import pygame
class Ship:
"""管理飞船的类"""
def __init__(self, ai_game):
"""初始化飞船并设置其初始位置"""
self.screen = ai_game.screen
self.settings = ai_game.settings
self.screen_rect = ai_game.screen.get_rect()
# 加载飞船图像并获取其外接矩形
self.image = pygame.image.load('images/ship.bmp')
self.rect = self.image.get_rect()
# 对于每艘新飞船,都将其放在屏幕底部的中央
self.rect.midbottom = self.screen_rect.midbottom
# 在飞船的属性x中存储小数值
self.x = float(self.rect.x)
self.moving_left = False
self.moving_right = False
def blitme(self):
"""在指定位置绘制飞船"""
self.screen.blit(self.image, self.rect)
def update(self):
if self.moving_left:
self.rect.x -= self.settings.ship_speed
if self.moving_right:
self.rect.x += self.settings.ship_speed
# 根据self.x更新rect对象
self.rect.x = self.x
请问为什么要先把self.rect.x转化为self.x再在最后变回来?