var currentImage= 0;
var thumbnails=new Array();
var descriptions=new Array();

function changeImage(id){
	document.getElementById('thumb'+currentImage).className = "thumbnail";
	document.getElementById('mainimage').src='files/alt2_'+ thumbnails[parseInt(id)];
	document.getElementById('imagedescription').innerHTML=descriptions[parseInt(id)];
	currentImage = id;
	//transition
	document.getElementById('thumb'+id).className = "thumbnailselected";
	//alert('img changed');
}
function nextImage(delta){
	var newImage = parseInt(currentImage) + parseInt(delta);
	if(newImage >= 0 && newImage < thumbnails.length){
		changeImage(newImage);
	}
	else if(newImage >= thumbnails.length){
		changeImage(0);
	}
	else if(newImage < 0){
		changeImage((thumbnails.length-1));
	}
	
}




function showpager(id){
	if(id == 'l'){
		document.getElementById('leftpager').style.opacity = 0.6;
		document.getElementById('leftpager').style.filter  = "alpha(opacity=60)";
	}
	else if(id == 'r'){
		document.getElementById('rightpager').style.opacity = 0.6;
		document.getElementById('rightpager').style.filter  = "alpha(opacity=60)";
	}
	
}

function hidepager(id){
	if(id == 'l'){
		document.getElementById('leftpager').style.opacity = 0.2;
		document.getElementById('leftpager').style.filter  = "alpha(opacity=20)";
	}
	else if(id == 'r'){
		document.getElementById('rightpager').style.opacity = 0.2;
		document.getElementById('rightpager').style.filter  = "alpha(opacity=20)";
	}
}