var px_scroll_amt = 10;
var xhr_support = Boolean(window.XMLHttpRequest !== undefined);

/* fon preload */
containers = [];
containers[0]=["#zvezdabg", "main/zvezdabg.jpg"];
containers[1]=["#bgseam", "main/bgSeam.png"];
containers[2]=["", "clouds.png"];
containers[3]=["body", "main/bgTop_new.jpg"];

var preload_layer = function(number) {

	if(containers[number]) {
		
		$("<img/>").bind("load", function() {
			
			if(containers[number][0]) $(containers[number][0]).addClass("loaded");
			if(containers[number+1]) preload_layer(number+1);
			else {
				run_parallax();
			}
		}).attr("src","/i/"+containers[number][1]);
	
	}
}

var run_parallax = function() {
	var offset = $(document).scrollTop();
	var height = $(document).height() - 1116- $(window).height();
	var opacity = (height-offset)/height;	
	
	$(document.body).css({
		'backgroundPosition': 'center -' + (offset / px_scroll_amt) + 'px',
		'backgroundAttachment': 'fixed'
	});
	
	if (xhr_support) {
		//(ie7 and up, gecko, webkit and opera support XHR)
		/*
		$("#clouds").css({
			'opacity': opacity
		});
		'filter': "progid:DXImageTransform.Microsoft.AlphaImageLoader(src='/i/clouds.png',sizingMethod='scale')"
		*/
		var clouds_height =  $("#container-content").height() - 1116;
		$("#clouds div").css({
			'height': clouds_height + 'px',
			'backgroundImage': 'url(/i/clouds.png)',
			'backgroundPosition': 'center -' + (offset / px_scroll_amt) + 'px',
			'backgroundAttachment': 'fixed'
		});
	}
}

$(document).ready(function() {
	// сначала предщагружаем фон
	// облака
	// звезда
	// тайл
	// планета
	preload_layer(0);
	
	$(window).scroll(function() {
		var offset = $(document).scrollTop();
		var height = $(document).height() - 1116 - $(window).height();
		var opacity = (height-offset)/height;
		
		$(document.body).css({
		  'backgroundPosition': 'center -' + (offset/ px_scroll_amt) + 'px'
		});
		
		
		if (xhr_support) {
			/*
			$("#clouds").css({
				'opacity': opacity
			});
			*/
			$("#clouds div").css({
			  'backgroundPosition': 'center -' + (offset / (px_scroll_amt / 3)) + 'px'
			});
		}
	});
});