CGAL users discussion list

[kinju <>]

Hello,

I have a polygon with one exterior contour and 0 or more interior holes.

I'm trying to build a 2D skeleton from predefine simple polygon, a box of
10x10 while a hole in the middle of 5x5. The goal is to obtain triangles in
order to draw the polygon without holes.

typedef CGAL::Exact_predicates_inexact_constructions_kernel                   
          K;

typedef K::Point_2                                                            
                                                  Point;
typedef CGAL::Polygon_2<K>                                                    
                                          Polygon;
typedef CGAL::Polygon_with_holes_2<K>                                         
                          Polygon_with_holes;
typedef boost::shared_ptr<Polygon>                                            
                                  PolygonPtr;
typedef std::vector<PolygonPtr>                                               
                                  PolygonSequence ;

typedef CGAL::Straight_skeleton_2<K>                                          
                          Ss;
typedef boost::shared_ptr<Ss>                                                 
                                  SsPtr;

typedef Ss::Vertex_const_handle                                               
                                  Vertex_const_handle;
typedef Ss::Halfedge_const_handle                                             
                                  Halfedge_const_handle;
typedef Ss::Halfedge_const_iterator                                           
                                  Halfedge_const_iterator;

Polygon outer;
outer.push_back(0.0, 0.0);
outer.push_back(0.0, 10.0);
outer.push_back(10.0, 10.0);
outer.push_back(10.0, 0.0);

Polygon_with_holes poly(outer);

Polygon hole;
hole.push_back(2.5, 2.5);
hole.push_back(2.5, 7.5);
hole.push_back(7.5, 7.5);
hole.push_back(7.5, 2.5);

SsPtr iss = CGAL::create_interior_straight_skeleton_2(poly);
Ss& ss = *iss;

I print the result :
  std::cout << "Straight skeleton with " << ss.size_of_vertices() 
            << " vertices, " << ss.size_of_halfedges()
            << " halfedges and " << ss.size_of_faces()
            << " faces" << std::endl ;

  for ( Halfedge_const_iterator i = ss.halfedges_begin(); i !=
ss.halfedges_end(); ++i )
  {
                const Point& p = i->opposite()->vertex()->point();
                std::cout << "(" << p.x() << "," << p.y() << ")" ;
                std::cout << "->" ;
                std::cout << "(" << p.x() << "," << p.y() << ")" ;
                std::cout << " " << ( i->is_bisector() ? "bisector" : 
"contour" ) <<
std::endl;
  }

And I have this result :
(0,10) -> (0,10) contour
(0,0) -> (0,0) contour
(0,0) -> (0,0) contour
(10,0) -> (10,0) contour
(10,0) -> (10,0) contour
(10,10) -> (10,10) contour
(10,10) -> (10,10) contour
(0,10) -> (0,10) contour
(0,0) -> (0,0) bisector
(5,5) -> (5,5) bisector
(10,0) -> (10,0) bisector
(5,5) -> (5,5) bisector
(10,0) -> (10,0) bisector
(5,5) -> (5,5) bisector
(0,10) -> (0,10) bisector
(5,5) -> (5,5) bisector

I've checked vertices, I have 4 vertices witch define the outer contour, and
one which is (5,5)..

I think I'm not using the right functionalities for my problem..

Can you help me ?

Thank you very much (and sorry for my bad english),

Aurélien
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