var rb_totalBanners = 3;
var rb_fadeAmount   = 100;        //cycles it takes for a fade to occur
var rb_showTime     = 6000;      //time [ms] before the next fade is called
var rb_fadeCycleDuration = 30;   //time [ms] it takes for a fadecycle to occur


// the topmost banner
var rb_topBanner = 1;

var rb_IDs = new Array(); //almacena los IDs de cada banner
	rb_IDs[0] = 'ban0';
	rb_IDs[1] = 'ban1';
	rb_IDs[2] = 'ban2';

function rb_init(){
	for(var i=0; i<rb_totalBanners; i++) rb_setZIndex(i, 0); //all equally bottom	
}

function rb_setZIndex(indice, zInd){ //sets an object Z-axis position
	document.getElementById( rb_IDs[indice] ).style.zIndex = zInd;
	document.getElementById( rb_IDs[indice] ).zIndex = zInd;
}

function rb_setOpacity(id){
	document.getElementById( rb_IDs[id] ).style.opacity = rb_fadeAmount/100;		
	document.getElementById( rb_IDs[id] ).style.filter = 'progid:DXImageTransform.Microsoft.Alpha(Opacity=' + 
	                                                           (rb_fadeAmount - (100-rb_fadeAmount))  + ')';
	document.getElementById( rb_IDs[id] ).filter = "alpha(opacity=" + (rb_fadeAmount - (100-rb_fadeAmount)) + ");";
}

function rb_fadeBanner(){
	if( rb_fadeAmount > -1 ){
		rb_setOpacity( rb_topBanner );
		rb_fadeAmount--;
		setTimeout("rb_fadeBanner()", rb_fadeCycleDuration);
	}else{ //places faded banner in the back and makes it visible
		rb_setZIndex(rb_topBanner, 0);
		rb_fadeAmount = 100;
		rb_setOpacity(rb_topBanner);	
		rb_setBanner();
	}
}

function rb_setBanner(){
	rb_topBanner--;
	if(rb_topBanner < 0 ) rb_topBanner = rb_totalBanners-1;
	
	rb_setZIndex(rb_topBanner,3); 
	
	if( rb_topBanner-1 < 0 )
		rb_setZIndex(rb_totalBanners-1,2); 
	else
		rb_setZIndex(rb_topBanner-1,2); 

	setTimeout("rb_fadeBanner()", rb_showTime);
}

window.onload = function(){
   rb_init();
   rb_setBanner();
}