtk.framerate_diagnostics
+      end
+
+      def tick args
+        return unless @console.visible?
+
+        @menu_shown ||= :hidden
+
+        if @menu_shown == :hidden
+          @buttons = [
+            (button id: :show_menu,       row: 0, col: 10, text: "show menu", method: :show_menu_clicked),
+          ]
+        else
+          @buttons = [
+            (button id: :record,      row: 0, col:  4, text: "framerate diagnostics",   method: :framerate_diagnostics_clicked),
+            (button id: :record,      row: 0, col:  5, text: "record",      method: :record_clicked),
+            (button id: :replay,      row: 0, col:  6, text: "replay",      method: :replay_clicked),
+            (button id: :reset,       row: 0, col:  7, text: "reset",       method: :reset_clicked),
+            (button id: :scroll_up,   row: 0, col:  8, text: "scroll up",   method: :scroll_up_clicked),
+            (button id: :scroll_down, row: 0, col:  9, text: "scroll down", method: :scroll_down_clicked),
+            (button id: :close,       row: 0, col: 10, text: "close",       method: :close_clicked),
+          ]
+        end
+
+        # render
+        args.outputs.reserved << @buttons.map { |b| b[:primitives] }
+
+        # inputs
+        if args.inputs.mouse.click
+          clicked = @buttons.find { |b| args.inputs.mouse.inside_rect? b[:rect] }
+          if clicked
+            send clicked[:method]
+          end
+        end
+      end
+
+      def rect_for_layout row, col
+        col_width  = 100
+        row_height = 50
+        col_margin = 5
+        row_margin = 5
+        x = (col_margin + (col * col_width)  + (col * col_margin))
+        y = (row_margin + (row * row_height) + (row * row_margin) + row_height).from_top
+        { x: x, y: y, w: col_width, h: row_height }
+      end
+
+      def button args
+        id, row, col, text, method = args[:id], args[:row], args[:col], args[:text], args[:method]
+
+        font_height = @console.font_style.line_height_px.half
+        {
+          id: id,
+          rect: (rect_for_layout row, col),
+          method: method
+        }.let do |entity|
+          primitives = []
+          primitives << entity[:rect].merge(a: 80).solid
+          primitives << entity[:rect].merge(r: 255, g: 255, b: 255).border
+          primitives << text.wrapped_lines(5)
+                            .map_with_index do |l, i|
+                              [
+                                entity[:rect][:x] + entity[:rect][:w].half,
+                                entity[:rect][:y] + entity[:rect][:h].half + font_height - (i * (font_height + 2)),
+                                l, -3, 1, 255, 255, 255
+                              ]
+                            end.labels
+
+          entity.merge(primitives: primitives)
+        end
+      end
+
+      def serialize
+        {
+          not_supported: "#{self}"
+        }
+      end
+    end
+  end
+end
+
+</pre>
+<h1 id='--./dragon/console_prompt.rb'>./dragon/console_prompt.rb</h1>
+<pre># Copyright 2019 DragonRuby LLC
+# MIT License
+# console_prompt.rb has been released under MIT (*only this file*).
+
+# Contributors outside of DragonRuby who also hold Copyright:
+# - Kevin Fischer: https://github.com/kfischer-okarin
+
+module GTK
+  class Console
+    class Prompt
+      attr_accessor :current_input_str, :font_style, :console_text_width, :last_input_str, :last_input_str_changed
+
+      def initialize(font_style:, text_color:, console_text_width:)
+        @prompt = '-> '
+        @current_input_str = ''
+        @font_style = font_style
+        @text_color = text_color
+        @cursor_color = Color.new [187, 21, 6]
+        @console_text_width = console_text_width
+
+        @last_autocomplete_prefix = nil
+        @next_candidate_index = 0
+      end
+
+      def <<(str)
+        @current_input_str << str
+        @current_input_changed_at = Kernel.global_tick_count
+        reset_autocomplete
+      end
+
+      def backspace
+        @current_input_str.chop!
+        reset_autocomplete
+      end
+
+      def clear
+        @current_input_str = ''
+        reset_autocomplete
+      end
+
+      def autocomplete
+        if !@last_autocomplete_prefix
+          @last_autocomplete_prefix = calc_autocomplete_prefix
+
+          puts "* AUTOCOMPLETE CANDIDATES: #{current_input_str}.."
+          pretty_print_strings_as_table method_candidates(@last_autocomplete_prefix)
+        else
+          candidates = method_candidates(@last_autocomplete_prefix)
+          return if candidates.empty?
+
+          candidate = candidates[@next_candidate_index]
+          candidate = candidate[0..-2] + " = " if candidate.end_with? '='
+          @next_candidate_index += 1
+          @next_candidate_index = 0 if @next_candidate_index >= candidates.length
+          self.current_input_str = display_autocomplete_candidate(candidate)
+        end
+      end
+
+      def pretty_print_strings_as_table items
+        if items.length == 0
+          puts <<-S.strip
++--------+
+| (none) |
++--------+
+S
+        else
+          # figure out the largest string
+          string_width = items.sort_by { |c| -c.to_s.length }.first
+
+          # add spacing to each side of the string which represents the cell width
+          cell_width = string_width.length + 2
+
+          # add spacing to each side of the cell to represent the column width
+          column_width = cell_width + 2
+
+          # determine the max number of columns that can fit on the screen
+          columns = @console_text_width.idiv column_width
+          columns = items.length if items.length < columns
+
+          # partition the original list of items into a string to be printed
+          items.each_slice(columns).each_with_index do |cells, i|
+            pretty_print_row_seperator string_width, cell_width, column_width, columns
+            pretty_print_row cells, string_width, cell_width, column_width, columns
+          end
+
+          pretty_print_row_seperator string_width, cell_width, column_width, columns
+        end
+      end
+
+      def pretty_print_row cells, string_width, cell_width, column_width, columns
+        # if the number of cells doesn't match the number of columns, then pad the array with empty values
+        cells += (columns - cells.length).map { "" }
+
+        # right align each cell value
+        formated_row = "|" + cells.map do |c|
+          "#{" " * (string_width.length - c.length) } #{c} |"
+        end.join
+
+        # remove seperators between empty values
+        formated_row = formated_row.gsub("  |  ", "     ")
+
+        puts formated_row
+      end
+
+      def pretty_print_row_seperator string_width, cell_width, column_width, columns
+        # this is a joint: +--------
+        column_joint = "+#{"-" * cell_width}"
+
+        # multiple joints create a row seperator: +----+----+
+        puts (column_joint * columns) + "+"
+      end
+
+      def render(args, x:, y:)
+        args.outputs.reserved << font_style.label(x: x, y: y, text: "#{@prompt}#{current_input_str}", color: @text_color)
+        args.outputs.reserved << font_style.label(x: x - 2, y: y + 3, text: (" " * (@prompt.length + current_input_str.length)) + "|", color: @cursor_color)
+      end
+
+      def tick
+        if (@current_input_changed_at) &&
+           (@current_input_changed_at < Kernel.global_tick_count) &&
+           (@last_input_str != @current_input_str)
+          @last_input_str_changed = true
+          @last_input_str = "#{@current_input_str}"
+          @current_input_changed_at = nil
+        else
+          @last_input_str_changed = false
+        end
+      end
+
+      private
+
+      def last_period_index
+        current_input_str.rindex('.')
+      end
+
+      def calc_autocomplete_prefix
+        if last_period_index
+          current_input_str[(last_period_index + 1)..-1]
+        else
+          current_input_str
+        end
+      end
+
+      def current_object
+        return Kernel unless last_period_index
+
+        Kernel.eval(current_input_str[0...last_period_index])
+      rescue NameError
+        nil
+      end
+
+      def method_candidates(prefix)
+        current_object.autocomplete_methods.map(&:to_s).select { |m| m.start_with? prefix }
+      end
+
+      def display_autocomplete_candidate(candidate)
+        if last_period_index
+          @current_input_str[0..last_period_index] + candidate.to_s
+        else
+          candidate.to_s
+        end
+      end
+
+      def reset_autocomplete
+        @last_autocomplete_prefix = nil
+        @next_candidate_index = 0
+      end
+    end
+  end
+end
+
+</pre>
+<h1 id='--./dragon/controller.rb'>./dragon/controller.rb</h1>
+<pre># coding: utf-8
+# Copyright 2019 DragonRuby LLC
+# MIT License
+# controller.rb has been released under MIT (*only this file*).
+
+module GTK
+  # @gtk
+  class Controller
+    # Access to keys that have been pressed down.
+    #
+    # @return [Controller::Keys]
+    # @gtk
+    attr_reader :key_down
+
+    # Access to keys that have been released up.
+    #
+    # @return [Controller::Keys]
+    # @gtk
+    attr_reader :key_up
+
+    # Access to keys that have been held down.
+    #
+    # @return [Controller::Keys]
+    # @gtk
+    attr_reader :key_held
+
+    # @gtk
+    attr_accessor :left_analog_x_raw,
+                  :left_analog_y_raw,
+                  :left_analog_x_perc,
+                  :left_analog_y_perc,
+                  :right_analog_x_raw,
+                  :right_analog_y_raw,
+                  :right_analog_x_perc,
+                  :right_analog_y_perc
+
+
+    def initialize
+      @key_down = Controller::Keys.new
+      @key_up   = Controller::Keys.new
+      @key_held = Controller::Keys.new
+      @left_analog_x_raw = 0
+      @left_analog_y_raw = 0
+      @left_analog_x_perc = 0
+      @left_analog_y_perc = 0
+      @right_analog_x_raw = 0
+      @right_analog_y_raw = 0
+      @right_analog_x_perc = 0
+      @right_analog_y_perc = 0
+    end
+
+    def serialize
+      {
+        key_down: @key_down.serialize,
+        key_held: @key_held.serialize,
+        key_up:   @key_up.serialize
+      }
+    end
+
+    # Clear all current key presses.
+    #
+    # @return [void]
+    def clear
+      @key_down.clear
+      @key_up.clear
+      @key_held.clear
+    end
+
+    def up
+      @key_up.up || @key_held.up
+    end
+
+    def down
+      @key_up.down || @key_held.down
+    end
+
+    def left
+      @key_up.left || @key_held.left
+    end
+
+    def right
+      @key_up.right || @key_held.right
+    end
+
+    # Activates a key into the down position.
+    #
+    # @param key [Symbol] The key to press down.
+    #
+    # @return [void]
+    def activate_down(key)
+      key_down.activate(key)
+      key_held.deactivate(key)
+      key_up.deactivate(key)
+    end
+
+    # Activates a key into the held down position.
+    #
+    # @param key [Symbol] The key to hold down.
+    #
+    # @return [void]
+    def activate_held(key)
+      key_down.deactivate(key)
+      key_held.activate(key) unless key_held.send(key)
+      key_up.deactivate(key)
+    end
+
+
+    # Activates a key release into the up position.
+    #
+    # @param key [Symbol] The key release up.
+    #
+    # @return [void]
+    def activate_up(key)
+      key_down.deactivate(key)
+      key_held.deactivate(key)
+      key_up.activate(key)
+    end
+
+    include DirectionalInputHelperMethods
+  end
+end
+
+
+</pre>
+<h1 id='--./dragon/controller/config.rb'>./dragon/controller/config.rb</h1>
+<pre># coding: utf-8
+# Copyright 2019 DragonRuby LLC
+# MIT License
+# controller/config.rb has been released under MIT (*only this file*).
+
+# !!! FIXME: add console command to forget custom binding(s)
+# !!! FIXME: add console command to forget replace existing binding(s)
+# !!! FIXME: add console command go into play_around mode to make sure controller isn't wonky.
+
+module GTK
+  class Controller
+    class Config
+      def initialize runtime
+        @runtime = runtime
+        @raw_joysticks = {}   # things that aren't game controllers to try to configure.
+        @target = nil
+        @animation_duration = (1.5).seconds
+        @toggled_at = 0
+        @fading = 0
+        @current_part = 0
+        @part_alpha = 0
+        @part_alpha_increment = 10
+        @joystick_state = {}
+        @playing_around = false
+        @used_bindings = {}
+        @bindings = []
+        @parts = [
+          [ 919, 282, 'A button', 'a' ],
+          [ 960, 323, 'B button', 'b' ],
+          [ 878, 323, 'X button', 'x' ],
+          [ 919, 365, 'Y button', 'y' ],
+          [ 433, 246, 'left stick left', '-leftx' ],
+          [ 497, 246, 'left stick right', '+leftx' ],
+          [ 466, 283, 'left stick up', '-lefty' ],
+          [ 466, 218, 'left stick down', '+lefty' ],
+          [ 466, 246, 'left stick button', 'leftstick' ],
+          [ 741, 246, 'right stick left', '-rightx' ],
+          [ 802, 246, 'right stick right', '+rightx' ],
+          [ 773, 283, 'right stick up', '-righty' ],
+          [ 773, 218, 'right stick down', '+righty' ],
+          [ 772, 246, 'right stick button', 'rightstick' ],
+          [ 263, 465, 'left shoulder button', 'leftshoulder' ],
+          [ 263, 503, 'left trigger', 'lefttrigger' ],
+          [ 977, 465, 'right shoulder button', 'rightshoulder' ],
+          [ 977, 503, 'right trigger', 'righttrigger' ],
+          [ 318, 365, 'D-pad up', 'dpup' ],
+          [ 360, 322, 'D-pad right', 'dpright' ],
+          [ 318, 280, 'D-pad down', 'dpdown' ],
+          [ 275, 322, 'D-pad left', 'dpleft' ],
+          [ 570, 402, 'select/back button', 'back'],
+          [ 619, 448, 'guide/home button', 'guide' ],
+          [ 669, 402, 'start button', 'start' ],
+        ]
+      end
+
+      def rawjoystick_connected jid, joystickname, guid
+        return if jid < 0
+        @raw_joysticks[jid] = { name: joystickname, guid: guid }
+      end
+
+      def rawjoystick_disconnected jid
+        return if jid < 0
+        if @raw_joysticks[jid] != nil
+          @raw_joysticks.delete(jid)
+          @runtime.ffi_misc.close_raw_joystick(jid)
+          # Fade out the config screen if we were literally configuring this controller right now.
