如何在pygame中添加主菜单和重试菜单

import pygame
from pygame.locals import *

pygame.init()
screen = pygame.display.set_mode((800, 600))
pygame.display.set_caption("My Game")

def show_main_menu():
    # 清空屏幕
    screen.fill((0, 0, 0))
    
    # 显示主菜单标题
    font = pygame.font.Font(None, 36)
    title = font.render("Main Menu", True, (255, 255, 255))
    title_rect = title.get_rect(center=(400, 200))
    screen.blit(title, title_rect)
    
    # 显示菜单选项
    font = pygame.font.Font(None, 24)
    option1 = font.render("Start Game", True, (255, 255, 255))
    option1_rect = option1.get_rect(center=(400, 300))
    screen.blit(option1, option1_rect)
    
    option2 = font.render("Quit", True, (255, 255, 255))
    option2_rect = option2.get_rect(center=(400, 350))
    screen.blit(option2, option2_rect)
    
    # 更新屏幕显示
    pygame.display.flip()

def show_retry_menu():
    # 清空屏幕
    screen.fill((0, 0, 0))
    
    # 显示重试菜单标题
    font = pygame.font.Font(None, 36)
    title = font.render("Retry Menu", True, (255, 255, 255))
    title_rect = title.get_rect(center=(400, 200))
    screen.blit(title, title_rect)
    
    # 显示菜单选项
    font = pygame.font.Font(None, 24)
    option1 = font.render("Retry", True, (255, 255, 255))
    option1_rect = option1.get_rect(center=(400, 300))
    screen.blit(option1, option1_rect)
    
    option2 = font.render("Quit", True, (255, 255, 255))
    option2_rect = option2.get_rect(center=(400, 350))
    screen.blit(option2, option2_rect)
    
    # 更新屏幕显示
    pygame.display.flip()

running = True
main_menu = True
retry_menu = False

while running:
    for event in pygame.event.get():
        if event.type == QUIT:
            running = False
        
        if event.type == KEYDOWN:
            if event.key == K_ESCAPE:
                running = False
            
            if event.key == K_RETURN:
                if main_menu:
                    if option1_rect.collidepoint(pygame.mouse.get_pos()):
                        # 开始游戏
                        main_menu = False
                        retry_menu = False
                        # 添加开始游戏的逻辑代码
                        
                    if option2_rect.collidepoint(pygame.mouse.get_pos()):
                        # 退出游戏
                        running = False
                
                if retry_menu:
                    if option1_rect.collidepoint(pygame.mouse.get_pos()):
                        # 重试游戏
                        main_menu = False
                        retry_menu = False
                        # 添加重试游戏的逻辑代码
                        
                    if option2_rect.collidepoint(pygame.mouse.get_pos()):
                        # 退出游戏
                        running = False
    
    if main_menu:
        show_main_menu()
    
    if retry_menu:
        show_retry_menu()