Pygame逻辑问题

Question

我想用pygame开发一个Brick Breaker/Breakout游戏，但是我正面临着一个恼人的问题，那就是当我用箭头移动时，会在桨（玩家）上弄脏“球”给你看看代码。

import pygame 

pygame.init() 

isRunning = True 

WIDTH = 800 
HEIGHT = 600 

FPS = 60 

clock = pygame.time.Clock() 

window = pygame.display.set_mode((WIDTH, HEIGHT)) 

class Player(pygame.sprite.Sprite): 
    def __init__(self): 
     pygame.sprite.Sprite.__init__(self) 

     self.image = pygame.Surface((60, 30)) 
     self.image.fill((200, 255, 200)) 
     self.rect = self.image.get_rect() 
     self.rect.centerx = WIDTH/2 
     self.rect.bottom = HEIGHT - 30 

    def update(self): 
     self.speedx = 0 

     keystate = pygame.key.get_pressed() 
     if keystate[pygame.K_a]: 
      self.speedx = -5 

     if keystate[pygame.K_d]: 
      self.speedx = 5 

     self.rect.x += self.speedx 

     if self.rect.right + self.speedx > WIDTH: 
      self.rect.right = WIDTH 

     if self.rect.left + self.speedx < 0: 
      self.rect.left = 0 

     ball = Ball(self.rect.centerx, self.rect.top) 
     for i in all_sprites: 
      print(i) 
     all_sprites.add(ball) 

    def shoot(self): 
     ball = Ball(self.rect.centerx, self.rect.top) 
     all_sprites.add(ball) 
     balls.add(ball) 

class Ball(pygame.sprite.Sprite): 
    def __init__(self, x, y): 
     pygame.sprite.Sprite.__init__(self) 
     self.image = pygame.Surface((10, 10)) 
     self.image.fill((100, 150, 200)) 
     self.rect = self.image.get_rect() 
     self.rect.bottom = y 
     self.rect.centerx = x 
     self.speedy = -3 

    def update(self): 
     pass 
     #self.rect.y += self.speedy 

all_sprites = pygame.sprite.Group() 
balls = pygame.sprite.Group() 
player = Player() 
all_sprites.add(player) 

while isRunning: 

    clock.tick(FPS) 

    for event in pygame.event.get(): 
     if event.type == pygame.QUIT: 
      isRunning = False 

     if event.type == pygame.KEYDOWN: 
      if event.key == pygame.K_SPACE: 
       player.shoot() 

    window.fill((0, 0, 30)) 

    all_sprites.update() 

    all_sprites.draw(window) 

    pygame.display.flip() 

pygame.quit() 
quit() 

Answer 1

我不确定我是否理解您的问题，但代码的问题在于您每次更新播放器时都会创建一个球。只需删除播放器更新方法中的最后四行，并取消注释球的更新方法中的一行，并且所有内容都按照原样运行。

其他提示

删除球，当他们退出屏幕。这将防止游戏运行缓慢或崩溃。可以通过在球更新方法中添加if self.rect.bottom < 0: self.kill()来实现。

适当时使用elif。

在播放器更新方法中，您定义了一个属性self.speedx，该属性仅在该方法内部使用，因此最好仅使用局部变量。此外，在__init__方法之外定义属性是不利的。

这是您的代码稍作修改。

import pygame 
pygame.init() 

is_running = True # Use lowercase_and_underscore for variable names. 

WIDTH = 800 
HEIGHT = 600 
FPS = 60 

clock = pygame.time.Clock() 
window = pygame.display.set_mode((WIDTH, HEIGHT)) 


class Player(pygame.sprite.Sprite): 
    def __init__(self): 
     pygame.sprite.Sprite.__init__(self) 

     self.image = pygame.Surface((60, 30)) 
     self.image.fill((200, 255, 200)) 
     self.rect = self.image.get_rect() 
     self.rect.centerx = WIDTH/2 
     self.rect.bottom = HEIGHT - 30 

    def update(self): 
     speedx = 0 # Don't define attributes outside __init__. Local variable works in this case instead. 

