function rnd(max)
{
	var rndNum = max * Math.random();
	rndNum = Math.ceil (rndNum);
	return rndNum;
}



// Fade-Funktionen

var nextPicNumber=1;
var picsMax=6;
var nextPic=new Image();
var fadeChangeTime=3000;

function switchFadePic()
{	
	nextPicNumber++;
	var nextPicSrc="/assets/images/headerbilder/headerbild_"+nextPicNumber+".jpg";
	nextPic.src=nextPicSrc;
	
	if(nextPicNumber>picsMax)
	{
		nextPicNumber=0;
	}
	
	document.getElementById("head_image").style.backgroundImage="url("+nextPic.src+")"; 
	setTimeout("fadeOut('fadePic', 1)", fadeChangeTime);
}

// Parameter festlegen
var fadeInTimer=new Array();
var fadeOutTimer=new Array();
var opacitiyProgress=new Array();
var opacitiyAvailable=true;
var opacity=0;
var opacityFull=1;
var fadeEnd=0;
var opacityZero=0;
var fadeInStep=0.05;
var fadeOutStep=0.05;
var stepTime=40;


function fadeIn(id, opacity)
{
	if(!opacitiyAvailable) return;
	
	clearTimeout(fadeOutTimer[id]);
	
	opacity=opacity+fadeInStep;
	opacitiyProgress[id]=opacity;
	
	setOpacitiy(id, opacity);
	
	if(opacity+fadeInStep<opacityFull) fadeInTimer[id]=setTimeout("fadeIn('"+id+"', "+opacitiyProgress[id]+")", stepTime);
	else 
	{
		setOpacitiy(id, opacityFull);
		opacitiyProgress[id]=opacityFull;

		document.getElementById('fadePic').src=nextPic.src;
		setOpacitiy('fadePic', 1);
		switchFadePic();
	}
}

function fadeOut(id, opacity)
{	
	if(!opacitiyAvailable) return;
	
	clearTimeout(fadeInTimer[id]);
	
	opacity=opacity-fadeOutStep;
	opacitiyProgress[id]=opacity;
	
	setOpacitiy(id, opacity);
	
	if(opacity-fadeOutStep>fadeEnd) fadeOutTimer[id]=setTimeout("fadeOut('"+id+"', "+opacitiyProgress[id]+")", stepTime);
	else
	{
		setOpacitiy(id, fadeEnd);
		opacitiyProgress[id]=fadeEnd;

		document.getElementById('fadePic').src=nextPic.src;
		setOpacitiy('fadePic', 1);
		if(nextPicNumber!=1) switchFadePic();
	}
}

function getFadeOpacity(id)
{	
	if(!opacitiyAvailable) return;

	// überprüfen ob Tranparenz unterstützt wird
	if(document.getElementById(id).style.filter=="undefined" && document.getElementById(id).style.opacity=="undefined")
	{
		opacitiyAvailable=false;
		return;
	}
	else
	{		
		if(opacitiyProgress[id]) return opacitiyProgress[id];
		else return 0;
	}	
}

function setOpacitiy(id, opacity)
{
	if(document.all) document.getElementById(id).style.filter="Alpha(opacity="+opacity*100+")";
	else document.getElementById(id).style.opacity=opacity;
}