蛇游戏：试图让身体部分跟随玩家控制的头部

Question

我想实现一个蛇游戏。这个程序运行得很好，直到蛇与食物发生碰撞并产生新的身体部位为止。我试图通过以下步骤让这个身体部分跟随我的玩家控制的蛇头（在代码中称为player）：

1. bodypart在世界（屏幕）中以与头部相同的方向和速度创建和绘制，位于头部的侧面（取决于蛇来自何处）。这部分起作用

2. 当检测到键盘输入时，蛇的x和y位置被记录在一个列表中，然后它改变方向。这同样有效

3. 身体部分继续移动，直到蛇的x和y坐标==身体部分的x和y坐标。一旦出现这种情况，身体部分应该改变它的方向，并在蛇后移动。这部分不起作用(身体部分只是继续移动超过记录的x/y坐标点，在离开屏幕之前不会改变方向）

   ''' 
   setup
   '''
   import pygame
   import random
   import sys
   import os
   lefta = pygame.K_LEFT
   leftk = ord("a")
   Black = [0,0,0]
   counter = 0
   bodypartspawn = "False"
   player_locationx = []
   player_locationy = []
   worldx = 1600
   worldy = 900
   fps = 5
   ani = 100
   clock = pygame.time.Clock()
   pygame.init()
   world = pygame.display.set_mode([worldx, worldy])
   
   class BodyPart(pygame.sprite.Sprite):
    def __init__(self):
           pygame.sprite.Sprite.__init__(self)
           self.movex = player.movex
           self.movey = player.movey
           self.frame = 0
           self.images = []
           img = pygame.image.load(os.path.join('images','white_block.png')).convert()
           self.images.append(img)
           self.image = self.images[0]
           self.image = pygame.transform.scale(self.image, (50, 50))
           self.rect  = self.image.get_rect()
    def controlbodypart(self):
           global counter
           if self.rect.x == player_locationx[counter] and self.rect.y == player_locationy[counter]:
            counter = counter +1
            if direction == "left":           
             self.movex = -10      
             self.movey = 0
            if direction == "right":
             self.movex = 10
             self.movey = 0
            if direction == "up":
             self.movex = 0
             self.movey = -10
            if direction == "down":
             self. movex = 0
             self.movey = 10
   
       def updateofbodypart(self):
           self.rect.x = self.rect.x + self.movex
           self.rect.y = self.rect.y + self.movey
   
   
   '''
   Main Loop
   '''
   Main = True
   while Main == True:
    for event in pygame.event.get():
      if event.type == pygame.KEYDOWN:
       if leftk == event.key and direction !="right" or lefta == event.key and direction !="right": 
   #this if statement is repeated for all four directions
        direction = "left"
        if bodypartspawn == "True":
         player_locationx.append(player.rect.x) #player class is defined in my code, but i did not copy it here
         player_locationy.append(player.rect.y)
         #print (player_locationx) and
         #print (player_locationy) were used to test if the lists work. They show the correct coordinates.
         bodypart.controlbodypart()
        player.control(-10, 0) #this changes direction of the snake head
    if player.rect.colliderect(food.rect): #food class is defined in my code, but i have not copied it here
     food.kill()
     food = Food()
     food.rect.x = random.randint(80, 1500)
     food.rect.y = random.randint(80, 800)
     player_list.add(food)
     if direction == "left":
      bodypart = BodyPart()
      bodypart.rect.x = player.rect.x+50 #snake head and body are 50 pixels large, thats why i move it this distance to the side
      bodypart.rect.y = player.rect.y
     bodypartspawn = "True"
    player.updateofplayer()
    if bodypartspawn =="True": 
     player_list.add(bodypart)
     bodypart.updateofbodypart()
    world.fill (Black)
    player_list.draw(world)
    pygame.display.flip()
    clock.tick(fps)
   

我尽了最大努力删除了与问题无关的所有内容，但是我的代码非常复杂且无组织，因此我可能删除了一些对您的理解至关重要的内容。如果是，请告诉我，我会编辑

再次：我没有收到任何错误消息，除了上面的问题，其他一切都正常