pygame改变发射子弹相对于舰船起始位置的方向

Question

我正在编写一个2D外星人射击游戏，并设法将飞船顺时针旋转90度。但是，我无法更改子弹对象以从船面对的新方式进行射击。船顺时针面向90度。

我尝试过更改bullet rect对象并将属性从中上切换到右侧。没有成功。

bullet.py

    def __init__(self, ai_game):
    """Create a bullet object at the ship's current position."""

    # Create a bullet rect at (0, 0) and then set correct position.
    self.rect = pygame.Rect(0, 0, self.settings.bullet_width,
    self.settings.bullet_height)
    self.rect.midtop = ai_game.ship.rect.midtop

    # Store the bullet's position as a decimal value.
    self.y = float(self.rect.y)

    def update(self):
    """Move the bullet up the screen."""
    # Update the decimal position of the bullet.
    self.y -= self.settings.bullet_speed

    # Update the rect position.
    self.rect.y = self.y

ship.py

def __init__(self, ai_game):
    """Initialize the ship and set its starting position."""
    self.screen = ai_game.screen
    self.settings = ai_game.settings
    self.screen_rect = ai_game.screen.get_rect()

    # Load the ship image and get its rect.
    self.image = pygame.image.load('images/ship.bmp').convert()
    image = self.image.copy()
    rot = -90
    self.rect = self.image.get_rect()
    self.image = pygame.transform.rotate(image, rot)

子弹从飞船的左翼向上射击。