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Re:Re: [cgal-discuss] 3D surface mesh generation


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  • From: weihy1984 <>
  • To: cgal-discuss <>
  • Subject: Re:Re: [cgal-discuss] 3D surface mesh generation
  • Date: Wed, 20 May 2009 09:37:45 +0800 (CST)

Anyway, thanks all of you. I think there is a easy way to avoid such kind mistake. we just need to give more notation in the file of examples/Surface_mesher/mesh_an_implicit_function.cpp, just as following,
 
// defining the surface
Surface_3 surface(sphere_function, // pointer to function
                  Sphere_3(CGAL::ORIGIN, 2.)); // bounding sphere with squared radius 2.0
 
Of caurse, in the cgal_manual.pdf, we can do the same thing.
在2009-05-20,"Daniel Russel" <> 写道:

But that is all. One can, for example, give the equation of a infinite
implicit surface, such as x^x+y^x-1 = 0, and the bounding sphere gives the
limit of the output surface mesh (in that case it is very important that the
tag CGAL::Manifold_with_boundaries_tag is used instead of CGAL::Manifold_tag).
Fair enough. But if Manifold_with_boundaries_tag is used, the mesher produces reasonable output (just truncated). If it is not used the mesher crashes or gets stuck in an infinite loop in my experience. Rather than crashing it makes sense in the latter case to check that the surface does not intersect the bounding sphere. For example by trying a few points on the sphere when the surface comes near the sphere. If any of these points are inside the surface, then it is an error.

If it were me, I would start by sampling the surface of the sphere and making sure all the sampled points were outside the surface if it is supposed to be a manifold since, from what I understand, the mesher won't necessarily work if the surface ever crosses the sphere, even if it is on a different connected component. But I like code with tons of sanity checks.




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