patch function (3D visualization)

[Dima]

Hi.

  I am porting my 3D visualization package from
Matlab to Octave. One of the things the package
does is a plot of level lines (isolines) for
a function defined on a 2D manifold embedded in 3D.

  Level lines are actually a 'wire plot',
i.e. it is a set of curved lines.

  On Matlab I used the function 'patch' to plot it
in the following way: each basic patch was a small
line segment (bound in 3D). I.e. for a wire model with N
vertices and M line segments the function 'patch'
received a Nx3 vertices array and a Mx2 faces array.

  It is also of importance that 'patch' returned a handle
to my wire plot, which allowed further controlling it.

  It seems that Octave's patch does not support plotting
line segments as faces, but only triangular patches.

  My questions are as follows:

1. With the current state of Octave, what would be the
   best way to create a wire plot and to get a handle to it?
   Is there something better than creating degenerated
   triangles?

2. Will it be easy to implement support for wires in 'patch'?
   I have examined its source code and seems that it nearly
   immediatedly calls to some C/C++ function, and I did not
   trace it further. Does someone has expertise in 'patch'
   sources? - I would like at least to get a complete call tree
   of 'patch'.

Thanks, regards,
  Dima.

P.S.
  It is a 3rd attempt, this time via ISP's mail relay. Does
this mail list go with the fashion of filtering out mails
from dynamic IP addresses?