//zadefinovanie odkazov
var odkazy = new Array("http://www.google.com","http://www.facebook.com","http://www.twiter.com");
//zadefinovanie oneskorenia
var timed = 5000;
//zadefinovanie rychlosti
var speed = 20;
//zistenie browsera
function brow()
{
	if(navigator.userAgent.indexOf("MSIE")!=-1)
	{browser = "IE";}
	else
	{browser = "Mozilla";}
	return browser;
}
//nastavenie priehladnosti
function setOpacity(element, o)
{
	var browser = brow();
	var item = element;
	if (item != undefined && item.style != undefined) {
		if(browser=="IE")
		{
			item.style.filter = "alpha(opacity=" + (o*100) + ")";
		}
		else
		{
			item.style.opacity = o;
		}
	 }
}
//zistenie priehladnosti
function getOpacity(element)
{
	var opacity = null;
	var browser = brow();

	if (element != undefined && element.style != undefined) {
		if(browser=="IE")
		{
			filter = element.style.filter;
			if(filter)
			{
				alpha = filter.split("alpha(opacity=");
				opacity = alpha[1].substr(0,(alpha[1].length-1))/100;
			}
		}
		else
		{
			opacity = element.style.opacity;
		}
	}

	return opacity;
}
//zvysovanie priehladnosti
function opacityplus()
{
    var element = active();
    var op = getOpacity(element);
    var op = op -(-0.05);

    setOpacity(element, op);

    if(op<1)
    {
      setTimeout("opacityplus();",speed);
    }
    else
    {
      setTimeout("opacityminus();",timed);
    }
}
//znizovanie priehladnosti
function opacityminus()
{
    var element = active();
    var op = getOpacity(element);
    var op = op -0.05;

    setOpacity(element, op);

    if(op>0)
    {
      setTimeout("opacityminus();",speed);
    }
    else
    {

      change();

    }
}
//zmena obrazka a odkazu
function change()
{



    if(document.getElementById('b').style.display == 'block')
    {
    	document.getElementById('b').style.display = 'none';
    	document.getElementById('c').style.display = 'block';
    	var element = document.getElementById('c');
    	document.getElementById('anchor').href = odkazy['2'];
    	var o = 0;
	    setOpacity(element, o);
	    opacityplus();

    }
    else
    {
	if(document.getElementById('a').style.display == 'block')
    {
    	document.getElementById('a').style.display = 'none';
    	document.getElementById('b').style.display = 'block';
    	var element = document.getElementById('b');
    	document.getElementById('anchor').href = odkazy['1'];
    	var o = 0;
	    setOpacity(element, o);
	    opacityplus();


    }
    if(document.getElementById('c').style.display == 'block')
    {
    	document.getElementById('c').style.display = 'none';
    	document.getElementById('a').style.display = 'block';
    	var element = document.getElementById('a');
    	document.getElementById('anchor').href = odkazy['0'];
    	var o = 0;
	    setOpacity(element, o);
	    opacityplus();
	}
    }



}
//zistenie aktivneho obrazka
function active()
{
	if(document.getElementById('a')!= undefined && document.getElementById('a').style.display == 'block')
    {
    	var active = document.getElementById('a');
    }
    if(document.getElementById('b')!= undefined && document.getElementById('b').style.display == 'block')
    {
    	var active = document.getElementById('b');
    }
    if(document.getElementById('c')!= undefined && document.getElementById('c').style.display == 'block')
    {
    	var active = document.getElementById('c');
    }
    return active;
}