QQ登录框的蓝色Canvas动画
大家对这个QQ登录框的这个不断波动的蓝色动画想必还是很熟悉的吧，这个可不是SWF文件写出来的，而是用了Html5的canvas特效，本站顶部也是用了这个腾讯出品的效果。来看看怎么实现的！
蓝色canvas动画
DEMO如下，这个蓝色会不断波动，扭转，想必大家很熟悉了。这里就不再多说。
代码部分
下面给出整个代码部分，把下面的代码另存为一个html文件，打开就可以看见canvas特效。这个代码有css（这里无关紧要），javascript，html三个部分组成，要想实现这么一个效果，就要加载这三块：
首先在网站里面加载jquery库，想必大家已经早就加载过了。
接着网页还需加载以下代码的<script>标签的js代码。
在网页里面添加代码的HTML部分，这里是一个id为container的div。可以根据个人需求更换宽度和高度，比如本站作为页面顶部，自然就不需要700px的高了。
<html xmlns="http://www.w3.org/1999/xhtml"><head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>html5背景</title>
</head>
<body><style type="text/css">
*{margin:0;padding:0;list-style-type:none;}
a,img{border:0;}
</style>
<div id="container" style="width:100%;height:700px;">
<div id="anitOut"><canvas width="1265" height="700" style="display: block;"></canvas></div>
</div>
<script type="text/javascript" src="//libs.baidu.com/jquery/1.11.1/jquery.min.js"></script>
<script type="text/javascript">
$(function () {
if (!window.ActiveXObject && !!document.createElement("canvas").getContext) {
$.getScript("http://im-img.qq.com/pcqq/js/200/cav.js?_=1428576021379",
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');
}
});
</script>
</body></html>
为了方便里面整个代码被我切成了三段，分别是css部分，html部分和js部分，这样看起来是不是又好理解了一点呢？
另外还有一点就是如何把canvas图层放在顶部文字的下面，这里我们需要用一个css的绝对定位。形式上比如以下：
#header {
position: absolute;
top: 0px;
left: 100px;}
还有一些细节需要修改，就是这个案例中的canvas图层js代码中的height如果还是以前的1.5，则图片看起来会变成了矮胖子，我们把js代码中的height改成10即可！
标签：CSS