+          if [email protected]? && @target[0] == jid
+            @target[0] = nil
+            @toggled_at = Kernel.global_tick_count
+            @fading = -1
+          end
+        end
+      end
+
+      def build_binding_string
+        bindingstr = ''
+        skip = false
+
+        for i in [email protected]
+          if skip ; skip = false ; next ; end
+
+          binding = @bindings[i]
+          next if binding.nil?
+
+          part = @parts[i][3]
+
+          # clean up string:
+          #  if axis uses -a0 for negative and +a0 for positive, just make it "leftx:a0" instead of "-leftx:-a0,+leftx:+a0"
+          #  if axis uses +a0 for negative and -a0 for positive, just make it "leftx:a0~" instead of "-leftx:+a0,+leftx:-a0"
+          if part == '-leftx' || part == '-lefty' || part == '-rightx' || part == '-righty'
+            nextbinding = @bindings[i+1]
+            if binding.start_with?('-a') && nextbinding.start_with?('+a') && binding[2..-1] == nextbinding[2..-1]
+              skip = true
+              part = part[1..-1]
+              binding = binding[1..-1]
+            elsif binding.start_with?('+a') && nextbinding.start_with?('-a') && binding[2..-1] == nextbinding[2..-1]
+              skip = true
+              part = part[1..-1]
+              binding = "#{binding[1..-1]}~"
+            end
+          end
+
+          bindingstr += "#{!bindingstr.empty? ? ',' : ''}#{part}:#{binding}"
+        end
+
+        details = @target[1]
+
+        # !!! FIXME: no String.delete in mRuby?!?! Maybe so when upgrading.
+        #name = details[:name].delete(',')
+        # !!! FIXME: ...no regexp either...  :/
+        #name = details[:name].gsub(/,/, ' ')  # !!! FIXME: will SDL let you escape these instead?
+        unescaped = details[:name]
+        name = ''
+        for i in 0..unescaped.length-1
+          ch = unescaped[i]
+          name += (ch == ',') ? ' ' : ch
+        end
+        return "#{details[:guid]},#{name},platform:#{@runtime.platform},#{bindingstr}"
+      end
+
+      def move_to_different_part part
+        if !@joystick_state[:axes].nil?
+          @joystick_state[:axes].each { |i| i[:farthestval] = i[:startingval] if !i.nil? }
+        end
+        @current_part = part
+      end
+
+      def previous_part
+        if @current_part > 0
+          # remove the binding that we previous had here so it can be reused.
+          bindstr = @bindings[@current_part - 1]
+          @bindings[@current_part - 1] = nil
+          @used_bindings[bindstr] = nil
+          move_to_different_part @current_part - 1
+        end
+      end
+
+      def next_part
+        if @current_part < (@parts.length - 1)
+          move_to_different_part @current_part + 1
+        else
+          @playing_around = true
+        end
+      end
+
+      def set_binding bindstr
+        return false if !@used_bindings[bindstr].nil?
+        @used_bindings[bindstr] = @current_part
+        @bindings[@current_part] = bindstr
+        return true
+      end
+
+      # Called when a lowlevel joystick moves an axis.
+      def rawjoystick_axis jid, axis, value
+        return if @target.nil? || jid != @target[0] || @fading != 0 # skip if not currently considering this joystick.
+
+        @joystick_state[:axes] ||= []
+        @joystick_state[:axes][axis] ||= {
+          moving: false,
+          startingval: 0,
+          currentval: 0,
+          farthestval: 0
+        }
+
+        # this is the logic from SDL's controllermap.c, more or less, since this is hard to get right from scratch.
+        state = @joystick_state[:axes][axis]
+        state[:currentval] = value
+        if !state[:moving]
+          state[:moving] = true
+          state[:startingval] = value
+          state[:farthestval] = value
+        end
+
+        current_distance = (value - state[:startingval]).abs
+        farthest_distance = (state[:farthestval] - state[:startingval]).abs
+        if current_distance > farthest_distance
+          state[:farthestval] = value
+          farthest_distance = (state[:farthestval] - state[:startingval]).abs
+        end
+
+        # If we've gone out far enough and started to come back, let's bind this axis
+        if (farthest_distance >= 16000) && (current_distance <= 10000)
+          next_part if set_binding("#{(state[:farthestval] < 0) ? '-' : '+'}a#{axis}")
+        end
+      end
+
+      # Called when a lowlevel joystick moves a hat.
+      def rawjoystick_hat jid, hat, value
+        return if @target.nil? || jid != @target[0] || @fading != 0 # skip if not currently considering this joystick.
+
+        @joystick_state[:hats] ||= []
+        @joystick_state[:hats][hat] = value
+
+        return if value == 0   # 0 == centered, skip it
+        next_part if set_binding("h#{hat}.#{value}")
+      end
+
+      # Called when a lowlevel joystick moves a button.
+      def rawjoystick_button jid, button, pressed
+        return if @target.nil? || jid != @target[0] || @fading != 0 # skip if not currently considering this joystick.
+
+        @joystick_state[:buttons] ||= []
+        @joystick_state[:buttons][button] = pressed
+
+        return if !pressed
+        next_part if set_binding("b#{button}")
+      end
+
+      def calc_fading
+        if @fading == 0
+          return 255
+        elsif @fading > 0   # fading in
+          percent = @toggled_at.global_ease(@animation_duration, :flip, :quint, :flip)
+          if percent >= 1.0
+            percent = 1.0
+            @fading = 0
+          end
+        else  # fading out
+          percent = @toggled_at.global_ease(@animation_duration, :flip, :quint)
+          if percent <= 0.0
+            percent = 0.0
+            @fading = 0
+          end
+        end
+
+        return (percent * 255.0).to_i
+      end
+
+      def render_basics args, msg, fade=255
+        joystickname = @target[1][:name]
+        args.outputs.primitives << [0, 0, $gtk.logical_width, $gtk.logical_height, 255, 255, 255, fade].solid
+        args.outputs.primitives << [0, 0, $gtk.logical_width, $gtk.logical_height, 'dragonruby-controller.png', 0, fade, 255, 255, 255].sprite
+        args.outputs.primitives << [$gtk.logical_width / 2, 700, joystickname, 2, 1, 0, 0, 0, fade].label
+        args.outputs.primitives << [$gtk.logical_height / 2, 650, msg, 0, 1, 0, 0, 0, 255].label if !msg.empty?
+      end
+
+      def render_part_highlight args, part, alpha=255
+        partsize = 41
+        args.outputs.primitives << [part[0], part[1], partsize, partsize, 255, 0, 0, alpha].border
+        args.outputs.primitives << [part[0]-1, part[1]-1, partsize+2, partsize+2, 255, 0, 0, alpha].border
+        args.outputs.primitives << [part[0]-2, part[1]-2, partsize+4, partsize+4, 255, 0, 0, alpha].border
+      end
+
+      def choose_target
+        if @target.nil?
+          while !@raw_joysticks.empty?
+            t = @raw_joysticks.shift  # see if there's a joystick waiting on us.
+            next if t[0] < 0  # just in case.
+            next if t[1][:guid].nil?  # did we already handle this guid? Dump it.
+            @target = t
+            break
+          end
+          return false if @target.nil?   # nothing to configure at the moment.
+          @toggled_at = Kernel.global_tick_count
+          @fading = 1
+          @current_part = 0
+          @part_alpha = 0
+          @part_alpha_increment = 10
+          @joystick_state = {}
+          @used_bindings = {}
+          @playing_around = false
+          @bindings = []
+        end
+        return true
+      end
+
+      def render_part_highlight_from_bindstr args, bindstr, alpha=255
+        partidx = @used_bindings[bindstr]
+        return if partidx.nil?
+        render_part_highlight args, @parts[partidx], alpha
+      end
+
+      def play_around args
+        return false if !@playing_around
+
+        if args.inputs.keyboard.key_down.escape
+          @current_part = 0
+          @part_alpha = 0
+          @part_alpha_increment = 10
+          @used_bindings = {}
+          @playing_around = false
+          @bindings = []
+        elsif args.inputs.keyboard.key_down.space
+          jid = @target[0]
+          bindingstr = build_binding_string
+          #puts("new controller binding: '#{bindingstr}'")
+          @runtime.ffi_misc.add_controller_config bindingstr
+          @runtime.ffi_misc.convert_rawjoystick_to_controller jid
+          @target[0] = -1  # Conversion closes the raw joystick.
+
+          # Handle any other pending joysticks that have the same GUID (so if you plug in four of the same model, we're already done!)
+          guid = @target[1][:guid]
+          @raw_joysticks.each { |jid, details|
+            if details[:guid] == guid
+              @runtime.ffi_misc.convert_rawjoystick_to_controller jid
+              details[:guid] = nil
+            end
+          }
+
+          # Done with this guy.
+          @playing_around = false
+          @toggled_at = Kernel.global_tick_count
+          @fading = -1
+          return false
+        end
+
+        render_basics args, 'Now play around with the controller, and make sure it feels right!'
+        args.outputs.primitives << [$gtk.logical_width / 2, 90, '[ESCAPE]: Reconfigure, [SPACE]: Save this configuration', 0, 1, 0, 0, 0, 255].label
+
+        axes = @joystick_state[:axes]
+        if !axes.nil?
+          for i in 0..axes.length-1
+            next if axes[i].nil?
+            value = axes[i][:currentval]
+            next if value.nil? || (value.abs < 16000)
+            render_part_highlight_from_bindstr args, "#{value < 0 ? '-' : '+'}a#{i}"
+          end
+        end
+
+        hats = @joystick_state[:hats]
+        if !hats.nil?
+          for i in 0..hats.length-1
+            value = hats[i]
+            next if value.nil? || (value == 0)
+            render_part_highlight_from_bindstr args, "h#{i}.#{value}"
+          end
+        end
+
+        buttons = @joystick_state[:buttons]
+        if !buttons.nil?
+          for i in 0..buttons.length-1
+            value = buttons[i]
+            next if value.nil? || !value
+            render_part_highlight_from_bindstr args, "b#{i}"
+          end
+        end
+
+        return true
+      end
+
+      def should_tick?
+        return true if @play_around
+        return true if @target
+        return false
+      end
+
+      def tick args
+        return true if play_around args
+        return false if !choose_target
+
+        jid = @target[0]
+
+        if @fading == 0
+          # Cancel config?
+          if args.inputs.keyboard.key_down.escape
+            # !!! FIXME: prompt to ignore this joystick forever or just this run
+            @toggled_at = Kernel.global_tick_count
+            @fading = -1
+          end
+        end
+
+        if @fading == 0
+          if args.inputs.keyboard.key_down.backspace
+            previous_part
+          elsif args.inputs.keyboard.key_down.space
+            next_part
+          end
+        end
+
+        fade = calc_fading
+        if (@fading < 0) && (fade == 0)
+          @runtime.ffi_misc.close_raw_joystick(jid) if jid >= 0
+          @target = nil   # done with this controller
+          return false
+        end
+
+        render_basics args, (@fading >= 0) ? "We don't recognize this controller, so tell us about it!" : '', fade
+
+        return true if fade < 255  # all done for now
+
+        part = @parts[@current_part]
+        args.outputs.primitives << [$gtk.logical_width / 2, 575, "Please press the #{part[2]}.", 0, 1, 0, 0, 0, 255].label
+        render_part_highlight args, part, @part_alpha
+        args.outputs.primitives << [$gtk.logical_width / 2, 90, '[ESCAPE]: Ignore controller, [BACKSPACE]: Go back one button, [SPACE]: Skip this button', 0, 1, 0, 0, 0, 255].label
+
+        @part_alpha += @part_alpha_increment
+        if (@part_alpha_increment > 0) && (@part_alpha >= 255)
+          @part_alpha = 255
+          @part_alpha_increment = -10
+        elsif (@part_alpha_increment < 0) && (@part_alpha <= 0)
+          @part_alpha = 0
+          @part_alpha_increment = 10
+        end
+
+        return true
+      end
+    end
+  end
+end
+
+</pre>
+<h1 id='--./dragon/controller/keys.rb'>./dragon/controller/keys.rb</h1>
+<pre># coding: utf-8
+# Copyright 2019 DragonRuby LLC
+# MIT License
+# controller/keys.rb has been released under MIT (*only this file*).
