子弹

bullet.py

@@ -20,4 +20,11 @@ class Bullet(Sprite):
         self.y = float(self.rect.y)
 
         self.color = ai_settings.bullet_color
-        self.speed_factor = ai_settings.bullet_speed_factor
+        self.speed_factor = ai_settings.bullet_speed_factor
+
+        def update(self):
+            """向上移动子弹"""
+            # 更新表示子弹位置的小数值
+            self.y -= self.speed_factor
+            # 更新表示子弹的rect的位置
+            self.rect.y = self.y