http://www.actionscript-flash-guru.com/blog/33-scale-around-a-point-transform-multiple-objects-actionscript-3-as3

at the bottom of the page there is a drawing program that uses your program to detect line selections.

Take care, Nico out! :)

I’m sorry if that confused anyone else who might have tried to use this class. Hopefully even with the adjustment you had to make the class still saved you some time.

I see in your demo fla that everything seems to work.

ellipseClip.graphics.lineStyle(1,0×000000,.2);
ellipseClip.graphics.drawEllipse(0,0,ELLIPSE_WIDTH,ELLIPSE_HEIGHT);
ellipseClip.x = (STAGE_WIDTH-ELLIPSE_WIDTH)/2;
ellipseClip.y = (STAGE_HEIGHT-ELLIPSE_HEIGHT)/2;

Because you adjust the graphics drawing API to work with your data model.
The drawEllipse x and y parameters are not to be confused with your EllipseExt x and y parameters. Flash does use x and y as the top left hand corner of the bounding box, where as you use the x and y as the center. In short the view and model are not the same. You make sure they line up by transposing the ellipseClip. But, if you are doing a visualization without transposing the outer movie clip you have to adjust drawEllipse directly so that it looks like the following:

ellipseClip.graphics.drawEllipse(x-(ELLIPSE_WIDTH/2), y-(ELLIPSE_WIDTH/2), ELLIPSE_WIDTH, ELLIPSE_HEIGHT);

However in my code I get some weird stuff going on: To make the above work I have to use:

EllipseExt(ELLIPSE_CENTER.x-(ELLIPSE_WIDTH/2), ELLIPSE_CENTER.y-(ELLIPSE_HEIGHT/2), ELLIPSE_WIDTH, ELLIPSE_HEIGHT);

Otherwise the intersection points do not match up to the ellipse. Which means there is a difference if you are doing everything in one graphics object versus transposing outer movies like you are doing. But I’m a bit confuse why it would be any different. Anyways its not a problem for me. I just adjust the EllipseExt constructor accordingly. It’s just peculiar observation.

Anyone else run into this?

You are correct. That was an oversight on my part. Good call. :)

if(radicand == 0){
trace( Math.sqrt(radicand) )
}

is redundant inside of an if statement that checks to make sure radicand is 0. There is no need for the Math.sqrt since the answer will always be 0. No need to run a function call if there is no need for it. :)

I’ll have to spend some time looking at the code from your 3rd comment and get back to you.

function isEllipseIntersectingLineSeg(linePoint1:Point, linePoint2:Point, x:Number, y:Number, width:Number, height:Number):Boolean{
width = MathUtil.truncate(width, SS.PRECISION);
height = MathUtil.truncate(height, SS.PRECISION);
var ellipse:Ellipse = new Ellipse(x, y, width, height);
var resultsArray:Array = ellipse.getIntersections(linePoint1, linePoint2);
var isIntersecting:Boolean;
var angle1 : Number;
var angle2 : Number;

if (resultsArray[0] != null){
Render._debugVis.graphics.beginFill(0xff0000, .5);
Render._debugVis.graphics.drawCircle(Point(resultsArray[0]).x, Point(resultsArray[0]).y, .5);
Render._debugVis.graphics.endFill();
isIntersecting = true;
}
if (resultsArray[1] != null){
Render._debugVis.graphics.beginFill(0xff0000, .5);
Render._debugVis.graphics.drawCircle(Point(resultsArray[1]).x, Point(resultsArray[1]).y, .5);
Render._debugVis.graphics.endFill();
isIntersecting = true;
}
return isIntersecting;
}

if(radicand == 0){
// in this case both points will result in the same, so we only need to calculate one point
p3.x = (-B-Math.sqrt(radicand))/(2*A);

why are you calculating the square root of 0?