+
+module GTK
+  class Controller
+    class Keys
+      include Serialize
+
+      LABELS = [
+        :up, :down, :left, :right,
+        :a, :b, :x, :y,
+        :l1, :r1,
+        :l2, :r2,
+        :l3, :r3,
+        :start, :select,
+        :directional_up, :directional_down, :directional_left, :directional_right
+      ].freeze
+
+      LABELS.each do |label|
+        attr_reader label
+      end
+
+      # Activate a key.
+      #
+      # @return [void]
+      def activate key
+        instance_variable_set("@#{key}", Kernel.tick_count + 1)
+      end
+
+      # Deactivate a key.
+      #
+      # @return [void]
+      def deactivate key
+        instance_variable_set("@#{key}", nil)
+      end
+
+      # Clear all key inputs.
+      #
+      # @return [void]
+      def clear
+        LABELS.each { |label| deactivate(label) }
+      end
+
+      def truthy_keys
+        LABELS.select { |label| send(label) }
+      end
+    end
+  end
+end
+
+</pre>
+<h1 id='--./dragon/directional_input_helper_methods.rb'>./dragon/directional_input_helper_methods.rb</h1>
+<pre># coding: utf-8
+# Copyright 2019 DragonRuby LLC
+# MIT License
+# directional_input_helper_methods.rb has been released under MIT (*only this file*).
+
+module GTK
+  # This is a module that contains normalization of behavior related to `up`|`down`|`left`|`right` on keyboards and controllers.
+  module DirectionalInputHelperMethods
+    def self.included klass
+      key_state_methods = [:key_held, :key_down]
+      directional_methods = [:up, :down, :left, :right]
+      method_results = (directional_methods + key_state_methods).map {|m| [m, klass.instance_methods.include?(m)] }
+
+      error_message = <<-S
+* ERROR
+The GTK::DirectionalKeys module should only be included in objects that respond to the following api heirarchy:
+
+- (#{ directional_methods.join("|") })
+- key_held.(#{ directional_methods.join("|") })
+- key_down.(#{ directional_methods.join("|") })
+
+#{klass} does not respond to all of these methods (here is the diagnostics):
+#{method_results.map {|m, r| "- #{m}: #{r}"}.join("\n")}
+
+Please implement the methods that returned false inthe list above.
+S
+      unless method_results.map {|m, result| result}.all?
+        raise error_message
+      end
+    end
+
+    # Returns a signal indicating left (`-1`), right (`1`), or neither ('0').
+    #
+    # @return [Integer]
+    def left_right
+      return -1 if self.left
+      return  1 if self.right
+      return  0
+    end
+
+    # Returns a signal indicating up (`1`), down (`-1`), or neither ('0').
+    #
+    # @return [Integer]
+    def up_down
+      return  1 if self.up
+      return -1 if self.down
+      return  0
+    end
+
+    # Returns a normal vector (in the form of an Array with two values). If no directionals are held/down, the function returns nil.
+    #
+    # The possible results are:
+    #
+    # - ~nil~ which denotes that no directional input exists.
+    # - ~[   0,    1]~ which denotes that only up is being held/pressed.
+    # - ~[   0,   -1]~ which denotes that only down is being held/pressed.
+    # - ~[ 0.5,  0.5]~ which denotes that right and up are being pressed/held.
+    # - ~[-0.5, -0.5]~ which denotes that left and down are being pressed/held.
+    #
+    # @gtk
+    def directional_vector
+      lr, ud = [self.left_right, self.up_down]
+
+      if lr == 0 && ud == 0
+        return nil
+      elsif lr.abs == ud.abs
+        return [lr.half, ud.half]
+      else
+        return [lr, ud]
+      end
+    end
+
+    def method_missing m, *args
+      # combine the key with ctrl_
+      if m.to_s.start_with?("ctrl_")
+        other_key = m.to_s.split("_").last
+        define_singleton_method(m) do
+          return self.key_up.send(other_key.to_sym) && self.key_up.control
+        end
+
+        return send(m)
+      else
+      # see if the key is either held or down
+        define_singleton_method(m) do
+          self.key_down.send(m) || self.key_held.send(m)
+        end
+
+        return send(m)
+      end
+    end
+  end
+end
+
+</pre>
+<h1 id='--./dragon/geometry.rb'>./dragon/geometry.rb</h1>
+<pre># coding: utf-8
+# Copyright 2019 DragonRuby LLC
+# MIT License
+# geometry.rb has been released under MIT (*only this file*).
+
+module GTK
+  module Geometry
+    # Returns f(t) for a cubic Bezier curve.
+    def self.cubic_bezier t, a, b, c, d
+      s  = 1 - t
+      s0 = 1
+      s1 = s
+      s2 = s * s
+      s3 = s * s * s
+
+      t0 = 1
+      t1 = t
+      t2 = t * t
+      t3 = t * t * t
+
+      1 * s3 * t0 * a +
+      3 * s2 * t1 * b +
+      3 * s1 * t2 * c +
+      1 * s0 * t3 * d
+    end
+
+    # Returns true if a primitive's rectangle is entirely inside another primitive's rectangle.
+    # @gtk
+    def inside_rect? outer
+      Geometry.inside_rect? self, outer
+    end
+
+    # Returns true if a primitive's rectangle overlaps another primitive's rectangle.
+    # @gtk
+    def intersect_rect? other, tolerance = 0.1
+      Geometry.intersect_rect? self, other, tolerance
+    end
+
+    def intersects_rect? *args
+      Geometry.intersects_rect?(*args)
+    end
+
+    def scale_rect_extended percentage_x: percentage_x,
+                            percentage_y: percentage_y,
+                            anchor_x: anchor_x,
+                            anchor_y: anchor_y
+
+      Geometry.scale_rect_extended self,
+                                   percentage_x: percentage_x,
+                                   percentage_y: percentage_y,
+                                   anchor_x: anchor_x,
+                                   anchor_y: anchor_y
+    end
+
+    # Scales a primitive rect by a percentage.
+    # @gtk
+    def scale_rect percentage, *anchors
+      Geometry.scale_rect self, percentage, *anchors
+    end
+
+    # Returns the angle from one primitive to another primitive.
+    # @gtk
+    def angle_to other_point
+      Geometry.angle_to self, other_point
+    end
+
+    # Returns the angle to one primitive from another primitive.
+    # @gtk
+    def angle_from other_point
+      Geometry.angle_from self, other_point
+    end
+
+    # Returns true if a primitive is within a circle specified by the circle's center and radius.
+    # @gtk
+    def point_inside_circle? circle_center_point, radius
+      Geometry.point_inside_circle? self, circle_center_point, radius
+    end
+
+    def center_inside_rect other_rect
+      offset_x = (other_rect.w - w).half
+      offset_y = (other_rect.h - h).half
+      new_rect = self.shift_rect(0, 0)
+      new_rect.x = other_rect.x + offset_x
+      new_rect.y = other_rect.y + offset_y
+      new_rect
+    rescue Exception => e
+      raise e, <<-S
+* ERROR:
+center_inside_rect for self #{self} and other_rect #{other_rect}. Failed with exception #{e}.
+S
+    end
+
+    def center_inside_rect_y other_rect
+      offset_y = (other_rect.h - h).half
+      new_rect = self.shift_rect(0, 0)
+      new_rect.y = other_rect.y + offset_y
+      new_rect
+    rescue Exception => e
+      raise e, <<-S
+* ERROR:
+center_inside_rect_y for self #{self} and other_rect #{other_rect}. Failed with exception #{e}.
+S
+    end
+
+    def center_inside_rect_x other_rect
+      offset_x = (other_rect.w - w).half
+      new_rect = self.shift_rect(0, 0)
+      new_rect.x = other_rect.x + offset_x
+      new_rect
+    rescue Exception => e
+      raise e, <<-S
+* ERROR:
+center_inside_rect_x for self #{self} and other_rect #{other_rect}. Failed with exception #{e}.
+S
+    end
+
+    # Returns a primitive that is anchored/repositioned based off its retangle.
+    # @gtk
+    def anchor_rect anchor_x, anchor_y
+      current_w = self.w
+      current_h = self.h
+      delta_x = -1 * (anchor_x * current_w)
+      delta_y = -1 * (anchor_y * current_h)
+      self.shift_rect(delta_x, delta_y)
+    end
+
+    def angle_given_point other_point
+      raise ":angle_given_point has been deprecated use :angle_from instead."
+    end
+
+    # @gtk
+    def self.shift_line line, x, y
+      if line.is_a?(Array) || line.is_a?(Hash)
+        new_line = line.dup
+        new_line.x  += x
+        new_line.x2 += x
+        new_line.y  += y
+        new_line.y2 += y
+        new_line
+      else
+        raise "shift_line for #{line} is not supported."
+      end
+    end
+
+    def self.intersects_rect? *args
+      raise <<-S
+intersects_rect? (with an \"s\") has been deprecated.
+Use intersect_rect? instead (remove the \"s\").
+
+* NOTE:
+Ruby's naming convention is to *never* include the \"s\" for
+interrogative method names (methods that end with a ?). It
+doesn't sound grammatically correct, but that has been the
+rule for a long time (and why intersects_rect? has been deprecated).
+
+S
+    end
+
+    # @gtk
+    def self.line_y_intercept line
+      line.y - line_slope(line) * line.x
+    end
+
+    # @gtk
+    def self.angle_between_lines line_one, line_two, replace_infinity: nil
+      m_line_one = line_slope line_one, replace_infinity: replace_infinity
+      m_line_two = line_slope line_two, replace_infinity: replace_infinity
+      Math.atan((m_line_one - m_line_two) / (1 + m_line_two * m_line_one)).to_degrees
+    end
+
+    # @gtk
+    def self.line_slope line, replace_infinity: nil
+      (line.y2 - line.y).fdiv(line.x2 - line.x)
+                        .replace_infinity(replace_infinity)
+    end
+
+    # @gtk
+    def self.ray_test point, line
+      slope = (line.y2 - line.y).fdiv(line.x2 - line.x)
+
+      if line.x > line.x2
+        point_two, point_one = [point_one, point_two]
+      end
+
+      r = ((line.x2 - line.x) * (point.y - line.y) -
+           (point.x -  line.x) * (line.y2 - line.y))
+
+      if r == 0
+        return :on
+      elsif r < 0
+        return :right if slope >= 0
+        return :left
+      elsif r > 0
+        return :left if slope >= 0
+        return :right
+      end
+    end
+
+    # @gtk
+    def self.line_rect line
+      if line.x > line.x2
+        x  = line.x2
+        y  = line.y2
+        x2 = line.x
+        y2 = line.y
+      else
+        x  = line.x
+        y  = line.y
+        x2 = line.x2
+        y2 = line.y2
+      end
+
+      w = x2 - x
+      h = y2 - y
+
+      { x: x, y: y, w: w, h: h }
+    end
+
+    # @gtk
+    def self.line_intersect line_one, line_two
+      m1 = line_slope(line_one)
+      m2 = line_slope(line_two)
+      b1 = line_y_intercept(line_one)
+      b2 = line_y_intercept(line_two)
+      x = (b1 - b2) / (m2 - m1)
+      y = (-b2.fdiv(m2) + b1.fdiv(m1)).fdiv(1.fdiv(m1) - 1.fdiv(m2))
+      [x, y]
+    end
+
+    def self.contract_intersect_rect?
+      [:left, :right, :top, :bottom]
+    end
+
+    # @gtk
+    def self.intersect_rect? rect_one, rect_two, tolerance = 0.1
+      return false if rect_one.right - tolerance < rect_two.left + tolerance
+      return false if rect_one.left + tolerance > rect_two.right - tolerance
+      return false if rect_one.top - tolerance < rect_two.bottom + tolerance
+      return false if rect_one.bottom + tolerance > rect_two.top - tolerance
+      return true
+    rescue Exception => e
+      context_help_rect_one = (rect_one.help_contract_implementation contract_intersect_rect?)[:not_implemented_methods]
+      context_help_rect_two = (rect_two.help_contract_implementation contract_intersect_rect?)[:not_implemented_methods]
+      context_help = ""
+      if context_help_rect_one && context_help_rect_one.length > 0
+        context_help += <<-S
+rect_one needs to implement the following methods: #{context_help_rect_one}
+
+You may want to try include the ~AttrRect~ module which will give you these methods.
+S
+      end
+
+      if context_help_rect_two && context_help_rect_two.length > 0
+        context_help += <<-S
+* FAILURE REASON:
+rect_two needs to implement the following methods: #{context_help_rect_two}
+NOTE: You may want to try include the ~GTK::Geometry~ module which will give you these methods.
+S
+      end
+
+      raise e, <<-S
+* ERROR:
+:intersect_rect? failed for
+- rect_one: #{rect_one}
+- rect_two: #{rect_two}
+#{context_help}
+S
+    end
+
+    # @gtk
+    def self.to_square size, x, y, anchor_x = 0.5, anchor_y = nil
+      anchor_y ||= anchor_x
+      x = x.shift_left(size * anchor_x)
+      y = y.shift_down(size * anchor_y)
+      [x, y, size, size]
+    rescue Exception => e
+      raise e, ":to_square failed for size: #{size} x: #{x} y: #{y} anchor_x: #{anchor_x} anchor_y: #{anchor_y}."
