给我写一个贪吃蛇代码，代码里面有详细的注释

好的，以下是一个简单的贪吃蛇代码，带有详细的注释：

import pygame
import random

# 初始化pygame
pygame.init()

# 设置游戏窗口大小
WINDOW_WIDTH = 640
WINDOW_HEIGHT = 480
WINDOW_SIZE = (WINDOW_WIDTH, WINDOW_HEIGHT)

# 设置游戏窗口标题
pygame.display.set_caption('Snake Game')

# 定义颜色
BLACK = (0, 0, 0)
WHITE = (255, 255, 255)
RED = (255, 0, 0)
GREEN = (0, 255, 0)
BLUE = (0, 0, 255)

# 创建游戏窗口
screen = pygame.display.set_mode(WINDOW_SIZE)

# 设置游戏时钟
clock = pygame.time.Clock()

# 设置游戏变量
score = 0  # 得分
game_over = False  # 游戏结束标志

# 定义方向常量
UP = 1
DOWN = 2
LEFT = 3
RIGHT = 4

# 定义贪吃蛇类
class Snake:
    def __init__(self):
        self.x = 0  # 贪吃蛇头部x坐标
        self.y = 0  # 贪吃蛇头部y坐标
        self.direction = RIGHT  # 贪吃蛇初始方向
        self.body = []  # 贪吃蛇身体列表
        self.length = 3  # 贪吃蛇初始长度

    def move(self):
        # 根据方向移动贪吃蛇
        if self.direction == UP:
            self.y -= 20
        elif self.direction == DOWN:
            self.y += 20
        elif self.direction == LEFT:
            self.x -= 20
        elif self.direction == RIGHT:
            self.x += 20

        # 将新的头部坐标加入贪吃蛇身体列表
        self.body.insert(0, (self.x, self.y))

        # 如果贪吃蛇的长度大于指定长度，则删除尾部坐标
        if len(self.body) > self.length:
            self.body.pop()

    def draw(self):
        # 绘制贪吃蛇
        for x, y in self.body:
            pygame.draw.rect(screen, GREEN, (x, y, 20, 20))

    def collision(self):
        # 判断贪吃蛇是否与边界或自身碰撞
        if self.x < 0 or self.x > WINDOW_WIDTH - 20 or self.y < 0 or self.y > WINDOW_HEIGHT - 20:
            return True
        for x, y in self.body[1:]:
            if self.x == x and self.y == y:
                return True
        return False

    def eat(self, food):
        # 判断贪吃蛇是否吃到食物
        if self.x == food.x and self.y == food.y:
            self.length += 1  # 贪吃蛇长度加1
            return True
        return False

# 定义食物类
class Food:
    def __init__(self):
        self.x = random.randrange(0, WINDOW_WIDTH - 20, 20)  # 食物x坐标
        self.y = random.randrange(0, WINDOW_HEIGHT - 20, 20)  # 食物y坐标

    def draw(self):
        # 绘制食物
        pygame.draw.rect(screen, RED, (self.x, self.y, 20, 20))

# 创建贪吃蛇和食物对象
snake = Snake()
food = Food()

# 游戏循环
while not game_over:
    # 处理事件
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            game_over = True
        elif event.type == pygame.KEYDOWN:
            if event.key == pygame.K_UP and snake.direction != DOWN:
                snake.direction = UP
            elif event.key == pygame.K_DOWN and snake.direction != UP:
                snake.direction = DOWN
            elif event.key == pygame.K_LEFT and snake.direction != RIGHT:
                snake.direction = LEFT
            elif event.key == pygame.K_RIGHT and snake.direction != LEFT:
                snake.direction = RIGHT

    # 移动贪吃蛇
    snake.move()

    # 判断是否吃到食物
    if snake.eat(food):
        # 创建新的食物对象
        food = Food()
        # 得分加1
        score += 1

    # 绘制背景
    screen.fill(BLACK)

    # 绘制得分文本
    font = pygame.font.SysFont(None, 30)
    text = font.render('Score: ' + str(score), True, WHITE)
    screen.blit(text, (10, 10))

    # 绘制贪吃蛇和食物
    snake.draw()
    food.draw()

    # 判断是否与边界或自身碰撞
    if snake.collision():
        game_over = True

    # 更新屏幕
    pygame.display.update()

    # 设置游戏帧率
    clock.tick(10)

# 退出pygame
pygame.quit()

希望对你有帮助！