How can I use "ease" for smoother dragging? - actionscript-3

Question

I have dragging mc called "box" but the dragging is not smooth at all.
So how can I make it smoother by using "ease" var.
I'm trying to use "/ease" anywhere but not work.
var topY:int = stage.stageHeight - box.height;
var botY:int = 0;
box.addEventListener(MouseEvent.MOUSE_DOWN, onDown);
box.addEventListener(MouseEvent.MOUSE_UP, onUp);
var constrainY:Rectangle = new Rectangle(box.x, topY ,0, box.y+ (box.height-stage.stageHeight) );
var dragxy:String = "";
function onDown(e:MouseEvent):void
{
dragxy = mouseX + "_" + mouseY;
e.currentTarget.startDrag(false, constrainY);
removeEventListener(MouseEvent.MOUSE_DOWN, onDown);
addEventListener(MouseEvent.MOUSE_UP, onUp);
}
function onUp(e:MouseEvent):void
{
e.currentTarget.stopDrag();
addEventListener(MouseEvent.MOUSE_DOWN, onDown);
removeEventListener(MouseEvent.MOUSE_UP, onUp);
}

Answer 1

a simple example of an easing function would be:
private function easeTo(obj:MovieClip,currentGoalx:Number,currentGoaly:Number,easeFac:Number):void{
obj.x += (currentGoalx-obj.x)/easeFac;
obj.y += (currentGoaly-obj.y)/easeFac;
}
first you will need a timer or enter frame loop such as this added to the stage:
addEventListener(Event.ENTER_FRAME,enterFrame);
then in your enterFrame function do this:
private function enterFrame(e:Event):void{
easeTo(box,stage.mouseX,stage.mouseY,3);
}
an easeFac of 3 is a slower and smoother ease-in than an easeFac of 2, and 4 is even smoother and buttery-er.
or something like that. The idea is that the obj goes half the distance to the goal on each function call. So if this function is getting called on every frame, you'll get a smooth "ease in" effect. If you set currentGoal as the mouse position, then the obj will follow the mouse wherever it goes, but not in a 1:1 matching, rather it will trail behind and smoothly catch up.