+    end
+
+    # @gtk
+    def self.distance point_one, point_two
+      Math.sqrt((point_two.x - point_one.x)**2 + (point_two.y - point_one.y)**2)
+    rescue Exception => e
+      raise e, ":distance failed for point_one: #{point_one} point_two #{point_two}."
+    end
+
+    # @gtk
+    def self.angle_from start_point, end_point
+      d_y = end_point.y - start_point.y
+      d_x = end_point.x - start_point.x
+      Math::PI.+(Math.atan2(d_y, d_x)).to_degrees
+    rescue Exception => e
+      raise e, ":angle_from failed for start_point: #{start_point} end_point: #{end_point}."
+    end
+
+    # @gtk
+    def self.angle_to start_point, end_point
+      angle_from end_point, start_point
+    rescue Exception => e
+      raise e, ":angle_to failed for start_point: #{start_point} end_point: #{end_point}."
+    end
+
+    # @gtk
+    def self.point_inside_circle? point, circle_center_point, radius
+      (point.x - circle_center_point.x) ** 2 + (point.y - circle_center_point.y) ** 2 < radius ** 2
+    rescue Exception => e
+      raise e, ":point_inside_circle? failed for point: #{point} circle_center_point: #{circle_center_point} radius: #{radius}"
+    end
+
+    # @gtk
+    def self.inside_rect? inner_rect, outer_rect
+      inner_rect.x >= outer_rect.x &&
+      inner_rect.right <= outer_rect.right &&
+      inner_rect.y >= outer_rect.y &&
+      inner_rect.top <= outer_rect.top
+    rescue Exception => e
+      raise e, ":inside_rect? failed for inner_rect: #{inner_rect} outer_rect: #{outer_rect}."
+    end
+
+    # @gtk
+    def self.scale_rect_extended rect,
+                                 percentage_x: percentage_x,
+                                 percentage_y: percentage_y,
+                                 anchor_x: anchor_x,
+                                 anchor_y: anchor_y
+      anchor_x ||= 0.0
+      anchor_y ||= 0.0
+      percentage_x ||= 1.0
+      percentage_y ||= 1.0
+      new_w = rect.w * percentage_x
+      new_h = rect.h * percentage_y
+      new_x = rect.x + (rect.w - new_w) * anchor_x
+      new_y = rect.y + (rect.h - new_h) * anchor_y
+      if rect.is_a? Array
+        return [
+          new_x,
+          new_y,
+          new_w,
+          new_h,
+          *rect[4..-1]
+        ]
+      elsif rect.is_a? Hash
+        return rect.merge(x: new_x, y: new_y, w: new_w, h: new_h)
+      else
+        rect.x = new_x
+        rect.y = new_y
+        rect.w = new_w
+        rect.h = new_h
+        return rect
+      end
+    rescue Exception => e
+      raise e, ":scale_rect_extended failed for rect: #{rect} percentage_x: #{percentage_x} percentage_y: #{percentage_y} anchors_x: #{anchor_x} anchor_y: #{anchor_y}."
+    end
+
+    # @gtk
+    def self.scale_rect rect, percentage, *anchors
+      anchor_x, anchor_y = *anchors.flatten
+      anchor_x ||= 0
+      anchor_y ||= anchor_x
+      Geometry.scale_rect_extended rect,
+                                   percentage_x: percentage,
+                                   percentage_y: percentage,
+                                   anchor_x: anchor_x,
+                                   anchor_y: anchor_y
+    rescue Exception => e
+      raise e, ":scale_rect failed for rect: #{rect} percentage: #{percentage} anchors [#{anchor_x} (x), #{anchor_y} (y)]."
+    end
+  end # module Geometry
+end # module GTK
+
+</pre>
+<h1 id='--./dragon/grid.rb'>./dragon/grid.rb</h1>
+<pre># coding: utf-8
+# Copyright 2019 DragonRuby LLC
+# MIT License
+# grid.rb has been released under MIT (*only this file*).
+
+module GTK
+  class Grid
+    include Serialize
+    SCREEN_Y_DIRECTION = -1.0
+
+    # The coordinate system currently in use.
+    #
+    # @return [Symbol] `:bottom_left` or `:center`
+    attr_accessor :name
+
+    # Returns the "x" coordinate indicating the bottom of the screen.
+    #
+    # @return [Float]
+    attr_accessor :bottom
+
+    # Returns the "x" coordinate indicating the top of the screen.
+    #
+    # @return [Float]
+    attr_accessor :top
+
+    # Returns the "y" coordinate indicating the left of the screen.
+    #
+    # @return [Float]
+    attr_accessor :left
+
+    # Returns the "y" coordinate indicating the right of the screen.
+    #
+    # @return [Float]
+    attr_accessor :right
+
+    # Returns the "x" coordinate indicating the center of the screen.
+    #
+    # @return [Float]
+    attr_accessor :center_x
+
+    # Returns the "y" coordinate indicating the center of the screen.
+    #
+    # @return [Float]
+    attr_accessor :center_y
+
+    # Returns the bottom left and top right coordinates in a single list.
+    #
+    # @return [[Float, Float, Float, Float]]
+    attr_accessor :rect
+
+    # Returns the "x" coordinate of the origin.
+    #
+    # @return [Float]
+    attr_accessor :origin_x
+
+    # Returns the "y" coordinate of the origin.
+    #
+    # @return [Float]
+    attr_accessor :origin_y
+
+    attr_accessor :left_margin, :bottom_margin
+
+    def initialize runtime
+      @runtime = runtime
+      @ffi_draw = runtime.ffi_draw
+      origin_bottom_left!
+    end
+
+    # Returns `x` plus the origin "x".
+    #
+    # @return [Float]
+    def transform_x x
+      @origin_x + x
+    end
+
+    # Returns `x` minus the origin "x".
+    #
+    # @return [Float]
+    def untransform_x x
+      x - @origin_x
+    end
+
+    # Returns `y` plus the origin "y".
+    #
+    # @return [Float]
+    def transform_y y
+      @origin_y + y * SCREEN_Y_DIRECTION
+    end
+
+    # Returns `y` minus the origin "y".
+    #
+    # @return [Float]
+    def untransform_y y
+      @origin_y + y * SCREEN_Y_DIRECTION
+    end
+
+    def ffi_draw
+      @ffi_draw
+    end
+
+    def ffi_draw= value
+      @ffi_draw = value
+    end
+
+    # Sets the rendering coordinate system to have its origin in the bottom left.
+    #
+    # @return [void]
+    # @gtk
+    def origin_bottom_left!
+      return if @name == :bottom_left
+      @name = :bottom_left
+      @origin_x = 0.0
+      @origin_y = @runtime.logical_height
+      @left   = 0.0
+      @right  = @runtime.logical_width
+      @top    = @runtime.logical_height
+      @bottom = 0.0
+      @left_margin = 0.0
+      @bottom_margin = 0.0
+      @center_x = @runtime.logical_width.half
+      @center_y = @runtime.logical_height.half
+      @rect   = [@left, @bottom, @runtime.logical_width, @runtime.logical_height].rect
+      @center = [@center_x, @center_y].point
+      @ffi_draw.set_grid @origin_x, @origin_y, SCREEN_Y_DIRECTION
+    end
+
+    # Sets the rendering coordinate system to have its origin in the center.
+    #
+    # @return [void]
+    # @gtk
+    def origin_center!
+      return if @name == :center
+      @name = :center
+      @origin_x = @runtime.logical_width.half
+      @origin_y = @runtime.logical_height.half
+      @left   =  [email protected]_width.half
+      @right  =   @runtime.logical_width.half
+      @top    =   @runtime.logical_height.half
+      @bottom =  [email protected]_height.half
+      @center_x = 0.0
+      @center_y = 0.0
+      @rect   = [@left, @bottom, @runtime.logical_width, @runtime.logical_height].rect
+      @center = [@center_x, @center_y].point
+      @ffi_draw.set_grid @origin_x, @origin_y, SCREEN_Y_DIRECTION
+    end
+
+    # The logical width used for rendering.
+    #
+    # @return [Float]
+    def w
+      @runtime.logical_width
+    end
+
+    # Half the logical width used for rendering.
+    #
+    # @return [Float]
+    def w_half
+      w.half
+    end
+
+    # The logical height used for rendering.
+    #
+    # @return [Float]
+    def h
+      @runtime.logical_height
+    end
+
+    # Half the logical height used for rendering.
+    #
+    # @return [Float]
+    def h_half
+      h.half
+    end
+
+    # Returns the coordinates indicating the center of the screen.
+    #
+    # @return [[Float, Float]]
+    def center
+      @center
+    end
+
+    # Returns the coordinates indicating the bottom right of the screen.
+    #
+    # @return [[Float, Float]]
+    def bottom_right
+      [@right, @bottom].point
+    end
+  end
+end
+
+</pre>
+<h1 id='--./dragon/inputs.rb'>./dragon/inputs.rb</h1>
+<pre># coding: utf-8
+# Copyright 2019 DragonRuby LLC
+# MIT License
+# inputs.rb has been released under MIT (*only this file*).
+
+module GTK
+  # Represents all the keys available on the keyboard.
+  # @gtk
+  class KeyboardKeys
+    include Serialize
+
+    # @gtk
+    attr_accessor :exclamation_point,
+                  :zero, :one, :two, :three, :four,
+                  :five, :six, :seven, :eight, :nine,
+                  :backspace, :delete, :escape, :enter, :tab,
+                  :open_round_brace, :close_round_brace,
+                  :open_curly_brace, :close_curly_brace,
+                  :open_square_brace, :close_square_brace,
+                  :colon, :semicolon, :equal_sign,
+                  :hyphen, :space, :dollar_sign,
+                  :double_quotation_mark,
+                  :single_quotation_mark,
+                  :backtick,
+                  :tilde, :period, :comma, :pipe,
+                  :underscore,
+                  :a, :b, :c, :d, :e, :f, :g, :h,
+                  :i, :j, :k, :l, :m, :n, :o, :p,
+                  :q, :r, :s, :t, :u, :v, :w, :x,
+                  :y, :z,
+                  :shift, :control, :alt, :meta,
+                  :left, :right, :up, :down, :pageup, :pagedown,
+                  :char, :plus, :at, :forward_slash, :back_slash, :asterisk,
+                  :less_than, :greater_than, :carat, :ampersand, :superscript_two,
+                  :circumflex,
+                  :question_mark, :section_sign, :ordinal_indicator,
+                  :raw_key
+
+    def self.sdl_to_key raw_key, modifier
+      return nil unless (raw_key >= 0 && raw_key <= 255) ||
+                        raw_key == 1073741903 ||
+                        raw_key == 1073741904 ||
+                        raw_key == 1073741905 ||
+                        raw_key == 1073741906 ||
+                        raw_key == 1073741899 ||
+                        raw_key == 1073741902
+
+      char = KeyboardKeys.char_with_shift raw_key, modifier
+      names = KeyboardKeys.char_to_method char, raw_key
+      names << :alt if (modifier & (256|512)) != 0    # alt key
+      names << :meta if (modifier & (1024|2048)) != 0 # meta key (command/apple/windows key)
+      names << :control if (modifier & (64|128)) != 0 # ctrl key
+      names << :shift if (modifier & (1|2)) != 0      # shift key
+      names
+    end
+
+    def self.utf_8_char raw_key
+      return "²" if raw_key == 178
+      return "§" if raw_key == 167
+      return "º" if raw_key == 186
+      return raw_key.chr
+    end
+
+    def self.char_with_shift raw_key, modifier
+      return nil unless raw_key >= 0 && raw_key <= 255
+      if modifier != 1 && modifier != 2 && modifier != 3
+        return utf_8_char raw_key
+      else
+        @shift_keys ||= {
+          '`' => '~', '-' => '_', "'" => '"', "1" => '!',
+          "2" => '@', "3" => '#', "4" => '$', "5" => '%',
+          "6" => '^', "7" => '&', "8" => '*', "9" => '(',
+          "0" => ')', ";" => ":", "=" => "+", "[" => "{",
+          "]" => "}", '\'=> "|", '/' => "?", '.' => ">",
+          ',' => "<", 'a' => 'A', 'b' => 'B', 'c' => 'C',
+          'd' => 'D', 'e' => 'E', 'f' => 'F', 'g' => 'G',
+          'h' => 'H', 'i' => 'I', 'j' => 'J', 'k' => 'K',
+          'l' => 'L', 'm' => 'M', 'n' => 'N', 'o' => 'O',
+          'p' => 'P', 'q' => 'Q', 'r' => 'R', 's' => 'S',
+          't' => 'T', 'u' => 'U', 'v' => 'V', 'w' => 'W',
+          'x' => 'X', 'y' => 'Y', 'z' => 'Z'
+        }
+
+        @shift_keys[raw_key.chr.to_s] || raw_key.chr.to_s
+      end
+    end
+
+    def self.char_to_method_hash
+      @char_to_method ||= {
+        'A'  => [:a, :shift],
+        'B'  => [:b, :shift],
+        'C'  => [:c, :shift],
+        'D'  => [:d, :shift],
+        'E'  => [:e, :shift],
+        'F'  => [:f, :shift],
+        'G'  => [:g, :shift],
+        'H'  => [:h, :shift],
+        'I'  => [:i, :shift],
+        'J'  => [:j, :shift],
+        'K'  => [:k, :shift],
+        'L'  => [:l, :shift],
+        'M'  => [:m, :shift],
+        'N'  => [:n, :shift],
+        'O'  => [:o, :shift],
+        'P'  => [:p, :shift],
+        'Q'  => [:q, :shift],
+        'R'  => [:r, :shift],
+        'S'  => [:s, :shift],
+        'T'  => [:t, :shift],
+        'U'  => [:u, :shift],
+        'V'  => [:v, :shift],
+        'W'  => [:w, :shift],
+        'X'  => [:x, :shift],
+        'Y'  => [:y, :shift],
+        'Z'  => [:z, :shift],
+        "!"  => [:exclamation_point],
+        "0"  => [:zero],
+        "1"  => [:one],
+        "2"  => [:two],
+        "3"  => [:three],
+        "4"  => [:four],
+        "5"  => [:five],
+        "6"  => [:six],
+        "7"  => [:seven],
+        "8"  => [:eight],
+        "9"  => [:nine],
+        "\b" => [:backspace],
+        "\e" => [:escape],
+        "\r" => [:enter],
+        "\t" => [:tab],
+        "("  => [:open_round_brace],
+        ")"  => [:close_round_brace],
+        "{"  => [:open_curly_brace],
+        "}"  => [:close_curly_brace],
+        "["  => [:open_square_brace],
+        "]"  => [:close_square_brace],
+        ":"  => [:colon],
+        ";"  => [:semicolon],
+        "="  => [:equal_sign],
+        "-"  => [:hyphen],
+        " "  => [:space],
+        "$"  => [:dollar_sign],
+        "\"" => [:double_quotation_mark],
+        "'"  => [:single_quotation_mark],
+        "`"  => [:backtick],
+        "~"  => [:tilde],
+        "."  => [:period],
+        ","  => [:comma],
+        "|"  => [:pipe],
+        "_"  => [:underscore],
+        "#"  => [:hash],
+        "+"  => [:plus],
+        "@"  => [:at],
+        "/"  => [:forward_slash],
+        "\" => [:back_slash],
+        "*"  => [:asterisk],
+        "<"  => [:less_than],
+        ">"  => [:greater_than],
+        "^"  => [:circumflex],
+        "&"  => [:ampersand],
+        "²"  => [:superscript_two],
+        "§"  => [:section_sign],
+        "?"  => [:question_mark],
+        '%'  => [:percent_sign],
+        "º"  => [:ordinal_indicator],
+        1073741903 => [:right],
+        1073741904 => [:left],
+        1073741905 => [:down],
+        1073741906 => [:up],
+        1073741899 => [:pageup],
+        1073741902 => [:pagedown],
+        127 => [:delete]
+      }
+    end
+
+    def self.char_to_method char, int = nil
+      char_to_method_hash[char] || char_to_method_hash[int] || [char.to_sym || int]
+    end
+
+    def clear
+      set truthy_keys, false
+      @scrubbed_ivars = nil
+    end
+
+    # @gtk
+    def left_right
+      return -1 if self.left
+      return  1 if self.right
+      return  0
+    end
+
+    # @gtk
+    def up_down
+      return  1 if self.up
+      return -1 if self.down
+      return  0
+    end
+
+    # @gtk
+    def truthy_keys
+      get(all).find_all { |_, v| v }
+              .map { |k, _| k.to_sym }
+    end
+
+    # @gtk
+    def all? keys
+      values = get(keys.map { |k| k.without_ending_bang })
+      all_true = values.all? do |k, v|
+        v
+      end
+
+      if all_true
+        keys.each do |k|
+          clear_key k if k.end_with_bang?
