HTML5 canvas画的摇摆的树

来源：互联网发布：淘宝商城首页编辑：程序博客网时间：2024/04/30 04:01

<!doctype html>
<html>
<head>
<meta charset='UTF-8' />
<title>Tree</title>
</head>
<body>
<canvas id="pad" width='1000' height='500'><a href='http://www.cssass.com'>cssass.com</a>提醒您：ie9以下用户请一边惭愧去吧</canvas>
</body>
<script>
var con=document.getElementById("pad").getContext('2d');
con.strokeStyle = '#0f0';
con.lineWidth=1.8;
var Tree=function(x, y, l, angle, n){
var a=[],rand=0,dir=1,val;
this.init=function(x, y, l, angle, n) {
var that=this;
if (n>0) {
var a_l, a_r, x1, y1, x2, y2;
x1 = x+0.5*l*Math.cos(angle*Math.PI/180);
y1 = y-0.5*l*Math.sin(angle*Math.PI/180);
x2 = x+l*Math.cos(angle*Math.PI/180);
y2 = y-l*Math.sin(angle*Math.PI/180);
a.push([x, y, x2, y2]);
a_l = angle+30;
a_r = angle-30;
l=l*2/3;
that.init(x2, y2, l, angle+rand, n-1);
that.init(x1, y1, l*2/3, a_l+rand/2, n-1);
that.init(x1, y1, l*2/3, a_r+rand/2, n-1);
that.init(x2, y2, l*2/3, a_l+rand/2, n-1);
that.init(x2, y2, l*2/3, a_r+rand/2, n-1);
};
};
this.run=function(){
con.clearRect(0,0,1000,500);
for(var i=0; i<a.length; i++){
this.dw(a[i][0],a[i][1],a[i][2],a[i][3]);
};
a=[];
};
this.move=function(){
var that = this;
var _s=function(){
that.change();
that.init(x, y, l, angle, n);
that.run();
setTimeout(_s,100);
};
_s();
};
this.change=function(){
val=Math.random()*2;
rand+=dir*val;
if(rand>10 || rand<-2){dir=-dir;}
};
this.init(x, y, l, angle, n);
this.run();
};
Tree.prototype.dw=function(ax, ay, bx, by){
con.beginPath()
con.moveTo(ax, ay);
con.lineTo(bx, by);
con.stroke();
};

var ss=new Tree(300, 500, 200, 90, 6).move();
</script>
</html>