CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

I'll answer in the duplicated thread here: 
https://github.com/CGAL/cgal/issues/8725

Sebastien.

On 2/4/25 19:10, Eric Bird ( via cgal-discuss 
Mailing List) wrote:
> Issue Details
> I am seeking assistance on an approach to generate a multimaterial 
> tetrahedral mesh of an object with internal polyhedrals whose surfaces 
> and edges should be preserved (i.e. with feature detection). I start 
> with this example:
>
> _https://doc.cgal.org/latest/Mesh_3/ 
> Mesh_3_2mesh_polyhedral_domain_with_surface_inside_8cpp-example.html 
> <https://doc.cgal.org/latest/Mesh_3/ 
> Mesh_3_2mesh_polyhedral_domain_with_surface_inside_8cpp-example.html>_
> where an internal polyhedral and a bounding polyhedral are defined. 
> However, feature detection fails for internal polyhedrals that are 
> overlapping (it hangs the program).
> My input polyhedral will be a collection of alpha wrapped surfaces that 
> are merged together (overlayed on top of one another) into a single .off 
> file. Directly using make_mesh_3 creates a decent tetrahedral mesh with 
> surfaces respected, but there is no feature detection. As a result, 
> edges are not clean and there are many jagged tetrahedrals around the 
> edge interfaces.
>
> Can feature detection be used in this case? How would I identify each 
> closed surface as a subdomain in CGAL and mesh it with edges and 
> surfaces preserved? Thank you.
>
> Source Code
> My source code is attached as main.cpp, which is a modified version of 
> the CGAL example from above. The two input files, cube2.off and 
> cube2_bl.off, are also attached. cube2.off (internal domain) is a mesh 
> containing two closed cube surfaces that are intersecting one another. 
> cube2_bl (bounding domain) is an offset mesh of cube2.off. You can see 
> that disabling detect_features runs successfully, but enabling 
> detect_features causes the program to stall.
>
> Environment
>
>   * Operating system (Windows/Mac/Linux, 32/64 bits): WSL Ubuntu 22.04
>   * Compiler: C/C++: g++-11 build active file
>   * Release or debug mode: Release
>   * Specific flags used (if any): cmake -
>     DCGAL_DIR=$CMAKE_INSTALLED_PREFIX/lib/CGAL -DCGAL_USE_GMP=ON -
>     DCMAKE_CXX_FLAGS="-pthread" -DCMAKE_BUILD_TYPE=Release .\n
>   * CGAL version: 6.0.1
>   * Boost version: 1.74.0.3ubuntu7
>   * Other libraries versions if used (Eigen, TBB, etc.): eigen: 3.4.0,
>     TBB: 2021.5.0-7ubuntu2
>
>
>
> Regards,
>
> Eric
>
>
>
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