fadeStep=1; // Size of the fade "step". Must be a multiple of 100.

fadeInterval=5; // Amount of time in-between the increments of fading

readingTime=3; // Amount of time the user has to see the image (seconds)

images = new Array(
"http://www.nightskyproject.com/img/1.gif",
"http://www.nightskyproject.com/img/2.gif",
"http://www.nightskyproject.com/img/3.gif",
"http://www.nightskyproject.com/img/4.png",
"http://www.nightskyproject.com/img/5.png");

// Do not edit the following variables
var currTransp=100;
var currDir=0;
var currNum=0;

function nextSlide() {
	currNum++;
	if (currNum == images.length) {
		currNum=0;
	}
	document.getElementById("disp-slide").src=images[currNum];
}

function prevSlide() {
	currNum--;
	if(currNum == -1) {
		currNum=images.length-1;
	}
	document.getElementById("disp-slide").src=images[currNum];
}

//Fading for different browsers
function changeOpac() {
	var doc_id = document.getElementById("disp-slide").style;
	doc_id.opacity = (currTransp / 100);
	doc_id.MozOpacity = (currTransp / 100);
	doc_id.KhtmlOpacity = (currTransp / 100);
	doc_id.filter = "alpha(opacity=" + currTransp + ")";
			}

function fadeSlide() {
fading = window.setTimeout("fadeSlide()", fadeInterval);
	if (currTransp == 100 - fadeStep && currDir == 1) {
		window.clearTimeout(fading);
	}
	if (currTransp < 0) {
		currTransp=0;
	}
	if (currTransp > 100) {
		currTransp=100;
	}
	if (currDir==0 && currTransp > 0) {
		currTransp=currTransp-fadeStep;
		//Fading for different browsers
		changeOpac();
	}

	else if (currDir==1 && currTransp < 100) {
		currTransp=currTransp+fadeStep;
		//Fading for different browsers
		changeOpac();
	}
	else if (currDir==0 && currTransp == 0) {
		currDir=1;
		nextSlide();
	}
	if (currDir==1 && currTransp == 100) {
		window.setTimeout("commenceFade()", (readingTime * 1000));
	}
}

function commenceFade() {
	currDir=0;
	fadeSlide(1);
}

window.setTimeout("commenceFade()", readingTime * 1000 );