Triangulation_2/polylines_triangulation.cpp

#include <CGAL/Exact_predicates_exact_constructions_kernel.h>
#include <CGAL/Polygon_2.h>
#include <CGAL/Constrained_Delaunay_triangulation_2.h>
#include <CGAL/Constrained_triangulation_plus_2.h>

#include <vector>

typedef CGAL::Exact_predicates_exact_constructions_kernel                 K;
typedef CGAL::Polygon_2<K>                                                Polygon_2;
typedef CGAL::Exact_intersections_tag                                     Itag;
typedef CGAL::Constrained_Delaunay_triangulation_2<K,CGAL::Default, Itag> CDT;
typedef CGAL::Constrained_triangulation_plus_2<CDT>                       CDTP;

typedef CDTP::Point                                                       Point;
typedef CDTP::Constraint_id                                               Cid;
typedef CDTP::Vertex_handle                                               Vertex_handle;

void 
print(const CDTP& cdtp, Cid cid)
{
  typedef CDTP::Vertices_in_constraint Vertices_in_constraint;

  std::cout << "Polyline constraint:" << std::endl;
  for(Vertices_in_constraint it = cdtp.vertices_in_constraint_begin(cid);
      it !=cdtp.vertices_in_constraint_end(cid);
      it++){
    Vertex_handle vh = *it;
    std::cout << vh->point() << std::endl;
  }
}


void 
contexts(const CDTP& cdtp)
{
  CDTP::Subconstraint_iterator
    beg = cdtp.subconstraints_begin(),
    end = cdtp.subconstraints_end();

  for(; beg!=end; ++beg){
    Vertex_handle vp = beg->first.first, vq = beg->first.second;

    if(cdtp.number_of_enclosing_constraints(vp, vq) == 2){
      CDTP::Context_iterator cbeg = cdtp.contexts_begin(vp,vq),
        cend = cdtp.contexts_end(vp,vq);
      std::cout << "subconstraint " << vp->point() << " " << vq->point() 
                << " is on constraints starting at:\n";
      for(; cbeg !=  cend; ++cbeg){
        CDTP::Context c = *cbeg;
        std::cout << (*(c.vertices_begin()))->point() << std::endl;
      }
    }
  }
}

int
main( )
{
  CDTP cdtp;

  cdtp.insert_constraint(Point(0,0), Point(1,1));

  std::vector<Point> points;
  points.push_back(Point(1,1));
  points.push_back(Point(5,2));
  points.push_back(Point(6,0));
  points.push_back(Point(3,0));
  Cid id1 = cdtp.insert_constraint(points.begin(), points.end());

  print(cdtp, id1);

  Polygon_2 poly;
  poly.push_back(Point(2,3));
  poly.push_back(Point(4,0));
  poly.push_back(Point(5,0));
  poly.push_back(Point(6,2));

  Cid id2 = cdtp.insert_constraint(poly.vertices_begin(), poly.vertices_end(), true);

  print(cdtp, id1);
  print(cdtp, id2);

  contexts(cdtp);

  return 0;
}