CGAL users discussion list

[Thomas Recouvreux <>]

2012/2/6 Sebastien Loriot (GeometryFactory) <>

On 02/06/2012 05:11 PM, Thomas Recouvreux wrote:

Hi,

Thanks the Delaunay triangulation works well.
Do you have a piece of code to remove edges ?

Do you mean removing constrained edges?

No I mean remove some edges to fusion triangle into convex polygons. 

And is there an index for each faces or shall I put it in FaceInfo
structure ?

You need to use Face_with_info.
Note that a Face_handle can be use as a key in a map for example.

How can I use Face_handle as a key ?? 

Sebastien.

Thomas


2012/1/18 Mariette Yvinec <

<mailto:>>

   Starting from the constrained triangulation of your polygons
   you can appraoch a minimal convex subdivision
   (I think at most twice the number of parts of the optimal)
   by pulling out as much as you can
   of non constrained triangulation edges
   without forming angles greater than 90 degrees.

   Le 18/01/12 09:27, Sebastien Loriot (GeometryFactory) a écrit :

   The input polygon should be simple and without holes.
   In you case you might want to try to use a constrained (Delaunay)
   triangulation (edges of your polygon are constraints).
   The decomposition would be minimal at all but it will be convex.


   See:
   http://www.cgal.org/Manual/latest/doc_html/cgal_manual/Triangulation_2/Chapter_main.html#Section_36.7


   Sebastien.

   Thomas Recouvreux wrote:

   Hi,

   I've have found some examples about partitionning a Polygon_2,
   but I didn't see functions for partitionning a Poly_2 with holes.
   Is there any function to do so or shall I decompose first my
   polygon with holes in polygons without holes and apply the
   partitionning function ?

   An other question, I tried to use partition function on a polygon
   with tangente edges (see below), and the function return the
   whole polygon without partionning it, did I miss something ?

   +---------------------------------------+
   |                                       / |
   |                                     /   |
   |                        +----------+   |
   |                         |           |    |
   |                        +----------+   |
   |                                         |
   |                                         |
   +---------------------------------------+
   polygon.push_back(Point_2(0, 0));
   polygon.push_back(Point_2(10, 0));
   polygon.push_back(Point_2(6, 2));
   polygon.push_back(Point_2(2, 2));
   polygon.push_back(Point_2(2, 6));
   polygon.push_back(Point_2(6, 6));
   polygon.push_back(Point_2(6, 2));
   polygon.push_back(Point_2(10, 0));
   polygon.push_back(Point_2(10, 10));
   polygon.push_back(Point_2(0,10));


   Best
   Thomas

   --
   Mariette Yvinec
   Geometrica project team
   INRIA  Sophia-Antipolis

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