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+=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