侏儒蛇吃它的食物

Question

我最近开始使用pygame，我正在关注newbostons的youtube教程。以下是我的主要游戏循环：

def game_loop():
    global direction
    global tdirection

    lead_x=display_width/2
    lead_y=display_height/2

    block_size=10
    change_x=10
    change_y=0

    game_exit=False
    GameOver=False
    main_menu=False


    snakelist=[]
    snakelength=1

    applethickness=20

    RandAppleX=round(random.randrange(0, display_width-applethickness )/10.0)*10.0
    RandAppleY=round(random.randrange(0, display_height-applethickness )/10.0)*10.0



    while not game_exit:


        while GameOver==True:
            game_display.fill(white)
            message_screen('You lost, Press Q to quit or C to retry.', red)
            pygame.display.update()
            for event in pygame.event.get():
                if event.type==pygame.KEYDOWN:
                    if event.key==pygame.K_q:
                        loss.play()
                        game_exit=True
                        GameOver= False


                    elif event.key==pygame.K_c:
                        direction='right'
                        game_loop()


                if event.type==pygame.QUIT:
                    game_exit=True
                    GameOver= False




        for event in pygame.event.get():


            if event.type==pygame.QUIT:
                game_exit=True

            if event.type==pygame.KEYDOWN:
                if event.key==pygame.K_a:

                    change_x=-block_size
                    direction='left'

                    change_x=-block_size                        
                    change_y=0
                elif event.key==pygame.K_d:
                    direction='right'

                    change_x=block_size
                    change_y=0  
                elif event.key==pygame.K_w:
                    direction='up'

                    change_y=-block_size
                    change_x=0
                elif event.key==pygame.K_s:
                    direction='down'

                    change_y=block_size
                    change_x=0

                elif event.key==pygame.K_ESCAPE:
                    pause()





        if lead_x>=display_width or lead_x<0 or lead_y>=display_height or lead_y<0:
            loss.play()
            GameOver=True



        lead_x+=change_x
        lead_y+=change_y




        clock.tick(FPS)





        snakehead=[]

        snakehead.append(lead_x)
        snakehead.append(lead_y)

        snakelist.append(snakehead)


        if len(snakelist)>snakelength:
            del snakelist[0]

        for segment in snakelist[:-1]:
            if segment==snakehead:
                loss.play()
                GameOver=True






        game_display.fill(white)
        game_display.blit(aimg, (RandAppleX, RandAppleY))   

        snake(snakelist, block_size)
        score(snakelength-1)




        if lead_x>= RandAppleX and lead_x<= RandAppleX+applethickness and lead_y<= RandAppleY+applethickness and lead_y>= RandAppleY:


            RandAppleX=round(random.randrange(0, display_width-applethickness )/10.0)*10.0
            RandAppleY=round(random.randrange(0, display_height-applethickness )/10.0)*10.0
            snakelength+=1
            effect.play()





        pygame.display.update()




    pygame.quit()
    quit()

现在我需要防止蛇在向某个方向移动时吃掉自己。例如，它向右移动，按键盘上的A键会立即让它吃自己，如果它向上移动，按S键也会做同样的事情。有没有办法防止这种情况发生？你知道吗

Answer 1

更改方向时，只需检查方向是否与当前方向相反，如果是，则不设置新方向。这就解决了问题。你知道吗

Answer 2

一个简单的解决方法是通过检查蛇移动的方向是否与请求的方向相反，来防止蛇倒退到自己身上。这将涉及一些额外的检查。像这样：

        if event.type==pygame.KEYDOWN:
            if event.key==pygame.K_a and direction != 'right':

                change_x=-block_size
                direction='left'

                change_x=-block_size                        
                change_y=0
            elif event.key==pygame.K_d and direction != 'left':
                direction='right'

                change_x=block_size
                change_y=0  
            elif event.key==pygame.K_w and direction != 'down':
                direction='up'

                change_y=-block_size
                change_x=0
            elif event.key==pygame.K_s and direction != 'right':
                direction='down'

                change_y=block_size
                change_x=0