var BGCONFIG = {
	bgfolder: 'images',
	timeout: 5000, //ms
	layer1: 'div#wallpaper',
	layer2: 'div.transparency',
	list: [
		'wallpaper2.jpg',
		'wallpaper5.jpg',
		'wallpaper3.jpg',
		'wallpaper4.jpg'
	]
};


$(document).ready(function(){	
	// accordion menu
	$('a.menus').click(function() {
		$(this).next('ul').slideToggle();
		return false;
	}).next('ul').hide();

	var layer1 = $(BGCONFIG.layer1);
	var layer2 = $(BGCONFIG.layer2);
	var index = 0;
	var switcher = 0;
	var bgimages = [];

	// set initial bg
	bgimages[index] = new Image();
	$(bgimages[index]).load(function() {
		layer2.css({'background': 'url('+bgimages[index].src+') no-repeat'});
	});
	bgimages[index].src = BGCONFIG.bgfolder+'/'+BGCONFIG.list[index];
	
	setInterval(function() {
		if (index < BGCONFIG.list.length)
			index++;
		else
			index = 0;
			
		bgimages[index] = new Image();
		$(bgimages[index]).load(function() {
			if ( switcher == 1 ) {				
				layer2.css({'background': 'url('+bgimages[index].src+') no-repeat'});
				layer2.fadeIn(3000);
				switcher = 0;
			} else {
				layer1.css({'background': 'url('+bgimages[index].src+') no-repeat'});
				layer2.fadeOut(3000);
				switcher = 1;
			}			
		});
		bgimages[index].src = BGCONFIG.bgfolder+'/'+BGCONFIG.list[index];
	}, BGCONFIG.timeout);
});