自己用canvas写的贪吃蛇代码
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<style type="text/css">
#btn{
width: 200px;
height: 300px;
position: absolute;
left: 620px;top: 10px;
}
[type=button]{
width: 70px;
height: 50px;
margin-left: 20px;
margin-top: 20px;
background: lawngreen;
outline: none;
}
#score{
width: 50px;
height: 50px;
margin: 10px auto;
line-height: 50px;
font-size: 40px;
text-align: center;
}
</style>
</head>
<body>
<canvas id="board" width="601" height="601" style="background: #ccc;display: block;"></canvas>
<div id="btn">
<input type="button" name="start" id="start" value="开始" onclick="startBtn()"/>
<input type="button" name="end" id="end" value="暂停" onclick="endBtn()"/>
<br /><br /><br />
<p><center>得分:</center></p>
<div id="score"></div>
</div>
</body>
</html>
<script type="text/javascript">
var board = document.getElementById('board');
var score = document.getElementById('score');
var context = board.getContext('2d');
//主要类
var num = 0;
score.innerHTML = num;//定义一个分数记录器
var snakeArray = [];//定义一个存储每一节身体的数组;
var aSnake = new Snake(20,0,'yellow')//游戏开始一节身体;
snakeArray.push(aSnake)
aSnake.drwaSnake(context);
var aFood = new Food(200,400)//定义一个食物
var aboard = new canvasBoard();//定义一个画布
aboard.drwaCanvas();
aFood.drawFood();//定义一个食物;
//控制方向和前进像素个数
var speedX = 20;
var speedY = 0;
var x = 0;
var y = 0;
var timer = null;
var lock = false;
//游戏开始函数
function startGame(t){
var t = t;
timer = setInterval(function(){
context.clearRect(0,0,board.width,board.height);//清除画布
var aboard = new canvasBoard();//定义一个画布
aboard.drwaCanvas();
aFood.drawFood();//定义一个食物;
var FoodHit = FoodHitCheck(snakeArray[0],aFood);//检测和食物碰撞
if(FoodHit){
clearInterval(timer);
timer = null;
num++;
score.innerHTML = num;//分数;
aFood.x = randPlace();//改变随机位置
aFood.y = randPlace();
aFood.drawFood();
addSnake(snakeArray);
t -=10
if(t <= 100){
t=100;
}
startGame(t);
}
//操作上下左右
document.onkeydown = function(event){
var ev = event || window.event;
Handle(ev);
}
var len = snakeArray.length;//缓存数组的长度
snakeArray[len-1].x = snakeArray[0].x+speedX;
snakeArray[len-1].y = snakeArray[0].y+speedY;
var a = snakeArray.pop();
snakeArray.unshift(a);
for(var i = 0;i < snakeArray.length;i++){
snakeArray[i].drwaSnake(context)
}
//判断和墙壁碰撞
var isHit = HitCheck(snakeArray[0],board);
if(isHit){
clearInterval(timer)
timer = null;
alert('GAMEOVER');
}
//判断和身体相撞;
for(var i = 2;i < snakeArray.length;i++){
var selfHit = FoodHitCheck(snakeArray[0],snakeArray[i]);
if(selfHit){
clearInterval(timer)
timer = null;
alert('GAMEOVER');
}
}
},t)
}
//开始按钮
function startBtn(){
if(!lock){
startGame(200);
lock = true;
}
}
function endBtn(){
clearInterval(timer);
lock = false;
}
//操作类
function Handle(ev){
var evKeyCode = ev.keyCode;
switch(evKeyCode){
case 65:{
if(speedX <= 0){speedX = -20;speedY = 0;}
break;
}
case 87:{
if(speedY <= 0){speedX = 0;speedY = -20;}
break;
}
case 68:{
if(speedX >= 0){speedX = 20;speedY = 0;}
break;
}
case 83:{
if(speedY >= 0){speedX = 0;speedY = 20;}
break;
}
}
}
//加长身体;
function addSnake(snakeArray){
var l = snakeArray.length;
var sX = snakeArray[l-1].x;
var sY = snakeArray[l-1].y;
var snake = new Snake(sX,sY,'red');
snakeArray.push(snake);
}
//检测碰撞墙壁
function HitCheck(snake,board){
if(snake.x < 0 || snake.x > board.width || snake.y < 0 || snake.y > board.height){
return true
}
return false;
}
//检测碰撞食物
function FoodHitCheck(snake,food){
if(!(snake.x < food.x || snake.x > food.x+18 || snake.y < food.y || snake.y > food.y+18)){
return true
}
return false;
}
//随机位置
function randPlace(){
return (parseInt(Math.random()*30))*20;
}
//画布类
function canvasBoard(){
this.x = 20;//间距
this.y = 20;//
this.drwaCanvas = function(){
context.beginPath();
context.strokeStyle = '#ddd';
context.lineWidth = 1;
for(var i = 0;i < board.width/this.x;i++){
context.moveTo(i*this.x+0.5,0);
context.lineTo(i*this.x+0.5,board.height);
}
for(var i = 0;i < board.height/this.y;i++){
context.moveTo(0,i*this.y+0.5);
context.lineTo(board.width,i*this.y+0.5);
}
context.stroke();
}
}
//蛇类
function Snake(x,y,color){
this.x = x;
this.y = y;
this.width = 20;
this.height = 20;
this.color = color;
this.drwaSnake = function(context){
context.beginPath();
context.strokeStyle = "#ccc";
context.strokeRect(this.x,this.y,this.width,this.height);
context.fillStyle = this.color;
context.fillRect(this.x,this.y,this.width,this.height)
context.save();
}
}
//食物类
function Food(x,y){
this.x = x;
this.y = y;
this.w = 20;
this.h = 20;
this.color = 'green';
this.drawFood = function(){
context.beginPath();
context.fillStyle = this.color;
context.fillRect(this.x,this.y,this.w,this.h)
context.save();
}
}
</script>
效果如下图
原理是将每一节身体视为一个对象,将对象放入一个数组里,用定时器每次改变最后一节身体的位置放在最前面,同时改变数组里对象的位置,从而实现向前走的动画
