// Snowflake variables are at the top of the formula

var snowStorm=null;function SnowStorm()

{
this.flakesMax=120;
this.flakesMaxActive=120;
this.animationInterval=0;  					// This changes the rate of fall.  1=fast  40=floats   a higher number makes it slower and slower
this.flakeBottom=null;
this.targetElement=null;
this.followMouse=true;							//  This changes the directions of the snowfall based on the mouse position.  It falls away from the mouse position.  The other option is 'false'.
this.snowColor='#fff';								//  This changes the color of the snow
this.snowCharacter='•';					//  This changes the 'character' used.  EX: you can replace it with the & and see falling & symbols
this.snowStick=true;								//  This lets it stick to the bottom of the screen
this.useMeltEffect=false;			
this.useTwinkleEffect=false;					//  I believe this can create a star effect
this.usePositionFixed=false;
this.flakeLeftOffset=0;
this.flakeRightOffset=0;
this.flakeWidth=5;
this.flakeHeight=5;
this.vMaxX=2.5;
this.vMaxY=2.5;
this.zIndex=0;

var addEvent=(typeof(window.attachEvent)=='undefined'?function(o,evtName,evtHandler){return o.addEventListener(evtName,evtHandler,false);}:function(o,evtName,evtHandler){return o.attachEvent('on'+evtName,evtHandler);});

var removeEvent=(typeof(window.attachEvent)=='undefined'?function(o,evtName,evtHandler){return o.removeEventListener(evtName,evtHandler,false);}:function(o,evtName,evtHandler){return o.detachEvent('on'+evtName,evtHandler);});

function rnd(n,min){if(isNaN(min)){min=0;}
return(Math.random()*n)+min;}

function plusMinus(n){return(parseInt(rnd(2),10)==1?n*-1:n);}

var s=this;
var storm=this;this.timers=[];
this.flakes=[];
this.disabled=false;
this.active=false;
var isIE=navigator.userAgent.match(/msie/i);
var isIE6=navigator.userAgent.match(/msie 6/i);
var isOldIE=(isIE&&(isIE6||navigator.userAgent.match(/msie 5/i)));
var isWin9X=navigator.appVersion.match(/windows 98/i);
var isiPhone=navigator.userAgent.match(/iphone/i);
var isBackCompatIE=(isIE&&document.compatMode=='BackCompat');
var noFixed=((isBackCompatIE||isIE6||isiPhone)?true:false);
var screenX=null;
var screenX2=null;
var screenY=null;
var scrollY=null;
var vRndX=null;
var vRndY=null;
var windOffset=1;
var windMultiplier=2;
var flakeTypes=6;
var fixedForEverything=false;
var opacitySupported=(function(){try{document.createElement('div').style.opacity='0.5';}catch(e){return false;}
return true;})();
var docFrag=document.createDocumentFragment();if(s.flakeLeftOffset===null){s.flakeLeftOffset=0;}
if(s.flakeRightOffset===null){s.flakeRightOffset=0;}


this.meltFrameCount=20;this.meltFrames=[];for(var i=0;i<this.meltFrameCount;i++){this.meltFrames.push(1-(i/this.meltFrameCount));}


this.randomizeWind=function(){vRndX=plusMinus(rnd(s.vMaxX,0.2));vRndY=rnd(s.vMaxY,0.2);

if(this.flakes){for(var i=0;i<this.flakes.length;i++){if(this.flakes[i].active){this.flakes[i].setVelocities();}}}};
this.scrollHandler=function(){scrollY=(s.flakeBottom?0:parseInt(window.scrollY||document.documentElement.scrollTop||document.body.scrollTop,10));
if(isNaN(scrollY)){scrollY=0;}
if(!fixedForEverything&&!s.flakeBottom&&s.flakes){for(var i=s.flakes.length;i--;){if(s.flakes[i].active===0){s.flakes[i].stick();}}}};
this.resizeHandler=function(){if(window.innerWidth||window.innerHeight){screenX=window.innerWidth-(!isIE?16:2)-s.flakeRightOffset;screenY=(s.flakeBottom?s.flakeBottom:window.innerHeight);}
else{screenX=(document.documentElement.clientWidth||document.body.clientWidth||document.body.scrollWidth)-(!isIE?8:0)-s.flakeRightOffset;screenY=s.flakeBottom?s.flakeBottom:(document.documentElement.clientHeight||document.body.clientHeight||document.body.scrollHeight);}

