Python Snake Game with Pygame: Design Overview and Full Source Code

The document introduces a Snake game implemented in Python, describing the basic controls (arrow keys), gameplay rules (growth on eating food, death on wall collision or self‑collision), and two modes: normal and wall‑through.

An overall design diagram (image) outlines the game's architecture.

The development uses Python as the programming language and relies on several libraries: pygame for graphics and sound, random for generating food positions, time for timing utilities, and sys for program termination.

Key design components include a Position class for coordinates, objects for the snake head, body, and food, and an initialization interface offering three buttons (Normal Mode, Wall‑Through Mode, Exit). The game loop handles keyboard input, updates the snake’s direction, moves the snake, checks for collisions, updates the score, and renders the scene.

Important functions are explained:

new_food(head) : generates a new food position that does not overlap the snake head.

start_game() : implements the normal mode main loop, handling movement, collision detection, scoring, and rendering.

die_snake(head, snake_body) : determines death in normal mode by checking wall boundaries and self‑collision.

through_snake(head, snake_body) : handles death and wall‑through logic for the alternative mode.

start_kgame() : main loop for wall‑through mode, allowing the snake to reappear on the opposite side.

button(msg, x, y, w, h, ic, ac, action) : renders interactive buttons and triggers the corresponding actions.

into_game() : displays the initial menu and waits for the user to select a mode.

The full source code is provided below for reference and direct use.

