[ REQ 6223]: Need help with the gcl command syntax

[paul at eg426.berkeley.edu]

Hi Geomview team,

I've just found Geomview 1.6.1 on the net, and downloaded & installed
the binary distribution for my Linux platform (Red Hat 4.0).

I'm very impressed with the ability of the program to render 3D objects
in such an advanced way, and its just what I've been looking for to
help me in my geophysical research work.

I'm presently creating a 3D ray-tracing program, intended to compute
the ray paths & travel-times of seismic waves travelling between an
acoustic source, impinging on a 3D target, and travelling on to a
receiver. A 3D model consists of a half space, with a centrally located
borehole in which the receivers are placed, and numerous 3D "targets"
around and below the borehole. Many acoustic sources are placed on
the surface. Ray bending is currently being computed through a 1D 
velocity medium (in depth only), though 2D and 3D velocity functions
(maps) will follow.

The way I'm connecting my raytracer program to Geomview is via a
device pipe I created (/tmp/geomview/cmd  and /tmp/geomview/vis)
and then starting geomview with the commandline arg: -M  or: -Mc

My raytracer then sends either geometry objects, or commands containing
geometry objects to geomview for display.

Well, I've been somewhat successfull in my attempts at this. But the
overriding problem I'm having right now, is how to just up-date the
camera image with a newly traced ray, without wiping out the entire
previous image, and having it replaced by only the ray.

Is there some (elegant) way I can just up-date the present GEOM-ID
without having to write out the entire list of geom objects again?

I've tried dinking around with the concept of "handles", but I don't
really know what I'm doing. The gcl reference document I've been
reading is rather terse on the subject of "instance handles" and
how to use them.

I would really appreciate any help you can offer me!

If you want to find out more about what I do as a geophysicist,
go to: http://bozo-1.lbl.gov/
for our Engineering Geoscience web pages.

I'm currently a grad student at University of California, Berkeley.
Studying for a PHd.

Paul.

---------------
Paul A. Milligan
Engineering Geoscience
Bldg. 90,  rm 2002
Lawrence Berkeley National Labs
University of California
Berkeley, CA 94720

tel: 510-486-5748  (LBNL)
mail: paul at hmbrt.lbl.gov