JS贪吃蛇小游戏

Posted 2021-09-12 交社惧恐症

var sw = 20, // 一个方块的宽度

sh = 20,  // 高度
tr = 30,  // 行数
td = 30;  // 列数

var snake = null, // 蛇的实例

food = null,  // 食物的实例
game = null;  // 游戏实例

// 方块构造函数
function Square(x,y,classname) {

this.x = x*sw;
this.y = y*sh;
this.class = classname;

this.viewContent = document.createElement(\'div\');
this.viewContent.className = this.class;
this.parent = document.getElementById(\'snakeWrap\');

}

Square.prototype.create = function(){ // 创建方块dom

this.viewContent.style.position=\'absolute\';
this.viewContent.style.width = sw+\'px\';
this.viewContent.style.height = sh + \'px\';
this.viewContent.style.left = this.x +\'px\';
this.viewContent.style.top = this.y + \'px\';

this.parent.appendChild(this.viewContent)

}

Square.prototype.remove = function() {

this.parent.removeChild(this.viewContent);

}

// 蛇
function Snake () {

this.head = null; //蛇头
this.tail = null; // 蛇尾
this.pos = []; // 存储蛇身上的每一个方块的位置
this.directionNum = { // 存储蛇走的方向，用一个对象来表示
    left:{
        x:-1,
        y:0,
        rotate:180 // 蛇头旋转角度
    },
    right:{
        x:1,
        y:0,
        rotate:0
    },
    up:{
        x:0,
        y:-1,
        rotate:-90
    },
    down:{
        x:0,
        y:1,
        rotate:90
    }
}

}

Snake.prototype.init = function() {

// 创建蛇头
var snakeHead = new Square(2,0,\'snakeHead\');
snakeHead.create();
this.head = snakeHead; // 存储蛇头信息
this.pos.push([2,0])  // 存储蛇头位置
// 创建蛇身体
var snakeBody1 = new Square(1,0,\'snakeBody\');
snakeBody1.create();
this.pos.push([1,0])  // 存储蛇身1位置

var snakeBody2 = new Square(0,0,\'snakeBody\');
snakeBody2.create();
this.tail = snakeBody2; // 存储蛇尾信息
this.pos.push([0,0])  // 存储蛇身1位置

// 形成链表关系
snakeHead.last = null;
snakeHead.next = snakeBody1;

snakeBody1.last = snakeHead;
snakeBody1.next = snakeBody2;

snakeBody2.last = snakeBody1;
snakeBody2.next = null;

// 给蛇添加一个属性，用来表示蛇走的方向
this.direction = this.directionNum.right; // 默认往右走

}

// 获取蛇头的下一个位置对应的元素，要根据元素做不同的事情
Snake.prototype.getNextPos = function() {

var nextPos = [
    this.head.x/sw+this.direction.x,
    this.head.y/sh+this.direction.y
]
// 下个点是自己，游戏结束
var selfCollied = false; //是否撞到了自己
this.pos.forEach(function(value) {
    if(value[0]==nextPos[0] && value[1]==nextPos[1]){
        selfCollied = true;
    }
});
if(selfCollied){
    console.log(\'撞到了自己\');

    this.strategies.die.call(this);
    return;
}
// 下个点是围墙，游戏结束
if(nextPos[0]<0 || nextPos[1]<0 || nextPos[0]>td-1 || nextPos[1]>tr-1){
    console.log(\'撞到了墙\');

    this.strategies.die.call(this);
    return;
}

// 下个点是食物，吃
if(food && food.pos[0]==nextPos[0] && food.pos[1]==nextPos[1]){
    // 如果这个条件成立说明现在蛇头要走的下一个点是食物的那个点；
    console.log(\'吃到食物了\');
    this.strategies.eat.call(this);
    return;
}


// 下个点什么都不是，走
this.strategies.move.call(this);

};

