CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

Song Lin wrote:
> Hi,
>
> I want to check if the edge between two adjacent vertices belongs to
> Alpha_shape_3:(to decide if the two vertices are in one group)
>
> vector<Vertex_handle> adjacent_vertices;
> as.finite_adjacent_vertices(vit,back_inserter(adjacent_vertices));
> for (int i=0;i<adjacent_vertices.size();i++)
> {
>         if(as.classify(###the edge between vit and
> adjacent_vertices[i]###,0)==Alpha_shape_3::EXTERIOR)
>         {
>                 
>         }
> }
>
> But I found that an edge was defined as:
> typedef Triple<Cell_handle, int, int> Edge;
>
> Can I build an edge without the information of Cell_handle? If can't,
> what should I do to build an edge that can be used in the function
> "as.classify()"?
>
> Best regards,
> Lin
Hello,

From the manual, you can see that the class Alpha_shape_3 inherits
from its template triangulation. All triangulation in CGAL inherits from
the class Triangulation_3.
From here:
http://www.cgal.org/Manual/last/doc_html/cgal_manual/Triangulation_3_ref/Class_Triangulation_3.html#Function_bool_is_edge6Vertex_handle_u+_Vertex_handle_v+_Cell_handle___c+_int___i+_int___j9_const;
you will find the function is_edge that will give you
the information needed to define the triple.

S.