/*
JavaScript for the demo: Recreating the Nikebetterworld.com Parallax Demo
Demo: Recreating the Nikebetterworld.com Parallax Demo
Author: Ian Lunn
Author URL: http://www.ianlunn.co.uk/
Demo URL: http://www.ianlunn.co.uk/demos/recreate-nikebetterworld-parallax/
Tutorial URL: http://www.ianlunn.co.uk/blog/code-tutorials/recreate-nikebetterworld-parallax/

License: http://creativecommons.org/licenses/by-sa/3.0/ (Attribution Share Alike). Please attribute work to Ian Lunn simply by leaving these comments in the source code or if you'd prefer, place a link on your website to http://www.ianlunn.co.uk/.

Dual licensed under the MIT and GPL licenses:
http://www.opensource.org/licenses/mit-license.php
http://www.gnu.org/licenses/gpl.html
*/

$(document).ready(function() { //when the document is ready...


	//save selectors as variables to increase performance
	var $window = $(window);
	var $introBG = $('#intro');
	var $missionBG = $('#mission');
	var $trophyBG = $('#trophy');
	var $prizesBG = $('#prizes');
	var $locationBG = $('#location');
	var $judgesBG = $('#judges');
	var $enterBG = $('#enter');
	var $pastBG = $('#past');
	var $aboutBG = $('#about');
	var flyingguy = $("#mission .bg");
	var moon = $("#location .bg");
	var goldman = $("#prizes .bg");
	var beachboy = $("#about .bg");
	
	var windowHeight = $window.height(); //get the height of the window
	
	
	//apply the class "inview" to a section that is in the viewport
	$('#intro, #mission, #trophy, #prizes, #location, #judges, #enter, #about, #past').bind('inview', function (event, visible) {
			if (visible == true) {
			$(this).addClass("inview");
			} else {
			$(this).removeClass("inview");
			}
		});
	
			
	//function that places the navigation in the center of the window
	//function RepositionNav(){
		//var windowHeight = $window.height(); //get the height of the window
		//var navHeight = $('#nav').height() / 2;
		//var windowCenter = (windowHeight / 2); 
		//var newtop = windowCenter - navHeight;
		//$('#nav').css({"top": newtop}); //set the new top position of the navigation list
	//}
	
	//function that is called for every pixel the user scrolls. Determines the position of the background
	/*arguments: 
		x = horizontal position of background
		windowHeight = height of the viewport
		pos = position of the scrollbar
		adjuster = adjust the position of the background
		inertia = how fast the background moves in relation to scrolling
	*/
	function newPos(x, windowHeight, pos, adjuster, inertia){
		return x + "% " + (-((windowHeight + pos) - adjuster) * inertia)  + "px";
	}
	
	//function to be called whenever the window is scrolled or resized
	function Move(){ 
		var pos = $window.scrollTop(); //position of the scrollbar

		//if the first section is in view...
		if($introBG.hasClass("inview")){
			//call the newPos function and change the background position
			$introBG.css({'backgroundPosition': newPos(50, windowHeight, pos, 900, 0.3)}); 
		}
		
		//if the second section is in view...
		if($missionBG.hasClass("inview")){
			//call the newPos function and change the background position
			$missionBG.css({'backgroundPosition': newPos(50, windowHeight, pos, 1400, 0.3)});
			//call the newPos function and change the secnond background position
			flyingguy.css({'backgroundPosition': newPos(50, windowHeight, pos, 2050, 0.6)});
		}
		
		
		//if the third section is in view...
		if($trophyBG.hasClass("inview")){
			//call the newPos function and change the background position
			$trophyBG.css({'backgroundPosition': newPos(50, windowHeight, pos, 2300, 0.3)});
		}
		
		//if the fourth section is in view...
		if($prizesBG.hasClass("inview")){
			//call the newPos function and change the background position
			$prizesBG.css({'backgroundPosition': newPos(50, windowHeight, pos, 3000, 0.3)});
			//call the newPos function and change the secnond background position
			goldman.css({'backgroundPosition': newPos(50, windowHeight, pos, 3800, 0.6)});
		}
		
		//if the sixth section is in view...
		if($locationBG.hasClass("inview")){
			//call the newPos function and change the background position
			$locationBG.css({'backgroundPosition': newPos(50, windowHeight, pos, 3000, 0.1)});
			//call the newPos function and change the secnond background position
			moon.css({'backgroundPosition': newPos(50, windowHeight, pos, 4800, 0.3)});
		}
		
			//if the second section is in view...
		if($judgesBG.hasClass("inview")){
			//call the newPos function and change the background position
			$judgesBG.css({'backgroundPosition': newPos(50, windowHeight, pos, 5250, .7)});
		}
		
		//if the third section is in view...
		if($enterBG.hasClass("inview")){
			//call the newPos function and change the background position
			$enterBG.css({'backgroundPosition': newPos(50, windowHeight, pos, 6000, 0.3)});
		}
		
		//if the fourth section is in view...
		if($pastBG.hasClass("inview")){
			//call the newPos function and change the background position for CSS3 multiple backgrounds
			$pastBG.css({'backgroundPosition': newPos(0, windowHeight, pos, 200, 0.9) + ", " + newPos(50, windowHeight, pos, 0, 0.7) + ", " + newPos(50, windowHeight, pos, 0, 0.5) + ", " + newPos(50, windowHeight, pos, 7000, 0.3)});
		}
		
		//if the sixth section is in view...
		if($aboutBG.hasClass("inview")){
			//call the newPos function and change the background position
			$aboutBG.css({'backgroundPosition': newPos(50, windowHeight, pos, 7000, 0.1)});
			//call the newPos function and change the secnond background position
			beachboy.css({'backgroundPosition': newPos(50, windowHeight, pos, 8200, 0.3)});
		}

		
		$('#pixels').html(pos); //display the number of pixels scrolled at the bottom of the page
	}
		
	//RepositionNav(); //Reposition the Navigation to center it in the window when the script loads//
	
	$window.resize(function(){ //if the user resizes the window...
		Move(); //move the background images in relation to the movement of the scrollbar
		//RepositionNav(); //reposition the navigation list so it remains vertically central
	});		
	
	$window.bind('scroll', function(){ //when the user is scrolling...
		Move(); //move the background images in relation to the movement of the scrollbar
	});
	
});