<Python编程>

外星人入侵游戏编程练习

1.键盘不动事件

找了半天,找不到键盘按下,飞船不动是什么原因,然后仔细对照自己的代码和书上的代码,发现事件监听错误,如下:

game_functions:

import sys

import pygame

def check_events(ship):
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            sys.exit()
        elif event.type == pygame.KEYDOWN:
            if event.event == pygame.K_RIGHT:
                # ship.rect.centerx += 100
                ship.moving_right = True
            elif event.event == pygame.K_LEFT:
                ship.moving_left = True
        elif event.type == pygame.KEYUP:
            if event.event == pygame.K_RIGHT:
                ship.moving_right = False
            elif event.event == pygame.K_LEFT:
                ship.moving_left = False
def update_screen(ai_settings, screen, ship):
    screen.fill(ai_settings.bg_color)
    ship.blitme()
    pygame.display.flip()

错误原因分析:

在pygame中,键盘是否按下监听事件是通过 event.type 事件;

而具体按键事件是要通过 event.key事件;

并且在重构ship类代码时也犯了错误:

下面代码时正确的,之前犯的错误是在update()方法中,更新的仍是rect属性,而不是新加的center属性.

import pygame

class Ship():

    def __init__(self, ai_settings, screen):
        #初始化飞船位置
        self.screen = screen
        self.ai_settings = ai_settings

        self.image = pygame.image.load('images/ship.bmp')
        self.rect = self.image.get_rect()
        self.screen_rect = screen.get_rect()

        self.rect.centerx = self.screen_rect.centerx
        self.rect.bottom = self.screen_rect.bottom

        self.center = float(self.rect.centerx)

        self.moving_right = False
        self.moving_left = False

    def update(self):
        if self.moving_right:
            self.center += self.ai_settings.ship_speed_factor
        elif self.moving_left:
            self.center -= self.ai_settings.ship_speed_factor
        self.rect.centerx = self.center

    def blitme(self):
        self.screen.blit(self.image, self.rect)