// 处理碰撞后要做的事
Snake.prototype.strategies = {

move:function(format) {  // 该参数用于决定是否删除蛇尾
    // 创建新身体，在旧蛇头的位置
    var newBody = new Square(this.head.x/sw,this.head.y/sh,\'snakeBody\');
    // 更新链表的关系
    newBody.next = this.head.next;
    newBody.next.last = newBody;
    newBody.last = null;

    this.head.remove(); // 把旧蛇头从原来的位置删除
    newBody.create();

    // 创建蛇头:蛇头下一个点
    var newHead = new Square(this.head.x/sw+this.direction.x,this.head.y/sh+this.direction.y,\'snakeHead\');

     // 更新链表的关系
     newHead.next = newBody;
     newHead.last = null;
     newBody.last = newHead;

     newHead.viewContent.style.transform = \'rotate(\'+this.direction.rotate+\'deg)\';
           
     newHead.create();

     // 更新蛇身上每一个方块的坐标
     this.pos.splice(0,0,[this.head.x/sw+this.direction.x,this.head.y/sh+this.direction.y]);
     this.head = newHead;  //更新this.head

    if(!format){  // false: 需要删除（处理吃之外的操作）
        this.tail.remove();
        this.tail = this.tail.last;
        this.pos.pop();

    }
    


},
eat:function(){
    this.strategies.move.call(this,true);
    createFood();
    game.score++;
},
die:function(){
    game.over();
}

}

snake = new Snake();
// snake.init();

// 创建食物
function createFood(){

// 食物的随机坐标
var x = null;
var y = null;
var include = true; // 循环跳出的条件,true表示食物坐标在蛇身上，false:表示不在
while(include){
    x = Math.round(Math.random()*(td-1));
    y = Math.round(Math.random()*(tr-1));
    snake.pos.forEach(function(value){
        if(x!=value[0] && y!=value[1]){
            //  坐标不在蛇身上
            include = false;
        }
    })
}
// 生成食物
food = new Square(x,y,\'food\');
food.pos = [x,y];  // 存储食物的坐标，用于跟蛇头下一个走的点作对比

var foodDom = document.querySelector(\'.food\');
if(foodDom){
    foodDom.style.left = x*sw +\'px\';
    foodDom.style.top = y*sh +\'px\';
}else{
    food.create();
}

}

// 创建游戏逻辑
function Game(){

this.timer = null;
this.score = 0;

}
Game.prototype.init = function(){

snake.init();
createFood();

document.onkeydown = function(ev) {
    //  用户按下左键， 蛇不能是正在往右走的
    if(ev.which == 37 &&  snake.direction != snake.directionNum.right){
        snake.direction = snake.directionNum.left;
    }else if(ev.which == 38 &&  snake.direction != snake.directionNum.down){
        snake.direction = snake.directionNum.up;
    }else if(ev.which == 39 &&  snake.direction != snake.directionNum.left){
        snake.direction = snake.directionNum.right;
    }else if(ev.which == 40 &&  snake.direction != snake.directionNum.up){
        snake.direction = snake.directionNum.down;
    }
}

this.start();

}

Game.prototype.start = function(){

// 开始游戏
this.timer = setInterval(function(){
    snake.getNextPos();
    
},200);

}
Game.prototype.pause = function() {

clearInterval(this.timer);

}
Game.prototype.over = function() {

clearInterval(this.timer);
alert(\'你的得分为：\'+ this.score);

// 游戏回到最初始的状态
var snakeWrap = document.getElementById(\'snakeWrap\');
snakeWrap.innerhtml = \'\';
snake = new Snake();
game = new Game();

var startBtnWrap = document.querySelector(\'.startBtn\');
startBtnWrap.style.display = \'block\';

}

// 开启游戏
game = new Game();

var startBtn = document.querySelector(\'.startBtn button\');
startBtn.onclick = function(){

startBtn.parentNode.style.display = \'none\';
game.init();

}

// 暂停游戏
var snakeWrap = document.getElementById(\'snakeWrap\');
var pauseBtn = document.querySelector(\'.pauseBtn button\');
snakeWrap.onclick = function() {

game.pause();
pauseBtn.parentNode.style.display=\'block\';

}
pauseBtn.onclick = function() {

game.start();
pauseBtn.parentNode.style.display=\'none\';

}