CGAL users discussion list

[Claus Volko <>]

Thanks, Sebastien, for your hints!

What I actually wanted to achieve was to merge vertices the coordinates of which only differ by a small difference. It seems that this code which I wrote myself does the job:

  for (Polygon_mesh::Vertex_iterator v1 = polygon_mesh.vertices_begin(); v1 != polygon_mesh.vertices_end(); v1++)
  {
      for (Polygon_mesh::Vertex_iterator v2 = polygon_mesh.vertices_begin(); v2 != polygon_mesh.vertices_end(); v2++)
      {
          if (v1 == v2) continue;
          if ((abs(v1->point().x() - v2->point().x()) < .01)
              && (abs(v1->point().y() - v2->point().y()) < .01)
              && (abs(v1->point().z() - v2->point().z()) < .01))
          {
              std::cout << "merging vertices " << v1->point() << " and " << v2->point() << std::endl;
              v2->point() = v1->point();
          }
      }
  }

Combining that with a call of stitch has the desired effect that a lot of small rectangles get merged into one big rectangle.

Am Mo., 11. Sept. 2023 um 08:52 Uhr schrieb Sebastien Loriot <>:

Yes, this will work. However, you cannot select all the vertices.
Fairing requires some unselected vertices.

Here are some useful function for selection:
expend_vertex_selection():
https://doc.cgal.org/latest/BGL/group__PkgBGLSelectionFct.html#ga49398c78507f5664b740439a92ca746b
reduce_vertex_selection():
https://doc.cgal.org/latest/BGL/group__PkgBGLSelectionFct.html#ga569127b818c04bfca7a5a5bca5b0bc24
locate a point within a mesh:
https://doc.cgal.org/latest/Polygon_mesh_processing/group__PMP__locate__grp.html

HTH,

Sebastien

On 9/11/23 06:49, Claus Volko ( via cgal-discuss
Mailing List) wrote:
> I suppose it can be done like this:
>
>    std::vector<Polygon_mesh::Vertex_handle> region;
>    for (Polygon_mesh::Vertex_iterator v = polygon_mesh.vertices_begin();
> v != polygon_mesh.vertices_end(); v++)
>    {
>        region.push_back(v);
>    }
>    CGAL::Polygon_mesh_processing::fair(polygon_mesh, region);
>
> Am So., 10. Sept. 2023 um 09:37 Uhr schrieb Claus Volko
> < <mailto:>>:
>
>     Polygon_mesh_processing/refine_fair_example.cpp
>     <https://doc.cgal.org/latest/Polygon_mesh_processing/Polygon_mesh_processing_2refine_fair_example_8cpp-example.html> contains the method extract_k_ring, which selects some vertices and puts them into a region. How can I select all vertices of a polygon mesh and put them into a region so that I can use PMP::fair with it?
>
>     --
>     Dipl.-Ing. Dr. Claus D. Volko, BSc
>     http://www.cdvolko.net/ <http://www.cdvolko.net/>
>
>
>
>
>
> --
> Dipl.-Ing. Dr. Claus D. Volko, BSc
> http://www.cdvolko.net/ <http://www.cdvolko.net/>
>
>
>
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Dipl.-Ing. Dr. Claus D. Volko, BSc
http://www.cdvolko.net/