var currentImageNumber = 1;
var nextImageNumber = 2;
var rotate;

function rotateImage()
{
    var nextImageNumber = currentImageNumber + 1;
     if(nextImageNumber == 6)
            nextImageNumber = 1;  
            
    // Keep cycling through images until we get to a non-blank one.
    while( $('image_' + nextImageNumber).getProperty('src').substring($('image_' + nextImageNumber).getProperty('src').length - 9) == "blank.gif" )
    {
        nextImageNumber++;
        if(nextImageNumber == 6)
            nextImageNumber = 1;    
    }
         
    viewImage(nextImageNumber, false);     
}

function viewImage(number, userClick)
{
    if(number != currentImageNumber)
    {
        var nextImage = 'image_' + number;
        var currentImage = 'image_' + currentImageNumber;
        
	    if($(currentImage).fx){$(currentImage).fx.stop();}
	    if($(nextImage).fx){$(nextImage).fx.stop();}
	    $(currentImage).fx = $(currentImage).effect('opacity', {duration: 2000}).start(0);
	    $(nextImage).fx = $(nextImage).effect('opacity', {duration: 2000}).start(1);
    	
	    currentImageNumber = number;
	   
	    if(userClick)
	        $clear(rotate);
	}
}

function startImageRotation(t)
{
    if( document.getElementById('image_' + currentImageNumber) != null)
        rotate = (function(){rotateImage()}).periodical(t);
}