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粒子拼字效果（getImageData方法）
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
<style>
*{margin:0;padding:0;}
body{background:#000;overflow:hidden;}
input{
width: 150px;
height: 30px;
margin-left:-75px;
position:absolute;
bottom:30px;
left:50%;
background: #fcfff4;
background: linear-gradient(to bottom, #fcfff4 0%, #dfe5d7 40%, #b3bead 100%);
box-shadow: 0px 2px 5px 0px rgba(0, 0, 0, 0.3);
border:none;
border-radius:10px;
text-indent:30px;
}
input,button:focus{
outline:none;
}
button{
width: 30px;
height: 30px;
margin-left:45px;
border:none;
border-radius:10px;
background: #fcfff4;
background: linear-gradient(to bottom, #fcfff4 0%, #dfe5d7 40%, #b3bead 100%);
box-shadow: 0px 2px 5px 0px rgba(0, 0, 0, 0.3);
position:absolute;
bottom:30px;
left:50%;
}
</style>
</head>
<script type="text/javascript">
window.onload = function(){
canvas = document.getElementById("mycanvas");
ctx = canvas.getContext("2d");
focallength = 250;
var txt = document.getElementById("txt");
var btn = document.getElementById("btn");
var particleArr = getImgData(txt.value);
var pause = false;
var timer;
//初始化位置
initMove();
function initMove(){
particleArr.forEach(function(){
this.locx =parseInt(Math.random()*canvas.width);
this.locy =parseInt(Math.random()*canvas.height);
this.locz =Math.random()*focallength*2 - focallength;
this.x =parseInt(Math.random()*canvas.width);
this.y =parseInt(Math.random()*canvas.height);
this.z = Math.random()*focallength*2 - focallength;
this.paint();
});
startMove();
}
//速度
var lastTime;
var derection = true;
function startMove(){
clearInterval(timer);
var thisTime = new Date();
ctx.clearRect(0,0,canvas.width , canvas.height);
particleArr.forEach(function(){
var particle = this;
if(derection){
if (Math.abs(particle.disx - particle.x) < 0.1 && Math.abs(particle.disy - particle.y) < 0.1 && Math.abs(particle.disz - particle.z)<0.1) {
particle.x = particle.disx;
particle.y = particle.disy;
particle.z = particle.disz;
if(thisTime - lastTime > 300){
derection = false;
}
}else{
particle.x = particle.x + (particle.disx - particle.x) * 0.1;
particle.y = particle.y + (particle.disy - particle.y) * 0.1;
particle.z = particle.z + (particle.disz - particle.z) * 0.1;
lastTime = new Date()
}
}else{
if (Math.abs(particle.locx - particle.x) < 0.1 && Math.abs(particle.locy - particle.y) < 0.1 && Math.abs(particle.locz - particle.z)<0.1) {
particle.x = particle.locx;
particle.y = particle.locy;
particle.z = particle.locz;
pause = true;
clearInterval(timer);
move();
}else{
particle.x = particle.x + (particle.locx - particle.x) * 0.1;
particle.y = particle.y + (particle.locy - particle.y) * 0.1;
particle.z = particle.z + (particle.locz - particle.z) * 0.1;
pause = false;
}
}
particle.paint();
});
if(!pause) {
if("requestAnimationFrame" in window){
requestAnimationFrame(startMove);
}
else if("webkitRequestAnimationFrame" in window){
webkitRequestAnimationFrame(startMove);
}
else if("msRequestAnimationFrame" in window){
msRequestAnimationFrame(startMove);
}
else if("mozRequestAnimationFrame" in window){
mozRequestAnimationFrame(startMove);
}
}
}
//点击改变文字
btn.onclick = function(){
if(!pause){
return
}
clearInterval(timer);
particleArr = getImgData(txt.value);
derection=true;
pause = false;
initMove();
}
//键盘回车按键
document.onkeydown=function(e) {
var e = e || event
if(!pause){
return
}
if(e.keyCode=="13"){
clearInterval(timer)
particleArr = getImgData(txt.value);
derection=true;
pause = false;
initMove();
}
}
function move(){
timer = setInterval(makeParticle,10)
}
function makeParticle(){
ctx.clearRect(0,0,1432,768);
for(var i = 0 ; i < particleArr.length; i++){
var particle = particleArr[i];
particle.paint();
}
}
}
Array.prototype.forEach = function(callback){
for(var i=0;i<this.length;i++){
callback.call(this[i]);
}
}
//根据getImageData接口重绘文字
function getImgData(text){
drawText(text);
var imgData = http://www.mamicode.com/ctx.getImageData(0,0,canvas.width,canvas.height);"200px 微软雅黑 bold";
ctx.fillStyle ="rgba(255,255,255,1)";//纯色 方便扫面
ctx.textAlign = "center";
ctx.textBaseline = "middle";
ctx.fillText(text , canvas.width/2 , canvas.height/2);
ctx.restore();
}
//定义粒子 构造函数
var Particle = function(x,y,z,r){
this.disx = x;//文字锁定的位置
this.disy = y;
this.disz = z;
this.x = x;
this.y = y;
this.z = z;
this.locx = 0;
this.locy = 0;// 运动前位置
this.locz = 0;
this.radius = r;
this.col = "rgba("+parseInt(Math.random()*255)+","+parseInt(Math.random()*255)+","+parseInt(Math.random()*255)+",1)";
}
Particle.prototype={
paint:function(){
ctx.save();
ctx.beginPath();
var scale = focallength/(focallength + this.z);
ctx.arc(canvas.width/2 + (this.x-canvas.width/2)*scale , canvas.height/2 + (this.y-canvas.height/2) * scale, this.radius*scale , 0 , 2*Math.PI);
ctx.fillStyle = "rgba("+parseInt(Math.random()*255)+","+parseInt(Math.random()*255)+","+parseInt(Math.random()*255)+","+ scale +")";
ctx.fill()
ctx.restore();
}
}
</script>
<body>
<canvas id = "mycanvas" width="1423" height = "768" ></canvas>
<input type="text" value="http://www.mamicode.com/Canvas" id="txt">
<button id = "btn">获取</button>
</body>
</html>
粒子拼字效果（getImageData方法）
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