function rnd(){return Math.random();}

var clouds = Array("images/clouds/cloud1.png","images/clouds/cloud2.png","images/clouds/cloud3.png","images/clouds/cloud4.png");
var numclouds = 10;
var T = 50;
var dx, x, y, vx, i;
var winwidth = 1024;
var winheight = 300;

function resize()
{
window.winwidth = window.innerWidth?window.innerWidth:document.body.clientWidth;
}

dx = new Array();
x = new Array();
y = new Array();
vx = new Array();

function initializeClouds() {
		
	resize();
	
	for (i = 0; i < numclouds; i++)
	{
		var cloudnumber=Math.floor(rnd()*clouds.length);
		var thiscloud = "" + clouds[cloudnumber];
		dx[i] = 0;
		
		x[i] = rnd()*(window.winwidth-242);
		y[i] = rnd()*winheight;
		vx[i] = 4-cloudnumber;
			
		var newImage = new Element('img', {
				'id': 'f' + i,
				'src': thiscloud,
		    'class': 'cloud'
		});

		newImage.inject($('clouds'), 'top');
				
	}

	startclouds();
	
}

function moveclouds(id,left,top)
{
		$(id).style.left=left + 'px';
		$(id).style.top=top + 'px';
}

function startclouds() {
	resize();
	for (i = 0; i < numclouds; ++ i) {
		if (x[i]-dx[i]+250 <= 0) {
			x[i] = window.winwidth-242;
			y[i] = rnd()*winheight;
			dx[i]=0;
		}
		dx[i] += vx[i];
		moveclouds("f"+i,x[i]-dx[i],y[i]);
	}
	setTimeout("startclouds()", T);
}
initializeClouds();