// JavaScript Document
function buttonClick(obj){
	document.getElementById('btn-physics').className = '';
 	document.getElementById('btn-programming').className = '';
  document.getElementById('btn-mathematics').className = '';
  document.getElementById('btn-engineering').className = '';
	document.getElementById(obj).className = 'btnON';
	
	var i = 'die!';
	
	if(obj == 'btn-physics'){
		
		document.getElementById('navPhysics').src = '/images/nav_physicsON.png';
		document.getElementById('navProgramming').src = '/images/nav_programming.png';
		document.getElementById('navMathematics').src = '/images/nav_mathematics.png';
		document.getElementById('navEngineering').src = '/images/nav_engineering.png';
		
		i = document.getElementById('page-physics').style.zIndex;
		document.getElementById('page-physics').style.zIndex = '5';
		
		if(document.getElementById('page-intro').style.zIndex > i){
			document.getElementById('page-intro').style.zIndex--;
		}
		
		if(document.getElementById('page-programming').style.zIndex > i){
			document.getElementById('page-programming').style.zIndex--;
		}
		
		if(document.getElementById('page-mathematics').style.zIndex > i){
			document.getElementById('page-mathematics').style.zIndex--;
		}
		
		if(document.getElementById('page-engineering').style.zIndex > i){
			document.getElementById('page-engineering').style.zIndex--;
		}
	}
	
	if(obj == 'btn-programming'){
		
		document.getElementById('navPhysics').src = '/images/nav_physics.png';
		document.getElementById('navProgramming').src = '/images/nav_programmingON.png';
		document.getElementById('navMathematics').src = '/images/nav_mathematics.png';
		document.getElementById('navEngineering').src = '/images/nav_engineering.png';
		
		i = document.getElementById('page-programming').style.zIndex;
		document.getElementById('page-programming').style.zIndex = '5';
		
		if(document.getElementById('page-intro').style.zIndex > i){
			document.getElementById('page-intro').style.zIndex--;
		}
		
		if(document.getElementById('page-physics').style.zIndex > i){
			document.getElementById('page-physics').style.zIndex--;
		}
		
		if(document.getElementById('page-mathematics').style.zIndex > i){
			document.getElementById('page-mathematics').style.zIndex--;
		}
		
		if(document.getElementById('page-engineering').style.zIndex > i){
			document.getElementById('page-engineering').style.zIndex--;
		}
	}
	
	if(obj == 'btn-mathematics'){
		
		document.getElementById('navPhysics').src = '/images/nav_physics.png';
		document.getElementById('navProgramming').src = '/images/nav_programming.png';
		document.getElementById('navMathematics').src = '/images/nav_mathematicsON.png';
		document.getElementById('navEngineering').src = '/images/nav_engineering.png';
		
		i = document.getElementById('page-mathematics').style.zIndex;
		document.getElementById('page-mathematics').style.zIndex = '5';
		
		if(document.getElementById('page-intro').style.zIndex > i){
			document.getElementById('page-intro').style.zIndex--;
		}
		
		if(document.getElementById('page-programming').style.zIndex > i){
			document.getElementById('page-programming').style.zIndex--;
		}
		
		if(document.getElementById('page-physics').style.zIndex > i){
			document.getElementById('page-physics').style.zIndex--;
		}
		
		if(document.getElementById('page-engineering').style.zIndex > i){
			document.getElementById('page-engineering').style.zIndex--;
		}
	}
	
	if(obj == 'btn-engineering'){
		
		document.getElementById('navPhysics').src = '/images/nav_physics.png';
		document.getElementById('navProgramming').src = '/images/nav_programming.png';
		document.getElementById('navMathematics').src = '/images/nav_mathematics.png';
		document.getElementById('navEngineering').src = '/images/nav_engineeringON.png';
		
		i = document.getElementById('page-engineering').style.zIndex;
		document.getElementById('page-engineering').style.zIndex = '5';
		
		if(document.getElementById('page-intro').style.zIndex > i){
			document.getElementById('page-intro').style.zIndex--;
		}
		
		if(document.getElementById('page-programming').style.zIndex > i){
			document.getElementById('page-programming').style.zIndex--;
		}
		
		if(document.getElementById('page-mathematics').style.zIndex > i){
			document.getElementById('page-mathematics').style.zIndex--;
		}
		
		if(document.getElementById('page-physics').style.zIndex > i){
			document.getElementById('page-physics').style.zIndex--;
		}
	}
	
}

function DD_swapImgRestore(swain){
	
	if(swain == 'btn-physics' && document.getElementById('page-physics').style.zIndex != '5'){	
		document.getElementById('navPhysics').src = '/images/nav_physics.png';
	}
	
	if(swain == 'btn-programming' && document.getElementById('page-programming').style.zIndex != '5'){	
		document.getElementById('navProgramming').src = '/images/nav_programming.png';
	}
	
	if(swain == 'btn-mathematics' && document.getElementById('page-mathematics').style.zIndex != '5'){	
		document.getElementById('navMathematics').src = '/images/nav_mathematics.png';
	}
	
	if(swain == 'btn-engineering' && document.getElementById('page-engineering').style.zIndex != '5'){	
		document.getElementById('navEngineering').src = '/images/nav_engineering.png';
	}
	
}


function debug(o,i){
	
	var str = 'current:' + o + '-' + i + '\n\n';
	
	str+= 'intro:' + document.getElementById('page-intro').style.zIndex + '\n';
	str+= 'physics:' + document.getElementById('page-physics').style.zIndex + '\n';
	str+= 'programming:' + document.getElementById('page-programming').style.zIndex + '\n';
	str+= 'mathematics:' + document.getElementById('page-mathematics').style.zIndex + '\n';
	str+= 'engineering:' + document.getElementById('page-engineering').style.zIndex + '\n';
	alert(str);
}