I did it this way
private function getStagePosition(cam:Camera3D,
obj:ObjectContainer3D):Vector3D
{
var camT:Matrix3D = cam.viewProjection.clone();
var planT:Matrix3D = obj.sceneTransform.clone();
camT.prepend(planT);
var pv:Vector3D = Utils3D.projectVector(camT, new Vector3D());
pv.x = (pv.x * stage.stageWidth / 2) + stage.stageWidth / 2
pv.y = (pv.y*-1 * stage.stageHeight / 2) + stage.stageHeight / 2
return pv;
}
Not really fully tested, but "seemed" to work.
