demo.py 文件源码

def add_if_below_threshold(cls, player, asteroid_list, at_least_x_existing):

        if len(asteroid_list) < at_least_x_existing:
            plus_or_minus_x = random.choice([1, -1])
            new_asteroid_x = player.sprite.rect.top - (cls.SPAWN_DISTANCE_FROM_PLAYER * plus_or_minus_x)

            if new_asteroid_x > player.sprite.rect.left:
                x_speed = -1
            else:
                x_speed = 1

            plus_or_minus_y = random.choice([1, -1])
            new_asteroid_y = player.sprite.rect.left - (cls.SPAWN_DISTANCE_FROM_PLAYER * plus_or_minus_y)

            if new_asteroid_y > player.sprite.rect.top:
                y_speed = -1
            else:
                y_speed = 1

            another_asteroid = Asteroid((new_asteroid_x, new_asteroid_y), 10, x_speed, y_speed)
            asteroid_list.add(another_asteroid)