css3中实现像flash中的时钟进度条

<style>
#cricle{width:200px;height:200px;position:relative;background:#333;overflow:hidden}
#cricle .left,#cricle .right,#cricle .text{width:200px;height:200px}
#cricle .text{position:absolute;top:0;left:0;z-index:41;color:#fff;font:26px/200px ´arial´;text-align:center}
#cricle .mask{z-index:40}
#cricle .mask,#cricle .bg{width:100px;height:200px;background:#333;position:absolute;top:0}
#cricle .bg{background:url(/2011/11/bg_green.png) no-repeat 0 0}
#cricle .mask,#cricle .left .bg{left:0}
#cricle .right{display:none}
#cricle .right .bg{background-position:right top;right:0}
</style>

<script>
var C = function(id){
 this.box = $("#"+id);
 this.left = this.box.find(".left");
 this.right = this.box.find(".right");
 this.mask = this.box.find(".mask");
 this.text = this.box.find(".text");
 this.d = 0;
 this.A = null;
 this.init();
}
C.prototype = {
 init : function(){
  var T = this;
  this.A = window.setInterval(function(){T.change()},80);
 },
 change : function(){
  var T = this;
  if(this.d>180){
   if(this.d>360){
    window.clearInterval(this.A);
    this.A = null;
    return;
   }
   this.right.show();
   this.mask.hide();
  }
  this.text.text(parseInt(this.d/3.6));
  this.left.css({
   "-webkit-transform":"rotate("+this.d+"deg)",
                        "-moz-transform":"rotate("+this.d+"deg)"
  })
  this.d += 6;
 }
}
</script>