CGAL 6.0 Surface Mesh enumerate edges vertices? - Stack Overflow

Is a way to get table of edges with first and second vertices indexes?

This is a way to enumerate vertices of mesh:

Surface_mesh m;
// ... fill m points...

// enumerate points:
for (auto& vertex : m.points()) {
  verts.push_back(std::vector<float>{ (float)CGAL::to_double(vertex.x()), (float)CGAL::to_double(vertex.y()), (float)CGAL::to_double(vertex.z()) });
}

This is a way to enumerate face's vertex indices of mesh:

for (auto& fi : m.faces() ){
    auto& hf = m.halfedge(fi);
    std::vector<unsigned int> vect_vert_id;
    for (auto& hi : halfedges_around_face(hf, m)){
        vertex_descriptor& vi = target(hi, m);
        vect_vert_id.push_back(vi.idx()); // index of vertex in face
    }
    // vect_vert_id - list of vertices of face
}

But how to get list of edges vertices id as list of pairs? (id1, id2),(id2, id3), ...

I try to use faces to get all edges (use halfedges_around_face to get all indexes in one face then got list of second face, remove duplicate edges vertices and so on...)

Some info about CGAL Surface Mesh

Is a way to get table of edges with first and second vertices indexes?

This is a way to enumerate vertices of mesh:

Surface_mesh m;
// ... fill m points...

// enumerate points:
for (auto& vertex : m.points()) {
  verts.push_back(std::vector<float>{ (float)CGAL::to_double(vertex.x()), (float)CGAL::to_double(vertex.y()), (float)CGAL::to_double(vertex.z()) });
}

This is a way to enumerate face's vertex indices of mesh:

for (auto& fi : m.faces() ){
    auto& hf = m.halfedge(fi);
    std::vector<unsigned int> vect_vert_id;
    for (auto& hi : halfedges_around_face(hf, m)){
        vertex_descriptor& vi = target(hi, m);
        vect_vert_id.push_back(vi.idx()); // index of vertex in face
    }
    // vect_vert_id - list of vertices of face
}

But how to get list of edges vertices id as list of pairs? (id1, id2),(id2, id3), ...

I try to use faces to get all edges (use halfedges_around_face to get all indexes in one face then got list of second face, remove duplicate edges vertices and so on...)

Some info about CGAL Surface Mesh

• mesh
• cgal

Share Improve this question Follow asked Jan 22 at 20:33 SatabolSatabol 9822 silver badges77 bronze badges 6

• There is no function returning a pair, but did you see the "source()" function? – Mael Commented Jan 22 at 23:04
• there's this method Vertex_index vertex (Edge_index e, unsigned int i) const returns the i'th vertex of edge e, for i=0 or 1. It works off the edge index rather than the half edge index though, so you'll need e = edge(hi), then vertex(e, 0) and vertex(e, 1) – Neil Butcher Commented Jan 23 at 9:43
• Or there's a edges() method to get the edges directly. – Neil Butcher Commented Jan 23 at 9:51
• Hi @NeilButcher! It is work! thank you! github.com/user-attachments/assets/… – Satabol Commented Jan 23 at 13:15
• @SatabolTen great, I'll post as an answer – Neil Butcher Commented Jan 23 at 13:22

 |  Show 1 more comment

1 Answer 1

Sorted by: Reset to default 1

There's a method edges() to get the Edge_range and iterate through all the edges of the Surface_mesh.

Then for each edge there is a method vertex (Edge_index e, unsigned int i) const

which can be called twice vertex(e,0) and vertex(e,1) to get the 2 vertices of the edge.