import sys
import time
import pygame
from random import *
# Position类，通过其构造函数，设置x和y
class Position(object):
    def __init__(self, x, y):
        self.x = x
        self.y = y
# 生成随机的食物
def new_food(head):
    while True:
        new_food = Position(randint(0, 48) * 20, randint(0, 29) * 20)
        # 判断新生成的事物是否和贪吃蛇蛇头重合，重合则不创键
        if new_food.x != head.x and new_food.y != head.y:
            break
        else:
            continue
    return new_food
# 绘制，在窗体中绘制贪吃蛇、食物
# color:颜色，position: 坐标
def rect(color, position):
    pygame.draw.circle(window, color, (position.x, position.y), 10)
# 初始界面和游戏中点差退出游戏时
def exit_end():
    pygame.quit()
    quit()
# 游戏结束时，显示得分的窗体的设置
def show_end():
    # 设计窗口
    # 定义窗口大小
    small_window = pygame.display.set_mode((960, 600))
    init_background = pygame.image.load("image/init_bgimg.jpg")
    small_window.blit(init_background, (0, 0))
    # 定义标题
    pygame.display.set_caption("贪吃蛇大冒险")
    # 定义背景图片
    font = pygame.font.SysFont("simHei", 40)
    fontsurf = font.render('游戏结束! 你的得分为: %s' % score, False, black)
    small_window.blit(fontsurf, (250, 200))
    pygame.display.update()
    time.sleep(2)
    pygame.quit()
    sys.exit()
# 正常模式死亡设置
# head: 蛇头， snake_body:蛇身
def die_snake(head, snake_body):
    # 定义标志物，默认为false，true时判定贪吃蛇碰到自己，死亡
    die_flag = False
    # 遍历存放贪吃蛇位姿的列表，从第1个开始，(第0个位蛇头)
    for body in snake_body[1:]:
        # 如果蛇头的xy和蛇身xy相等，则判定相撞，设置flag为ture
        if head.x == body.x and head.y == body.y:
            die_flag = True
    # 若蛇头的xy在显示窗体外，或flag为true，则显示结束界面，并退出游戏
    if head.x < 0 or head.x > 960 or head.y < 0 or head.y > 600 or die_flag:
        pygame.mixer.music.stop()
        show_end()
# 正常模式主体设置
def start_game():
    # 定义存分数的全局变量
    global score
    global color
    color = (randint(10, 255), randint(10, 255), randint(10, 255))
    # 定义存放玩家键盘输入运动方向的变量，初始为向右
    run_direction = "right"
    # 定义贪吃蛇运动方向的变量，初始为玩家键入方向
    run = run_direction
    # 实例化蛇头、蛇身、食物对象
    head = Position(160, 160)
    # 初始化蛇身长度为3个单位
    snake_body = [Position(head.x, head.y + 20), Position(head.x, head.y + 40), Position(head.x, head.y + 60)]
    # 初始化食物位置
    food = Position(300, 300)
    # 死循环
    while True:
        window.blit(background, (0,0))
        # 监听玩家键盘输入的运动方向值，并根据输入转为up、down、right或left，方便程序中调用
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                show_end()
            elif event.type == pygame.KEYDOWN:
                if event.key == pygame.K_UP:
                    run_direction = "up"
                elif event.key == pygame.K_RIGHT:
                    run_direction = "right"
                elif event.key == pygame.K_LEFT:
                    run_direction = "left"
                elif event.key == pygame.K_DOWN:
                    run_direction = "down"
        # 食物
        rect(color, food)
        # 蛇头
        rect(black, head)
        # 蛇身
        for pos in snake_body:
            rect(white, pos)
        # 判断贪吃蛇原运动方向与玩家键盘输入的运动方向是否违反正常运动情况
        if run == "up" and not run_direction == "down":
            run = run_direction
        elif run == "down" and not run_direction == "up":
            run = run_direction
        elif run == "left" and not run_direction == "right":
            run = run_direction
        elif run == "right" and not run_direction == "left":
            run = run_direction
        # 插入蛇头位置到蛇身列表中
        snake_body.insert(0, Position(head.x, head.y))
        # 根据玩家键入方向进行蛇头xy的更新
        if run == "up":
            head.y -= 20
        elif run == "down":
            head.y += 20
        elif run == "left":
            head.x -= 20
        elif run == "right":
            head.x += 20
        # 判断是否死亡
        die_snake(head, snake_body)
        # 判断蛇头和食物坐标，若相等，则加分，并生成新的食物
        if head.x == food.x and head.y == food.y:
            score += 1
            food = new_food(head)
            color = (randint(10, 255), randint(10, 255), randint(10, 255))
        else:
            snake_body.pop()
        font = pygame.font.SysFont("simHei", 25)
        mode_title = font.render('正常模式', False, grey)
        socre_title = font.render('得分: %s' % score, False, grey)
        window.blit(mode_title, (50, 30))
        window.blit(socre_title, (50, 65))
        # 绘制更新
        pygame.display.update()
        # 通过帧率设置贪吃蛇速度
        clock.tick(8)
# 可穿墙模式死亡设置
# head:蛇头，snake_body:蛇身
def through_snake(head, snake_body):
    # 定义标志位
    die_flag = False
    # 遍历，蛇头碰到蛇身时，flag为true退出游戏
    for body in snake_body[1:]:
        if head.x == body.x and head.y == body.y:
            die_flag = True
    if die_flag:
        pygame.mixer.music.stop()
        show_end()
    else:  # 当蛇头的xy出窗体时
        # 四种穿墙情况，分别设置
        if head.x < 0:
            head.x = 960
        if head.x > 960:
