CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

You can try that:

Gt::RT r = 0.75;
Rational rr( CGAL::exact(r).mpq() );

Sebastien

On 02/14/2013 11:50 AM, Myirci wrote:
> Bonjour,
>
> I'm using segment delaunay graphs and conics arrangements. At some point
> of my program I need to convert Ring Type variables to Rational
> variables to create the conic arcs. My original code is very long, but I
> generated the same condition in the program below. How can I do the
> conversion? For just one simple parabola I can supply the Rational
> coefficients by hand but in my original program, the numbers are not so
> simple and the coefficients are calculated in run time.
>
> Bonne journée
> Merci beaucoup
>
> #include<iostream>
>
> #include  <CGAL/Exact_predicates_exact_constructions_kernel.h>
>
> #include  <CGAL/Segment_Delaunay_graph_2.h>
>
> #include  <CGAL/Segment_Delaunay_graph_traits_2.h>
>
>
>
> typedef  CGAL::Exact_predicates_exact_constructions_kernel                    
>        Kernel;
>
> typedef  CGAL::Segment_Delaunay_graph_traits_without_intersections_2<
>
>          Kernel,
>
>
>          CGAL::Integral_domain_without_division_tag>                          
>                  Gt;
>
> typedef  Gt::Point_2                                                          
>                                     Point_2;
>
> typedef  CGAL::Segment_Delaunay_graph_2<Gt>                                   
>            SDG_2;
>
>
>
> #include  <CGAL/basic.h>
>
>
> #include  <CGAL/Cartesian.h>
>
>
> #include  <CGAL/CORE_algebraic_number_traits.h>
>
> #include  <CGAL/Arrangement_2.h>
>
> #include  <CGAL/Arr_conic_traits_2.h>
>
>
>
> typedef  CGAL::CORE_algebraic_number_traits                                   
>                Nt_traits;
>
> typedef  Nt_traits::Rational                                                  
>                                   Rational;
>
> typedef  Nt_traits::Algebraic                                                 
>                                  Algebraic;
>
> typedef  CGAL::Cartesian<Rational>                                            
>                         Rat_kernel;
>
> typedef  CGAL::Cartesian<Algebraic>                                           
>                        Alg_kernel;
>
> typedef  CGAL::Arr_conic_traits_2<Rat_kernel,  Alg_kernel,  Nt_traits>        
>         Traits_2;
>
> typedef  Traits_2::Curve_2                                                    
>                                Conic_arc_2;
>
> typedef  CGAL::Arrangement_2<Traits_2>                                        
>                    Arrangement_2;
>
>
>
> int  main(void)  {
>
>      //  Parabola:  y  =  -3/4x²
>
>      Gt::RT  r  =  0.75;
>
>      Gt::RT  s  =  0;
>
>      Gt::RT  t  =  0;
>
>      Gt::RT  u  =  0;
>
>      Gt::RT  v  =  1;
>
>      Gt::RT  w  =  0;
>
>      Point_2  ps  =  Point_2(2,  -3);
>
>      Point_2  pt  =  Point_2(-1,  0.75);
>
>
>
>      //  Does  not  compile:  RT  number  type  must  be  converted  to  
> Rational!  How?
>
>      Conic_arc_2  arc(r,s,t,u,v,w,  CGAL::COUNTERCLOCKWISE,  ps,  pt);
>
>      if(!arc.is_valid())  {  std::cout  <<  "NOT  VALID"  <<  std::endl;  }
>
>      return  0;
>
> }
>
>
> --
> Murat Yirci