var no = 25; // snow number
var speed = 50; // smaller number moves the snow faster
var snowflake = "/images/snowflake.gif";
var ns = (document.layers) ? 1 : 0;  // browser sniffer
var ie = (document.getElementById) ? 1 : 0;

var dx, xp, yp;    // coordinate and position variables
var am, stx, sty;  // amplitude and step variables
var i, doc_width, doc_height;

getDimensions();

dx = new Array();
xp = new Array();
yp = new Array();
am = new Array();
stx = new Array();
sty = new Array();
for (i = 0; i < no; ++ i) {  
	dx[i] = 0;                        // set coordinate variables
	xp[i] = Math.random()*(doc_width-50);  // set position variables
	yp[i] = Math.random()*doc_height;
	am[i] = Math.random()*20;         // set amplitude variables
	stx[i] = 0.02 + Math.random()/10; // set step variables
	sty[i] = 0.7 + Math.random();     // set step variables
	if (ns) {                      // set layers
			document.write('<layer name="dot' + i + '" left="15" top="15" visibility="show"><img src="' + snowflake + '" border="0"></layer>');
	} 
	else if (ie) {
			document.write('<div id="dot' + i + '" style="position:absolute; z-index:' + i + '; visibility:visible; top:-20px; left:-20px;"><img src="' + snowflake + '" border="0"></div>');
	}
}

function getDimensions() {
	if (ns) {
		doc_width = self.innerWidth;
		doc_height = self.innerHeight;
	} 
	else if (ie) {
		doc_width = document.body.clientWidth;
		doc_height = document.body.clientHeight;
	}
}

function letItSnow() {
		for (i = 0; i < no; ++ i) {  // iterate for every dot
		yp[i] += sty[i];
		if (yp[i] > doc_height-50) {
			xp[i] = Math.random()*(doc_width-am[i]-30);
			yp[i] = 0;
			stx[i] = 0.02 + Math.random()/10;
			sty[i] = 0.7 + Math.random();
			getDimensions();
		}
		dx[i] += stx[i];
		if (ns) {
			document.layers["dot"+i].top = yp[i];
			document.layers["dot"+i].left = xp[i] + am[i]*Math.sin(dx[i]);
		}	
		else if (ie) {
			document.getElementById("dot"+i).style.top = yp[i];
			document.getElementById("dot"+i).style.left = xp[i] + am[i]*Math.sin(dx[i]);
		}
	}
	setTimeout("letItSnow()", speed);
}