如何修复pygame中的精灵动画？

Question

我正在用python3为一个学校项目编写一个游戏（使用pygame），但我正在努力： 我试图让我的精灵在移动时有一个动画，但它只显示一个静态图像： 当我按左键时，精灵的图像将变为静态图像，而不是由3个png组成的动画。 下面是代码的一部分：

clock = pygame.time.Clock()

walkRight = [pygame.image.load('ressources/images/R1.png'), pygame.image.load('ressources/images/R2.png'), pygame.image.load('ressources/images/R3.png')]
walkLeft = [pygame.image.load('ressources/images/L1.png'), pygame.image.load('ressources/images/L2.png'), pygame.image.load('ressources/images/L3.png')]
walkUp = [pygame.image.load('ressources/images/U1.png'), pygame.image.load('ressources/images/U2.png'), pygame.image.load('ressources/images/U3.png')]
walkDown = [pygame.image.load('ressources/images/D1.png'), pygame.image.load('ressources/images/D2.png'), pygame.image.load('ressources/images/D3.png')]


#this is the player sprite

class Player(pygame.sprite.Sprite):
    def __init__(self):
        pygame.sprite.Sprite.__init__(self)
        self.image = (walkDown[4//3])
        self.rect = self.image.get_rect()
        self.rect.centerx = width / 2
        self.rect.bottom = height / 2
        self.speedx = 0
        self.speedy = 0
        self.velocity = 2


    def update(self):
        self.speedx = 0
        self.speedy = 0
        left = False
        right = False
        up = False
        down = False
        run = False  
        walkCount = 4
        runCount = 4   
        clock.tick(FPS)
        keys = pygame.key.get_pressed()

#I believe this is the part that has something wrong!
        if walkCount + 1 >= 9:
            walkCount = 0
        if (down == True and run == False):
            walkCount += 1
            self.image = (walkDown[walkCount//3])     
        elif (up == True and run == False):
            walkCount += 1
            self.image = (walkUp[walkCount//3])
        elif (right == True and run == False):
            walkCount += 1
            self.image = (walkRight[walkCount//3])
        elif (left == True and run == False):
            walkCount += 1
            self.image = (walkLeft[walkCount//3])

Answer 1

walkCount是方法update中的局部变量。每次调用update时，它都由4初始化。因此walkCount的值在函数的开头是相同的，每次都是一样的。这会导致图像看起来是静态的。
walkCount必须是类Player的属性，而不是局部变量：

class Player(pygame.sprite.Sprite):
    def __init__(self):
        pygame.sprite.Sprite.__init__(self)
        self.image = (walkDown[4//3])
        self.rect = self.image.get_rect()
        self.rect.centerx = width / 2
        self.rect.bottom = height / 2
        self.speedx = 0
        self.speedy = 0
        self.velocity = 2

        self.walkCount = 4 # <   add attribute

    def update(self):

        # [...]

        # walkCount = 4  <    delete local variable

        keys = pygame.key.get_pressed()
        down = keys[pygame.K_DOWN]
        up = keys[pygame.K_UP]
        right = keys[pygame.K_RIGHT]
        left = keys[pygame.K_LEFT]
        run = False

        if self.walkCount + 1 >= 9:
            self.walkCount = 0
        if (down == True and run == False):
            self.walkCount += 1
            self.image = (walkDown[self.walkCount//3])     
        elif (up == True and run == False):
            self.walkCount += 1
            self.image = (walkUp[self.walkCount//3])
        elif (right == True and run == False):
            self.walkCount += 1
            self.image = (walkRight[self.walkCount//3])
        elif (left == True and run == False):
            self.walkCount += 1
            self.image = (walkLeft[self.walkCount//3])