javaScript代码：

var minScale=.3;

var maxScale=1;

var minSpeed=.01;

var maxSpeed=.08;

var wind=3;

var numFlakes=500;

var context;

var snowflakeImage= new Image();

var snowflakes=[];

window.onload = function () {

  context = document.getElementById("canvas").getContext("2d");

  snowflakeImage.src="https://dl.dropboxusercontent.com/u/1256960/ Research/JS/Snowman/snowflake.png";

  snowflakeImage.onload=start;

  onResize();

  window.onresize=onResize;

  TweenMax.to("#head",1.5,{startAt:{rotation:-10},rotation:10,yoyo:true,transformOrigin:"50% 50%",repeat:-1,ease:Sine.easeInOut});

  TweenMax.to("#nose",1.5,{startAt:{rotation:-10},rotation:10,scaleX:.8,yoyo:true,transformOrigin:"5% 95%",repeat:-1,ease:Sine.easeInOut});

  TweenMax.to("#scarf",1.5,{startAt:{rotation:20},rotation:-20,yoyo:true,transformOrigin:"50% 10%",repeat:-1,ease:Sine.easeInOut});

  TweenMax.to("#shadow",1.5,{startAt:{x:-5},x:0,yoyo:true,repeat:-1,ease:Sine.easeInOut});

  TweenMax.to("#snowman",1.5,{startAt:{rotation:-5},rotation:7,yoyo:true,transformOrigin:"50% 90%",repeat:-1,ease:Sine.easeInOut});

  TweenMax.to("#snowman",.3,{scaleX:.95,scaleY:1.05,yoyo:true,transformOrigin:"50% 95%",repeat:-1,ease:Sine.easeInOut});

  blink();

  document.getElementById("snowman").addEventListener("click",knockHimDown);

}

function knockHimDown(){

  TweenMax.to("#snowman",.5,{rotation:-50,ease:Sine.easeOut});

  TweenMax.to("#snowman",1.2,{delay:1.2,rotation:0,ease:Sine.easeInOut});

  TweenMax.set("#mouth",{scaleY:-1,transformOrigin:"50% 80%"});

  TweenMax.to("#snowman",1.5,{delay:3,rotation:7,yoyo:true,transformOrigin:"50% 90%",repeat:-1,ease:Sine.easeInOut});

  TweenMax.to("#shadow",.5,{ x:-15,ease:Sine.easeOut});

  TweenMax.to("#shadow",1.2,{ delay:1.2,x:-5,ease:Sine.easeInOut});

  TweenMax.to("#shadow",1.5,{delay:3, x:0,yoyo:true,repeat:-1,ease:Sine.easeInOut});

}

function blink(){

  TweenMax.to(["#eye1,#eye2"],.1,{delay:5*Math.random(),scaleY:.2,yoyo:true,repeat:1,transformOrigin:"50% 50%",onComplete:blink});

}

function onResize(e){

  context.canvas.width=window.innerWidth;

  context.canvas.height=window.innerHeight;

}

function start(){

  for (var i=0;i

    var snowflake= {initX:((window.innerWidth+800)*Math.random())-800,initY:-(600*Math.random())-16,scale:Math.random(),speed:minSpeed,angle:Math.random()*Math.PI*2,x:0,y:0,offsetX:0};

    snowflake.x=window.innerWidth*Math.random();

    snowflake.y=((window.innerHeight+400)*Math.random())-400;

    snowflake.speed=(snowflake.scale*(maxSpeed-minSpeed))+minSpeed;

    snowflake.scale=(snowflake.scale*(maxScale-minScale))+minScale;

    snowflakes.push(snowflake);

  }

  animate();

}

function animate(){

  context.clearRect(0,0,window.innerWidth,window.innerHeight);

  for (var i=0;i

    var snowflake= snowflakes[i];

    snowflake.x=(Math.cos(snowflake.angle)*20)+snowflake.initX+snowflake.offsetX;

    snowflake.y+=(snowflake.speed*60);

    snowflake.offsetX+=wind;

    snowflake.angle+=snowflake.speed;

    if(snowflake.y>window.innerHeight||snowflake.x>window.innerWidth){

      snowflake.y=snowflake.initY;

      snowflake.x=snowflake.initX;

      snowflake.offsetX=0;

    }

    context.drawImage(snowflakeImage,snowflake.x,snowflake.y,16*snowflake.scale,16*snowflake.scale);

  }

  requestAnimFrame(animate);

}

window.requestAnimFrame = (function(){

  return  window.requestAnimationFrame       || 

    window.webkitRequestAnimationFrame || 

    window.mozRequestAnimationFrame    || 

    window.oRequestAnimationFrame      || 

    window.msRequestAnimationFrame     || 

    function(/* function */ callback, /* DOMElement */ element){

    window.setTimeout(callback, 1000 / 60);

  };

})();