pygame飞机大战[无计分关底]

import pygame
import sys
import random
class zhuji(pygame.sprite.DirtySprite):
    def __init__(self,image,locatian):
        pygame.sprite.DirtySprite.__init__(self)
        self.image = pygame.image.load(image)
        self.rect = self.image.get_rect()
        self.rect.topleft = locatian
class enemy(pygame.sprite.DirtySprite):
    def __init__(self,image,locatian):
        pygame.sprite.DirtySprite.__init__(self)
        self.image = pygame.image.load(image)
        self.rect = self.image.get_rect()
        self.rect.topleft = locatian
    def update(self):
        self.rect.topleft = (self.rect.topleft[0],self.rect.topleft[1]+1)
        root.blit(self.image,self.rect)
        if self.rect.topleft[1]>650:
            self.kill()
class bullet(pygame.sprite.DirtySprite):
    def __init__(self,image,locatian):
        pygame.sprite.DirtySprite.__init__(self)
        self.image = pygame.image.load(image)
        self.rect = self.image.get_rect()
        self.rect.topleft = locatian
    def update(self):
        self.rect.topleft = (self.rect.topleft[0],self.rect.topleft[1]-2)
        root.blit(self.image,self.rect)
        if self.rect.topleft[1]<0:
            self.kill()

bb = pygame.sprite.Group()
ee = pygame.sprite.Group()
po = (150,520)
po2 =(0,0)
speed = 0.0
k=0
pygame.init()
root = pygame.display.set_mode((400,650))
bg = pygame.image.load("background.jpeg")
plane = zhuji("AI改图-plane-100x102.png",po)
plane_enemy = enemy("plane-enemy.png",po2)
ee.add(plane_enemy)
def update():
    root.blit(bg,(0,0))
    root.blit(plane.image,po)
    bb.update()
    ee.update()
    pygame.display.update()
pygame.display.update()
c=pygame.time.Clock()
while 1:
    c.tick(300)
    for e in pygame.event.get():
        if e.type == pygame.QUIT:
            pygame.quit()
            sys.exit()
        if e.type == pygame.KEYDOWN:
            if e.key == pygame.K_a:
                speed=-1
                #po = (po[0]-10,po[1])
            if e.key == pygame.K_d:
                speed=1
                #po = (po[0] + 10, po[1])
            if e.key == pygame.K_SPACE:
                b =  bullet("bullet.png", (po[0]+43,po[1]))
                root.blit(b.image, b.rect)
                bb.add(b)
        if e.type==pygame.KEYUP:
            speed=0
    po = (po[0] + speed, po[1])
    if k == 400:
        po2 = (random.randint(0,400),0)
        plane_enemy = enemy("plane-enemy.png", po2)
        ee.add(plane_enemy)
        k=0
    k+=1
    pygame.sprite.groupcollide(ee,bb,True,True)
    XY = pygame.sprite.spritecollideany(plane,ee)
    if XY:
        root.blit(bg,(0,0))
        f = pygame.font.Font(None,40)
        xy = f.render("GAME OVER",True,(255,0,0))
        root.blit(xy,(110,325))
        pygame.display.update()
    else:
        update()