function changeOpac(opacity, id)
{
	var object = document.getElementById(id).style; 
	object.opacity = (opacity / 100);
	object.MozOpacity = (opacity / 100);
	object.KhtmlOpacity = (opacity / 100);
	object.filter = "alpha(opacity=" + opacity + ")";
}

function shiftOpacity(id, millisec)
{
	  /// if an element is invisible, make it visible, else make it ivisible
	if(document.getElementById(id).style.opacity == 0)
   {
		opacity(id, 0, 100, millisec);
	}
   else
   {
		opacity(id, 100, 0, millisec);
	}
}

function blendImage(div_id, img_id, img_src, twn_time)
{
   var start_a = 100;
   var end_a = 0;
	var div = document.getElementById(div_id);
	var img = document.getElementById(img_id);
	
	  /// set the current image as background
	div.style.backgroundImage = "url(" + img.src + ")";
	div.style.backgroundRepeat = 'no-repeat';
	
	  /// make image transparent
	changeOpac(0, img_id);
	
	  /// make new image
	img.src = img_src;

	  /// fade in image
   var tween_in = new OpacityTween(img, Tween.regularEaseOut, end_a, start_a, twn_time);
   tween_in.start();
}

function fadeImage(img_id, img_src, twn_time)
{
   var start_a = 100;
   var end_a = 0;
	var img = document.getElementById(img_id);
	
	  /// make image transparent
	changeOpac(0, img_id);
	
	  /// make new image
	img.src = img_src;

	  /// fade in image
   var tween_in = new OpacityTween(img, Tween.regularEaseOut, end_a, start_a, twn_time);
   tween_in.start();
}

function blendDiv(div_id, text_string, twn_time)
{
   var start_a = 100;
   var end_a = 0;
	var div = document.getElementById(div_id);
	
	  /// make div transparent
	changeOpac(end_a, div_id);
	
	  /// fill new text
	div.innerHTML = text_string;

	  /// fade in div
   var tween_in = new OpacityTween(div, Tween.regularEaseOut, end_a, start_a, twn_time);
   tween_in.start();
}

function currentOpac(id, opac_end, twn_time) {
	  /// standard opacity is 100
	var opac_current = 100;
	var img = document.getElementById(id)
	
	  /// if the element has an opacity set, get it
	if(img.style.opacity < 100)
   {
		opac_current = img.style.opacity * 100;
	}

	  /// call for the function that changes the opacity
	var tween = new OpacityTween(img, Tween.regularEaseOut, opac_current, opac_end, twn_time);
   tween.start();
}