// Layers-plugin
(function($){
	$.fn.layers = function(options) {
		var defaults = {
			factor: '0.5',
			speed : 6000,
			animate : true
		};

		var opts = $.extend(defaults, options);
		var el = this;
		var startTop = $(el).css('top');
				
		return $(el).each(function (){
			setPos();
			$(window).scroll(function () {
				setPos(); 
			});
		
		});
		
		function setPos(){
			var y = $(this).scrollTop();
			var newTop = parseInt(y) * parseFloat(opts['factor']) + parseInt(startTop);
			
			if (opts['animate']) {
				$(el).stop().animate({'top' : parseInt(newTop)},opts['speed']);
			}
			else {
				$(el).css({'top' : parseInt(newTop)});					
			}
		}
	};			

})(jQuery);


// Demo
$(function () {
	
	 $('#layer_1').layers({factor:'0.2'});
	 $('#layer_2').layers({factor:'0.3'});
	 $('#layer_3').layers({factor:'0.4'});
	 $('#layer_4').layers({factor:'0.5'});
	 $('#layer_5').layers({factor:'0'});
});