<canvas id="evanyou"></canvas>
<style type="text/css">
    #evanyou{
        position:fixed;
        width:100%;
        height:100%;
        left:0;
        top:0;
    }
</style>

// evanyou效果
var c = document.getElementById('evanyou'),
	x = c.getContext('2d'),
	pr = window.devicePixelRatio || 1,
	w = window.innerWidth,
	h = window.innerHeight,
	f = 90,
	q,
	m = Math,
	r = 0,
	u = m.PI * 2,
	v = m.cos,
	z = m.random;
c.width = w * pr;
c.height = h * pr;
x.scale(pr, pr);
x.globalAlpha = 0.6;
function evanyou() {
	x.clearRect(0, 0, w, h)
	q = [{ x: 0, y: h * .7 + f }, { x: 0, y: h * .7 - f }]
	while (q[1].x < w + f) d(q[0], q[1])
}
function d(i, j) {
	x.beginPath()
	x.moveTo(i.x, i.y)
	x.lineTo(j.x, j.y)
	var k = j.x + (z() * 2 - 0.25) * f,
		n = y(j.y)
	x.lineTo(k, n)
	x.closePath()
	r -= u / -50
	x.fillStyle = '#' + (v(r) * 127 + 128 << 16 | v(r + u / 3) * 127 + 128 << 8 | v(r + u / 3 * 2) * 127 + 128).toString(16)
	x.fill()
	q[0] = q[1]
	q[1] = { x: k, y: n }
}
function y(p) {
	var t = p + (z() * 2 - 1.1) * f
	return (t > h || t < 0) ? y(p) : t
}
document.onclick = evanyou
document.ontouchstart = evanyou
evanyou();