var urls = new Array ;
var current_state = new Array ;
var preloads = new Array ;
var preloaded_images = new Array ;

function setImg (img,state,url)
{
	if (urls[img] == null)
		urls[img] = new Array ;
	urls[img][state] = url ;
	add_preload_url(url) ;
}

function roll(img,state,force)
{
	if (state == null) {
		if (current_state[img] == null) {
			current_state[img] = 1 ;
		} else {
			current_state[img] = current_state[img] ? 0 : 1 ;
		}
	} else {
		if (current_state[img] != 2 || force == 1)
		{
			current_state[img] = state ;
		} else {
			current_state[img] = 2 ;
		}
	}

	if (urls[img][current_state[img]] == null)
		alert("it's time to tchurn the webmaster : image="+img+" state="+state) ;
		var imgId = document.getElementById(img);
		imgId.src=urls[img][current_state[img]];
}

function add_preload_url(url)
{
	var i ;
	for(i=0 ; i<preloads.length; i++)
	{
		if (preloads[i] == url)
			break ;
	}
	if (i == preloads.length)
	{
		preloads[i] = url ;
	}
}

function preload()
{
	var i ;
	for(i=0; i<preloads.length; i++)
	{
		preloaded_images[i] = new Image ();
		preloaded_images[i].src = preloads[i] ;
	}
}