CGAL users discussion list

[Mariette Yvinec <>]

You may detect the changes when removing a vertex as follows :
- the faces that will be removed
  are the faces incident to the vertex to be removed.
  They can be enumerated before the removal using incident_faces()
- The new created facets can be enumerated after the removal
  by calling get_conflicts on the position of the removed vertex.
 
  A better way would be to mark the external boundary of the region filled
with the removed faces and to find the faces that fill this region
in the updated triangulation. This is in principle better
because it does not need to call in-circle predicates
but it demands more coding.
 

Le 26/07/12 12:48, Op3rAtor a écrit :

Hey Guy,

which is the most efficient way to detect the change when i remove a vertex
from a delaunay 2d trangulation. Currently i use this implementation:

std::vector<Vertex_handle> incident_vertices;
Vertex_circulator  vertex_circ =
delaunay_terrain->incident_vertices(vertex);
Vertex_circulator  vertex_circ_end = vertex_circ;

CGAL_For_all(vertex_circ,vertex_circ_end)
{
    incident_vertices.push_back(vertex_circ);
}

delaunay_terrain->remove(vertex);

Face_circulator incident_faces_circ = NULL;
Face_circulator incident_faces_circ_end = NULL;

for(int i=0;i<incident_vertices.size();i++)
{
      incident_faces_circ =
delaunay_terrain->incident_faces(incident_vertices[i]);
      incident_faces_circ_end = incident_faces_circ;

       CGAL_For_all(incident_faces_circ,incident_faces_circ_end)
       {
          Face_handle actual_new_face = incident_faces_circ;

           [..] --> store new faces here
       }
}

Any idea for improvement?

Thanks! =)



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Mariette Yvinec
Geometrica project team
INRIA  Sophia-Antipolis