CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

On 09/15/2017 06:53 PM, Iasonm wrote:
> Hello,
> given a CGAL::Surface_Mesh<SomeKernel> what is the easiest way to extract
> mesh "connectivity" vectors like for example an edge_to_face vector of which
> the ith position holds another vector which holds the indices of all the
> faces that are adjacent to the ith edge?
>
> I tried:
>  for (CGALSurfaceMesh::edge_index ei : m_M.edges()) {
>       CGALSurfaceMesh::face_index f0(m_M.halfedge(ei, 0));
>       CGALSurfaceMesh::face_index f1(m_M.halfedge(ei, 1));

I don't understand why this compiles. You probably meant m_M.face( 
m_H.halfedge(ei)) and the same for the opposite halfedge (provided it is 
not a border halfedge).

Sebastien.

>       std::vector<size_t> facesOfEdge{size_t(f0), size_t(f1)};
>       edge_to_face[size_t(ei)] = facesOfEdge;
>     }
> the above gives face indices that are as big as twice the number of faces in
> the mesh. For example when the mesh has 90 faces I would get using the above
> indices up to 179. Why does the above not work and could you suggest me
> another way to get the needed connectivity vector?
>
>
>
> --
> Sent from: http://cgal-discuss.949826.n4.nabble.com/