34 lines
1.1 KiB
Python
34 lines
1.1 KiB
Python
import pygame
|
|
from pygame.sprite import Sprite
|
|
|
|
class AlienBullet(Sprite):
|
|
"""一个对外星人发射的子弹进行管理的类"""
|
|
|
|
def __init__(self, ai_settings, screen, alien):
|
|
"""在飞船所处的位置创建一个子弹对象"""
|
|
super().__init__()
|
|
self.screen = screen
|
|
|
|
# 在(0,0)处创建一个表示子弹的矩形，再设置正确的位置
|
|
self.rect = pygame.Rect(0, 0, ai_settings.bullet_width, ai_settings.bullet_height)
|
|
self.rect.centerx = alien.rect.centerx
|
|
self.rect.top = alien.rect.bottom
|
|
|
|
# 存储用小数表示的子弹位置
|
|
self.y = float(self.rect.y)
|
|
|
|
# 设置子弹颜色及速度(从ai_settings中读取)
|
|
self.color = ai_settings.alien_bullet_color
|
|
self.speed_factor = ai_settings.bullet_speed_factor
|
|
|
|
|
|
def update(self):
|
|
"""向下移动子弹"""
|
|
self.y += self.speed_factor
|
|
self.rect.y = self.y
|
|
|
|
|
|
def draw_alien_bullet(self):
|
|
"""在屏幕上绘制子弹"""
|
|
pygame.draw.rect(self.screen, self.color, self.rect)
|