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html 代码
<!DOCTYPE html>
<html>
<head>
<title>starry sky</title>
<meta charset=”gbk” />
<meta name=”Author” content=”̶aoliann” />
<style type=”text/css”>
* {
margin: 0;
padding: 0;
font-family: ‘Microsoft yahei’;
}
a {
text-decoration: none;
}
a img {
display: block;
border: none;
}
li {
list-style: none;
}
#canvas {
background: #000;
display: block;
}
</style>
</head>
<body>
<canvas id=”canvas”></canvas>
<script type=”text/javascript”>
var can = document.getElementById(‘canvas’)
var cxt = can.getContext(‘2d’)
var w = (can.width = window.innerWidth)
var h = (can.height = window.innerHeight)
var num = 200
var data = []
var move = {}
var liuXY = []
var k = -1
var range = Math.atan(k)
var length = 200
for (var i = 0; i < num; i++) {
data[i] = {
x: Math.random() * w,
y: Math.random() * h,
r: Math.random() * 8 + 3,
}
Cricle(data[i].x, data[i].y, data[i].r)
}
!(function draw() {
cxt.clearRect(0, 0, w, h)
for (var i = 0; i < num; i++) {
data[i].r += Math.random() * 2 – 1
data[i].r = Math.max(0, data[i].r)
data[i].r = Math.min(12, data[i].r)
Cricle(data[i].x, data[i].y, data[i].r)
}
if (liuXY.length) {
for (var i in liuXY) {
liuXY[i].cX -= 10
liuX(liuXY[i].cX, liuXY[i].y, liuXY[i].x)
if (
liuXY[i].cX < 0 ||
getY(liuXY[i].cX, liuXY[i].y, liuXY[i].x) > h
) {
liuXY.splice(i, 1)
}
}
}
if (Math.random() > 0.98) {
var a = Math.random() * (w – 400) + 400
liuXY.push({ x: a, y: 0, cX: a })
}
window.requestAnimationFrame(draw)
})()
function liuX(x, sX, sY) {
cxt.save()
var y = getY(x, sY, sX)
var r = 15
var rad = cxt.createRadialGradient(x, y, 0, x, y, r)
rad.addColorStop(0, ‘rgba(255,255,255,0.8)’)
rad.addColorStop(0.1, ‘rgba(255,255,255,0.8)’)
rad.addColorStop(0.2, ‘rgba(255,255,255,0.08)’)
rad.addColorStop(1, ‘rgba(255,255,255,0)’)
cxt.fillStyle = rad
cxt.beginPath()
cxt.arc(x, y, r, 0, 2 * Math.PI, true)
cxt.closePath()
cxt.fill()
cxt.restore()
var wX = x + Math.cos(range) * length
var wY = y + Math.sin(range) * length
var x1 = x + 3
var y1 = y
var x2 = x
var y2 = y – 3
cxt.save()
var rad2 = cxt.createRadialGradient(x, y, 0, x, y, length)
rad2.addColorStop(0, ‘rgba(255,255,255,0.1)’)
rad2.addColorStop(1, ‘rgba(255,255,255,0)’)
cxt.fillStyle = rad2
cxt.beginPath()
cxt.moveTo(x1, y1)
cxt.lineTo(x2, y2)
cxt.lineTo(wX, wY)
cxt.closePath()
cxt.fill()
cxt.restore()
}
function getY(x, startY, startX) {
return k * x + startY – k * startX
}
//????
function Cricle(x, y, r) {
cxt.save()
var rad = cxt.createRadialGradient(x, y, 0, x, y, r)
rad.addColorStop(0, ‘rgba(255,255,255,0.8)’)
rad.addColorStop(0.1, ‘rgba(255,255,255,0.8)’)
rad.addColorStop(0.2, ‘rgba(255,255,255,0.08)’)
rad.addColorStop(1, ‘rgba(255,255,255,0)’)
cxt.fillStyle = rad
cxt.beginPath()
cxt.arc(x, y, r, 0, 2 * Math.PI, true)
cxt.closePath()
cxt.fill()
cxt.restore()
}
</script>
</body>
</html>
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