basic implementation for isosurface, isocolors, isonormals

[Martin Helm]

Dear Octave maintainers,

recently I made some preliminary implementation for isocolors, isonormals, 
isosurface for my own use which I would like to share (isocaps will follow in 
the near future). My first intention was to make a package at octave-forge. As 
it turned out in the discussion at the OF mailing list that this functions 
should go into octave itself  because these are base matlab functions, I start 
this thread to continue the discussion which can be found at

http://sourceforge.net/mailarchive/forum.php?thread_name=200903051754.35446.martin%40mhelm.de&forum_name=octave-
dev

My functions can be found at 
http://www.mhelm.de/octave/pkg/visualize3d-0.1.5.tar.gz
and some examples
http://www.mhelm.de/octave/index.html

I try to summarize the previous discussion:

The iso* functions need a graphics backend which is able to visualize filled 
3d patches (at least triangle patches) if you want to visualize the results in 
a matlab compatible way.

This is at the moment possible with the fltk backend and also with the 
jhandles package but not with the gnuplot backend.

As discussed in the mailig list mentioned above there might be a chance to 
make filled 3d patches possible also with gnuplot for at least triangle 3d 
patches (using pm3d), but it is not completely sure at the moment if this will 
work or how fast it can be done.

So I would be glad to receive some thoughts from you if you see this functions 
as octave core functions (with the limitation in mind that they cannot be used 
with gnuplot in the worst case) or as an addon which belongs to octave-forge.

I would also like to restart the discussion about the possibility to introduce 
(a subset of) filled 3d patches with gnuplot backend here.

Regards
Martin Helm