javascript元素3D旋轉效果程式碼例項

admin發表於2017-04-05
JavaScript3D

本章節分享一段程式碼例項，它實現了元素的3D旋轉效果。

裡面涉及到一些數學相關的東西，感興趣的朋友可以自行進行一下分析。

程式碼例項如下:

[HTML] 純文字檢視 複製程式碼
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="author" content="http://www.softwhy.com/" />
<title>螞蟻部落</title>
<style type="text/css">
#show{
  position:relative;
  margin:20px auto;
  width:800px;
}
.item{
  position:absolute;
  height:40px;
  width:60px; 
  background:#999999;
  border:1px solid #eeeeee;
  cursor:pointer;
}
</style>
<script type="text/javascript">
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>

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