$(document).ready(function(){
	var picpos = [];
	$(window).load(function() {
		var windowheight = $(window).height();
		var docheight = $(document).height()-windowheight;
		var arrowheight = $("#toparrow").height();
		var menuheight = $("#menubox").innerHeight();
		var scrolltrack = windowheight-menuheight+(arrowheight*2);
		$("#portfoliopics img").each(function() {
			var pos = $(this).position();
			picpos.push(Math.ceil(pos.top));
		});		
		$(window).scroll( function() {
			$("#menubox").stop();
			var windowpos = $(window).scrollTop();
			var percent =(windowpos/docheight);	
			var menupos = (scrolltrack*percent)-arrowheight;
			menupos += "px";
			$("#menubox").animate({
				top: menupos
			},1000);
		});
	});
	function nextPic() {
		for (var i = 0; i < picpos.length; i++) {
			if ($(window).scrollTop() >= picpos[i] && $(window).scrollTop() < picpos[(i+1)]) {
				var newpos = picpos[i+1];
				$('html,body').animate({ scrollTop: newpos },500);
				break;
			}
		}
	}
	function prevPic() {
		for (var i = picpos.length-1; i >= 0; i--) {
			if ($(window).scrollTop() <= picpos[i] && $(window).scrollTop() > picpos[(i-1)]) {
				var newpos = picpos[i-1];
				$('html,body').animate({ scrollTop: newpos },500);
				break;
			}
		}
	}
	$(document).keydown(function(e){
		if (e.keyCode == 37) { 
			prevPic();
			return false;
		}
		if (e.keyCode == 39) { 
			nextPic();
			return false;
		}
	});

	$("#bottomarrow").click(function() {
		nextPic();
	});
	$("#toparrow").click(function() {
		prevPic();
	});
});