var r = 100;        // radius
var verzerrung = 3; //horizontale verzerrung als faktor - 1=normal - höhere werte schmalere ellipse
var pi = Math.PI;   // pi
var a=-1;	    // Startwinkel
var speed=2; // Schrittweite
var intervall = 10;
var xpos=230;
var ypos=150;
var lay1,lay2,lay3;
var rotationTimeout=false;

function initRotLayers(){
	lay1=document.getElementById ("rotLayer1").style;
	lay2=document.getElementById ("rotLayer2").style;
	lay3=document.getElementById ("rotLayer3").style;
	if (!rotationTimeout)rotateRotLayers();
}

function rotateRotLayers(){
	a=a+speed;
	lay1.left=(r * Math.cos(a*(pi/180)))/verzerrung + xpos+"px";
	lay1.top=(r * Math.sin(a*(pi/180))) + ypos+"px";
	lay2.left=(r * Math.cos((a+120)*(pi/180)))/verzerrung + xpos+"px";
	lay2.top=(r * Math.sin((a+120)*(pi/180)))  + ypos+"px";
	lay3.left=(r * Math.cos((a+240)*(pi/180)))/verzerrung + xpos+"px";
	lay3.top=(r * Math.sin((a+240)*(pi/180))) + ypos+"px";
	rotationTimeout = window.setTimeout ('rotateRotLayers()', intervall);
}

initRotLayers();