+        end
+      end
+
+      all_true
+    end
+
+    # @gtk
+    def any? keys
+      values = get(keys.map { |k| k.without_ending_bang })
+      any_true = values.any? do |k, v|
+        v
+      end
+
+      if any_true
+        keys.each do |k|
+          clear_key k if k.end_with_bang?
+        end
+      end
+
+      any_true
+    end
+
+    # @gtk
+    def clear_key key
+      @scrubbed_ivars = nil
+      self.instance_variable_set("@#{key.without_ending_bang}", false)
+    end
+
+    # @gtk
+    def all
+      @scrubbed_ivars ||= self.instance_variables
+                              .reject { |i| i == :@all || i == :@scrubbed_ivars }
+                              .map { |i| i.to_s.gsub("@", "") }
+
+      get(@scrubbed_ivars).map { |k, _| k }
+    end
+
+    # @gtk
+    def get collection
+      return [] if collection.length == 0
+      collection.map do |m|
+        if m.end_with_bang?
+          clear_after_return = true
+        end
+
+        value = self.instance_variable_get("@#{m.without_ending_bang}".to_sym)
+        clear_key m if clear_after_return
+        [m.without_ending_bang, value]
+      end
+    end
+
+    # @gtk
+    def set collection, value = true
+      return if collection.length == 0
+      @scrubbed_ivars = nil
+      value = Kernel.tick_count if value
+
+      collection.each do |m|
+        self.instance_variable_set("@#{m.to_s}".to_sym, value)
+      rescue Exception => e
+        raise e, <<-S
+* ERROR:
+Attempted to set the a key on the DragonRuby GTK's Keyboard data
+structure, but the property isn't available for raw_key #{raw_key} #{m}.
+
+You should contact DragonRuby and tell them to associate the raw_key #{raw_key}
+with a friendly property name (we are open to suggestions if you have any).
+[GTK::KeyboardKeys#set, GTK::KeyboardKeys#char_to_method]
+
+S
+      end
+    end
+
+    def method_missing m, *args
+      begin
+        define_singleton_method(m) do
+          r = self.instance_variable_get("@#{m.without_ending_bang}".to_sym)
+          clear_key m
+          return r
+        end
+
+        return self.send m
+      rescue Exception => e
+        log_important "#{e}"
+      end
+
+      raise <<-S
+* ERROR:
+There is no member on the keyboard called #{m}. Here is a to_s representation of what's available:
+
+#{KeyboardKeys.char_to_method_hash.map { |k, v| "[#{k} => #{v.join(",")}]" }.join("  ")}
+
+S
+    end
+
+    def serialize
+      hash = super
+      hash.delete(:scrubbed_ivars)
+      hash[:truthy_keys] = self.truthy_keys
+      hash
+    end
+  end
+end
+
+module GTK
+  # @gtk
+  class Keyboard
+
+    # @return [KeyboardKeys]
+    # @gtk
+    attr_accessor :key_up
+
+    # @return [KeyboardKeys]
+    # @gtk
+    attr_accessor :key_held
+
+    # @return [KeyboardKeys]
+    # @gtk
+    attr_accessor :key_down
+
+    # @return [Boolean]
+    # @gtk
+    attr_accessor :has_focus
+
+    def initialize
+      @key_up      = KeyboardKeys.new
+      @key_held    = KeyboardKeys.new
+      @key_down    = KeyboardKeys.new
+      @has_focus   = false
+    end
+
+    def p
+      @key_down.p || @key_held.p
+    end
+
+    # The left arrow or "a" was pressed.
+    #
+    # @return [Boolean]
+    def left
+      @key_up.left || @key_held.left || a
+    end
+
+    # The right arrow or "d" was pressed.
+    #
+    # @return [Boolean]
+    def right
+      @key_up.right || @key_held.right || d
+    end
+
+    # The up arrow or "w" was pressed.
+    #
+    # @return [Boolean]
+    def up
+      @key_up.up || @key_held.up || w
+    end
+
+    # The down arrow or "s" was pressed.
+    #
+    # @return [Boolean]
+    def down
+      @key_up.down || @key_held.down || s
+    end
+
+    # Clear all current key presses.
+    #
+    # @return [void]
+    def clear
+      @key_up.clear
+      @key_held.clear
+      @key_down.clear
+    end
+
+    def serialize
+      {
+        key_up: @key_up.serialize,
+        key_held: @key_held.serialize,
+        key_down: @key_down.serialize,
+        has_focus: @has_focus
+      }
+    end
+    alias_method :inspect, :serialize
+
+    # @return [String]
+    def to_s
+      serialize.to_s
+    end
+
+    def key
+      {
+        down: @key_down.truthy_keys,
+        held: @key_held.truthy_keys,
+        down_or_held: (@key_down.truthy_keys + @key_held.truthy_keys).uniq,
+        up: @key_up.truthy_keys,
+      }
+    end
+    alias_method :keys, :key
+
+    include DirectionalInputHelperMethods
+  end
+end
+
+module GTK
+  class MousePoint
+    include GTK::Geometry
+
+    # @gtk
+    attr_accessor :x, :y, :point, :created_at, :global_created_at
+
+    def initialize x, y
+      @x = x
+      @y = y
+      @point = [x, y]
+      @created_at = Kernel.tick_count
+      @global_created_at = Kernel.global_tick_count
+    end
+
+    def w; 0; end
+    def h; 0; end
+    def left; x; end
+    def right; x; end
+    def top; y; end
+    def bottom; y; end
+
+    def created_at_elapsed
+      @created_at.elapsed_time
+    end
+
+    def to_hash
+      serialize
+    end
+
+    def serialize
+      {
+        x: @x,
+        y: @y,
+        created_at: @created_at,
+        global_created_at: @global_created_at
+      }
+    end
+
+    def inspect
+      serialize.to_s
+    end
+
+    def to_s
+      serialize.to_s
+    end
+  end
+
+  # Provides access to the mouse.
+  #
+  # @gtk
+  class Mouse
+
+    # @gtk
+    attr_accessor :moved,
+                  :moved_at,
+                  :global_moved_at,
+                  :up, :has_focus,
+                  :button_bits, :button_left,
+                  :button_middle, :button_right,
+                  :button_x1, :button_x2,
+                  :wheel
+
+    attr_accessor :click
+    attr_accessor :previous_click
+    attr_accessor :x
+    attr_accessor :y
+
+    def initialize
+      @x = 0
+      @y = 0
+      @has_focus = false
+      @button_bits = 0
+      @button_left = false
+      @button_middle = false
+      @button_right = false
+      @button_x1 = false
+      @button_x2 = false
+      clear
+    end
+
+    def point
+      [@x, @y].point
+    end
+
+    def inside_rect? rect
+      point.inside_rect? rect
+    end
+
+    alias_method :position, :point
+
+    def clear
+      if @click
+        @previous_click = MousePoint.new @click.point.x, @click.point.y
+        @previous_click.created_at = @click.created_at
+        @previous_click.global_created_at = @click.global_created_at
+      end
+
+      @click = nil
+      @up    = nil
+      @moved = nil
+      @wheel = nil
+    end
+
+    def up
+      @up
+    end
+
+    def down
+      @click
+    end
+
+    def serialize
+      result = {}
+
+      if @click
+        result[:click] = @click.to_hash
+        result[:down] = @click.to_hash
+      end
+
+      result[:up] = @up.to_hash if @up
+      result[:x] = @x
+      result[:y] = @y
+      result[:moved] = @moved
+      result[:moved_at] = @moved_at
+      result[:has_focus] = @has_focus
+
+      result
+    end
+
+    def to_s
+      serialize.to_s
+    end
+
+    alias_method :inspect, :to_s
+  end
+end
+
+module GTK
+  # @gtk
+  class Inputs
+
+    # A list of all controllers.
+    #
+    # @return [Controller[]]
+    # @gtk
+    attr_reader :controllers
+
+    # @return [Keyboard]
+    # @gtk
+    attr_reader :keyboard
+
+    # @return [Mouse]
+    # @gtk
+    attr_reader :mouse
+
+    # @gtk
+    attr_accessor :text, :history
+
+    def initialize
+      @controllers = [Controller.new, Controller.new]
+      @keyboard = Keyboard.new
+      @mouse = Mouse.new
+      @text = []
+    end
+
+    def up
+      keyboard.up ||
+        (controller_one && controller_one.up)
+    end
+
+    def down
+      keyboard.down ||
+        (controller_one && controller_one.down)
+    end
+
+    def left
+      keyboard.left ||
+        (controller_one && controller_one.left)
+    end
+
+    def right
+      keyboard.right ||
+        (controller_one && controller_one.right)
+    end
+
+    def directional_vector
+      keyboard.directional_vector ||
+        (controller_one && controller_one.directional_vector)
+    end
+
+    # Returns a signal indicating right (`1`), left (`-1`), or neither ('0').
+    #
+    # @return [Integer]
+    def left_right
+      return -1 if self.left
+      return  1 if self.right
+      return  0
+    end
+
+    # Returns a signal indicating up (`1`), down (`-1`), or neither ('0').
+    #
+    # @return [Integer]
+    def up_down
+      return  1 if self.up
+      return -1 if self.down
+      return  0
+    end
+
+    # Returns the coordinates of the last click.
+    #
+    # @return [Float, Float]
+    def click
+      return nil unless @mouse.click
+      return @mouse.click.point
+    end
+
+    # The first controller.
+    #
+    # @return [Controller]
+    def controller_one
+      @controllers[0]
+    end
+
+    # The second controller.
