python - 如何重新触发之前的 'while' 循环

Question

所以我目前正在编写蛇代码，试图学习 pygame。我对编码很陌生，所以如果我解释得不好，我很抱歉。我有一个游戏循环，当 running = True 时处于事件状态，当蛇碰到边界时，running 变为 False，结束游戏循环并切换到另一个 while 循环，表示游戏结束。当然，我稍后会在此屏幕上添加更多内容。我目前只是想弄清楚当我单击 r 时如何做到这一点，在第二个循环中，运行再次变为 true，再次触发游戏循环以有效地重新启动该游戏。我真的很感激任何建议，谢谢!

import pygame

pygame.init()

display_x = 400
display_y = 300
display = pygame.display.set_mode((display_x, display_y))
pygame.display.set_caption("Ned's snake game")

x1 = display_x / 2
y1 = display_y / 2

x1_change = 0
y1_change = 0

clock = pygame.time.Clock()
fps = 45

game_over_font = pygame.font.Font("freesansbold.ttf", 16)


def game_over():
    over_text = game_over_font.render("GAME OVER", True, (200, 0, 0))
    display.blit(over_text, ((display_x / 2) - 54, (display_y / 2) - 16))


running = True

while running is True:
    print("thing")
    display.fill((50, 200, 20))
    pygame.draw.rect(display, (0, 0, 255), [x1, y1, 10, 10])

    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            pygame.quit()
        elif event.type == pygame.KEYDOWN:
            if event.key == pygame.K_LEFT:
                x1_change = -5
                y1_change = 0
            elif event.key == pygame.K_RIGHT:
                x1_change = 5
                y1_change = 0
            elif event.key == pygame.K_UP:
                y1_change = -5
                x1_change = 0
            elif event.key == pygame.K_DOWN:
                y1_change = 5
                x1_change = 0
            elif event.key == pygame.K_ESCAPE:
                pygame.quit()

    x1 += x1_change
    y1 += y1_change

    if x1 <= 0 or x1 >= display_x or y1 <= 0 or y1 >= display_y:
        running = False
        end_screen = True

    clock.tick(fps)
    pygame.display.update()

while end_screen is True:
    display.fill((255, 255, 255))
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            pygame.quit()
        elif event.type == pygame.KEYDOWN:
            if event.key == pygame.K_ESCAPE:
                pygame.quit()
            elif event.key == pygame.K_r:
                running = True
                end_screen = False

    game_over()
    pygame.display.update()  ```

Answer 1

解决此问题的一种方法是将整个 while running == True block 放入 def 中。这样做会使许多变量超出范围。为了解决这个问题，您可以将其中的大部分移至 def 内部，并使用 global 关键字访问其余部分，如我在代码中所示。

我将其称为 def playGame()，并且由于您已将该 block 放入 playGame() 中，因此您必须执行语句 playGame() 来启动它，正如您在代码中看到的那样。当 playGame() 中的 while 变为 false 时，它​​会进入 while end_screen == True block ，然后检查该 r 键，如果找到它，则重新运行 playGame()。

这是一个非常快速和肮脏的修复，可以让你快速到达你想要的地方，我怀疑这可能会导致创建一两个错误，但这是一个开始。如果我要给你一个建设性的批评，那就是你的程序中没有适当的游戏循环。如果今晚晚些时候我有时间，我会对此添加更多评论。

import pygame

pygame.init()

display_x = 400
display_y = 300
display = pygame.display.set_mode((display_x, display_y))
pygame.display.set_caption("Ned's snake game")


clock = pygame.time.Clock()
fps = 45

game_over_font = pygame.font.Font("freesansbold.ttf", 16)


def game_over():
    over_text = game_over_font.render("GAME OVER", True, (200, 0, 0))
    display.blit(over_text, ((display_x / 2) - 54, (display_y / 2) - 16))


def playGame():
    global display_x, display_y, end_screen  #"globals" are variables defined outside of the def block
    
    x1 = display_x / 2    #moved these inside the def block
    y1 = display_y / 2

    x1_change = 0
    y1_change = 0

    #just moved this inside of a def block
    running = True
    while running is True:
        #print("thing")
        display.fill((50, 200, 20))
        pygame.draw.rect(display, (0, 0, 255), [x1, y1, 10, 10])

        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                pygame.quit()
            elif event.type == pygame.KEYDOWN:
                if event.key == pygame.K_LEFT:
                    x1_change = -5
                    y1_change = 0
                elif event.key == pygame.K_RIGHT:
                    x1_change = 5
                    y1_change = 0
                elif event.key == pygame.K_UP:
                    y1_change = -5
                    x1_change = 0
                elif event.key == pygame.K_DOWN:
                    y1_change = 5
                    x1_change = 0
                elif event.key == pygame.K_ESCAPE:
                    pygame.quit()

        x1 += x1_change
        y1 += y1_change

        if x1 <= 0 or x1 >= display_x or y1 <= 0 or y1 >= display_y:
            running = False
            end_screen = True

        clock.tick(fps)
        pygame.display.update()

playGame()    #kickstart the game

while end_screen is True:
    display.fill((255, 255, 255))
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            pygame.quit()
        elif event.type == pygame.KEYDOWN:
            if event.key == pygame.K_ESCAPE:
                pygame.quit()
            elif event.key == pygame.K_r:
                running = True
                end_screen = False
                playGame()    #restart the game

    game_over()
    pygame.display.update()

pygame.quit()