tweening user fibers

tweening_actions.rb

module GTK
  class OpenEntity
    def move_to(target, duration, easing, &block)
      Fiber.new do
        start_time = $gtk.args.state.tick_count
        until self.x == target[:x] && self.y == target[:y]
          t = $gtk.args.easing.ease(start_time, $gtk.args.state.tick_count, duration, easing)
          self.x += t * (target[:x] - self.x)
          self.y += t * (target[:y] - self.y)
          Fiber.yield
        end
        yield(block) if block
      end
    end
  end
end

def initialize(args)
  args.state[:actions] = []
  args.state[:entities] = []
end

def tick(args)
  initialize(args) if args.state.tick_count.zero?

  # tick actions and remove dead
  args.state[:actions].each(&:resume).select!(&:alive?)

  if args.inputs.mouse.down
    args.state[:entities] << entity = args.state.new_entity(:entity, {
      x: args.inputs.mouse.x, y: args.inputs.mouse.y, h: 50, w: 50, path: 'sprites/square/red.png'
    })
    
    # move using quart easing over 1.5 seconds, then change the path to blue when complete
    args.state[:actions] << entity.move_to({x: 700, y: 400}, 90, :quart) { entity.path = 'sprites/square/blue.png'}
  end

  args.outputs.sprites << args.state[:entities]
end