+    #
+    # @return [Controller]
+    def controller_two
+      @controllers[1]
+    end
+
+    # Clears all inputs.
+    #
+    # @return [void]
+    def clear
+      @mouse.clear
+      @keyboard.clear
+      @controllers.each(&:clear)
+    end
+
+    # @return [Hash]
+    def serialize
+      {
+        controller_one: controller_one.serialize,
+        controller_two: controller_two.serialize,
+        keyboard: keyboard.serialize,
+        mouse: mouse.serialize,
+        text: text.serialize
+      }
+    end
+  end
+end
+
+</pre>
+<h1 id='--./dragon/log.rb'>./dragon/log.rb</h1>
+<pre># coding: utf-8
+# Copyright 2019 DragonRuby LLC
+# MIT License
+# log.rb has been released under MIT (*only this file*).
+
+XTERM_COLOR = {
+  black:          "\u001b[30m",
+  red:            "\u001b[31m",
+  green:          "\u001b[32m",
+  yellow:         "\u001b[33m",
+  blue:           "\u001b[34m",
+  magenta:        "\u001b[35m",
+  cyan:           "\u001b[36m",
+  white:          "\u001b[37m",
+  bright_black:   "\u001b[30;1m",
+  bright_red:     "\u001b[31;1m",
+  bright_green:   "\u001b[32;1m",
+  bright_yellow:  "\u001b[33;1m",
+  bright_blue:    "\u001b[34;1m",
+  bright_magenta: "\u001b[35;1m",
+  bright_cyan:    "\u001b[36;1m",
+  bright_white:   "\u001b[37;1m",
+  reset:          "\u001b[0m",
+}
+
+module GTK
+  class Log
+    def self.write_to_log_and_puts *args
+      return if $gtk.production
+      $gtk.append_file 'logs/log.txt', args.join("\n") + "\n"
+      args.each { |obj| $gtk.log obj, self }
+    end
+
+    def self.write_to_log_and_print *args
+      return if $gtk.production
+      $gtk.append_file 'logs/log.txt', args.join("\n")
+      Object.print(*args)
+    end
+
+    def self.puts_important *args
+      return if $gtk.production
+      $gtk.append_file 'logs/log.txt', args.join("\n")
+      $gtk.notify! "Important notification occurred."
+      args.each { |obj| $gtk.log obj }
+    end
+
+    def self.puts *args
+      message_id, message = args
+      message ||= message_id
+      write_to_log_and_puts message
+    end
+
+    def self.multiline? *args
+      return true if args.length > 1
+      return !args[0].to_s.multiline?
+    end
+
+    def self.join_lines args
+      return "" if args.length == 0
+      return args if args.is_a? String
+      return args[0] if args.length == 1
+      return args.to_s.join("\n")
+    end
+
+    def self.headline name
+      @asterisk_count ||= 1
+      @asterisk_count = @asterisk_count.greater(1)
+      result_from_yield = join_lines yield
+      result_from_yield = result_from_yield.each_line.map { |l| "  #{l}" }.join
+      r ="#{"*" * @asterisk_count} #{name}\n#{result_from_yield}"
+      @asterisk_count -= 1
+      @asterisk_count = @asterisk_count.greater(1)
+      r
+    end
+
+    def self.dynamic_block
+      "#+BEGIN:
+#{join_lines yield}
+#+END:
+
+"
+    end
+
+    def self.puts_error *args
+      args ||= []
+      title = args[0]
+      additional = args[1..-1] || []
+      additional = "" if additional.length == 0
+      if !title.multiline? && join_lines(additional).multiline?
+        message = headline "ERROR: #{title}" do
+          dynamic_block do
+            additional
+          end
+        end
+      elsif title.multiline?
+        message = headline "ERROR: " do
+          dynamic_block do
+            args
+          end
+        end
+      else
+        message = "* ERROR: #{title} #{additional}".strip
+      end
+
+      self.puts message
+    end
+
+    def self.puts_info *args
+      args ||= []
+      title = args[0]
+      additional = args[1..-1] || []
+      additional = "" if additional.length == 0
+      if !title.multiline? && join_lines(additional).multiline?
+        message = headline "INFO: #{title}" do
+          dynamic_block do
+            additional
+          end
+        end
+      elsif title.multiline?
+        message = headline "INFO: " do
+          dynamic_block do
+            args
+          end
+        end
+      else
+        message = "* INFO: #{title} #{additional}".strip
+      end
+
+      self.puts message
+    end
+
+    def self.puts_once *ids, message
+      id = "#{ids}"
+      @once ||= {}
+      return if @once[id]
+      @once[id] = id
+      if !$gtk.cli_arguments[:replay] && !$gtk.cli_arguments[:record]
+        $gtk.notify!("Open the DragonRuby Console by pressing [`] [~] [²] [^] [º] or [§]. [Message ID: #{id}].")
+      end
+      write_to_log_and_puts ""
+      write_to_log_and_puts "#{message.strip}"
+      write_to_log_and_puts ""
+      write_to_log_and_puts "[Message ID: #{id}]"
+      write_to_log_and_puts ""
+    end
+
+    def self.puts_once_info *ids, message
+      id = "#{ids}"
+      @once ||= {}
+      return if @once[id]
+      @once[id] = id
+      log_info message
+    end
+
+    def self.print *args
+      write_to_log_and_print(*args)
+    end
+  end
+end
+
+class Object
+  def log_print *args
+    GTK::Log.print(*args)
+  end
+
+  def log_important *args
+    GTK::Log.puts_important(*args)
+  end
+
+  def log *args
+    GTK::Log.puts(*args)
+  end
+
+  def log_with_color xterm_escape_code, *args
+    log_print xterm_escape_code
+    log(*args)
+  ensure
+    log_reset_color
+  end
+
+  def log_reset_color
+    log_print XTERM_COLOR[:reset]
+  end
+
+  def log_black *args
+    log_with_color XTERM_COLOR[:black], *args
+  end
+
+  def log_red *args
+    log_with_color XTERM_COLOR[:red], *args
+  end
+
+  def log_green *args
+    log_with_color XTERM_COLOR[:green], *args
+  end
+
+  def log_yellow *args
+    log_with_color XTERM_COLOR[:yellow], *args
+  end
+
+  def log_blue *args
+    log_with_color XTERM_COLOR[:blue], *args
+  end
+
+  def log_magenta *args
+    log_with_color XTERM_COLOR[:magenta], *args
+  end
+
+  def log_cyan *args
+    log_with_color XTERM_COLOR[:cyan], *args
+  end
+
+  def log_white *args
+    log_with_color XTERM_COLOR[:white], *args
+  end
+
+  def log_bright_black *args
+    log_with_color XTERM_COLOR[:bright_black], *args
+  end
+
+  def log_bright_red *args
+    log_with_color XTERM_COLOR[:bright_red], *args
+  end
+
+  def log_bright_green *args
+    log_with_color XTERM_COLOR[:bright_green], *args
+  end
+
+  def log_bright_yellow *args
+    log_with_color XTERM_COLOR[:bright_yellow], *args
+  end
+
+  def log_bright_blue *args
+    log_with_color XTERM_COLOR[:bright_blue], *args
+  end
+
+  def log_bright_magenta *args
+    log_with_color XTERM_COLOR[:bright_magenta], *args
+  end
+
+  def log_bright_cyan *args
+    log_with_color XTERM_COLOR[:bright_cyan], *args
+  end
+
+  def log_bright_white *args
+    log_with_color XTERM_COLOR[:bright_white], *args
+  end
+
+  def log_error *args
+    GTK::Log.puts_error(*args)
+  end
+
+  def log_info *args
+    GTK::Log.puts_info(*args)
+  end
+
+  def log_once *ids, message
+    GTK::Log.puts_once(*ids, message)
+  end
+
+  def log_once_info *ids, message
+    GTK::Log.puts_once_info(*ids, message)
+  end
+end
+
+</pre>
+<h1 id='--./dragon/numeric.rb'>./dragon/numeric.rb</h1>
+<pre># coding: utf-8
+# Copyright 2019 DragonRuby LLC
+# MIT License
+# numeric.rb has been released under MIT (*only this file*).
+
+class Numeric
+  include ValueType
+  include NumericDeprecated
+
+  alias_method :gte, :>=
+  alias_method :lte, :<=
+
+  # Converts a numeric value representing seconds into frames.
+  #
+  # @gtk
+  def seconds
+    self * 60
+  end
+
+  # Divides the number by `2.0` and returns a `float`.
+  #
+  # @gtk
+  def half
+    self / 2.0
+  end
+
+  def to_byte
+    clamp(0, 255).to_i
+  end
+
+  def elapsed_time tick_count_override = nil
+    (tick_count_override || Kernel.tick_count) - self
+  end
+
+  def elapsed_time_percent duration
+    elapsed_time.percentage_of duration
+  end
+
+  def new?
+    elapsed_time == 0
+  end
+
+  # Returns `true` if the numeric value has passed a duration/offset number.
+  # `Kernel.tick_count` is used to determine if a number represents an elapsed
+  # moment in time.
+  #
+  # @gtk
+  def elapsed? offset = 0, tick_count_override = Kernel.tick_count
+    (self + offset) < tick_count_override
+  end
+
+  def frame_index *opts
+    frame_count_or_hash, hold_for, repeat, tick_count_override = opts
+    if frame_count_or_hash.is_a? Hash
+      frame_count         = frame_count_or_hash[:count]
+      hold_for            = frame_count_or_hash[:hold_for]
+      repeat              = frame_count_or_hash[:repeat]
+      tick_count_override = frame_count_or_hash[:tick_count_override]
+    else
+      frame_count = frame_count_or_hash
+    end
+
+    tick_count_override ||= Kernel.tick_count
+    animation_frame_count = frame_count
+    animation_frame_hold_time = hold_for
+    animation_length = animation_frame_hold_time * animation_frame_count
+    return nil if Kernel.tick_count < self
+
+    if !repeat && (self + animation_length) < (tick_count_override - 1)
+      return nil
+    else
+      return self.elapsed_time.-(1).idiv(animation_frame_hold_time) % animation_frame_count
+    end
+  rescue Exception => e
+    raise <<-S
+* ERROR:
+#{opts}
+#{e}
+S
+  end
+
+  def zero?
+    self == 0
+  end
+
+  def zero
+    0
+  end
+
+  def one
+    1
+  end
+
+  def two
+    2
+  end
+
+  def five
+    5
+  end
+
+  def ten
+    10
+  end
+
+  alias_method :gt,        :>
+  alias_method :above?,    :>
+  alias_method :right_of?, :>
+
+  alias_method :lt,       :<
+  alias_method :below?,   :<
+  alias_method :left_of?, :<
+
+  def shift_right i
+    self + i
+  end
+
+  def shift_left i
+    shift_right(i * -1)
+  rescue Exception => e
+    raise_immediately e, :shift_left, i
+  end
+
+  def shift_up i
+    self + i
+  rescue Exception => e
+    raise_immediately e, :shift_up, i
+  end
+
+  def shift_down i
+    shift_up(i * -1)
+  rescue Exception => e
+    raise_immediately e, :shift_down, i
+  end
+
+  # This provides a way for a numeric value to be randomized based on a combination
+  # of two options: `:sign` and `:ratio`.
+  #
+  # @gtk
+  def randomize *definitions
+    result = self
+
+    if definitions.include?(:sign)
+      result = rand_sign
+    end
+
+    if definitions.include?(:ratio)
+      result = rand * result
+    end
+
+    result
+  end
+
+  def rand_sign
+    return self * -1 if rand > 0.5
+    self
+  end
+
+  def rand_ratio
+    self * rand
+  end
+
+  def remainder_of_divide n
+    mod n
+  end
+
+  # Easing function progress/percentage for a specific point in time.
+  #
+  # @gtk
+  def ease_extended tick_count_override, duration, default_before, default_after, *definitions
+    GTK::Easing.ease_extended self,
+                              tick_count_override,
+                              self + duration,
+                              default_before,
+                              default_after,
+                              *definitions
+  end
+
+  # Easing function progress/percentage for a specific point in time.
+  #
+  # @gtk
+  def global_ease duration, *definitions
+    ease_extended Kernel.global_tick_count,
+                  duration,
+                  GTK::Easing.initial_value(*definitions),
+                  GTK::Easing.final_value(*definitions),
+                  *definitions
+  end
+
+  # Easing function progress/percentage for a specific point in time.
+  #
+  # @gtk
+  def ease duration, *definitions
+    ease_extended Kernel.tick_count,
+                  duration,
+                  GTK::Easing.initial_value(*definitions),
+                  GTK::Easing.final_value(*definitions),
+                  *definitions
+  end
+
+  # Easing function progress/percentage for a specific point in time.
+  #
+  # @gtk
+  def ease_spline_extended tick_count_override, duration, spline
+    GTK::Easing.ease_spline_extended self,
+                                     tick_count_override,
+                                     self + duration,
+                                     spline
+  end
+
+  # Easing function progress/percentage for a specific point in time.
+  #
+  # @gtk
+  def global_ease_spline duration, spline
+    ease_spline_extended Kernel.global_tick_count,
+                         duration,
+                         spline
+  end
+
+  # Easing function progress/percentage for a specific point in time.