     keystate = pygame.key.get_pressed() 
     if keystate[pygame.K_a]: 
      speedx = -5 
     elif keystate[pygame.K_d]: # Use elif so it doesn't need to check this condition if the above is true. 
      speedx = 5 

     self.rect.x += speedx 

     if self.rect.right + speedx > WIDTH: 
      self.rect.right = WIDTH 
     elif self.rect.left + speedx < 0: # Use elif so it doesn't need to check this condition if the above is true. 
      self.rect.left = 0 

    def shoot(self): 
     ball = Ball(self.rect.centerx, self.rect.top) 
     all_sprites.add(ball) 
     balls.add(ball) 


class Ball(pygame.sprite.Sprite): 
    def __init__(self, x, y): 
     pygame.sprite.Sprite.__init__(self) 
     self.image = pygame.Surface((10, 10)) 
     self.image.fill((100, 150, 200)) 
     self.rect = self.image.get_rect() 
     self.rect.bottom = y 
     self.rect.centerx = x 
     self.speedy = -3 

    def update(self): 
     if self.rect.bottom < 0: # Chack if the ball has exit above the screen. 
      self.kill() # If it has it should delete itself. 
     self.rect.y += self.speedy 

all_sprites = pygame.sprite.Group() 
balls = pygame.sprite.Group() 
player = Player() 
all_sprites.add(player) 

while is_running: 

    clock.tick(FPS) 
    print(all_sprites) 

    for event in pygame.event.get(): 
     if event.type == pygame.QUIT: 
      is_running = False 
     elif event.type == pygame.KEYDOWN: 
      if event.key == pygame.K_SPACE: 
       player.shoot() 

    window.fill((0, 0, 30)) 
    all_sprites.update() 
    all_sprites.draw(window) 
    pygame.display.flip() 

pygame.quit() 
quit() 

编辑：让球放在桨，空间

先启动，你可以创建Player类的属性self.current_ball将参考在桨球。然后在Player类的更新方法中，更新球相对于桨的位置。

要将球保持在桨状态，必须将球的self.speedy更改为从0开始，否则它将在创建后直接移动。当您拨打player.shoot()方法时，您将设置self.speedy = -3这将启动球移动。

启动后，您只需在桨上创建一个新球并重复相同的过程。

import pygame 
pygame.init() 

is_running = True # Use lowercase_and_underscore for variable names. 

WIDTH = 800 
HEIGHT = 600 
FPS = 60 

clock = pygame.time.Clock() 
window = pygame.display.set_mode((WIDTH, HEIGHT)) 


class Player(pygame.sprite.Sprite): 
    def __init__(self): 
     pygame.sprite.Sprite.__init__(self) 

     self.image = pygame.Surface((60, 30)) 
     self.image.fill((200, 255, 200)) 
     self.rect = self.image.get_rect() 
     self.rect.centerx = WIDTH/2 
     self.rect.bottom = HEIGHT - 30 
     self.current_ball = Ball(self.rect.centerx, self.rect.top) 
     all_sprites.add(self.current_ball) 
     balls.add(self.current_ball) 

    def update(self): 
     speedx = 0 # Don't define attributes outside __init__. Local variable works in this case instead. 

     keystate = pygame.key.get_pressed() 
     if keystate[pygame.K_a]: 
      speedx = -5 
     elif keystate[pygame.K_d]: # Use elif so it doesn't need to check this condition if the above is true. 
      speedx = 5 

     self.rect.x += speedx 

     if self.rect.right + speedx > WIDTH: 
      self.rect.right = WIDTH 
     elif self.rect.left + speedx < 0: # Use elif so it doesn't need to check this condition if the above is true. 
      self.rect.left = 0 

     self.current_ball.rect.midbottom = self.rect.midtop # Set the ball position relative to paddle position. 

    def shoot(self): 
     self.current_ball.speedy = -3 # The ball should start moving. 
     self.current_ball = Ball(self.rect.centerx, self.rect.top) # Create a new ball on the paddle. 
     all_sprites.add(self.current_ball) 
     balls.add(self.current_ball) 


class Ball(pygame.sprite.Sprite): 
    def __init__(self, x, y): 
     pygame.sprite.Sprite.__init__(self) 
     self.image = pygame.Surface((10, 10)) 
     self.image.fill((100, 150, 200)) 
     self.rect = self.image.get_rect() 
     self.rect.bottom = y 
     self.rect.centerx = x 
     self.speedy = 0 # The ball don't move from the beginning. 

    def update(self): 
     if self.rect.bottom < 0: # Chack if the ball has exit above the screen. 
      self.kill() # If it has it should delete itself. 
     self.rect.y += self.speedy 

all_sprites = pygame.sprite.Group() 
balls = pygame.sprite.Group() 
player = Player() 
all_sprites.add(player) 

while is_running: 

    clock.tick(FPS) 
    print(all_sprites) 

    for event in pygame.event.get(): 
     if event.type == pygame.QUIT: 
      is_running = False 
     elif event.type == pygame.KEYDOWN: 
      if event.key == pygame.K_SPACE: 
       player.shoot() 

    window.fill((0, 0, 30)) 
    all_sprites.update() 
    all_sprites.draw(window) 
    pygame.display.flip() 

pygame.quit() 
quit()