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canvas原生js写的贪吃蛇

2017-12-21 11:09 239 查看
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>矩形</title>
<style type="text/css">
*{
padding: 0;
margin: 0;
}

.wrap{
width: 500px;
height: 500px;
border: 1px solid #ccc;
margin: 0 auto;
position: relative;
}
canvas{
position: absolute;
top: 0;
left: 0;
}
#gridC{
z-index: 2;
}
#canvas{
z-index: 1;
}
</style>
</head>

<body>
<div class="wrap">
<canvas id="gridC" width="500" height="500"></canvas>
<canvas id="canvas" width="500" height="500"></canvas>
</div>

</body>
<script type="text/javascript">
var theCanvas = document.getElementById('canvas');
var ctx = theCanvas.getContext("2d");
var run = false;
var maxBound = {};
var config = {
gridX:20,
gridY:20
}

var body = [
{
x:8,
y:8
},
{
x:8,
y:9
},
{
x:8,
y:10
}
];

var food = {
x:0,
y:0
}

var keyCodeMethod = {
'38':function(){
//上  : x不变,y减一
move('y',-1);
},
'40':function(){
//下: x不变，y加一
move('y',1);
},
'37':function(){
//左：y不变，x减一
move('x',-1);
},
'39':function(){
//右: y 不变，x加一
move('x',1);
}

}

drawnAll();

window.onkeydown = function(e){
var method = keyCodeMethod[e.keyCode];
if(method){
method();
}
}

//移动
function move(axis,speed){
for(var i = body.length-1; i > 0; i--){
body[i].x = body[i-1].x;
body[i].y = body[i-1].y;
}
body[0][axis] = body[0][axis] + speed;
//判断死亡
if(!isValid(body[0])){
gameOver();
}

//吃东西
eat(body[0]);

//数据修改完成，全部重新渲染
drawnAll();
}

//判断死亡
function isValid(option){
option = option || {};
var valid = true;
if(option.x < 0){
option.x = 0;
valid = false;
}
if(option.x > maxBound.x){
option.x = maxBound.x;
valid = false;
}
if(option.y < 0){
option.y = 0;
valid = false;
}
if(option.y > maxBound.y){
option.y = maxBound.y;
valid = false;
}
return valid;
}

//吃东西
function eat(option){
option = option || {};
if(food && option.x == food.x && option.y == food.y){
//吃到食物
body.push({
x:option.x,
y:option.y
});
//吃到食物就需要再创建一个食物
food = null;
createFood();
}
}

//创建食物
function createFood(){
var pos = axisPoint();
while(!validFood(pos)){
pos = axisPoint();
}
food = pos;
}

//随机创建位置
function axisPoint(){
var x = Math.floor(Math.random()*maxBound.x);
var y = Math.floor(Math.random()*maxBound.y);
return {x:x,y:y};
}
//验证食物的位置是否可用,不能再身体上
function validFood(option){
option = option || {};
var flag = true;
for(var i = 0; i < body.length; i++){
if(option.x == body[i].x && option.y == body[i].y){
flag = false;
break;
}
}
return flag;
}

//将原始坐标转化为canvas坐标
function pointTransform(option,color){
option = option || {};
var obj = {
width:config.gridX,
height:config.gridY,
color:color||''
};
obj.x = option.x * config.gridX;
obj.y = option.y * config.gridY;

return obj;
}

//收集可用的参数列表
function createOptionArr(){
var arr = [];
//身体
for(var i = 0; i < body.length; i++){
arr.push(pointTransform(body[i],'green'));
}
//食物
if(food){
arr.push(pointTransform(food,'pink'));
}

//设置头部的颜色
arr[0].color = 'red';
return arr;
}

//游戏结束
function gameOver(){
alert('游戏结束');
console.log('游戏结束');
}

//画所有
function drawnAll(){
ctx.clearRect(0,0,500,500);
var arr = createOptionArr();
for(var i = arr.length-1; i >= 0; i-- ){
drawReat(arr[i]);
}
}

//画矩形
function drawReat(option){
option  = option || {};
var x = option.x;
var y = option.y;
var width = option.width;
var height = option.height;
var radius = option.radius||0;
var color = option.color || 'green';
var type = option.type || 'fill';
ctx.beginPath();
ctx.moveTo(x, y+radius);
ctx.lineTo(x, y+height-radius);
ctx.quadraticCurveTo(x, y+height, x+radius, y+height);
ctx.lineTo(x+width-radius, y+height);
ctx.quadraticCurveTo(x+width, y+height, x+width, y+height-radius);
ctx.lineTo(x+width, y+radius);
ctx.quadraticCurveTo(x+width, y, x+width-radius, y);
ctx.lineTo(x+radius, y);
ctx.quadraticCurveTo(x, y, x, y+radius);
ctx[type + 'Style'] = color;
ctx.closePath();
ctx[type]();
}

//网格
maxBound = drawGrip();
function drawGrip(){
var gridC = document.getElementById('gridC');
var gridCtx = gridC.getContext("2d");
var width = gridC.width;
var height = gridC.height;
var gridX = config.gridX;
var gridY = config.gridY;
var maxBound = {
x:0,
y:0
}
//画横线
for(var i = gridY; i < height; i=i+gridY){
drawLine(gridCtx,0,i,width,i);
maxBound.y++;
}
//画竖线
for(var i = gridX; i < width; i = i + gridX){
drawLine(gridCtx,i,0,i,height);
maxBound.x++;
}
return maxBound;
}

function drawLine(ctx,startX,startY,endX,endY){
ctx.lineWidth=1;
ctx.beginPath();
ctx.moveTo(startX,startY);
ctx.lineTo(endX,endY);
ctx.closePath();
ctx.strokeStyle="#ddd";
ctx.stroke();
}

</script>
</html>
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