CGAL users discussion list

[Andreas Fabri <>]

Hello,

To get the graphicsitem compiled,  it would be enough to throw out
Ray, Line, Iso_rectangle from the classes
CGAL::Qt::Converter, which converts CGAL and Qt points,...
CGAL::Qt::Painter_ostream, which calls the Qt drawing functions.

I write "enough", as you are looking for a quick hack.

Best regards,

andreas fabri


On 27/11/2012 19:05, Anthony Truchet wrote:
> Hello,
>
> Thanks for whose taking some moment to read this information request and
> please does not hesitate to tell me if I break unwillingly some courtesy
> of this mailing list.
> I'm working with terrain data : basically level curves (polylines whose
> points all have the same elevation).
> I thus use constrained Delaunay triangulation in the spirit of exemple
> [37.5.2] to be able to evaluate the estimated elevation of any point. I
> would like to draw the 2D projection in Qt thanks to CGAL_Qt4.
>
> The code below works fine if I use pure 2D triangulations ::
>
> typedef CGAL::Exact_predicates_inexact_constructions_kernel       K;
> //typedef CGAL::Projection_traits_xy_3<K>                         Gt;
> typedef K  Gt; // XXX Dummy typedef to stay in pure 2D
> typedef CGAL::Triangulation_vertex_base_2<Gt>                      Vb;
> typedef CGAL::Triangulation_face_base_with_info_2<FaceInfo, Gt>    Fbb;
> typedef CGAL::Constrained_triangulation_face_base_2<Gt, Fbb>       Fb;
> typedef CGAL::Triangulation_data_structure_2<Vb, Fb>               TDS;
> typedef CGAL::Exact_predicates_tag                                Itag;
> typedef CGAL::Constrained_Delaunay_triangulation_2<Gt, TDS, Itag> CDT;
> typedef CDT::Point CGAL_Point;
> typedef CGAL::Polygon_2<Gt> CGAL_Polygon;
>
>     [...]
>      CGAL::Qt::TriangulationGraphicsItem<CDT>* p_cdt_gitem =
>          new CGAL::Qt::TriangulationGraphicsItem<CDT>(&cdt);
>     [...]
>      CGAL::Qt::PolygonGraphicsItem<CGAL_Polygon>* p_gi =
>              new CGAL::Qt::PolygonGraphicsItem<CGAL_Polygon>(p_p);
>
> But when I define the Geometric Traits Gt to be
> CGAL::Projection_traits_xy_3<K>, then the compilatioon fails deep inside
> CGAL::Qt functions in way I don't understand.
>
> I've tried blindly to use "pure 2D" variants of CDT, Point, Polygon
> together with the projected one but it of course failed because I was
> just trying blindly :-(
>
> So here are the questions :
> * is there an known way to get CGAL::Qt::TriangulationGraphicsItem and
> the like worh with CGAL::Projection_traits_xy_3<K>
> * if not, is there a way to build a pure 2D triangulation from a
> "projected 2D" triangulation, so that I could visualize the former to
> debug the latter (I don't mind for perf consideration as this will be a
> debug only visualization)
> * what are the right entry points to understand what's going on and
> contribute a working exemple back ?
>
> Thanks for your attention and have a nice day / evening / night :-)
> --
> Anthony Truchet
> Logilab S.A.
>
> PS : I'm using latest CGAL (4.1) compiled from sources on Debian Linux
> stable with GCC 4.4.5
>
> [37.5.2]
> http://www.cgal.org/Manual/latest/doc_html/cgal_manual/Triangulation_2/Chapter_main.html#Subsection_37.5.2


--
Andreas Fabri, PhD
Chief Officer, GeometryFactory
Editor, The CGAL Project

phone: +33.492.954.912    skype: andreas.fabri