Python 硬币没有出现

我想做一个宇宙飞船游戏，你可以控制一艘宇宙飞船并发射子弹摧毁敌舰。我试图让屏幕上满是硬币，但当我跑的时候，没有硬币出现？我怎样才能让硬币填满屏幕

这是我当前的代码（主要部件和零件省略或替换或通过）：

---

您必须在

coins

组中绘制硬币。此外，我建议限制硬币数量（例如100）：

coins=pygame.sprite.Group（）
# [...]
运行时：
# [...]
如果len（硬币）<100：
硬币。添加（硬币（（兰丁（-200200），兰丁（-200200）））
更新()
# [...]
硬币。画（屏幕）#好的。让我来编辑。谢谢你的帮助！
from tools import *


class Spaceship(pygame.sprite.Sprite):

    def __init__(self, s, x, y):
        pass

    def update(self):
        self.rect.center = (self.x, self.y)


class Bullet(pygame.sprite.Sprite):

    def __init__(self, s, x, y):
        pass

    def update(self):
        self.y -= 5
        self.rect.center = (self.x, self.y)
        if self.y < 0:
            self.kill()


class Enemy(pygame.sprite.Sprite):

    def __init__(self, s, x, y, t):
        pygame.sprite.Sprite.__init__(self)

        self.type = t
        self.screen, self.x, self.y = s, x, y
        self.image = pygame.image.load(get_enemy_image()[self.type])
        if self.type == "N1 Galaxy Fighter":
            self.image = pygame.transform.scale(self.image, (235, 215))
        elif self.type == "M7 Comet Glider":
            self.image = pygame.transform.scale(self.image, (155, 215))
        self.rect = self.image.get_rect()
        self.rect = self.image.get_rect()
        self.rect.center = (self.x, self.y)
        self.score_given = get_enemy_given_score()[self.type]

    def update(self):
        if self.y < 0:
            self.kill()
        self.y += 3
        self.rect.center = (self.x, self.y)


class GameOverBackground(pygame.sprite.Sprite):

    def __init__(self, s, x, y, size=(100, 100)):
        pygame.sprite.Sprite.__init__(self)

        self.screen, self.x, self.y = s, x, y
        self.size = size
        self.image = pygame.image.load("Game_Over.jpg")
        self.image = pygame.transform.scale(self.image, self.size)
        self.rect = self.image.get_rect()

    def blitme(self):
        self.screen.blit(self.image, self.rect)


class Coin(pygame.sprite.Sprite):

    def __init__(self, pos=(0, 0), size=(100, 100)):
        pygame.sprite.Sprite.__init__(self)

        self.x, self.y = pos[0], pos[1]
        self.size = size
        self.image = pygame.image.load("coin.png")
        self.image = pygame.transform.scale(self.image, self.size)
        self.rect = self.image.get_rect()
        self.rect.center = (self.x, self.y)

    def update(self):
        self.rect.center = (self.x, self.y)


bg = GameOverBackground(screen, 0, 0, size=(800, 500))

spaceship = Spaceship(screen, 400, 400)

bullets = pygame.sprite.Group()
enemies = pygame.sprite.Group()
coins = pygame.sprite.Group()

clock = pygame.time.Clock()

enemy_interval = 2000  # It's in milliseconds
enemy_event = pygame.USEREVENT + 1
pygame.time.set_timer(enemy_event, enemy_interval)

score = 0
lives = 3

with open("high_score.txt", "r") as file:
    highscore = file.read()

font = pygame.font.SysFont("Arial", 30)
score_text_surface = font.render("Score: {:,}".format(score), True, (0, 0, 0))
lives_text_surface = font.render("HP: %s" % lives, True, (0, 0, 0))
high_score_text_surface = font.render("High score: %s" % highscore, True, (0, 0, 0))

spaceship_collided = False

running = True
while running:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False
        if event.type == MOUSEBUTTONDOWN:
            bullet = Bullet(screen, spaceship.x, spaceship.y - 20)
            bullets.add(bullet)

        if event.type == enemy_event and not lives <= 0:
            enemy = Enemy(screen, randint(-100, 725), 0, choice(["N1 Galaxy Fighter", "M7 Comet Glider"]))
            enemies.add(enemy)

    screen.fill((255, 255, 255))  # DO NOT DRAW ANYTHING IN FRONT OF THIS LINE, I'M WARNING YOU

    bullets.update()

    key = pygame.key.get_pressed()
    amount = 5

    if key[pygame.K_a]:
        spaceship.x -= amount
    elif key[pygame.K_d]:
        spaceship.x += amount
    elif key[pygame.K_w]:
        spaceship.y -= amount
    elif key[pygame.K_s]:
        spaceship.y += amount

    spaceship.update()

    if not lives <= 0:
        screen.blit(spaceship.image, spaceship.rect)

    if not lives <= 0:
        bullets.draw(screen)
        enemies.draw(screen)

        for i in enemies:
            i.update()
            if pygame.sprite.spritecollide(i, bullets, True):
                score += i.score_given
                i.kill()
    if spaceship_collided and lives <= 0:
        bg.blitme()
        if score > int(highscore):
            with open("high_score.txt", "w") as file:
                file.write(str(score))

    if score >= 99999:
        score = 99999

    score_text_surface = font.render("Score: {:,}".format(score), True, (0, 0, 0))
    screen.blit(score_text_surface, (590, 0))

    lives_text_surface = font.render("HP: %s" % lives, True, (0, 0, 0))
    screen.blit(lives_text_surface, (260, 0))

    high_score_text_surface = font.render("High score: %s" % highscore, True, (0, 0, 0))
    screen.blit(high_score_text_surface, (360, 0))

    # Coins
    coins.add(Coin((randint(-200, 200), randint(-200, 200))))
    coins.update()

    if pygame.sprite.spritecollide(spaceship, enemies, dokill=True):
        lives -= 1
        spaceship_collided = True

    pygame.display.update()
    clock.tick(60)

def get_enemy_given_score():
    return {"N1 Galaxy Fighter": 10, "M7 Comet Glider": 20}


def get_enemy_image():
    return {"N1 Galaxy Fighter": "enemy1.png", "M7 Comet Glider": "enemy2.png"}