Jarek,
There was recently a similar enquiry on the Mesa mailing list.
Here is my reply, in full.
PS: I havn't seriously looked at supporting image-space CSG
using OSS Inventor, but seems like something that could be
done, and I've got source for a few different algorithms
including Goldfeather (also used by Weigand).
Nigel
> Hi!
> I need a boolean operations on objects in OpenInventor. I know that OI
> himself doesn't support them...
-------------------------
Antonio,
You may be interested in my PhD research:
http://www.nigels.com/research/
There is some source code there, although quite
an old snapshot, since I'm due to put some papers
out...
> - 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 -
glReadPixels/glDrawPixels
Tends to be slow, sucking data across the bus between graphics
hardware and main memory.
glCopyPixels
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:
http://www.nigels.com/research/scs/scs6.jpg
Last time I tried Onyx2 (a few years ago) the z-buffer copy
failed entirely:
http://www.nigels.com/research/scs/scs8.jpg
> 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?
Nigel
--
Nigel Stewart
Email: nigels@xxxxxxxxxx WWW: http://www.nigels.com
Research Student, Software Developer.
Just two stops down the line at Zoo Station.
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