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=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
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