CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

Note that you are iterating over constrained edges and in the same loop 
you modify the set
of constrained edges. This is invalidating the iterator you are using.

Sebastien.

On 04/27/2017 08:54 AM, 王进 wrote:
> hi all, I found Constrained_triangulation_plus_2 may crashed when
> insert_vertex_in_constraint called
> my codes:
>
> #include <CGAL/basic.h>
> #include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
> #include <CGAL/Constrained_Delaunay_triangulation_2.h>
> #include <CGAL/Triangulation_hierarchy_2.h>
> #include <CGAL/Constrained_triangulation_plus_2.h>
> typedef CGAL::Exact_predicates_inexact_constructions_kernel K;
> typedef CGAL::Exact_predicates_tag ITAG;
> typedef CGAL::Triangulation_vertex_base_2<K> TVBB;
> typedef CGAL::Triangulation_hierarchy_vertex_base_2<TVBB> TVB;
> typedef CGAL::Constrained_triangulation_face_base_2<K> TFB;
> typedef CGAL::Triangulation_data_structure_2<TVB, TFB> TDS;
> typedef CGAL::Constrained_Delaunay_triangulation_2<K, TDS, ITAG> CDT;
> typedef CGAL::Triangulation_hierarchy_2<CDT> CDTH;
> typedef CGAL::Constrained_triangulation_plus_2<CDTH> CDTP;
>
> typedef CGAL::Polygon_2<K> Polygon_2;
> typedef CDTP::Point  Point_2;
> typedef CDTP::Vertex_handle Vertex_handle;
> typedef CDTP::Constraint_id Constraint_id;
> typedef CDTP::Constraint_iterator Constraint_iterator;
> typedef CDTP::Vertices_in_constraint_iterator
> Vertices_in_constraint_iterator;
>
> #include "vector4.hpp"
> #include "Matrix4.hpp"
> #include "Math.hpp"
> int main() {
>  Polygon_2 polygon;
>  polygon.push_back(Point_2(0.00000000000000000, 71.289788474561647));
>  polygon.push_back(Point_2(42.553236484178342, 71.993132446252275));
>  polygon.push_back(Point_2(43.293765253096353, 0.70334397174883634));
>  polygon.push_back(Point_2(0.74052876897621900, 0.00000000000000000));
>  polygon.push_back(Point_2(0.00000000000000000, 71.289788474561647));
>
>  Point_2 p1(21.520543956896290, 71.645492202660535);
>  Point_2 p2(22.262916839332320, 0.35573420871514827);
>  Point_2 p3(21.520543956896290, 71.645492202660535);
>  CDTP cdtp;
>  Constraint_id id = cdtp.insert_constraint(polygon.vertices_begin(),
> polygon.vertices_end(), false);
>  int todo = 1;
>  for (Constraint_iterator cid = cdtp.constraints_begin(); cid !=
> cdtp.constraints_end(); cid++) {
>   Vertices_in_constraint_iterator vb =
> cdtp.vertices_in_constraint_begin(*cid);
>   if (vb == cdtp.vertices_in_constraint_end(*cid)) continue;
>   Vertex_handle P = *vb; vb++;
>   if (vb == cdtp.vertices_in_constraint_end(*cid)) continue;
>
>   for (; vb != cdtp.vertices_in_constraint_end(*cid); vb++) {
>    Vertex_handle Q = *vb;
>    if (todo)
>    {
>     //Vertex_handle W = cdtp.insert(Point_2(p1.x(),p1.y()));
>     Vertex_handle W = cdtp.insert(p1);
>     vb = cdtp.insert_vertex_in_constraint(*cid, vb, W);
>     P = Q;
>     vb++;
>     todo = 0;
>    }
>
>    //std::cout << P->point().x() << " " << P->point().y();// << " " <<
> Q->point().x() << " " << Q->point().y() << std::endl;
>   }
>  }
>     return 0;
> }
>
> I use Visual Studio 2015(update3) + CGAL-4.7(static library)
> something wrong?
>
> thanks for your help!
>
> WangJin