python之我的 pygame 角色在我移动时会留下痕迹

我一直在尝试用 Python 制作游戏，但当我移动我的角色时，它会留下痕迹。我知道它并没有显示出那么多，但如果你靠近你就可以看到踪迹，这真的让我很困扰。

这是我的代码:

import pygame 
import os 
from pygame import mixer 
 
pygame.init() 
mixer.init() 
 
width = 800 
height = 600 
 
black = (0,0,0) 
white = (255,255,255) 
 
ship_width = 56 
ship_height = 64 
 
disp = pygame.display.set_mode((width,height)) 
 
pygame.display.set_caption("space_game") 
 
clock = pygame.time.Clock() 
 
background = pygame.image.load(os.path.join("Backgrounds", "Space.png")) 
 
Ship00 = pygame.image.load(os.path.join("Images", "Animations", "Ship  
Animation", "Ship00.png")) 
Ship01 = pygame.image.load(os.path.join("Images", "Animations", "Ship  
Animation", "Ship01.png")) 
Ship02 = pygame.image.load(os.path.join("Images", "Animations", "Ship  
Animation", "Ship02.png")) 
Ship03 = pygame.image.load(os.path.join("Images", "Animations", "Ship  
Animation", "Ship03.png")) 
Ship04 = pygame.image.load(os.path.join("Images", "Animations", "Ship  
Animation", "Ship04.png")) 
Ship05 = pygame.image.load(os.path.join("Images", "Animations", "Ship  
Animation", "Ship05.png")) 
Ship06 = pygame.image.load(os.path.join("Images", "Animations", "Ship  
Animation", "Ship06.png")) 
Ship07 = pygame.image.load(os.path.join("Images", "Animations", "Ship  
Animation", "Ship07.png")) 
Ship08 = pygame.image.load(os.path.join("Images", "Animations", "Ship  
Animation", "Ship08.png")) 
Ship09 = pygame.image.load(os.path.join("Images", "Animations", "Ship  
Animation", "Ship09.png")) 
Ship10 = pygame.image.load(os.path.join("Images", "Animations", "Ship  
Animation", "Ship10.png")) 
Ship11 = pygame.image.load(os.path.join("Images", "Animations", "Ship  
Animation", "Ship11.png")) 
Ship12 = pygame.image.load(os.path.join("Images", "Animations", "Ship  
Animation", "Ship12.png")) 
Ship13 = pygame.image.load(os.path.join("Images", "Animations", "Ship  
Animation", "Ship13.png")) 
Ship14 = pygame.image.load(os.path.join("Images", "Animations", "Ship  
Animation", "Ship14.png")) 
Ship15 = pygame.image.load(os.path.join("Images", "Animations", "Ship  
Animation", "Ship15.png")) 
Ship16 = pygame.image.load(os.path.join("Images", "Animations", "Ship  
Animation", "Ship16.png")) 
 
images = [Ship00, Ship01, Ship02, Ship03, Ship04, Ship05, Ship06, Ship07,  
Ship08, Ship09, Ship10, Ship11, Ship12, Ship13, Ship14, Ship15, Ship16] 
 
mixer.music.load(os.path.join("Music", "space_song.wav")) 
mixer.music.play() 
 
def gameLoop(): 
    x = (width * 0.45) 
    y = (height * 0.8) 
 
    x_ch = 0 
    y_ch = 0 
 
    x_bg = 0 
 
    index = 0 
 
    gameExit = False 
 
    while not gameExit: 
        for event in pygame.event.get(): 
            if event.type == pygame.QUIT: 
                gameExit = True 
 
            if event.type == pygame.KEYDOWN: 
                if event.key == ord("a"): 
                    x_ch = -5 
 
                elif event.key == ord("d"): 
                    x_ch = 5 
 
                elif event.key == ord("w"): 
                    y_ch = -5 
 
                elif event.key == ord("s"): 
                    y_ch = 5 
 
            if event.type == pygame.KEYUP: 
                if event.key == ord("a") or event.key == ord("d"): 
                    x_ch = 0 
 
                if event.key == ord("w") or event.key == ord("s"): 
                    y_ch = 0 
 
        x += x_ch 
        y += y_ch 
 
        if x > width - ship_width or x < 0: 
            x_ch = 0 
 
        if y > height - ship_height or y < 0: 
            y_ch = 0 
 
        x_loop = x_bg % background.get_rect().height 
        disp.blit(background, (0, x_loop - background.get_rect().height)) 
 
        if x_loop < height: 
            disp.blit(background, (0, x_loop)) 
 
        x_bg += 5 
 
        index += 1 
        index %= len(images) 
        current_image = images[index] 
        disp.blit(current_image, (x,y)) 
 
        pygame.display.update() 
 
        clock.tick(60) 
 
gameLoop() 
pygame.quit() 
quit() 

我该如何解决这个问题？ (我知道轨迹几乎是看不见的，但我希望我的游戏表现出色)我有一个循环向下移动的背景，为什么轨迹不随之移动？