var Actor =
{
  init: function(xMax,spostamento)
  {
	  Actor.frameRate = 25;
	  Actor.duration = 1;
	  Actor.xMax=xMax;
	  Actor.div = document.getElementById("mask");
	  //Origine _x
	  Actor.originX = Actor.div.offsetLeft;
	  // destinazione
	  Actor.targetX = Actor.originX+spostamento;
	  // incremento
	  Actor.increment = (Actor.targetX - Actor.originX) / (Actor.duration * Actor.frameRate);
	  Actor.x = Actor.originX;
	  Actor.animate();
  },

	animate: function()
	{		
		document.getElementById("sx").style.display="none";
		document.getElementById("dx").style.display="none";
		
		Actor.x += Actor.increment;
		
		if ((Actor.targetX > Actor.originX && Actor.x >= Actor.targetX) || (Actor.targetX < Actor.originX && Actor.x <= Actor.targetX))
		{
			Actor.iscrolling=false;
			
			Actor.x = Actor.targetX;
			
			if ((Math.abs(Actor.x) == Actor.xMax) && (Math.abs(Actor.x) != 0))
			{
				document.getElementById("sx").style.display="none"; 
				document.getElementById("dx").style.display="block";
			}
			else if((Math.abs(Actor.x) == Actor.xMax) && (Math.abs(Actor.x) == 0))
			{
			  	document.getElementById("sx").style.display="block";
			 	document.getElementById("dx").style.display="none";
			}
			else
			{
			  	document.getElementById("sx").style.display="block";
			 	document.getElementById("dx").style.display="block";
			}
		}
		else
		{
			setTimeout(Actor.animate, 1000 / Actor.frameRate)
		}
		
		Actor.div.style.left = Math.round(Actor.x) + "px";    
	}
};