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Copy path旋转图形.html
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旋转图形.html
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<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="Generator" content="EditPlus®">
<meta name="Author" content="">
<meta name="Keywords" content="">
<meta name="Description" content="">
<title>Document</title>
<style>
body{background-color:black}
cnvas{margin:0 auto;display:block;padding:1px;}
</style>
</head>
<body>
<canvas id="canvas1" width="420" height="420">
Your browser doesn't support the canvas!Try another broswer.
</canvas>
<script>
var mycanvas =document.getElementById("canvas1");
var cntx=mycanvas.getContext('2d');
cntx.lineCap='round';
cntx.strokeStyle="#ffff00";
cntx.lineWidth=4;
function turn_it()
{
cntx.beginPath();
cntx.moveTo(0,0);
//离中心点的距离
move_num=2;//试着修改不同的值以获得不同的图形
//绕中心旋转的距离
rotate_num=0.1;//取0或1之间的值
//转换wei弧度
rads=rotate_num*2*Math.PI;
//计算围绕中心点的位置
for(i=1;i<=100;i++)
{
distance=i*move_num;
turn=i*rads;
//绘制的起始点
x=Math.cos(turn)*distance;
y=Math.sin(turn)*distance;
//绘制线段
cntx.lineTo(x,y);
}
}
cntx.translate(cntx.canvas.width/2,cntx.canvas.height/2);
setInterval(
function(){
cntx.clearRect(-cntx.canvas.width/2,-cntx.canvas.height/2,
cntx.canvas.width,cntx.canvas.height);
cntx.rotate(.01);//kong控制速率
turn_it.apply();
cntx.stroke();
},10);
</script>
</body>
</html>