CGAL users discussion list

[sergio <>]

Hello,

Im trying to implement an algorithm that let me detect, identify and count
which edges and vertex are non manifold. Searching by internet a found the
following discusion. 

http://cgal-discuss.949826.n4.nabble.com/Undetected-non-manifold-vertex-in-poly3-td4658551.html

The last solution is here:

typedef Polyhedron_3 EP_base; 

bool is_manifold(EP_base &mesh) 
{ 
        // count border edges (vertex halfedge circulator doesn't work on
non-manifold). 
        vector<int> nBorder(mesh.size_of_vertices(), 0); 
    for ( EP_base::Halfedge_const_iterator he = mesh.halfedges_begin() ; he
!= mesh.halfedges_end() ; he++ ) { 
                if ( !he->is_border() ) 
                        continue; 
                int v1 = he->vertex()->index(); 
                int v2 = he->opposite()->vertex()->index(); 
                nBorder[v1]++; 
                nBorder[v2]++; 
                if ( nBorder[v1] > 2 || nBorder[v2] > 2 ) 
                        return false; 
        } 

        return true; 
}

The discusion is only to identify Non manifold vertex and trying to test it,
i get an error that functions index() are not defined.

                int v1 = he->vertex()->index(); 
                int v2 = he->opposite()->vertex()->index();
                                
and for the added .off file the function is_border() is always false (I
don't know why)    

             if ( !he->is_border() ) 

these are the files:

box-nonmanifold-internal.off
<http://cgal-discuss.949826.n4.nabble.com/file/t375958/box-nonmanifold-internal.off>
  
boxes-nonmanifold-single-edge.off
<http://cgal-discuss.949826.n4.nabble.com/file/t375958/boxes-nonmanifold-single-edge.off>
  
                         
On the other hand I would like a suggestion of how iterate throw vertex to
find this manifold and count it. The same thing for the non manifold edges.

Im checking this manual:

https://doc.cgal.org/latest/HalfedgeDS/index.html#title9

but i would like a least some tips to implement it or why not an example :)

Best regards,

Sergio



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