<!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">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<style>
#show{position:relative;margin:20px auto;width:800px;border:1px solid #999999;}
.item{position:absolute;height:40px;width:60px;background:#999999;border:1px solid #eeeeee;cursor:pointer;}
</style>
<script>
var len;
var showerObj;
var listObj;
var showerWidth=800;
var showerHeight=400;
var r;
var cR=0;
var ccR=0;
var timer=0;
window.onload=function(){
showerObj=document.getElementById("show");
listObj=showerObj.getElementsByTagName("div");
len=listObj.length;
r=Math.PI/180*360/len;
for(var i=0;i<len;i++){
var item=listObj[i];
item.style.top=showerHeight/2+Math.sin(r*i)*showerWidth/2-20+"px";
item.style.left=showerWidth/2+Math.cos(r*i)*showerWidth/2-30+"px";
item.rotate=(r*i+2*Math.PI)%(2*Math.PI);
item.onclick=function(){
cR=Math.PI/2-this.rotate;
timer || (timer=setInterval(rotate,10));
}
}
var rX=showerObj.offsetLeft+showerWidth/2;
var ry=showerObj.offsetTop+showerHeight/2;
var rotate=function(){
ccR=(ccR+2*Math.PI)%(2*Math.PI);
if(cR-ccR<0) cR=cR+2*Math.PI;
if(cR-ccR<Math.PI){
ccR=ccR+(cR-ccR)/19;
}else{
ccR=ccR-(2*Math.PI+ccR-cR)/19;
}
if(Math.abs((cR+2*Math.PI)%(2*Math.PI)-(ccR+2*Math.PI)%(2*Math.PI))<Math.PI/720){
ccR=cR;
clearInterval(timer);
timer=0;
}
for(var i=0;i<len;i++){
var item=listObj[i];
var w,h;
var sinR=Math.sin(r*i+ccR);
var cosR=Math.cos(r*i+ccR);
w=60+0.6*60*sinR;
h=(40+0.6*40*sinR);
item.style.cssText +=";width:"+w+"px;height:"+h+"px;top:"+parseInt(showerHeight/2+sinR*showerWidth/2/3-w/2)+"px;left:"+parseInt(showerWidth/2+cosR*showerWidth/2-h/2)+"px;z-index:"+parseInt(showerHeight/2+sinR*showerWidth/2/3-w/2)+";";
}
}
document.getElementById("l").onclick=function(){
cR=(cR+r+2*Math.PI)%(2*Math.PI);
timer || (timer=setInterval(rotate,10));
}
document.getElementById("r").onclick=function(){
cR=(cR-r+2*Math.PI)%(2*Math.PI);
timer || (timer=setInterval(rotate,10));
}
rotate();
}
</script>
</head>
<body>
<input id="l" type="button" value="left" >
<input id="r" type="button" value="right" >
<div id="show">
<div class="item">1</div>
<div class="item">2</div>
<div class="item">3</div>
<div class="item">4</div>
<div class="item">5</div>
<div class="item">6</div>
<div class="item">7</div>
<div class="item">8</div>
<div class="item">9</div>
<div class="item">0</div>
<div class="item">a</div>
<div class="item">b</div>
<div class="item">1</div>
<div class="item">2</div>
<div class="item">3</div>
</div>
</body>
</html>