CODEWITHSUNDEEP
c++cgaldelaunay
Stéphane Laurent
Stéphane Laurent

Reputation: 84539

How to get the edges of a 3D Delaunay tessellation with CGAL?

The question is clear from the title. I tried a ton of variants of

  const DT3::Finite_edges itedges = mesh.finite_edges();
  for(DT3::Finite_edges_iterator eit = itedges.begin(); eit != itedges.end(); eit++) {
      const CGAL::Triple<DT3::Cell_handle, int, int> edge = *eit;
      edge.first->vertex((edge.second+1) % 3)->info();
      edge.first->vertex((edge.third+1) % 3)->info();
  }

but none has worked (I tried % 2, % 4, +2, etc).

I'm able to get the tetrahedra and the triangles. Of course I could extract the edges from them but that would require to remove some duplicates.

Upvotes: 1

Views: 184

Answers (1)

lrineau
lrineau

Reputation: 6274

No need to use addition or modular arithmetic. The solution is simpler:

  const DT3::Finite_edges itedges = mesh.finite_edges();
  for(DT3::Finite_edges_iterator eit = itedges.begin(); eit != itedges.end(); eit++) {
      const DT3::Edge edge = *eit;
      const DT3::Vertex::Info v1_info = edge.first->vertex(edge.second)->info();
      const DT3::Vertex::Info v2_info = edge.first->vertex(edge.third)->info();
  }

The documentation of the nested type Edge is here as well as in the section "Representation" of the user manual of 3D Triangulation Data Structure.

Edit: note that I have chosen to respect your coding style, ignoring modern C++ features. Using C++11 features, I prefer to write it this way, using auto and range-based for loop:

  for(const auto edge: mesh.finite_edges()) {
      const auto v1_info = edge.first->vertex(edge.second)->info();
      const auto v2_info = edge.first->vertex(edge.third)->info();
  }

Upvotes: 3

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