            head.x = 0
        if head.y < 0:
            head.y = 600
        if head.y > 600:
            head.y = 0
# 穿墙模式主体设置
def start_kgame():
    global score
    global color
    color = (randint(10, 255), randint(10, 255), randint(10, 255))
    # 定义蛇初始方向
    run_direction = "up"
    run = run_direction
    # 实例化蛇头、蛇身、食物对象
    head = Position(160, 160)
    # 三格
    snake_body = [Position(head.x, head.y + 20), Position(head.x, head.y + 40), Position(head.x, head.y + 60)]
    # 初始化事物位置
    food = Position(300, 300)
    # 死循环，监听键盘键值
    while True:
        window.blit(background, (0, 0))
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                show_end()
            elif event.type == pygame.KEYDOWN:
                if event.key == pygame.K_UP:
                    run_direction = "up"
                elif event.key == pygame.K_RIGHT:
                    run_direction = "right"
                elif event.key == pygame.K_LEFT:
                    run_direction = "left"
                elif event.key == pygame.K_DOWN:
                    run_direction = "down"
        # 食物
        rect(color, food)
        # 蛇头
        rect(black, head)
        # 蛇身
        for pos in snake_body:
            rect(white, pos)
        # 判断贪吃蛇原运动方向与玩家键盘输入的运动方向是否违反正常运动情况
        if run == "up" and not run_direction == "down":
            run = run_direction
        elif run == "down" and not run_direction == "up":
            run = run_direction
        elif run == "left" and not run_direction == "right":
            run = run_direction
        elif run == "right" and not run_direction == "left":
            run = run_direction
        # 插入蛇头位置到蛇身列表中
        snake_body.insert(0, Position(head.x, head.y))
        # 根据玩家键入方向进行蛇头xy的更新
        if run == "up":
            head.y -= 20
        elif run == "down":
            head.y += 20
        elif run == "left":
            head.x -= 20
        elif run == "right":
            head.x += 20
        # 穿墙实现
        through_snake(head, snake_body)
        # 判断是否加分和随机生成新的食物
        if head.x == food.x and head.y == food.y:
            score += 1
            food = new_food(head)
            color = (randint(10, 255), randint(10, 255), randint(10, 255))
        else:
            snake_body.pop()
        font = pygame.font.SysFont("simHei", 25)
        mode_title = font.render('穿墙模式', False, grey)
        socre_title = font.render('得分: %s' % score, False, grey)
        window.blit(mode_title, (50, 30))
        window.blit(socre_title, (50, 65))
        # 绘制更新
        pygame.display.update()
        # 通过帧率设置贪吃蛇速度
        clock.tick(8)
# 监听函数，监听键盘输入
def button(msg, x, y, w, h, ic, ac, action=None):
    # 获取鼠标位置
    mouse = pygame.mouse.get_pos()
    # 获取键盘输入
    click = pygame.mouse.get_pressed()
    if x + w > mouse[0] > x and y + h > mouse[1] > y:
        pygame.draw.rect(window, ac, (x, y, w, h))
        if click[0] == 1 and action != None:
            action()
    else:
        pygame.draw.rect(window, ic, (x, y, w, h))
    # 设置按钮中的文字样式和居中对齐
    font = pygame.font.SysFont('simHei', 20)
    smallfont = font.render(msg, True, white)
    smallrect = smallfont.get_rect()
    smallrect.center = ((x + (w / 2)), (y + (h / 2)))
    window.blit(smallfont, smallrect)
# 游戏初始界面，选择模式
def into_game():
    into = True
    while into:
        window.blit(init_background, (0, 0))
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                exit_end()
        # 设置字体
        font = pygame.font.SysFont("simHei", 50)
        # 初始界面显示文字
        fontsurf = font.render('欢迎来到贪吃蛇大冒险!', True, black)
        fontrect = fontsurf.get_rect()
        fontrect.center = ((width / 2), 200)
        window.blit(fontsurf, fontrect)
        button("正常模式", 370, 370, 200, 40, blue, brightred, start_game)
        button("可穿墙模式", 370, 420, 200, 40, violte, brightred, start_kgame)
        button("退出", 370, 470, 200, 40, red,brightred, exit_end)
        pygame.display.update()
        clock.tick(15)
if __name__ == '__main__':
    # 定义画布颜色
    white = (255, 255, 255)
    red = (200, 0, 0)
    green = (0, 128, 0)
    blue = (0, 202, 254)
    violte = (194, 8, 234)
    brightred = (255, 0, 0)
    brightgreen = (0, 255, 0)
    black = (0, 0, 0)
    grey = (129, 131, 129)
    score = 0
    # 设计窗口
    # 定义窗口大小
    width = 960
    height = 600
    window = pygame.display.set_mode((width, height))
    # 定义标题
    pygame.display.set_caption("贪吃蛇大冒险")
    # 定义背景图片
    init_background = pygame.image.load("image/init_bgimg.jpg")
    background = pygame.image.load("image/bgimg.jpg")
    # 背景音乐
    pygame.mixer.init()
    pygame.mixer.music.load("background.mp3")
    pygame.mixer.music.play(-1)
    # 创建时钟
    clock = pygame.time.Clock()
    # 初始化
    pygame.init()
    # 初始界面
    into_game()