CGAL users discussion list

[王进 <>]

hi Sebastien, thanks for your replay!

in the documentation 

  // Inserts vh before pos

  // Returns an iterator pointing on the newly inserted vertex

  // Writes the modified faces to out

  template <class OutputIterator>

  Vertices_in_constraint_iterator

  insert_vertex_in_constraint(Constraint_id cid, Vertices_in_constraint_iterator pos, 

     Vertex_handle vh, OutputIterator out)

  { ...}

this operation is same as stl list insert operation,the follow code had handled iterator to keep validated

vb = cdtp.insert_vertex_in_constraint(*cid, vb, W);
vb++;

and the example  procedure is not everytime crashed,maybe 5-10% chance.

WangJin

At 2017-04-27 15:15:05, "Sebastien Loriot (GeometryFactory)" <> wrote:
>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
>>
>>
>>
>>
>>
>>
>
>
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