var currentSnapshot = 'screenshot1.png';

function changeRight()
{
	var nextUrl;
	if (currentSnapshot == 'screenshot1.png') {
		nextUrl = 'images/' + 'screenshot2.png'; 
		currentSnapshot = 'screenshot2.png';
	} else if (currentSnapshot == 'screenshot2.png') {
		nextUrl = 'images/' + 'screenshot3.png'; 
		currentSnapshot = 'screenshot3.png';
	} else if (currentSnapshot == 'screenshot3.png') {
		nextUrl = 'images/' + 'screenshot1.png'; 
		currentSnapshot = 'screenshot1.png';
	} 
	$("#snapshot").css('background-image', 'url(' + nextUrl + ')');
}

function changeLeft()
{
	var previousUrl;
	if (currentSnapshot == 'screenshot1.png') {
		previousUrl = 'images/' + 'screenshot3.png'; 
		currentSnapshot = 'screenshot3.png';
	} else if (currentSnapshot == 'screenshot2.png') {
		previousUrl = 'images/' + 'screenshot1.png'; 
		currentSnapshot = 'screenshot1.png';
	} else if (currentSnapshot == 'screenshot3.png') {
		previousUrl = 'images/' + 'screenshot2.png'; 
		currentSnapshot = 'screenshot2.png';
	} 
	$("#snapshot").css('background-image', 'url(' + previousUrl + ')');
}