特效描述：html5 腾讯QQ 登录界面 背景动画特效。腾讯QQ登陆界面动态背景，直接从腾讯网站获取，js代码有加密，做了个简单地示例

代码结构

1. 引入JS

2. HTML代码

*{margin:0;padding:0;list-style-type:none;}

a,img{border:0;}

$(function () {

if (!window.ActiveXObject && !!document.createElement("canvas").getContext) {

$.getScript("cav.js",

function () {

var t = {

width: 1.5,

height: 1.5,

depth: 10,

segments: 12,

slices: 6,

xRange: 0.8,

yRange: 0.1,

zRange: 1,

ambient: "#525252",

diffuse: "#FFFFFF",

speed: 0.0002

};

var G = {

count: 2,

xyScalar: 1,

zOffset: 100,

ambient: "#002c4a",

diffuse: "#005584",

speed: 0.001,

gravity: 1200,

dampening: 0.95,

minLimit: 10,

maxLimit: null,

minDistance: 20,

maxDistance: 400,

autopilot: false,

draw: false,

bounds: CAV.Vector3.create(),

step: CAV.Vector3.create(Math.randomInRange(0.2, 1), Math.randomInRange(0.2, 1), Math.randomInRange(0.2, 1))

};

var m = "canvas";

var E = "svg";

var x = {

renderer: m

};

var i, n = Date.now();

var L = CAV.Vector3.create();

var k = CAV.Vector3.create();

var z = document.getElementById("container");

var w = document.getElementById("anitOut");

var D, I, h, q, y;

var g;

var r;

function C() {

F();

p();

s();

B();

v();

K(z.offsetWidth, z.offsetHeight);

o()

}

function F() {

g = new CAV.CanvasRenderer();

H(x.renderer)

}

function H(N) {

if (D) {

w.removeChild(D.element)

}

switch (N) {

case m:

D = g;

break

}

D.setSize(z.offsetWidth, z.offsetHeight);

w.appendChild(D.element)

}

function p() {

I = new CAV.Scene()

}

function s() {

I.remove(h);

D.clear();

q = new CAV.Plane(t.width * D.width, t.height * D.height, t.segments, t.slices);

y = new CAV.Material(t.ambient, t.diffuse);

h = new CAV.Mesh(q, y);

I.add(h);

var N, O;

for (N = q.vertices.length - 1; N >= 0; N--) {

O = q.vertices[N];

O.anchor = CAV.Vector3.clone(O.position);

O.step = CAV.Vector3.create(Math.randomInRange(0.2, 1), Math.randomInRange(0.2, 1), Math.randomInRange(0.2, 1));

O.time = Math.randomInRange(0, Math.PIM2)

}

}

function B() {

var O, N;

for (O = I.lights.length - 1; O >= 0; O--) {

N = I.lights[O];

I.remove(N)

}

D.clear();

for (O = 0; O < G.count; O++) {

N = new CAV.Light(G.ambient, G.diffuse);

N.ambientHex = N.ambient.format();

N.diffuseHex = N.diffuse.format();

I.add(N);

N.mass = Math.randomInRange(0.5, 1);

N.velocity = CAV.Vector3.create();

N.acceleration = CAV.Vector3.create();

N.force = CAV.Vector3.create()

}

}

function K(O, N) {

D.setSize(O, N);

CAV.Vector3.set(L, D.halfWidth, D.halfHeight);

s()

}

function o() {

i = Date.now() - n;

u();

M();

requestAnimationFrame(o)

}

function u() {

var Q, P, O, R, T, V, U, S = t.depth / 2;

CAV.Vector3.copy(G.bounds, L);

CAV.Vector3.multiplyScalar(G.bounds, G.xyScalar);

CAV.Vector3.setZ(k, G.zOffset);

for (R = I.lights.length - 1; R >= 0; R--) {

T = I.lights[R];

CAV.Vector3.setZ(T.position, G.zOffset);

var N = Math.clamp(CAV.Vector3.distanceSquared(T.position, k), G.minDistance, G.maxDistance);

var W = G.gravity * T.mass / N;

CAV.Vector3.subtractVectors(T.force, k, T.position);

CAV.Vector3.normalise(T.force);

CAV.Vector3.multiplyScalar(T.force, W);

CAV.Vector3.set(T.acceleration);

CAV.Vector3.add(T.acceleration, T.force);

CAV.Vector3.add(T.velocity, T.acceleration);

CAV.Vector3.multiplyScalar(T.velocity, G.dampening);

CAV.Vector3.limit(T.velocity, G.minLimit, G.maxLimit);

CAV.Vector3.add(T.position, T.velocity)

}

for (V = q.vertices.length - 1; V >= 0; V--) {

U = q.vertices[V];

Q = Math.sin(U.time + U.step[0] * i * t.speed);

P = Math.cos(U.time + U.step[1] * i * t.speed);

O = Math.sin(U.time + U.step[2] * i * t.speed);

CAV.Vector3.set(U.position, t.xRange * q.segmentWidth * Q, t.yRange * q.sliceHeight * P, t.zRange * S * O - S);

CAV.Vector3.add(U.position, U.anchor)

}

q.dirty = true

}

function M() {

D.render(I)

}

function J(O) {

var Q, N, S = O;

var P = function (T) {

for (Q = 0, l = I.lights.length; Q < l; Q++) {

N = I.lights[Q];

N.ambient.set(T);

N.ambientHex = N.ambient.format()

}

};

var R = function (T) {

for (Q = 0, l = I.lights.length; Q < l; Q++) {

N = I.lights[Q];

N.diffuse.set(T);

N.diffuseHex = N.diffuse.format()

}

};

return {

set: function () {

P(S[0]);

R(S[1])

}

}

}

function v() {

window.addEventListener("resize", j)

}

function A(N) {

CAV.Vector3.set(k, N.x, D.height - N.y);

CAV.Vector3.subtract(k, L)

}

function j(N) {

K(z.offsetWidth, z.offsetHeight);

M()

}

C();

})

} else {

alert('调用cav.js失败');

}

});