CGAL users discussion list

["Laurent Rineau (CGAL/GeometryFactory)" <>]

Le Friday 10 June 2016 14:49:31 Yann GAVET a écrit :
> Hello all,
> 
> I basically want to implement a code for stipple algorithm
> (https://mrl.nyu.edu/~ajsecord/stipples.html), which uses a centroidal
> voronoi diagram weighted by a gray level image (the center of the
> Voronoi cells move to the center of mass instead of the centroid).
> 
> What would be the best way to code this algorithm with CGAL, efficiently
> ? is their a way to transform Lloyd mesh optimization
> (CGAL::lloyd_optimize_mesh_2) for using the center of mass given by an
> exterior constraint on each cell (here, given by the pixels of the image
> laying in the cell).

Have a look at the function `lloyd_optimize_mesh_2_impl` from 
`<CGAL/lloyd_optimize_mesh_2.h>`. It starts with:

    typedef Mesh_2::Mesh_sizing_field<CDT>           Sizing;
    typedef Mesh_2::Lloyd_move_2<CDT, Sizing>        Mv;
    typedef Mesh_2::Mesh_global_optimizer_2<CDT, Mv> Optimizer;

    Optimizer lloyd(cdt,
                    convergence_ratio,
                    freeze_bound);

If you replace `Mesh_2::Lloyd_move_2` by a modification of it, it can do what 
you want. You will need to copy and paste `<CGAL/Mesh_2/Lloyd_move_2.h>` and 
then modify the function `operator()` that computes the move. As for the 
modification of that function `operator()`, you are on your own.

-- 
Laurent Rineau, PhD
R&D Engineer at GeometryFactory           http://www.geometryfactory.com/
Release Manager of the CGAL Project       http://www.cgal.org/