CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

A point property map is usually a map associating a point to a vertex.
All the default models of FaceGraph provided by CGAL do have a default
one and you don't need to provide one to the functions you call.
In case you want to have a custom point map you need to comply with
boost concepts:

https://www.boost.org/doc/libs/1_67_0/libs/property_map/doc/property_map.html

For the purpose of the exercise, let's say you want to write a
map for a Surface_mesh that is translating its points by a constant
vector. You would write something like that:


template <class Point, class Vector>
struct Translate_point_map
{
  typedef Point value_type;
  typedef Point reference;
  typedef boost::readable_property_map_tag category;
  typedef CGAL::Surface_mesh<Point>::Vertex_index key_type;

  Translate_point_map(const CGAL::Surface_mesh<Point>& sm,
                      const Vector& v)
    : sm(sm)
    , v(v)
  {}

  friend value_type get(const Translate_point_map& m, key_type k)
  {
    return m.sm.point(k)+v;
  }

  const Surface_mesh<Point> sm;
  Vector v;
};

A complete example is here:
https://gist.github.com/sloriot/7093e7e4a77a494f0df8b3389f09e8f7

You might also want to read about properties that you can attach
to a surface mesh object:

https://doc.cgal.org/latest/Surface_mesh/#title6



Sebastien.

On 07/06/2018 08:21 PM, Annie-Pier L. wrote:
> Hi, I would like to create a pointPropertyMap for the
> CGAL::segmentation_via_sdf_values function. How can I do it?
>
> Cheer,
> Annie-Pier
>
>
>
>
>
> --
> Sent from: http://cgal-discuss.949826.n4.nabble.com/