<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="renderer" content="webkit" />
<meta name="viewport" content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0" />
<title>星空背景</title>
<link rel="stylesheet" href="css/bootstrap.min.css" />
</head>
<!--[if lt IE 9]>
<script src="https://cdn.bootcss.com/html5shiv/3.7.3/html5shiv.min.js"></script>
<script src="https://cdn.bootcss.com/respond.js/1.4.2/respond.min.js"></script>
<![endif]-->
<body>
<canvas id="canvas" width="1920" height="960">
<div class="clearfix"></div>
<div id="ee" style="width: 100px;height: 100px;background-color: red;border: 1px solid darkorange;z-index: -1;">
</div>
</canvas>
</body>
<script type="text/javascript" src="js/jquery-1.12.4.min.js"></script>
<script>
var canvas = document.getElementById('canvas');
ctx = canvas.getContext('2d');
w = canvas.width = window.innerWidth;
h = canvas.height = window.innerHeight;
hue = 217,
stars = [],
count = 0,
maxStars = 1200;
var canvas2 = document.createElement('canvas');
ctx2 = canvas2.getContext('2d');
canvas2.width = 100;
canvas2.height = 100;
var half = canvas2.width / 2;
gradient2 = ctx2.createRadialGradient(half, half, 0, half, half, half);
gradient2.addColorStop(0.025, '#fff');
gradient2.addColorStop(0.1, 'hsl(' + hue + ', 61%, 33%)');
gradient2.addColorStop(0.25, 'hsl(' + hue + ', 64%, 6%)');
gradient2.addColorStop(1, 'transparent');
ctx2.fillStyle = gradient2;
ctx2.beginPath();
ctx2.arc(half, half, half, 0, Math.PI * 2);
ctx2.fill();
function random(min, max) {
if(arguments.length < 2) {
max = min;
min = 0;
}
if(min > max) {
var hold = max;
max = min;
min = hold;
}
return Math.floor(Math.random() * (max - min + 1)) + min;
}
function maxOrbit(x, y) {
var max = Math.max(x, y);
diameter = Math.round(Math.sqrt(max * max + max * max));
return diameter / 2;
}
var Star = function() {
this.orbitRadius = random(maxOrbit(w, h));
this.radius = random(60, this.orbitRadius) / 12;
this.orbitX = w / 2;
this.orbitY = h / 2;
this.timePassed = random(0, maxStars);
this.speed = random(this.orbitRadius) / 900000;
this.alpha = random(2, 10) / 10;
count++;
stars[count] = this;
}
Star.prototype.draw = function() {
var x = Math.sin(this.timePassed) * this.orbitRadius + this.orbitX;
y = Math.cos(this.timePassed) * this.orbitRadius + this.orbitY;
twinkle = random(10);
if(twinkle === 1 && this.alpha > 0) {
this.alpha -= 0.05;
} else if(twinkle === 2 && this.alpha < 1) {
this.alpha += 0.05;
}
ctx.globalAlpha = this.alpha;
ctx.drawImage(canvas2, x - this.radius / 2, y - this.radius / 2, this.radius, this.radius);
this.timePassed += this.speed;
}
for(var i = 0; i < maxStars; i++) {
new Star();
}
function animation() {
ctx.globalCompositeOperation = 'source-over';
ctx.globalAlpha = 0.8;
ctx.fillStyle = 'hsla(' + hue + ', 64%, 6%, 1)';
ctx.fillRect(0, 0, w, h);
ctx.globalCompositeOperation = 'lighter';
for(var i = 1, l = stars.length; i < l; i++) {
stars[i].draw();
};
window.requestAnimationFrame(animation);
}
animation();
</script>
</html>