+  #
+  # @gtk
+  def ease_spline duration, spline
+    ease_spline_extended Kernel.tick_count,
+                         duration,
+                         spline
+  end
+
+  # Converts a number representing an angle in degrees to radians.
+  #
+  # @gtk
+  def to_radians
+    self * Math::PI.fdiv(180)
+  end
+
+  # Converts a number representing an angle in radians to degress.
+  #
+  # @gtk
+  def to_degrees
+    self / Math::PI.fdiv(180)
+  end
+
+  # Given `self`, a rectangle primitive is returned.
+  #
+  # @example
+  #   5.to_square 100, 300 # returns [100, 300, 5, 5]
+  #
+  # @gtk
+  def to_square x, y, anchor_x = 0.5, anchor_y = nil
+    GTK::Geometry.to_square(self, x, y, anchor_x, anchor_y)
+  end
+
+  # Returns a normal vector for a number that represents an angle in degress.
+  #
+  # @gtk
+  def vector max_value = 1
+    [vector_x(max_value), vector_y(max_value)]
+  end
+
+  # Returns the y component of a normal vector for a number that represents an angle in degress.
+  #
+  # @gtk
+  def vector_y max_value = 1
+    max_value * Math.sin(self.to_radians)
+  end
+
+  # Returns the x component of a normal vector for a number that represents an angle in degress.
+  #
+  # @gtk
+  def vector_x max_value = 1
+    max_value * Math.cos(self.to_radians)
+  end
+
+  def x_vector max_value = 1
+    vector_x max_value
+  end
+
+  def y_vector max_value = 1
+    vector_y max_value
+  end
+
+  # @gtk
+  def mod n
+    self % n
+  end
+
+  # @gtk
+  def mod_zero? *ns
+    ns.any? { |n| mod(n) == 0 }
+  end
+
+  def mult n
+    self * n
+  end
+
+  # @gtk
+  def fdiv n
+    self / n.to_f
+  end
+
+  # Divides `self` by a number `n` as a float, and converts it `to_i`.
+  #
+  # @gtk
+  def idiv n
+    (self / n.to_f).to_i
+  end
+
+  # Returns a numeric value that is a quantity `magnitude` closer to
+  #`self`. If the distance between `self` and `target` is less than
+  #the `magnitude` then `target` is returned.
+  #
+  # @gtk
+  def towards target, magnitude
+    return self if self == target
+    delta = (self - target).abs
+    return target if delta < magnitude
+    return self - magnitude if self > target
+    return self + magnitude
+  end
+
+  # Given `self` and a number representing `y` of a grid. This
+  # function will return a one dimensional array containing the value
+  # yielded by an implicit block.
+  #
+  # @example
+  #   3.map_with_ys 2 do |x, y|
+  #     x * y
+  #   end
+  #   #     x y   x y  x y  x y  x y  x y
+  #   #     0*0,  0*1  1*0  1*1  2*0  2*1
+  #   # => [  0,    0,   0,   1,   0,   2]
+  #
+  # @gtk
+  def map_with_ys ys, &block
+    self.times.flat_map do |x|
+      ys.map_with_index do |y|
+        yield x, y
+      end
+    end
+  rescue Exception => e
+    raise_immediately e, :map_with_ys, [self, ys]
+  end
+
+  def combinations other_int
+    self.numbers.product(other_int.numbers)
+  end
+
+  def percentage_of n
+    (self / n.to_f).cap_min_max(0, 1)
+  end
+
+  def cap i
+    return i if self > i
+    self
+  end
+
+  def cap_min_max min, max
+    return min if self < min
+    return max if self > max
+    self
+  end
+
+  def lesser other
+    return other if other < self
+    self
+  end
+
+  def greater other
+    return other if other > self
+    self
+  end
+
+  def subtract i
+    self - i
+  end
+
+  def minus i
+    self - i
+  end
+
+  def add i
+    self + i
+  end
+
+  def plus i
+    self + i
+  end
+
+  def numbers
+    (0..self).to_a
+  end
+
+  def >= other
+    return false if !other
+    return gte other
+  end
+
+  def > other
+    return false if !other
+    return gt other
+  end
+
+  def <= other
+    return false if !other
+    return lte other
+  end
+
+  def < other
+    return false if !other
+    return gt other
+  end
+
+  alias_method(:original_eq_eq, :==) unless Numeric.instance_methods.include?(:original_eq_eq)
+  def == other
+    return true if self.original_eq_eq(other)
+    if other.is_a?(OpenEntity)
+      return self.original_eq_eq(other.entity_id)
+    end
+    return self.original_eq_eq(other)
+  end
+
+  # @gtk
+  def map
+    unless block_given?
+      raise <<-S
+* ERROR:
+A block is required for Numeric#map.
+
+S
+    end
+
+    self.to_i.times.map do
+      yield
+    end
+  end
+
+  # @gtk
+  def map_with_index
+    unless block_given?
+      raise <<-S
+* ERROR:
+A block is required for Numeric#map.
+
+S
+    end
+
+    self.to_i.times.map do |i|
+      yield i
+    end
+  end
+
+  def check_numeric! sender, other
+    return if other.is_a? Numeric
+
+    raise <<-S
+* ERROR:
+Attempted to invoke :+ on #{self} with the right hand argument of:
+
+#{other}
+
+The object above is not a Numeric.
+
+S
+  end
+
+  def - other
+    return nil unless other
+    check_numeric! :-, other
+    super
+  end
+
+  def + other
+    return nil unless other
+    check_numeric! :+, other
+    super
+  end
+
+  def * other
+    return nil unless other
+    check_numeric! :*, other
+    super
+  end
+
+  def / other
+    return nil unless other
+    check_numeric! :/, other
+    super
+  end
+
+  def serialize
+    self
+  end
+
+  def from_top
+    return 720 - self unless $gtk
+    $gtk.args.grid.h - self
+  end
+end
+
+class Fixnum
+  include ValueType
+
+  alias_method(:original_eq_eq, :==) unless Fixnum.instance_methods.include?(:original_eq_eq)
+
+  def - other
+    return nil unless other
+    check_numeric! :-, other
+    super
+  end
+
+  # Returns `true` if the numeric value is evenly divisible by 2.
+  #
+  # @gtk
+  def even?
+    return (self % 2) == 0
+  end
+
+  # Returns `true` if the numeric value is *NOT* evenly divisible by 2.
+  #
+  # @gtk
+  def odd?
+    return !even?
+  end
+
+  def + other
+    return nil unless other
+    check_numeric! :+, other
+    super
+  end
+
+  def * other
+    return nil unless other
+    check_numeric! :*, other
+    super
+  end
+
+  def / other
+    return nil unless other
+    check_numeric! :/, other
+    super
+  end
+
+  def == other
+    return true if self.original_eq_eq(other)
+    if other.is_a?(GTK::OpenEntity)
+      return self.original_eq_eq(other.entity_id)
+    end
+    return self.original_eq_eq(other)
+  end
+
+  # Returns `-1` if the number is less than `0`. `+1` if the number
+  # is greater than `0`. Returns `0` if the number is equal to `0`.
+  #
+  # @gtk
+  def sign
+    return -1 if self < 0
+    return  1 if self > 0
+    return  0
+  end
+
+  # Returns `true` if number is greater than `0`.
+  #
+  # @gtk
+  def pos?
+    sign > 0
+  end
+
+  # Returns `true` if number is less than `0`.
+  #
+  # @gtk
+  def neg?
+    sign < 0
+  end
+
+  # Returns the cosine of a represented in degrees (NOT radians).
+  #
+  # @gtk
+  def cos
+    Math.cos(self.to_radians)
+  end
+
+  # Returns the cosine of a represented in degrees (NOT radians).
+  #
+  # @gtk
+  def sin
+    Math.sin(self.to_radians)
+  end
+end
+
+class Float
+  include ValueType
+
+  def - other
+    return nil unless other
+    check_numeric! :-, other
+    super
+  end
+
+  def + other
+    return nil unless other
+    check_numeric! :+, other
+    super
+  end
+
+  def * other
+    return nil unless other
+    check_numeric! :*, other
+    super
+  end
+
+  def / other
+    return nil unless other
+    check_numeric! :/, other
+    super
+  end
+
+  def serialize
+    self
+  end
+
+  # @gtk
+  def sign
+    return -1 if self < 0
+    return  1 if self > 0
+    return  0
+  end
+
+  def replace_infinity scalar
+    return self if !scalar
+    return self unless self.infinite?
+    return -scalar if self < 0
+    return  scalar if self > 0
+  end
+end
+
+class Integer
+  alias_method(:original_round, :round) unless Fixnum.instance_methods.include?(:original_round)
+
+  def round *args
+    original_round
+  end
+end
+
+</pre>
+<h1 id='--./dragon/runtime/framerate_diagnostics.rb'>./dragon/runtime/framerate_diagnostics.rb</h1>
+<pre># Copyright 2019 DragonRuby LLC
+# MIT License
+# framerate_diagnostics.rb has been released under MIT (*only this file*).
+
+module GTK
+  class Runtime
+    # @visibility private
+    module FramerateDiagnostics
+      def framerate_get_diagnostics
+        <<-S
+* INFO: Framerate Diagnostics
+You can display these diagnostics using:
+
+#+begin_src
+  args.outputs.debug << args.gtk.framerate_diagnostics_primitives
+#+end_src
+
+** Draw Calls: ~<<~ Invocation Perf Counter
+Here is how many times ~args.outputs.PRIMITIVE_ARRAY <<~ was called:
+
+  #{$perf_counter_outputs_push_count} times invoked.
+
+If the number above is high, consider batching primitives so you can lower the invocation of ~<<~. For example.
+
+Instead of:
+
+#+begin_src
+  args.state.enemies.map do |e|
+    e.alpha = 128
+    args.outputs.sprites << e # <-- ~args.outputs.sprites <<~ is invoked a lot
+  end
+#+end_src
+
+Do this:
+
+#+begin_src
+  args.outputs.sprites << args.state
+                              .enemies
+                              .map do |e| # <-- ~args.outputs.sprites <<~ is only invoked once.
+    e.alpha = 128
+    e
+  end
+#+end_src
+
+** Array Primitives
+~Primitives~ represented as an ~Array~ (~Tuple~) are great for prototyping, but are not as performant as using a ~Hash~.
+
+Here is the number of ~Array~ primitives that were encountered:
+
+  #{$perf_counter_primitive_is_array} Array Primitives.
+
+If the number above is high, consider converting them to hashes. For example.
+
+Instead of:
+
+#+begin_src
+  args.outputs.sprites << [0, 0, 100, 100, 'sprites/enemy.png']
+#+begin_end
+
+Do this:
+
+#+begin_src
+  args.outputs.sprites << { x: 0,
+                            y: 0,
+                            w: 100,
+                            h: 100,
+                            path: 'sprites/enemy.png' }
+#+begin_end
+
+** Primitive Counts
+Here are the draw counts ordered by lowest to highest z order:
+
+PRIMITIVE   COUNT, STATIC COUNT
+solids:     #{@args.outputs.solids.length}, #{@args.outputs.static_solids.length}
+sprites:    #{@args.outputs.sprites.length}, #{@args.outputs.static_sprites.length}
+primitives: #{@args.outputs.primitives.length}, #{@args.outputs.static_primitives.length}
+labels:     #{@args.outputs.labels.length}, #{@args.outputs.static_labels.length}
+lines:      #{@args.outputs.lines.length}, #{@args.outputs.static_lines.length}
+borders:    #{@args.outputs.borders.length}, #{@args.outputs.static_borders.length}
+debug:      #{@args.outputs.debug.length}, #{@args.outputs.static_debug.length}
+reserved:   #{@args.outputs.reserved.length}, #{@args.outputs.static_reserved.length}
+
+** Additional Help
+Come to the DragonRuby Discord channel if you need help troubleshooting performance issues. http://discord.dragonruby.org.
+
+Source code for these diagnostics can be found at: [[https://github.com/dragonruby/dragonruby-game-toolkit-contrib/]]
+S
+      end
+
+      def framerate_warning_message
+        <<-S
+* WARNING:
+Your average framerate dropped below 60 fps for two seconds.
+
+The average FPS was #{current_framerate}.
+
+** How To Disable Warning
+If this warning is getting annoying put the following in your tick method:
+
+#+begin_src
+  args.gtk.log_level = :off
+#+end_src
+
+#{framerate_get_diagnostics}
+  S
+      end
+
+      def current_framerate_primitives
+        framerate_diagnostics_primitives
+      end
+
+      def framerate_diagnostics_primitives
+        [
+          { x: 0, y: 93.from_top, w: 500, h: 93, a: 128 }.solid,
+          {
+            x: 5,
+            y: 5.from_top,
+            text: "More Info via DragonRuby Console: $gtk.framerate_diagnostics",
+            r: 255,
+            g: 255,
+            b: 255,
+            size_enum: -2
+          }.label,
+          {
+            x: 5,
+            y: 20.from_top,
+            text: "FPS: %.2f" % args.gtk.current_framerate,
+            r: 255,
+            g: 255,
+            b: 255,
+            size_enum: -2
+          }.label,
+          {
+            x: 5,
+            y: 35.from_top,
+            text: "Draw Calls: #{$perf_counter_outputs_push_count}",
+            r: 255,
+            g: 255,
+            b: 255,
+            size_enum: -2
+          }.label,
+          {
+            x: 5,
+            y: 50.from_top,
+            text: "Array Primitives: #{$perf_counter_primitive_is_array}",
+            r: 255,
+            g: 255,
+            b: 255,
+            size_enum: -2
+          }.label,
+          {
+            x: 5,
+            y: 65.from_top,
+            text: "Mouse: #{@args.inputs.mouse.point}",
+            r: 255,
+            g: 255,
+            b: 255,
+            size_enum: -2
+          }.label,
+        ]
+      end
+
+    end
+  end
+end
+
+</pre>
+<h1 id='--./dragon/string.rb'>./dragon/string.rb</h1>
+<pre># coding: utf-8
+# Copyright 2019 DragonRuby LLC
+# MIT License
+# string.rb has been released under MIT (*only this file*).
