def __init__(self):
        super(NewScene, self).__init__()

        EventManager.subscribe(self, "onMouseDown")

        self.pool = GameObjectPool(Sprite, (ResourceLoader.load("data/crosshair.png"),))
        self.add(self.pool)
class NewScene(Scene):
    def __init__(self):
        super(NewScene, self).__init__()

        EventManager.subscribe(self, "onMouseDown")

        self.pool = GameObjectPool(Sprite, (ResourceLoader.load("data/crosshair.png"),))
        self.add(self.pool)

    def onMouseDown(self, event):
        if event.button is 1:
            sprite = self.pool.getNextAvailable()
            sprite.position = Game.camera_to_world(event.pos)