Animated drawing of curve

Question

Hey
I have searched the internet, but have not found any solutions.
How can I animate a curve being drawn with as3 drawing api.
I am not interested in masking it out or other tricks. I am interested in drawing it whith the api.
This would be the equivalent, but only a straight line:
var steps:Number = 30;
var currentStep:Number = 0;
var startPoint:Point = new Point(100,100);
var endPoint:Point = new Point(300,300);
var g:Graphics = graphics;
g.lineStyle(1);
g.moveTo(startPoint.x,startPoint.y);
addEventListener(Event.ENTER_FRAME, thisEnterFrame);
function thisEnterFrame(e:Event):void
currentStep++;
g.lineTo(startPoint.x+(endPoint.x-startPoint.x)/steps*currentStep, startPoint.y+(endPoint.y-startPoint.y)/steps*currentStep);//startPoint.y+(endPoint.y-star tPoint.y)*currentStep);
if(currentStep==steps) removeEventListener(Event.ENTER_FRAME, thisEnterFrame);
Does anybody have the math skills to do this with a curve?
Jakob

Answer 1

One way that I've used on a few occasions is to use TweenLite/Max's bezier curve generation. You can use as many points as you like and it will create a smooth curve through them - then you use the onUpdate function to do your drawing. Works great.
It would work like so:
import com.greensock.TweenMax;
var a:Sprite = new Sprite();
a.x = 100;
a.y = 100;
graphics.lineStyle(1, 0x000000);
graphics.moveTo(a.x, a.y);
TweenMax.to(a, 5, {bezier:[{x:310, y:130}, {x:131, y:276}, {x:300, y:345}], onUpdate:drawLine});
function drawLine(){
     graphics.lineTo(a.x, a.y);