var WAIT=5; 

var i=0;
var nexti=0;
var iMax=0;
var timer=0;
var changing=false;

function setOpacity(obj, val) {
   if(!+"\v1") {
		typeof obj.filters.alpha != 'undefined'
      ? obj.filters.alpha.opacity = val * 100
	   : obj.style.filter = 'alpha(opacity=' + val * 100 + ');';
	}

	obj.style.opacity = val;
}


function prepareNextImg(){
	clearTimeout(timer);

	document.getElementById('rnd-image'+i).style.zIndex=500;
	setOpacity(document.getElementById('rnd-image'+nexti),0);
	document.getElementById('rnd-image'+nexti).style.zIndex=501;

	var alpha=0;
	timer=window.setInterval(function(){
		alpha+=10;
		setOpacity(document.getElementById('rnd-image'+nexti),alpha/100);
		if(alpha==100){
			setOpacity(document.getElementById('rnd-image'+i),0);
			i=nexti;
			changing=false;
			clearInterval(timer);
			resetTimer();
		}
	}, 40);
}

function resetTimer(){
	timer=window.setTimeout(nextImage, WAIT*1000);
}

function nextImage(){
	if(!changing){
		changing=true;
		nexti++;
		if(nexti==iMax)
			nexti=0;

		prepareNextImg();
	}
}

function prevImage(){
	if(!changing){
		changing=true;
		nexti--;
		if(nexti==-1)
			nexti=iMax-1;

		prepareNextImg();
	}
}

function init(){
	while(document.getElementById('rnd-image'+iMax)){
		iMax++;
	}
	i=0;

	resetTimer();
}
window.onload=init;