CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

The user manual of the package was updated some time ago and we now
mention as way to extract each segment into a mesh:

https://doc.cgal.org/latest/Surface_mesh_segmentation/Surface_mesh_segmentation_2extract_segmentation_into_mesh_example_8cpp-example.html

Sebastien.

On 02/13/2018 04:15 PM, Iasonm wrote:
> I am trying to make the following code faster. Initializing the size of
> points and faces would make the code faster but is there a way to know the
> number of unique vertices of a segment without traversing its faces? Any
> other ideas are welcomed..
>
>          const auto &segmentMap = m_segmentFaceMap; //the output of the sdf
> segmentation algorithm
>          std::vector<Kernel::Point_3> points;
>          std::vector<std::vector&lt;size_t>> faces;
>          for (CGALSurfaceMesh::Face_iterator it = M.faces_begin();
>               it != M.faces_end(); it++) {
>                  CGALSurfaceMesh::Face_index fIndex(*it);
>                  if (segmentMap[fIndex] == segmentIndex) {
>                          CGALSurfaceMesh::Halfedge_index h =
> M.halfedge(fIndex);
>
>                          CGALSurfaceMesh::Vertex_index v1;  //= M.source(h);
>                          CGALSurfaceMesh::Vertex_index v2;  //= M.target(h);
>                          CGALSurfaceMesh::Vertex_index v3;  //=
> M.target(hNext);
>
>                          auto vri = M.vertices_around_face(h);
>                          v1 = *vri.begin();
>                          v2 = *(++vri.begin());
>                          v3 = *(++++vri.begin());
>
>                          CGALSurfaceMesh::Point p1(M.point(v1));
>                          CGALSurfaceMesh::Point p2(M.point(v2));
>                          CGALSurfaceMesh::Point p3(M.point(v3));
>
>                          size_t i1 = std::distance(
>                              points.begin(),
>                              std::find(points.begin(), points.end(), p1));
> //find index of p1
>                          if (i1 == points.size()) { //if p1 does not exist in
> points add it and update its index
>                                  points.push_back(p1);
>                                  i1 = points.size() - 1;
>                          }
>
>                          size_t i2 = std::distance(
>                              points.begin(),
>                              std::find(points.begin(), points.end(), p2));
> //same as p1
>                          if (i2 == points.size()) {
>                                  points.push_back(p2);
>                                  i2 = points.size() - 1;
>                          }
>
>                          size_t i3 = std::distance(
>                              points.begin(),
>                              std::find(points.begin(), points.end(), p3));
> //same as p1
>                          if (i3 == points.size()) {
>                                  points.push_back(p3);
>                                  i3 = points.size() - 1;
>                          }
>
>                          std::vector<size_t> face{i1, i2, i3};
>                          faces.push_back(face);
>                  }
>          }
>          CGALSurfaceMesh outputMesh;
>          CGAL::Polygon_mesh_processing::polygon_soup_to_polygon_mesh(
>              points, faces, outputMesh);
>          return outputMesh;
>
>
>
>
> --
> Sent from: http://cgal-discuss.949826.n4.nabble.com/