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- From: "Wayne C. Gramlich" <>
- To:
- Subject: Re: [cgal-discuss] Nef_polyhedron_3 boolean operations
- Date: Tue, 09 Feb 2010 13:45:58 -0800
Chris Hamilton wrote:
Makes sense. However, the intersection of any two closed and boundedI'm not sure what you say is true. I can easily come up with two
polyhedra should itself be a closed and bounded polyhedron, which should
be representable by the .off file format. Whatever the degeneracy
implied by "intersecting constraints", it should be representable in
Polyhedron_3 objects (and hence .off files) somehow, no?
.off files which when intersected would not be representable in
.off format.
Yeah, a little bit of a rash statement on my part. Definitely possible
to come up with counter-examples. However, the whole point of
Nef_polyhedra is to get around these ugly cases (ie: where the
intersection are or contain surfaces, etc). Is it possible for two
nef_polyhedron_3 without holes to produce an intersection with holes?
Easily. Take a cube, hollow it out some, and cut it in half.
Nudge the two halves towards one another and intersect. You will
get a flat square plate with a square hole in it.
I have pounded on Nef3 and basically "it just works".
[snip intersecting constraints]
Yes. The unmodified nef_3_homgeneous program can read,There is a file format called .nef3 that can represent allAre these files viewable somehow, or is only the internals of CGAL that
.nef3 objects. The demo program ../dem/Nef_3/nef_3_homgeneous
can read .nef3 objects. It used to be able to write .nef3
objects but that code was removed for some reason. I have
a snippet of code that adds back the "savenef3" command
to the demo program if you are interested.
can make use of them?
intersect, and display both .off and .nef3 files. The only
thing it can not do (currently) is write .nef3 files. For
example:
nef_3_homogeneous loadoff file1.off loadoff file2.off int reg vis
will read in file1.off, followed by file2.off, compute the
intersection, regularize it, and then display the result in
a visualization window.
Excellent. Thanks for this.
Glad to help.
-Wayne
- Re: [cgal-discuss] Nef_polyhedron_3 boolean operations, Laure Guicherd, 02/09/2010
- Re: [cgal-discuss] Nef_polyhedron_3 boolean operations, Wayne C. Gramlich, 02/09/2010
- Re: [cgal-discuss] Nef_polyhedron_3 boolean operations, Chris Hamilton, 02/09/2010
- Re: [cgal-discuss] Nef_polyhedron_3 boolean operations, Wayne C. Gramlich, 02/09/2010
- Re: [cgal-discuss] Nef_polyhedron_3 boolean operations, Chris Hamilton, 02/09/2010
- Re: [cgal-discuss] Nef_polyhedron_3 boolean operations, Wayne C. Gramlich, 02/09/2010
- Re: [cgal-discuss] Nef_polyhedron_3 boolean operations, Fred Dorosh, 02/09/2010
- Re: [cgal-discuss] Nef_polyhedron_3 boolean operations, Chris Hamilton, 02/09/2010
- Re: [cgal-discuss] Nef_polyhedron_3 boolean operations, Chris Hamilton, 02/09/2010
- Re: [cgal-discuss] Nef_polyhedron_3 boolean operations, Wayne C. Gramlich, 02/09/2010
- Re: [cgal-discuss] Nef_polyhedron_3 boolean operations, Chris Hamilton, 02/09/2010
- Re: [cgal-discuss] Nef_polyhedron_3 boolean operations, Wayne C. Gramlich, 02/09/2010
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