[away3d] Mouse picking help, moving camera

[John]

Hello,
I am trying to create add some mouse picking to a project (to test it
out I am just removing objects when they are clicked on), the objects
to be picked are spheres (planets) which are in an array.I am using a
perspective projection and I can make it work fine when the camera is
at position (0,0.0) however as soon as I move the camera at all it
either stops working completely or will become inaccurate (pick the
wrong sphere or not at all).

I am confused because I assumed that calling mousePos.add(mousePos,
cam.position); would account for the camera position , but obviously
not.

Thankyou very much to anybody who can help :)
Please see code below:


        public function onMouseClick(e:MouseEvent):void
        {
                var mousePos:Number3D = cam.unproject(view.mouseX, view.mouseY);
                mousePos.add(mousePos, cam.position);

                var ray:Ray = new Ray();
                ray.orig = cam.position;
                ray.dir = mousePos;
                ray.dir.normalize();

                for each(var planet:Sphere in planets)
                {
                        if (ray.intersectBoundingRadius(planet.position , 
planet.radius))
                        {
                                view.scene.removeChild(planet);

                        }
                }