From: Antonio MATTA <amatta@at...> - 2001-08-10 14:21:39
I have been developing an aplication that has to do with
solid modeling using Constructive Solid Modeling (CSG).
I have been followin the Instruccions found on the
" Interactive Rendering of CSG Modeling" by
I do not know how to implement with OpenGL some of the
topics that are explained on that paper.
- What pattern of classification it is used to group
the surfaces on a product?
- How to implement restore or save depth buffer?
I was wondering if anyone can help me with those topics
or where can I find some source code of the algorithms described
on that paper.
I also would like to know if any of you has
T.F. Wiegand e-mail.
Thanks a lot for your help
Computer Science Student
Pontificia Universidad Javeriana - Cali.
From: Nigel Stewart <nigels@ni...> - 2001-08-10 16:54:46
You may be interested in my PhD research:
There is some source code there, although quite
an old snapshot, since I'm due to put some papers
> - What pattern of classification it is used to group
> the surfaces on a product?
The Goldfeather algorithm uses a stencil test to isolate
each surface of a primitive, then uses a stencil test to
clip that surface in the z-buffer before merging the z-buffer
result with all the other clipped surfaces.
> - How to implement restore or save depth buffer?
Two choices -
Tends to be slow, sucking data across the bus between graphics
hardware and main memory.
Subdivide the viewport and use half of the framebuffer as your
second z-buffer. Still fairly slow, though.
Also, depending on your graphics hardware and driver, copying
z-buffer pixels may not be totally reliable. On NVIDIA hardware
for example, "far" values tend to fail. See:
Last time I tried Onyx2 (a few years ago) the z-buffer copy
> I was wondering if anyone can help me with those topics
> or where can I find some source code of the algorithms described
> on that paper.
If you find other source code, let me know, I'd be interested
in it too...
> I also would like to know if any of you has
> T.F. Wiegand e-mail.
I don't think he's at Cambridge anymore, but you should be
able track down some people that might know where he's gone...
So, what kind of application are you looking at?
Email: nigels@... WWW: http://www.nigels.com
Research Student, Software Developer.
Just two stops down the line at Zoo Station.