var pictureid = "Pic";
var imgprefix = "Images/pic";
var imgsuffix = ".jpg";
var numofpics = 35;
var numweshow = 4; // we show 4 pictures on the top of theh page
var imgfadetm = 3 * 1000; // how many seconds between each picture fade in/out?

var arr    = new Array(numofpics + 1);
var imgarr = new Array(numofpics + 1);
var timeout;

var i, j;

// we skip index 0 for sanity
for(i = 1; i <= numofpics; i++)
{
	arr[i] = i; // what's showing right now
}

// preload pictures
for(i = 1; i <= numofpics; i++)
{
	imgarr[i] = new Image();
	imgarr[i].src = imgprefix + i + imgsuffix;
}

// find an image that is not currently being displayed
function getDifferentImage()
{
	var otherpics = numofpics - numweshow;

	return (Math.floor(otherpics * Math.random()) + 1 + numweshow);
}

function fadeImageIn()
{
	timeout = setTimeout(fadeImageIn, imgfadetm);

	var arrindex = getDifferentImage();
	var imgindex = arr[arrindex];
	var newimg   = imgarr[imgindex];

	var imgtoswap = Math.floor(numweshow * Math.random()) + 1;

	var tmp;
	tmp            = arr[imgtoswap];
	arr[imgtoswap] = arr[arrindex];
	arr[arrindex]  = tmp;

	var img = document.getElementById(pictureid + imgtoswap);
	img.src = newimg.src;
}

timeout = setTimeout(fadeImageIn, imgfadetm);