Date: Thu, 12 Mar 2009 22:27:00 -0500 (CDT)
   From: Mark Jacobson <jacobson@cns.uni.edu>
     To: 810-088-11-spring@uni.edu
Subject: Pool table problems...

Hello Maya students,

     I had two or three students email me with problems with the pool
balls falling through the pool table, and I was able to reproduce the
problem.  It turns out you must make the Polygonal Primitive into a Passive
Rigid Body BEFORE you do anything else to the Polytonal Primitive.

The Polygonal Primitive is probably a POLYGONAL CUBE named

    pCube1   or   pCube2    if you are using a polygonal cube

    or it is:
              pPlane1   if you are using a polygonal plane

    AFTER you put holes into the pCube1 it is NO LONGER a Primitive Cube.

    The following instructions explain how to do it wrong, followed by
         how to do it correctly so it works, at least according to my
         experiments tonight:

You must make the Polygonal Cube into a Passive Hard Body BEFORE you do
anything else to it.

I have been able to reproduce the problems you and two other students have
described by doing the following:

    1.  Make the Polygonal Cube or Plane.

    2.  Modify the Cube or Plane by using the Booleans Difference to cut
        holes in the Polygon.  (DO NOT DO THIS STEP BEFORE STEP #3)
                                   ---

    3.  Then, too late, I select the thing that is NO LONGER a POLYGONAL
        PRIMITIVE plane or cube, and do the make PASSIVE RIGID BODY.

    VIP: Step #3 has to be done BEFORE step #2.

    The above 3 steps do NOT work!  They CAUSE the problem!

   You need to do the following:

   1. Make the Polygonal Cube or Plane.

   2. Immediately, BEFORE doing any changes to it, make it into a
         Passive Rigid Body.  (See *** footnote)

   3. Only now, can you make changes to it such as cutting out faces
         for square holes (perhaps, I have not tested this) but for sure,
         cutting out holes using the Boolean Difference operation.

      (*** footnote)
      Do this for each of the POOL table sides
      too, if you are doing anything to the 4 sides of the pool table.

      Don't worry, I don't think very many students are having the sides
      cut out with part of the pool ball holes.

      And do remember, having holes instead of squares is NOT required.
      You can do it the way the handout describes or the way I showed
      with just removing 4 FACES from the pool table surface.
      (*** footnote)


   Sorry about the unforseen problems.  Unfortunately, I did not hear
about them until this evening!

    Mark