CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

Have a look at the attached file where vertex and halffacet have an 
extra data member.

Sebastien.

On 04/24/2012 09:14 AM, Johannes Ulén wrote:
> Thank you for the reply.
> Is there a way to change the point construct?
>
> Let me very breifly explain what I want to do and my problem might
> become clearer.
> 1) I want to create a polytope where each vertex starts with boolean
> value set to false.
> 2) For each vertex which is false I do some calculations and perform
> an intersection with a halfspace. The polytope is now reshaped and has
> more vertices.
> 3) A certain opertaion will mark a vertex as "true" and I then dont
> need to bother with it anymore.
>
> My programing instict tells me that the easiet way to to do this would
> be to change point class, but I might be wrong?
>
> -- Johannes
>
>
> Den 24 april 2012 08:37 skrev Sebastien Loriot (GeometryFactory)
> <>:
> > On 04/23/2012 02:55 PM, 
> >
> >  wrote:
> > > I'm trying the add one property to the point class.
> > >
> > > By help from  StackOverflow I was directed to Manual Chapter 11.5
> > > Extensible
> > > Kernel using this I wrote the code below.
> > >
> > > The code  will not compile and I get the error:
> > > ‘typename CGAL::Extended_homogeneous::Base’ names
> > > 'CGAL::Extended_homogeneous::Base’, which is not a class template|
> > >
> > > == CODE ==
> > > #include<CGAL/Extended_homogeneous.h>
> > >
> > > template<    typename K_, typename K_Base>
> > > class My_base  : public K_Base::template Base<K_>::Type
> > > {
> > >    typedef typename K_Base::template Base<K_>::Type   OldK;
> > >
> > > public:
> > >    typedef K_                               Kernel;
> > >
> > >    template<    typename Kernel2>
> > >    struct Base { typedef My_base<Kernel2, K_Base>     Type; };
> > >   };
> > >
> > > template<    typename RT_>
> > > struct MyKernel  : public
> > > CGAL::Type_equality_wrapper<My_base<MyKernel<RT_>,
> > > CGAL::Homogeneous<RT_>    >,  MyKernel<RT_>    >
> > > {};
> > >
> > > #include<CGAL/Nef_polyhedron_3.h>
> > > typedef MyKernel<CGAL::Gmpz>      Kernel;
> > >
> > > typedef CGAL::Nef_polyhedron_3<Kernel>    Nef_Polyhedron;
> > > typedef Nef_Polyhedron::Plane_3  Plane;
> > >
> > > int main()
> > > {
> > >    Nef_Polyhedron half_space(Plane(1,1,1,1), Nef_Polyhedron::EXCLUDED);
> > >
> > >    return 0;
> > > }
> > > ====
> > >
> > > If the inhertiance is changed to "public K_Base::Base::template
> > > B<K_>::Type" it
> > > will compile but Then I miss the propeties from Extentensions I guess?
> > > Because
> > > I get the error "Constructor not available for this kernel" when I run the
> > > program.
> >
> >
> > The point constructors are not changed by this mechanism. This means that
> > only those documented are available. If you want to initialize your extra
> > data, you need to first create an object of type My_point and then init a
> > point of type MyKernel::Point_3 with it.
> >
> > The class in the kernel is a kind of interface while My_point is the
> > representation.
> >
> > Sebastien.
> >
> >
> >
> >
> >
> > --
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> > To unsubscribe or access the archives, go to
> > https://lists-sop.inria.fr/wws/info/cgal-discuss

#include <CGAL/Exact_predicates_exact_constructions_kernel.h>
#include <CGAL/Polyhedron_3.h>
#include <CGAL/IO/Polyhedron_iostream.h>
#include <CGAL/Nef_polyhedron_3.h>
#include <CGAL/IO/Nef_polyhedron_iostream_3.h>
#include <CGAL/OFF_to_nef_3.h>
#include <iostream>
#include <fstream>


/////////// Defining an item class with data in Vertex and Halffacets ///////////
template <class Kernel,class Refs,class T>
class Vertex_base_with_data: public CGAL::Default_items<Kernel>::Items:: template Vertex<Refs>{
  mutable T m_data;
public:
  T& data() const {return m_data;}
};

template <class Kernel,class Refs,class T>
class Halffacet_base_with_data: public CGAL::Default_items<Kernel>::Items:: template Halffacet<Refs>{
  mutable T m_data;
public:
  T& data() const {return m_data;}
};

//Kernel is the type used as Kernel for the Nef polyhedron T is the tyep of extra data that
//need to be stored
template<class Kernel,class T>
struct SNC_item_with_data : public CGAL::Default_items<Kernel>::Items{
  template <class Refs> class Vertex :    public Vertex_base_with_data<Kernel,Refs,T> {};
  template <class Refs> class Halffacet : public Halffacet_base_with_data<Kernel,Refs,T>{};
};
/////////// DONE ///////////

//Test this is working

typedef CGAL::Exact_predicates_exact_constructions_kernel  Kernel;
typedef CGAL::Polyhedron_3<Kernel>  Polyhedron;
typedef CGAL::Nef_polyhedron_3<Kernel,SNC_item_with_data<Kernel,int> > Nef_polyhedron;
typedef Nef_polyhedron::Vertex_iterator Vertex_iterator;
typedef Nef_polyhedron::Vertex_const_iterator Vertex_const_iterator;
typedef Nef_polyhedron::Halffacet_const_iterator Halffacet_const_iterator;



int main(int argc, char *argv[]) {
  if (argc<2){std::cerr <<"Please provided an input off file\n"; return 1;}
  std::ifstream off(argv[1]);
  if (!off){ std::cerr<<"Cannot open file " << argv[1] <<"\n"; return 1;  }
  Polyhedron P;
  off >> P;
  Nef_polyhedron N(P);

  
  for (Vertex_const_iterator vit=N.vertices_begin(),
                             vit_end=N.vertices_end();
                             vit!=vit_end;++vit)
  {
    vit->data()=1;
    std::cout << vit->data() << std::endl;
  }

  for (Halffacet_const_iterator hfit=N.halffacets_begin(),
                                hfit_end=N.halffacets_end();
                                hfit!=hfit_end;++hfit)
  {
    hfit->data()=2;
    std::cout << hfit->data() << std::endl;
  }
}