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This code shows the interaction between a character (sprite) and a sword (image). I created this for a student of mine to reference.
system('clear')
require 'ruby2d'
set title: 'Sprite animation'
set background: 'blue'
Zero = 0
# hero parameters
@hero_width = 78
@hero_height = 99
@hero_time = 150
@hero_direction = ''
@move_by = 4
@sprint_speed = 2
# sword parameters
@sword_height = 64
@sword_width = 64
# @sword_x = 150
# @sword_y = 390
@sword_x = Window.width/2 - @sword_width/2
@sword_y = Window.height/2 - @sword_height/2
# load assests
# images
@sword = Image.new(
'./assets/sword.png',
height: @sword_height,
width: @sword_width,
rotate: 180,
x: @sword_x,
y: @sword_y
)
# sprites
@hero = Sprite.new(
'./assets/hero.png',
width: @hero_width,
height: @hero_height,
clip_width: @hero_width,
clip_height: @hero_height,
x: Zero,
y: Window.height - @hero_height,
time: @hero_time,
animations: {
walk: 1..2,
climb: 3..4,
cheer: 5..6
}
)
# methods
# this method ensures that objects stay within the game window
# e.g. call set_boundaries(@hero) to keep @hero within the limits
def set_boundaries(obj)
# x-axis boundaries
if obj.x >= Window.width - obj.width
obj.x = Window.width - obj.width
end
if obj.x <= Zero
obj.x = Zero
end
#y-axis boundaries
if obj.y >= Window.height - obj.height
obj.y = Window.height - obj.height
end
if obj.y <= Zero
obj.y = Zero
end
end
# this method determines if two objects have collided
def is_collided(obj_one, obj_two)
# if first_object.x <= second_object.x + second_object.width && first_object.x + first_object.width >= second_object.x && first_object.y <= second_object.y + second_object.height && first_object.y + first_object.height >= second_object.y
if obj_one.x <= obj_two.x + obj_two.width && obj_one.x + obj_one.width >= obj_two.x && obj_one.y <= obj_two.y + obj_two.height && obj_one.y + obj_one.height >= obj_two.y
puts 'object one is colliding with object two :)'
else
puts 'object one is not colliding with object two :)'
end
end
# handle user input
on :key_held do |event|
case event.key
when 'left'
# animation
@hero.play animation: :walk, loop: false, flip: :horizontal
# movement
@hero.x = @hero.x - @move_by
@hero_direction = 'left'
when 'right'
# animation
@hero.play animation: :walk, loop: false
# movement
@hero.x = @hero.x + @move_by
@hero_direction = 'right'
when 'up'
# animation
@hero.play animation: :climb, loop: false
# movement
@hero.y = @hero.y - @move_by
@hero_direction = 'up'
when 'down'
# animation
@hero.play animation: :climb, loop: false
# movement
@hero.y = @hero.y + @move_by
@hero_direction = 'down'
when 'c'
@hero.play animation: :cheer, loop: false
when 's'
# update so character stops moving when hero_direction key is released
if @hero_direction == 'left'
@hero.x = @hero.x - @move_by - @sprint_speed
end
if @hero_direction == 'right'
@hero.x = @hero.x + @move_by + @sprint_speed
end
if @hero_direction == 'up'
@hero.y = @hero.y - @move_by - @sprint_speed
end
if @hero_direction == 'down'
@hero.y = @hero.y + @move_by + @sprint_speed
end
end
# pass hero to the method responsible for keeping objects within the game screen boundaries
set_boundaries(@hero)
is_collided(@hero, @sword)
end
on :key_up do |event|
case event.key
when 'left'
@hero_direction = ''
when 'right'
@hero_direction = ''
when 'up'
@hero_direction = ''
when 'down'
@hero_direction = ''
end
end
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