请问如何修改图像粒子粉碎的js代码，是它能有别的效果？

下载了这个图像粒子粉碎的代码，想修改一下，能不能换个效果出现，但实在不知如何动手，比如想能有好几个图片一起粉碎，或者粉碎有先后关系。自己编程能力太低了，看都看不懂。。

  var canvas
 var context
 var img
 var imgArr = new Array();
 var ox = 350
 var oy = 50
 var w = 100
 var h = 100;
 var th = 1;
 var bottom;
 var posData = new Array();
 var oldPos = new Array();
 var currentData = new Array();
 var targetData = posData

 var reversed = false;
 
 for(var i=0;i<h;i++){
     posData[i] = new Array();
     oldPos[i] = new Array();
     currentData[i] = new Array();
     for(var j=0;j<w;j++){
         posData[i][j] = {x:ox+j,y:oy+i};
         oldPos[i][j] = {x:Math.random()*800,y:Math.random()*600};
          currentData[i][j] = {x:Math.random()*800,y:Math.random()*600,vx:0,vy:0,ax:.16-Math.random()*.08,ay:.16-Math.random()*.08,nx:.4+Math.random()*.3,ny:.3+Math.random()*.2};
         
     }
 }
 
 window.onload = init;
 window.onclick = onClick;
function init(){
    canvas = $('canvas');
    context = canvas.getContext('2d');
    bottom = canvas.height - 1;
    img = new Image();
    img.src = "ryan.gif"
    img.onload = function () {
        //
        var interval = setInterval(run,10);
        context.drawImage(img,0,0);
        for(var i=0;i<h;i++){
            imgArr[i] = [];
            for(var j=0;j<w;j++){
                imgArr[i][j] = context.getImageData(j,i,1,1);
            }
        }
        context.clearRect(0,0,canvas.width,canvas.height);
    }
 }
 
 function run(){
     context.clearRect(0,0,canvas.width,canvas.height);
     if(!reversed){
         if(th<h) th++;
         for(var i=0;i<h;i++){
            for(var j=0;j<w;j++){
                var target = targetData[i][j];
                var current = currentData[i][j];
                if(i<th){
                    var xdiff = target.x - current.x;
                    var ydiff = target.y - current.y;
                    if(Math.abs(xdiff)<.5) {
                        current.x = target.x;
                    } else {
                        current.x+= (target.x - current.x)*current.ax;
                    }
                    if(Math.abs(ydiff)<.5) {
                        current.y = target.y;
                    } else {
                        current.y+= (target.y - current.y)*current.ay;
                    }
                }
                context.putImageData(imgArr[i][j],current.x,current.y);
             }
         }
     } else {
         for(var i=0;i<h;i++){
            for(var j=0;j<w;j++){
                var current = currentData[i][j];
                current.x+=current.vx;
                current.y+=current.vy;
                
                if(current.y>=bottom){
                    current.y = bottom;
                    current.vy = -current.ny*current.vy;
                    if(Math.abs(current.vy)<=1) {
                        current.vy = 0;
                    }
                    current.vx*=current.nx;
                    if(Math.abs(current.vx)<=1) current.vx = 0;
                } else {
                    current.vy+=1;
                }
                context.putImageData(imgArr[i][j],current.x,current.y);
            }
        }
     }
     
 }
 
 function onClick(){
     reversed = !reversed;
     if(reversed){
         for(var i=0;i<h;i++){
            for(var j=0;j<w;j++){
                var current = currentData[i][j];
                current.vx = (Math.random()-Math.random())*3;
                current.vy = -Math.random()*10;
            }
         }
     } else {
         th=1;
         targetData = posData
     }
 }
 
 
 function $(id){
     return document.getElementById(id);
 }