CGAL users discussion list

[Andreas Fabri <>]

Hi Matthew,

The triangulation is parameterized with a triangulation datastructure
which is parameterized with a vertex and face class.


______________________________________________
Parameters
The class Triangulation_2<Traits,Tds> has two template parameters. The first one Traits is the geometric traits, it is to be instantiated by a model of the concept 
TriangulationTraits_2.

The second parameter is the triangulation data structure, it has to be instantiated by a model of the concept TriangulationDataStructure_2. By default, the triangulation 
data structure is instantiated by CGAL::Triangulation_data_structure_2 < CGAL::Triangulation_vertex_base_2<Gt>, CGAL::Triangulation_face_base_2<Gt> > >.


Source: 
http://www.cgal.org/Manual/3.4/doc_html/cgal_manual/Triangulation_2_ref/Class_Triangulation_2.html#Cross_link_anchor_1166
______________________________________________


Whe you click on    CGAL::Triangulation_face_base_2<Gt>   you find

______________________________________________

Is Model for the Concepts
TriangulationFaceBase_2

http://www.cgal.org/Manual/3.4/doc_html/cgal_manual/Triangulation_2_ref/Class_Triangulation_face_base_2.html
______________________________________________


"Model of a concept" means    implementations of a specification,
so when you click on   TriangulationFaceBase_2 and there on     
TriangulationDSFaceBase_2

you are one click away from what you search

http://www.cgal.org/Manual/3.4/doc_html/cgal_manual/TDS_2_ref/Concept_TriangulationDSFaceBase_2.html#Cross_link_anchor_1178


The whole thing is rather decomposed, but it makes little sense to repeat the 
documentation
of the concept for each model.


andreas




Matthew Denno wrote:
> Hi,
>
> I am hoping that someone can point me in the right direction to a
> solution for my problem.  I am new to both CGAL and C++ so I apologize
> if my questions should be obvious.
>
> I started out with one of the example problems.  After I have added
> the points to the Triangulation, I use a Face_iterator to iterate
> through the faces (I think through this part is ok).  The problem is I
> can't figure out how to access the verticies of each face as I iterate
> over them.
>
> If someone could point me in the right direction I would really
> appreciate it.  Maybe just a hint of what I should look for in the
> manual.
>
> The code I have been testing with is below.
>
> Thanks so much.
>
> Matt
>
> #include <fstream>
> #include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
> #include <CGAL/Triangulation_2.h>
>
> struct K : CGAL::Exact_predicates_inexact_constructions_kernel {};
>
> typedef CGAL::Triangulation_2<K>         Triangulation;
> typedef Triangulation::Vertex_circulator Vertex_circulator;
> typedef Triangulation::Point             Point;
> typedef Triangulation::Face_iterator     Face_iterator;
> typedef Triangulation::Vertex_handle     Vertex_handle;
> typedef Triangulation::Vertex_iterator   Vertex_iterator;
>
> int main() {
>   std::ifstream in("data/triangulation_prog1.cin");
>   std::istream_iterator<Point> begin(in);
>   std::istream_iterator<Point> end;
>
>   Triangulation t;
>   t.insert(begin, end);
>
>   for (Face_iterator fit = t.faces_begin();
>          fit != t.faces_end();
>          ++fit){
>
>         //This is where the problem is.
>         //print out the x and y coordinates of all three verticies of each 
> face
>
>   }
>   return 0;
> }