[GRASS5] NVIZ updates

[Bob Covill]

Hello,

I have applied a bunch of NVIZ updates to CVS. These changes include:

- Accelerated surface and sites drawing.

- Improved animation setup with changes to the KEY_MASK. Animations can
be saved and loaded from the key frame GUI. The center of view can now
be changed through the animation. Twist and Field of View added to
KEY_MASK. Minor changes to the Key Frame "Run and Save" menu. Users can
now set the starting frame number allowing animations to be renderred in
pieces if wanted.

- Added "Twist" slider to main menu to twist the view.

- Added option to move center of view via the "puck" canvas.

- Enabled 3D View load and save options. These are mostly working now.
The only problem is that there is currently no routine to update the
NVIZ GUI to match the loaded view. 

- The off-screen rendering is included in the code. By default I have
left it buried in an ifdef. Unfortunately, it currently requires a
recent version of OpenGL. For those who want to try it simply add a
-DOS_RENDER flag to the Gmakefiles in ogsf and NVIZ2.2/src. It is
particularly useful for rendering large animations in the background,
without having to worry about screen-savers, other windows, etc.

If there are any questions or problems please let me know.

-- 
Bob Covill

Tekmap Consulting
P.O. Box 2016
Fall River, N.S.
B2T 1K6
Canada

E-Mail: bcovill at tekmap.ns.ca
Phone: 902-860-1496
Fax: 902-860-1498