bullet.py

import pygame
from pygame.sprite import Sprite

class Bullet(Sprite):
    """子弹类"""
    def __init__(self,ai_settings,screen,ship):
        """飞船位置创建子弹对象类"""
        super(Bullet,self).__init__()
        self.screen = screen
        
        #在（0,0）处创建一个表示子弹的矩形，再设置
        self.rect = pygame.Rect(0,0,ai_settings.bullet_width,ai_settings.bullet_height)
        self.rect.centerx = ship.rect.centerx
        self.rect.top = ship.rect.top
        
        #使用小数存储子弹位置
        self.y = float(self.rect.y)
        
        self.color = ai_settings.bullet_color
        self.speed_factor = ai_settings.bullet_speed_factor
    
    def update(self):
        #向上移动子弹
        self.y -= self.speed_factor
        self.rect.y = self.y
    
    def draw_bullet(self):
        pygame.draw.rect(self.screen,self.color,self.rect)