+
+class String
+  include ValueType
+
+  def wrapped_lines_recur word, rest, length, aggregate
+    if word.nil?
+      return aggregate
+    elsif rest[0].nil?
+      aggregate << word + "\n"
+      return aggregate
+    elsif (word + " " + rest[0]).length > length
+      aggregate << word + "\n"
+      return wrapped_lines_recur rest[0], rest[1..-1], length, aggregate
+    elsif (word + " " + rest[0]).length <= length
+      next_word = (word + " " + rest[0])
+      return wrapped_lines_recur next_word, rest[1..-1], length, aggregate
+    else
+      log <<-S
+WARNING:
+#{word} is too long to fit in length of #{length}.
+
+S
+      next_word = (word + " " + rest[0])
+      return wrapped_lines_recur next_word, rest[1..-1], length, aggregate
+    end
+  end
+
+  def end_with_bang?
+    self[-1] == "!"
+  end
+
+  def without_ending_bang
+    return self unless end_with_bang?
+    self[0..-2]
+  end
+
+  # @gtk
+  def wrapped_lines length
+    self.each_line.map do |l|
+      l = l.rstrip
+      if l.length < length
+        l + "\n"
+      else
+        words = l.split ' '
+        wrapped_lines_recur(words[0], words[1..-1], length, []).flatten
+      end
+    end.flatten
+  end
+
+  # @gtk
+  def wrap length
+    wrapped_lines(length).join.rstrip
+  end
+
+  # @gtk
+  def multiline?
+    include? "\n"
+  end
+
+  def indent_lines amount, char = " "
+    self.each_line.each_with_index.map do |l, i|
+      if i == 0
+        l
+      else
+        char * amount + l
+      end
+    end.join
+  end
+
+  def quote
+    "\"#{self}\""
+  end
+
+  def trim
+    strip
+  end
+
+  def trim!
+    strip!
+  end
+
+  def ltrim
+    lstrip
+  end
+
+  def ltrim!
+    lstrip!
+  end
+
+  def rtrim
+    rstrip
+  end
+
+  def rtrim!
+    rstrip!
+  end
+end
+
+</pre>
+<h1 id='--./dragon/tests.rb'>./dragon/tests.rb</h1>
+<pre># coding: utf-8
+# Copyright 2019 DragonRuby LLC
+# MIT License
+# tests.rb has been released under MIT (*only this file*).
+
+module GTK
+  class Tests
+    attr_accessor :failed, :passed, :inconclusive
+
+    def initialize
+      @failed = []
+      @passed = []
+      @inconclusive = []
+    end
+
+    def run_test m
+      args = Args.new $gtk, nil
+      assert = Assert.new
+      begin
+        log_test_running m
+        send(m, args, assert)
+        if !assert.assertion_performed
+          log_inconclusive m
+        else
+          log_passed m
+        end
+      rescue Exception => e
+        if test_signature_invalid_exception? e, m
+          log_test_signature_incorrect m
+        else
+          mark_test_failed m, e
+        end
+      end
+    end
+
+    def test_methods_focused
+      Object.methods.find_all { |m| m.start_with?( "focus_test_") }
+    end
+
+    def test_methods
+      Object.methods.find_all { |m| m.start_with? "test_" }
+    end
+
+    # @gtk
+    def start
+      log "* TEST: gtk.test.start has been invoked."
+      if test_methods_focused.length != 0
+        @is_running = true
+        test_methods_focused.each { |m| run_test m }
+        print_summary
+        @is_running = false
+      elsif test_methods.length == 0
+        log_no_tests_found
+      else
+        @is_running = true
+        test_methods.each { |m| run_test m }
+        print_summary
+        @is_running = false
+      end
+    end
+
+    def mark_test_failed m, e
+      message = "Failed."
+      self.failed << { m: m, e: e }
+      log message
+    end
+
+    def running?
+      @is_running
+    end
+
+    def log_inconclusive m
+      self.inconclusive << {m: m}
+      log "Inconclusive."
+    end
+
+    def log_passed m
+      self.passed << {m: m}
+      log "Passed."
+    end
+
+    def log_no_tests_found
+      log <<-S
+No tests were found. To create a test. Define a method
+that begins with test_. For example:
+#+begin_src
+def test_game_over args, assert
+
+end
+#+end_src
+S
+    end
+
+    def log_test_running m
+      log "** Running: #{m}"
+    end
+
+    def test_signature_invalid_exception? e, m
+      e.to_s.include?(m.to_s) && e.to_s.include?("wrong number of arguments")
+    end
+
+    def log_test_signature_incorrect m
+      log "TEST METHOD INVALID:", <<-S
+I found a test method called :#{m}. But it needs to have
+the following method signature:
+#+begin_src
+def #{m} args, assert
+
+end
+#+end_src
+Please update the method signature to match the code above. If you
+did not intend this to be a test method. Rename the method so it does
+not start with "test_".
+S
+    end
+
+    def print_summary
+      log "** Summary"
+      log "*** Passed"
+      log "#{self.passed.length} test(s) passed."
+      self.passed.each { |h| log "**** :#{h[:m]}" }
+      log "*** Inconclusive"
+      if self.inconclusive.length > 0
+        log_once :assertion_ok_note, <<-S
+NOTE FOR INCONCLUSIVE TESTS: No assertion was performed in the test.
+Add assert.ok! at the end of the test if you are using your own assertions.
+S
+      end
+      log "#{self.inconclusive.length} test(s) inconclusive."
+      self.inconclusive.each { |h| log "**** :#{h[:m]}" }
+      log "*** Failed"
+      log "#{self.failed.length} test(s) failed."
+      self.failed.each do |h|
+        log "**** Test name: :#{h[:m]}"
+        log "#{h[:e].to_s.gsub("* ERROR:", "").strip}"
+      end
+    end
+  end
+end
+
+</pre>
+<h1 id='--./dragon/trace.rb'>./dragon/trace.rb</h1>
+<pre># coding: utf-8
+# Copyright 2019 DragonRuby LLC
+# MIT License
+# trace.rb has been released under MIT (*only this file*).
+
+module GTK
+  module Trace
+    IGNORED_METHODS = [
+      :define_singleton_method, :raise_immediately, :instance_of?,
+      :raise_with_caller, :initialize_copy, :class_defined?,
+      :instance_variable_get, :format, :purge_class, :instance_variable_defined?,
+      :metadata_object_id, :instance_variable_set, :__printstr__,
+      :instance_variables, :is_a?, :p, :kind_of?, :==, :log_once,
+      :protected_methods, :log_once_info, :private_methods, :open,
+      :!=, :initialize, :object_id, :Hash, :methods, :tick, :!,
+      :respond_to?, :yield_self, :send, :instance_eval, :then,
+      :__method__, :__send__, :log_print, :dig, :itself, :log_info,
+      :remove_instance_variable, :raise, :public_methods, :instance_exec,
+      :gets, :local_variables, :tap, :__id__, :class, :singleton_class,
+      :block_given?, :_inspect, :puts, :global_variables, :getc, :iterator?,
+      :hash, :to_enum, :printf, :frozen?, :print, :original_puts,
+      :srand, :freeze, :rand, :extend, :eql?, :equal?, :sprintf, :clone,
+      :dup, :to_s, :primitive_determined?, :inspect, :primitive?, :help,
+      :__object_methods__, :proc, :__custom_object_methods__, :Float, :enum_for,
+      :__supports_ivars__?, :nil?, :fast_rand, :or, :and,
+      :__caller_without_noise__, :__gtk_ruby_string_contains_source_file_path__?,
+      :__pretty_print_exception__, :__gtk_ruby_source_files__,
+      :String, :log, :Array, :putsc, :Integer, :===, :here,
+      :raise_error_with_kind_of_okay_message, :better_instance_information,
+      :lambda, :fail, :method_missing, :__case_eqq, :caller,
+      :raise_method_missing_better_error, :require, :singleton_methods,
+      :!~, :loop, :numeric_or_default, :`, :state, :inputs, :outputs, "args=".to_sym,
+      :grid, :gtk, :dragon, :args, :passes, :tick, :grep_source, :grep_source_file,
+      :numeric_or_default, :f_or_default, :s_or_default, :i_or_default,
+      :comment, :primitive_marker, :xrepl, :repl
+    ]
+
+    def self.traced_classes
+      @traced_classes ||= []
+      @traced_classes
+    end
+
+    def self.mark_class_as_traced! klass
+      @traced_classes << klass
+    end
+
+    def self.untrace_classes!
+      traced_classes.each do |klass|
+        klass.class_eval do
+          all_methods = klass.instance_methods false
+          if klass.instance_methods.respond_to?(:__trace_call_depth__)
+            undef_method :__trace_call_depth__
+          end
+
+          GTK::Trace.filter_methods_to_trace(all_methods).each do |m|
+            original_method_name = m
+            trace_method_name = GTK::Trace.trace_method_name_for m
+            if klass.instance_methods.include? trace_method_name
+              alias_method m, trace_method_name
+            end
+          end
+        end
+      end
+      $last_method_traced = nil
+      @traced_classes.clear
+      $trace_enabled = false
+      if !$gtk.production
+        $gtk.write_file 'logs/trace.txt', "Add trace!(SOMEOBJECT) to the top of ~tick~ and this file will be populated with invocation information.\n"
+      end
+    end
+
+    def self.trace_method_name_for m
+      "__trace_original_#{m}__".to_sym
+    end
+
+    def self.original_method_name_for m
+      return m unless m.to_s.start_with?("__trace_original_") && m.to_s.end_with?("__")
+      m[16..-3]
+    end
+
+    def self.filter_methods_to_trace methods
+      methods.reject { |m| m.start_with? "__trace_" }.reject { |m| IGNORED_METHODS.include? m }
+    end
+
+    def self.flush_trace pad_with_newline = false
+      $trace_puts ||= []
+      if $trace_puts.length > 0
+        text = $trace_puts.join("")
+        if pad_with_newline
+          $gtk.append_file 'logs/trace.txt', "\n" + text.strip
+        else
+          $gtk.append_file 'logs/trace.txt', text.strip
+        end
+      end
+      $trace_puts.clear
+    end
+
+    # @gtk
+    def self.trace! instance = nil
+      $trace_history ||= []
+      $trace_enabled = true
+      $trace_call_depth ||=0
+      flush_trace
+      instance = $top_level unless instance
+      return if Trace.traced_classes.include? instance.class
+      all_methods = instance.class.instance_methods false
+      instance.class.class_eval do
+        attr_accessor :__trace_call_depth__ unless instance.class.instance_methods.include?(:__trace_call_depth__)
+        GTK::Trace.filter_methods_to_trace(all_methods).each do |m|
+          original_method_name = m
+          trace_method_name = GTK::Trace.trace_method_name_for m
+          alias_method trace_method_name, m
+          $trace_puts << "Tracing #{m} on #{instance.class}.\n"
+          define_method(m) do |*args|
+            instance.__trace_call_depth__ ||= 0
+            tab_width = " " * (instance.__trace_call_depth__ * 8)
+            instance.__trace_call_depth__ += 1
+            $trace_call_depth = instance.__trace_call_depth__
+            parameters = "#{args}"[1..-2]
+            $trace_puts << "\n  #{tab_width}#{m}(#{parameters})"
+            execution_time = Time.new.to_i
+            $last_method_traced = trace_method_name
+            $trace_history << [m, parameters]
+            result = send(trace_method_name, *args)
+            completion_time = Time.new.to_i
+            instance.__trace_call_depth__ -= 1
+            instance.__trace_call_depth__ = instance.__trace_call_depth__.greater 0
+            $trace_puts << "\n #{tab_width} success: #{m}"
+            if instance.__trace_call_depth__ == 0
+              $trace_puts << "\n"
+              $trace_history.clear
+            end
+            result
+          rescue Exception => e
+            instance.__trace_call_depth__ -= 1
+            instance.__trace_call_depth__ = instance.__trace_call_depth__.greater 0
+            $trace_puts << "\n #{tab_width} failed: #{m}"
+            if instance.__trace_call_depth__ == 0
+              $trace_puts << "\n #{tab_width}         #{e}"
+              $trace_puts << "\n"
+            end
+            $trace_call_depth = 0
+            GTK::Trace.flush_trace true
+            raise e
+          end
+        end
+      end
+      mark_class_as_traced! instance.class
+    end
+  end
+end
+
+</pre>
 
     </div>
   </body>