How to detect coordinates of the Augmented 3D Object

I am trying to develop a game wherein a user can swipe a ball into an Augmented 3D Goal post. For this I am using the Java API provided by the latest Vuforia SDK  for android -(version 2.8) . I am overlaying a new view on the glview to display the ball and it is the same view which handles all the touch and swipe events.  I want to detect the 2d mapped cordinates of the Goal post , so that I can find out the intersection of the Goalpost frame and the frame of the ball object to determine whether the ball was flicked correctly into the goal or outside the goal . My query is how do I detect the coordinates of the Augmented 3d Goal post and map it to my  2d screen coordinates .