Mouse driven rotations

[Bates TAD/HRNAB ms294 x2601]

     Personally, I prefere driving rotations based on the change in mouse
position.  I have used programs that use the absolute position, but most of
the time I don't like it.  However, there have been a few cases where absolute
positioning has been better.  If you want to return to a specific orientation
or if you want to limit the amount of movement.  I have a sample FORTRAN
source I can send you that reads in x,y,z coordinates and allows you to
rotate them about all 3-axes of rotation, translate, zoom, change
perspective, Gouraud shade sufaces with and with out Z-buffering.  It is
constantly in flux, as I try new and different things, but it will give you
a good start.  I will send it in my next message (almost 1000 lines).  If you
have any questions or suggestions for improvement let me know.