/******************************************************************

sidebar project elements

******************************************************************/

var num_projects_per_page 	= 2;
var num_sidebar_projects 		= 0;
var project_height					= 178;
var current_top_project			= 0;
var animation_speed					= 300;

function initScrollPosition()
{
	var distance = project_height * (current_top_project) ;
	$('#portfolio_table').css('top', "-" + distance + "px");
}			

function currentBottomProject()
{
	return current_top_project + num_projects_per_page;
}

function checkNavArrows()
{
	if (canScrollUp()) {
		$('#portfolio_nav_up').css('background-position', '0 -178px');
	}
	else {	
		$('#portfolio_nav_up').css('background-position', '0 0');		
	}

	if (canScrollDown()) {
		$('#portfolio_nav_down').css('background-position', '0 -178px');		
	}
	else {
		$('#portfolio_nav_down').css('background-position', '0 0');		
	}
}	

function canScrollDown()
{
	return (current_top_project > 0);
}			

function canScrollUp()
{
	return (currentBottomProject() < num_sidebar_projects);
}			

function scrollDown()
{
	var distance = project_height * (current_top_project + 1) ;
	$("#portfolio_table").animate({ 
		left: 0,
		top: -distance
	}, animation_speed );

	current_top_project += 1;					
	checkNavArrows();					
}			

function scrollUp()
{
	var distance = project_height * (current_top_project - 1) ;
	$("#portfolio_table").animate({ 
		left: 0,
		top: -distance
	}, animation_speed );

	current_top_project -= 1;					
	checkNavArrows();
}