各位大佬，为什么我的地板不动

代码：
import sys
import pygame
import random,os

# Constants 常量
W,H = 288,512
FPS = 30

# Setup 设置
pygame.init()
SCREEN = pygame.display.set_mode((W,H))
pygame.display.set_caption('  flappy bird  ')
CLOCK = pygame.time.Clock()

# Haterials 素材
IMAGES = {}
for image in os.listdir('999'):
    name,extension = os.path.splitext(image)
    path = os.path.join('999',image)
    IMAGES[name] = pygame.image.load(path)


FLOOR_Y = H - IMAGES['floor'].get_height()
start = pygame.mixer.Sound('999')
die = pygame.mixer.Sound('999')
flap = pygame.mixer.Sound('999')
hit = pygame.mixer.Sound('999')
score = pygame.mixer.Sound('999')

def main():
    while True:
        start.play()
        IMAGES['bgpic'] = IMAGES[random.choice(['day','night'])]
        color = random.choice(['red','yellow','blue'])
        IMAGES['birds'] = [IMAGES[color+'-up'],IMAGES[color+'-mid'],IMAGES[color+'-down']]
        pipe = IMAGES[random.choice(['green-pipe','red-pipe'])]
        IMAGES['pipes'] = [pipe,pygame.transform.flip(pipe,False,True)]
        menv_window()
        game_window()
        end_window()


def menv_window():

    floor_gap = IMAGES['floor'].get_width() - W
    floor_x = 0

    guide_x = (W - IMAGES['guide'].get_width())/2
    guide_y = (FLOOR_Y - IMAGES['guide'].get_height())/2
    bird_x = W * 0.2
    bird_y = (H - IMAGES['red-up'].get_height())/2

    while True:
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                sys.exit()
            if event.type == pygame.KEYDOWN and event.key == pygame.K_SPACE:
                return

        floor_x -= 4
        if floor_x <= - floor_gap:
            floor_x = 0

        SCREEN.blit(IMAGES['bgpic'],(0,0))
        SCREEN.blit(IMAGES['floor'],(0,FLOOR_Y))
        SCREEN.blit(IMAGES['guide'],(guide_x,guide_y))
        SCREEN.blit(IMAGES['birds'][0],(bird_x,bird_y))
        pygame.display.update()
        CLOCK.tick(FPS)


def game_window():
   
    floor_gap = IMAGES['floor'].get_width() - W
    floor_x = 0


    while True:
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                sys.exit()
            if event.type == pygame.KEYDOWN:
                if event.key == pygame.K_SPACE:
                    return

        floor_x -= 4
        if floor_x <= - floor_gap:
            floor_x = 0

        SCREEN.blit(IMAGES['bgpic'],(0,0))
        SCREEN.blit(IMAGES['pipes'][0],(W/2,H/2))
        SCREEN.blit(IMAGES['floor'],(0,FLOOR_Y))
        SCREEN.blit(IMAGES['birds'][0],(W/2,H*0.3))
        pygame.display.update()
        CLOCK.tick(FPS)



def end_window():

    floor_gap = IMAGES['floor'].get_width() - W
    floor_x = 0


    gameover_x = (W - IMAGES['gameover'].get_width())/2
    gameover_y = (FLOOR_Y - IMAGES['gameover'].get_height())/2

    while True:
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                sys.exit()
            if event.type == pygame.KEYDOWN and event.key == pygame.K_SPACE:
                return

        floor_x -= 4
        if floor_x <= - floor_gap:
            floor_x = 0

        SCREEN.blit(IMAGES['bgpic'],(0,0))
        SCREEN.blit(IMAGES['floor'],(0,FLOOR_Y))
        SCREEN.blit(IMAGES['gameover'],(gameover_x,gameover_y))
        SCREEN.blit(IMAGES['birds'][0],(W / 2,H * 0.3))
        pygame.display.update()
        CLOCK.tick(FPS)



main()



图片请各位大佬自行寻找
要添加地址的地方为999