JavaScript - NIEVE ACUMULÁNDOSE SOBRE UNA IMAGEN

AQUI CONTINÚA EN SCRIPT (por razones del foro no me acepta todo de una)
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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) { // X-axis scroll check
s.x = 0;
} else if (vX < 0 && s.x-storm.flakeLeftOffset<0-storm.flakeWidth) {
s.x = screenX-storm.flakeWidth-1; // flakeWidth;
}
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) {
// ~1/1000 chance of melting mid-air, with each frame
s.melting = true;
s.melt();
// only incrementally melt one frame
// s.melting = false;
}
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() {
// main animation loop
// move, check status, die etc.
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;
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;
};

this.recycle(); // set up x/y coords etc.
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); // create initial batch
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) {
// already loaded and running
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; // re-map handler to get element instead of screen dimensions
}
s.resizeHandler(); // get bounding box elements
s.usePositionFixed = (s.usePositionFixed && !noFixed); // whether or not position:fixed is supported
fixedForEverything = s.usePositionFixed;
if (screenX && screenY && !s.disabled) {
s.init();
s.active = true;
}
};

function doStart() {
s.start(true);
}

if (document.addEventListener) {
// safari 3.0.4 doesn't do DOMContentLoaded, maybe others - use a fallback to be safe.
document.addEventListener('DOMContentLoaded',doStart,false);
window.addEventListener('load',doStart,false);
} else {
addEvent(window,'load',doStart);
}

}

snowStorm = new SnowStorm();
//]]>
</script>
<!-- Fin del script para nieve -->

Notas:
[1] He respetado los créditos al autor original: Schillmania