var currentslide=1;
var totalslides=1;
var nextslide=1;
var transitioning=false;
function jump(n){
	if(!transitioning){
		nextslide=n;
		trans();
	}
}
function next(){
	
	if(!transitioning){
		nextslide=currentslide+1;
		if(nextslide>totalslides){
			nextslide=1;
		}
		trans();
	}
}
function prev(){
	if(!transitioning){
		nextslide=currentslide-1;
		if(nextslide<1){
			nextslide=totalslides;
		}
		trans();
	}
}
function trans(){
	
	transitioning=true;
	new Effect.Opacity('s'+currentslide,
    { duration: .5, 
      transition: Effect.Transitions.linear, 
      from: 1.0, to: 0.0 ,
      afterFinish: finishTrans});
}
function finishTrans(obj){
	$('s'+currentslide).style.display='none';
	$('s'+nextslide).style.display='block';
	new Effect.Opacity('s'+nextslide,
    { duration: .5, 
      transition: Effect.Transitions.linear, 
      from: 0.0, to: 1.0,
      afterFinish: finish
      });
}
function finish(){
	currentslide=nextslide;
	transitioning=false;
}