var tetaS;
var tetaH;
var fadeInt  = null;
var showInt  = null;
var fadeElem = null;
var showElem = null;
var fadeUpTo = null;
var doHide;
var isIE     = null;
var currPageOn = null;


function checkIE(){
	if(document.all) isIE = true;
	else isIE = false;
}

checkIE();

function setOpacity(elem, value){
	if(isIE){
		elem.style.filter  = "alpha(opacity="+(Math.ceil(value*100))+")";
	} else {
		elem.style.opacity = value;
	}
}

function getOpacity(elem){
	if(isIE){
		retVal = parseFloat(elem.style.filter.replace("alpha(opacity=", "").replace(")", ""))/100;
	} else {
		retVal = elem.style.opacity;
	}
	return retVal;
}


function fade(){
	opacity = getOpacity(fadeElem);
	if (opacity <= fadeUpTo){
		clearInterval(fadeInt);
		fadeInt = null;
		if(doHide) fadeElem.style.display = "none";
		if(fadeCallBack) {
			fadeCallBack();
		}
	}
	
	setOpacity(fadeElem, Math.sin(tetaH));
	tetaH += 5*(Math.PI/180);
	
}

var fadeCallBack = null;
function startFade(elem, upto, hide, callBack){
	if(callBack){
		fadeCallBack = callBack;
	}
	if(fadeInt == null){
		fadeElem   = elem;
		fadeUpTo   = upto;
		doHide     = hide;
		
		setOpacity(elem, 1);
		
		tetaH      = Math.PI/2;
		fadeInt = setInterval("fade()", 50);
	}
}	

function show(){
	opacity = getOpacity(showElem);
	if (opacity >= 1){
		clearInterval(showInt);
		showInt = null;
	}
	setOpacity(showElem, Math.sin(tetaS));
	tetaS +=  5*(Math.PI/180);
	
}


function startShow(elem){
	if(showInt == null){
		showElem   = elem;
		setOpacity(elem, 0)
		elem.style.display = "";
		tetaS       = 0;
		showInt = setInterval("show()", 100);
	}
	var currPageOn = elem;

}