screenX2=parseInt(screenX/2,10);};
this.resizeHandlerAlt=function(){screenX=s.targetElement.offsetLeft+s.targetElement.offsetWidth-s.flakeRightOffset;screenY=s.flakeBottom?s.flakeBottom:s.targetElement.offsetTop+s.targetElement.offsetHeight;screenX2=parseInt(screenX/2,10);};
this.freeze=function(){if(!s.disabled){s.disabled=1;}else{return false;}
for(var i=s.timers.length;i--;){clearInterval(s.timers[i]);}};
this.resume=function(){if(s.disabled){s.disabled=0;}else{return false;}
s.timerInit();};
this.toggleSnow=function(){if(!s.flakes.length){s.start();}else{s.active=!s.active;if(s.active){s.show();s.resume();}else{s.stop();s.freeze();}}};
this.stop=function(){this.freeze();for(var i=this.flakes.length;i--;){this.flakes[i].o.style.display='none';}
removeEvent(window,'scroll',s.scrollHandler);
removeEvent(window,'resize',s.resizeHandler);
if(!isOldIE){removeEvent(window,'blur',s.freeze);removeEvent(window,'focus',s.resume);}};
this.show=function(){for(var i=this.flakes.length;i--;){this.flakes[i].o.style.display='block';}};
this.SnowFlake=function(parent,type,x,y){var s=this;
var storm=parent;
this.type=type;
this.x=x||parseInt(rnd(screenX-20),10);
this.y=(!isNaN(y)?y:-rnd(screenY)-12);
this.vX=null;
this.vY=null;
this.vAmpTypes=[1,1.2,1.4,1.6,1.8];
this.vAmp=this.vAmpTypes[this.type];
this.melting=false;
this.meltFrameCount=storm.meltFrameCount;
this.meltFrames=storm.meltFrames;
this.meltFrame=0;
this.twinkleFrame=0;
this.active=1;
this.fontSize=(10+(this.type/5)*10);
this.o=document.createElement('div');
this.o.innerHTML=storm.snowCharacter;
this.o.style.color=storm.snowColor;
this.o.style.position=(fixedForEverything?'fixed':'absolute');
this.o.style.width=storm.flakeWidth+'px';
this.o.style.height=storm.flakeHeight+'px';
this.o.style.fontFamily='arial,verdana';
this.o.style.overflow='hidden';
this.o.style.fontWeight='normal';
this.o.style.zIndex=storm.zIndex;
docFrag.appendChild(this.o);
this.refresh=function(){if(isNaN(s.x)||isNaN(s.y)){return false;}
s.o.style.left=s.x+'px';
s.o.style.top=s.y+'px';};
this.stick=function(){if(noFixed||(storm.targetElement!=document.documentElement&&storm.targetElement!=document.body)){s.o.style.top=(screenY+scrollY-storm.flakeHeight)+'px';}
else if(storm.flakeBottom){s.o.style.top=storm.flakeBottom+'px';}
else{s.o.style.display='none';
s.o.style.top='auto';
s.o.style.bottom='0px';
s.o.style.position='fixed';
s.o.style.display='block';}};
this.vCheck=function(){if(s.vX>=0&&s.vX<0.2){s.vX=0.2;}
else if(s.vX<0&&s.vX>-0.2){s.vX=-0.2;}
if(s.vY>=0&&s.vY<0.2){s.vY=0.2;}};
this.move=function(){var vX=s.vX*windOffset;s.x+=vX;s.y+=(s.vY*s.vAmp);
if(s.x>=screenX||screenX-s.x<storm.flakeWidth){s.x=0;}
else if(vX<0&&s.x-storm.flakeLeftOffset<0-storm.flakeWidth){s.x=screenX-storm.flakeWidth-1;}
s.refresh();
var yDiff=screenY+scrollY-s.y;
if(yDiff<storm.flakeHeight){s.active=0;if(storm.snowStick){s.stick();}
else{s.recycle();}}


