先给大家分享效果图：
给大家分享一个使用CSS+JS实现的唯美星空轨迹运动效果， 这样的效果不输给Flash 。相关代码如下：
<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>cloth</title>
<style>
body {
background: #000;
}
img {
display: block;
float: left;
margin: 0 1px 0 0;
}
canvas {
background: #131c35 linear-gradient(#192853, #131c35);
display: block;
float: left;
/* uncomment to test overlay */
/*
position: absolute;
left: 0;
opacity: .5;
top: 0;
*/
}
</style>
</head>
<body>
<div id="container"></div>
<script type="text/javascript" src="http://cdn.gbtags.com/jquery/1.11.1/jquery.min.js"></script>
<canvas id="c"></canvas>
<img src="http://dribbble.s3.amazonaws.com/users/36991/screenshots/674715/game.png" />
<script>
var c = document.getElementById('c'),
ctx = c.getContext('2d'),
cw = c.width = 400,
ch = c.height = 300,
rand = function(a,b){return ~~((Math.random()*(b-a+1))+a);},
dToR = function(degrees){
return degrees * (Math.PI / 180);
},
circle = {
x: (cw / 2) + 5,
y: (ch / 2) + 22,
radius: 90,
speed: 2,
rotation: 0,
angleStart: 270,
angleEnd: 90,
hue: 220,
thickness: 18,
blur: 25
},
particles = [],
particleMax = 100,
updateCircle = function(){
if(circle.rotation < 360){
circle.rotation += circle.speed;
} else {
circle.rotation = 0;
}
},
renderCircle = function(){
ctx.save();
ctx.translate(circle.x, circle.y);
ctx.rotate(dToR(circle.rotation));
ctx.beginPath();
ctx.arc(0, 0, circle.radius, dToR(circle.angleStart), dToR(circle.angleEnd), true);
ctx.lineWidth = circle.thickness;
ctx.strokeStyle = gradient1;
ctx.stroke();
ctx.restore();
},
renderCircleBorder = function(){
ctx.save();
ctx.translate(circle.x, circle.y);
ctx.rotate(dToR(circle.rotation));
ctx.beginPath();
ctx.arc(0, 0, circle.radius + (circle.thickness/2), dToR(circle.angleStart), dToR(circle.angleEnd), true);
ctx.lineWidth = 2;
ctx.strokeStyle = gradient2;
ctx.stroke();
ctx.restore();
},
renderCircleFlare = function(){
ctx.save();
ctx.translate(circle.x, circle.y);
ctx.rotate(dToR(circle.rotation+185));
ctx.scale(1,1);
ctx.beginPath();
ctx.arc(0, circle.radius, 30, 0, Math.PI *2, false);
ctx.closePath();
var gradient3 = ctx.createRadialGradient(0, circle.radius, 0, 0, circle.radius, 30);
gradient3.addColorStop(0, 'hsla(330, 50%, 50%, .35)');
