[HELP] Motion based on external coordinates

I would like to apply force to an object based on another object’s orientation.

My needs:

  • An Empty that the user can rotate around the Z coord at 90 degree increments
  • With another another set of controls the user pushes a sphere around, forward, backwards, left and right. But those movements must be based on the current X and Y of the Empty.I think I can get 1 going myself, and I have the forward, backward, left and right sorted out for 2, but right now it’s in Global coordinates.

How can I make the object move based on the orientation of my Empty?

Thanks.

Note: I’m using Builder SVN Trunk.