else{if(storm.useMeltEffect&&s.active&&s.type<3&&!s.melting&&Math.random()>0.998){s.melting=true;s.melt();}
if(storm.useTwinkleEffect){if(!s.twinkleFrame){if(Math.random()>0.9){s.twinkleFrame=parseInt(Math.random()*20,10);}}
else{s.twinkleFrame--;s.o.style.visibility=(s.twinkleFrame&&s.twinkleFrame%2===0?'hidden':'visible');}}}};
this.animate=function(){s.move();};
this.setVelocities=function(){s.vX=vRndX+rnd(storm.vMaxX*0.12,0.1);
s.vY=vRndY+rnd(storm.vMaxY*0.12,0.1);};
this.setOpacity=function(o,opacity){if(!opacitySupported){return false;}
o.style.opacity=opacity;};
this.melt=function(){if(!storm.useMeltEffect||!s.melting){s.recycle();}
else{if(s.meltFrame<s.meltFrameCount){s.meltFrame++;s.setOpacity(s.o,s.meltFrames[s.meltFrame]);
s.o.style.fontSize=s.fontSize-(s.fontSize*(s.meltFrame/s.meltFrameCount))+'px';
s.o.style.lineHeight=storm.flakeHeight+2+(storm.flakeHeight*0.75*(s.meltFrame/s.meltFrameCount))+'px';}
else{s.recycle();}}};
this.recycle=function(){s.o.style.display='none';s.o.style.position=(fixedForEverything?'fixed':'absolute');
s.o.style.bottom='auto';
s.setVelocities();
s.vCheck();
s.meltFrame=0;									//  This affects the rate of fall.  Not sure why yet.  100=makes it fall real slow.  Was set to '0'.  '-50' didn't change anything from what I saw
s.melting=false;
s.setOpacity(s.o,1);
s.o.style.padding='0px';
s.o.style.margin='0px';
s.o.style.fontSize=s.fontSize+'px';
s.o.style.lineHeight=(storm.flakeHeight+2)+'px';
s.o.style.textAlign='center';
s.o.style.verticalAlign='baseline';
s.x=parseInt(rnd(screenX-storm.flakeWidth-20),10);
s.y=parseInt(rnd(screenY)*-1,10)-storm.flakeHeight;
s.refresh();
s.o.style.display='block';
s.active=1;};										//  Seems to be necessary to set to '1'
this.recycle();
this.refresh();};

this.snow=function(){var active=0;var used=0;var waiting=0;var flake=null;
for(var i=s.flakes.length;i--;){if(s.flakes[i].active==1){s.flakes[i].move();active++;}
else if(s.flakes[i].active===0){used++;}else{waiting++;}
if(s.flakes[i].melting){s.flakes[i].melt();}}




if(active<s.flakesMaxActive){flake=s.flakes[parseInt(rnd(s.flakes.length),10)];
if(flake.active===0){flake.melting=true;}}};
this.mouseMove=function(e){if(!s.followMouse){return true;}
var x=parseInt(e.clientX,10);
if(x<screenX2){windOffset=-windMultiplier+(x/screenX2*windMultiplier);}
else{x-=screenX2;windOffset=(x/screenX2)*windMultiplier;}};
this.createSnow=function(limit,allowInactive){for(var i=0;i<limit;i++){s.flakes[s.flakes.length]=new s.SnowFlake(s,parseInt(rnd(flakeTypes),10));
if(allowInactive||i>s.flakesMaxActive){s.flakes[s.flakes.length-1].active=-1;}}
storm.targetElement.appendChild(docFrag);};
this.timerInit=function(){s.timers=(!isWin9X?[setInterval(s.snow,s.animationInterval)]:[setInterval(s.snow,s.animationInterval*3),setInterval(s.snow,s.animationInterval)]);};
this.init=function(){s.randomizeWind();
s.createSnow(s.flakesMax);
addEvent(window,'resize',s.resizeHandler);
addEvent(window,'scroll',s.scrollHandler);
if(!isOldIE){addEvent(window,'blur',s.freeze);
addEvent(window,'focus',s.resume);}
s.resizeHandler();
s.scrollHandler();
if(s.followMouse){addEvent(document,'mousemove',s.mouseMove);}
s.animationInterval=Math.max(20,s.animationInterval);
s.timerInit();};
var didInit=false;
this.start=function(bFromOnLoad){if(!didInit){didInit=true;}else if(bFromOnLoad){return true;}
if(typeof s.targetElement=='string'){var targetID=s.targetElement;s.targetElement=document.getElementById(targetID);
if(!s.targetElement){throw new Error('Snowstorm: Unable to get targetElement "'+targetID+'"');}}
if(!s.targetElement){s.targetElement=(!isIE?(document.documentElement?document.documentElement:document.body):document.body);}
if(s.targetElement!=document.documentElement&&s.targetElement!=document.body){s.resizeHandler=s.resizeHandlerAlt;}
s.resizeHandler();
s.usePositionFixed=(s.usePositionFixed&&!noFixed);
fixedForEverything=s.usePositionFixed;
if(screenX&&screenY&&!s.disabled){s.init();s.active=true;}};
function doStart(){s.start(true);}
if(document.addEventListener){document.addEventListener('DOMContentLoaded',doStart,false);
window.addEventListener('load',doStart,false);}
else{addEvent(window,'load',doStart);}}
snowStorm=new SnowStorm();