python项目《外星人入侵》增加上下操作

python项目《外星人入侵》增加上下操作

目的：

1. 可以上下移动
2. 确保上下不会过界

ship.py（新增y轴存储，飞船移动及上下边界）:

import pygame
class Ship():
    def __init__(self,ai_settings,screen):
        '''初始化飞船并设置其初始位置'''
        self.screen = screen
        self.ai_settings = ai_settings

        #加载飞船图像并获取外接矩形
        self.image = pygame.image.load('image/ship.png')
        self.rect = self.image.get_rect()
        self.screen_rect = screen.get_rect()

        #将每个新飞船图像放在屏幕地步中央
        self.rect.centerx = self.screen_rect.centerx
        self.rect.bottom = self.screen_rect.bottom


        #在飞船的属性center中存储小数值
        self.centerx = float(self.rect.centerx)
        self.centery = float(self.rect.centery)

        #移动标志
        self.moving_right = False
        self.moving_left = False
        self.moving_up = False
        self.moving_down = False

    def update(self):
        '''根据移动标志调整飞船的位置'''
        if self.moving_right and self.rect.right < self.screen_rect.right:
            self.centerx += self.ai_settings.ship_speed_factor
        if self.moving_left and self.rect.left > 0 :
            self.centerx -= self.ai_settings.ship_speed_factor
        if self.moving_down and self.rect.bottom < self.screen_rect.bottom:
            self.centery += self.ai_settings.ship_speed_factor
        if self.moving_up and self.rect.top > 0 :
            self.centery -= self.ai_settings.ship_speed_factor

        #根据self.center更新rect对象
        self.rect.centerx = self.centerx
        self.rect.centery = self.centery

    def bitme(self):
        '''在指定位置绘制飞船'''
        self.screen.blit(self.image,self.rect)

game_functions.py（新增上下响应）:

import sys
import pygame

def check_keydown_events(event,ship):
    '''响应按键'''
    if event.key == pygame.K_RIGHT:
        ship.moving_right = True
    if event.key == pygame.K_LEFT:
        ship.moving_left = True
    if event.key == pygame.K_UP:
        ship.moving_up = True
    if event.key == pygame.K_DOWN:
        ship.moving_down = True
def check_keyup_event(event,ship):
    '''响应松开'''
    if event.key == pygame.K_RIGHT:
        ship.moving_right = False
    if event.key == pygame.K_LEFT:
        ship.moving_left = False
    if event.key == pygame.K_UP:
        ship.moving_up = False
    if event.key == pygame.K_DOWN:
        ship.moving_down = False

def check_events(ship):
    '''响应按键和鼠标事件'''
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            sys.exit()
        elif event.type ==pygame.KEYDOWN:
            check_keydown_events(event,ship)

        elif event.type ==pygame.KEYUP:
            check_keyup_event(event,ship)

def update_screen(ai_settings,screen,ship):
    '''更新屏幕上的图像，并切换到新屏幕'''
    # 每次循环时都重绘制屏幕
    screen.fill(ai_settings.bg_color)
    ship.bitme()
    # 让最近绘制的屏幕可见
    pygame.display.flip()