<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>贪吃蛇</title>
<style>
.wrap{
width: 100%;
height: 100%;
display: flex;
flex-direction: column;
justify-content: center;
align-items: center;
}
.header{
display: flex;
justify-content: space-between;
align-items: center;
width: 900px;
height: 50px;
}
</style>
</head>
<body>
<div class="wrap">
<div class="header">
<p>
<button id="start" type="button">开始游戏</button>
<span>得分：</span><span class="score">0</span>分
</p>
</div>
<div class="content">
<canvas id="canvas" width="900" height="650" style="border:5px solid teal;"></canvas>
</div>
<div class="footer">
<span>按键：</span>
1：小蛇加速
2：小蛇减速
space-空格键 暂停/继续
↑ ↓ ← → 控制方向
</div>
</div>
<img hidden="hidden" src="image/up.png" id="up">
<img hidden="hidden" src="image/down.png" id="down">
<img hidden="hidden" src="image/left.png" id="left">
<img hidden="hidden" src="image/right.png" id="right">
<img hidden="hidden" src="image/food.png" id="food">
<img hidden="hidden" src="image/body.png" id="body">
<script>
/**
* 蛇-移动-吃食物
*
* 获取贪吃蛇图片
*
* 初始化参数
* 按键设置
* 食物随机
* 判断食物是否被吃
* 画 背景-蛇-食物
*
*/
window.onload = function(){
// 获取图片
var up = document.getElementById('up');
var down = document.getElementById('down');
var left = document.getElementById('left');
var right = document.getElementById('right');
var foods = document.getElementById('food');
var body = document.getElementById('body');
var canvas = document.getElementById('canvas');
var ctx = canvas.getContext("2d");
var start_btn = document.getElementById('start');
// 定义初始值
var length;
var snakeX = new Array(816);//蛇的X
var snakeY = new Array(816);//蛇的Y
var foodX;
var foodY;
var direction = "right";
var score;
var timeout;
init();
var time;
function start(){
// 定时
time = setInterval(function(){
getKey();
eat();
draw();
die();
move();
document.getElementsByClassName('score')[0].innerHTML = score;
},timeout)
}
// 初始化
function init(){
length = 3;
snakeX[0] = 100;snakeY[0] = 100;
snakeX[1] = 75;snakeY[1] = 100;
snakeX[2] = 50;snakeY[2] = 100;
Food();
score = 0;
timeout = 100;
}
// 移动
function move(){
for (var i = length-1; i > 0; i--) {
snakeX[i]=snakeX[i-1];
snakeY[i]=snakeY[i-1];
}
if (direction == "right"){
snakeX[0] = snakeX[0]+25;
if (snakeX[0]>850) snakeX[0] = 25;
}else if (direction == "left"){
snakeX[0] = snakeX[0]-25;
if (snakeX[0]<25) snakeX[0] = 850;
}else if (direction == "up"){
snakeY[0] = snakeY[0]-25;
if (snakeY[0]<25) snakeY[0] = 600;
}else if (direction == "down"){
snakeY[0] = snakeY[0]+25;
if (snakeY[0]>600) snakeY[0] = 25;
}
}
// 画图
function draw(){
ctx.fillStyle = "#333333"
ctx.fillRect(25,25,850,600);
// 食物
ctx.drawImage(foods,foodX,foodY,25,25);
//蛇的头通过方向变量来判断
if (direction == "right"){
ctx.drawImage(right,snakeX[0],snakeY[0],25,25);
}else if (direction == "left"){
ctx.drawImage(left,snakeX[0],snakeY[0],25,25);
}else if (direction == "up"){
ctx.drawImage(up,snakeX[0],snakeY[0],25,25);
}else if (direction == "down"){
ctx.drawImage(down,snakeX[0],snakeY[0],25,25);
}
// 身体
for (var i = 1; i <length; i++) {
ctx.drawImage(body,snakeX[i],snakeY[i],25,25);
}
}
// 蛇吃到食物
function eat(){
if(foodX == snakeX[0]&&foodY == snakeY[0]){
length++;
score=score+10;
Food();
}
}
// 获取按键
function getKey() {
document.onkeydown=function(event){
var e = event || window.event || arguments.callee.caller.arguments[0];
if(e && e.keyCode==38){//上
if (direction !== 'down')
direction = 'up'
}
if(e && e.keyCode == 37){//左
if (direction !== 'right')
direction = 'left'
}
if(e && e.keyCode == 39){//右
if (direction !== 'left')
direction = 'right'
}
if(e && e.keyCode == 40){//下
if (direction !== 'up')
direction = 'down'
}
if(e && e.keyCode == 32){//空格
confirm("游戏已暂停")
}
// 加速
if(e && e.keyCode == 49){//1
clearInterval(time)
timeout-=10;
time = setInterval(function(){
getKey();
eat();
draw();
die();
move();
document.getElementsByClassName('score')[0].innerHTML = score;
},timeout)
}
// 减速
if(e && e.keyCode == 50){//2
clearInterval(time)
timeout+=10;
time = setInterval(function(){
getKey();
eat();
draw();
die();
move();
document.getElementsByClassName('score')[0].innerHTML = score;
},timeout)
}
};
}
// 失败判定
function die(){
for (var i = 1; i < length; i++) {
if(snakeX[0] == snakeX[i] && snakeY[0] == snakeY[i]){
fail()
alert("游戏失败")
start_btn.removeAttribute("disabled")
}
}
}
//时间停止
function fail(){
clearInterval(time)
}
// 食物位置
function Food(){
foodX = 25+parseInt(Math.random() * 34) * 25;
foodY = 25+parseInt(Math.random() * 24) * 25;
}
draw();
// 点击开始
start_btn.onclick = function(){
init();
start();
start_btn.setAttribute("disabled",true)
}
}
</script>
</body>
</html>
