CGAL users discussion list

[Pol Monsó Purtí <>]

Hello Laurent,

Sorry for the late reply, I've quickly tried what you've suggested right now, to no avail. I've added 4 vertices that contain the others and then called refine. The number of faces and vertices is the same and all faces are outside the domain.

I still feel I'm doing something wrong.

An excerpt of the relevant code:

typedef CGAL::Exact_predicates_inexact_constructions_kernel K;

typedef CGAL::Projection_traits_xy_3<K>  Gt;

typedef K::Point_3   Point3;

typedef CGAL::Triangulation_vertex_base_2<Gt> Vb;

typedef CGAL::Delaunay_mesh_face_base_2<Gt> Fb;

typedef CGAL::Triangulation_data_structure_2<Vb, Fb> Tds;

//TODO check wether Exact_intersections_tag is more appropriate

typedef CGAL::Constrained_Delaunay_triangulation_2<Gt, Tds, CGAL::Exact_predicates_tag> CDTb;

typedef CGAL::Constrained_triangulation_plus_2<CDTb> CDT; //handles breaklines intersections

typedef CGAL::Delaunay_mesh_size_criteria_2<CDT> Criteria;

typedef CDT::Vertex_handle Vertex_handle;

typedef CDT::Point Point;

[...]
int QD::triangulate(const std::vector<cgal_utils::Point>& points,

                           const std::vector<std::vector<cgal_utils::Point>>& breaklines,

                           cgal_utils::CDT& cdt,

                           const bool& saveTriangulation,

                           const fs::path& outdir,

                           const fs::path& outfname)

{

    std::cout << "Start triangulation" << std::endl;

    //constraints

    for( std::vector<Point> breakline : breaklines)

    {

        for(unsigned int i=0; i < breakline.size()-1; i++)

        {

            cdt.insert_constraint(breakline[i], breakline[i+1]);

        }

    }

    cdt.insert(points.begin(), points.end());

    double margin = 50;

    cgal_utils::Point bbul(727250.0 - margin, 6880620.0 + margin, 0.0);

    cgal_utils::Point bbbl(bbul.x(), bbul.y() - 20000.0 - margin, 0.0);

    cgal_utils::Point bbur(bbul.x() + 17000.0 + margin, bbul.y(), bbul.z() + 200.0 + margin);

    cgal_utils::Point bbbr(bbul.x() + 17000.0 + margin, bbul.y() - 20000.0 - margin, bbul.z() + 200.0 + margin);

    cdt.insert(bbul);

    cdt.insert(bbbl);

    cdt.insert(bbur);

    cdt.insert(bbbr);

    std::cout << "Bounding box: " << bbul << " " << bbbr << std::endl;

    std::cout << "Refining the " << cdt.number_of_vertices() << " vertices." << std::endl;

    std::cout << "Number of points and faces of CDT: "

              << cdt.number_of_vertices() << " " << cdt.number_of_faces() << std::endl;

    CGAL::refine_Delaunay_mesh_2(cdt, Criteria(0.1, 0.1));

    std::cout << "Number of points and faces of CDT: "

              << cdt.number_of_vertices() << " " << cdt.number_of_faces() << std::endl;

    if(saveTriangulation)

    {

        fs::path outoff(outdir);

        outoff /= outfname;

        outoff.replace_extension(".off");

        std::ofstream outstream1(outoff);

        if(!outstream1)

        {

            std::cerr << "error writing to " << outoff << std::endl;

            return EXIT_FAILURE;

        }

        outstream1 << std::fixed << std::setprecision(4) ;

        outstream1 << "OFF\n"  << cdt.number_of_vertices()

                   << " "  << cdt.number_of_faces() << " 0" << std::endl;

        std::map<CDT::Vertex_handle,int> indices;

        int counter = 0;

        for(CDT::Finite_vertices_iterator it = cdt.finite_vertices_begin();

            it != cdt.finite_vertices_end(); ++it)

        {

          //K::Point_3 p = it->point();

          //outstream1 << p.x() << " " << p.y() << " " << p.z() << std::endl;

          outstream1 << it->point() << std::endl;

          indices.insert(std::pair<CDT::Vertex_handle,int>(it, counter++));

        }

        for(CDT::Finite_faces_iterator it = cdt.finite_faces_begin(); it != cdt.finite_faces_end(); ++it)

        {

            bool indomain = it->is_in_domain();

            if(!indomain)

            {

                outstream1 << "3 " << indices[it->vertex(0)]

                           << " "  << indices[it->vertex(1)]

                           << " "  << indices[it->vertex(2)] << std::endl;

            }

        }

        std::cout << "Saved triangulation at " << outoff << std::endl;

    }

    return 0;

}

On Fri, Jun 10, 2016 at 6:00 PM, Laurent Rineau (CGAL/GeometryFactory) <> wrote:

Le Friday 10 June 2016 17:28:46 Pol Monsó Purtí a écrit :
> Hello Laurent, thank you for your interest,
>
> *All* the faces are said to be outside the domain, not only those long
> faces. Otherwise I'd be done by checking wether it is in or out. Should I
> check that my cdt constitutes indeed a *planar straight line graph *? Is it
> possible it doesn't at all?

I suggest you insert in the CDT a closed polygon with four vertices, a "box",
that contains all the other ones. That way, you will be sure that everything
is inside the domain bounded by that box.

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


--
You are currently subscribed to cgal-discuss.
To unsubscribe or access the archives, go to
https://sympa.inria.fr/sympa/info/cgal-discuss

Attachment: edges_cgal.PNG
Description: PNG image