CGAL users discussion list

[Andreas Fabri <>]

On 15/03/2010 22:43, Ian Bentley wrote:
> Thanks for the help, but it doesn't really clarify for me. I am using
> the point type
>
> CGAL::Point_2< CGAL::Cartesian<double > >
>
> and CGAL/Exact_predicates_inexact_constructions_kernel.h
> <http://www.cgal.org/Manual/3.2/doc_html/cgal_manual/Kernel_23_ref/Class_Exact_predicates_inexact_constructions_kernel.html>
>
> says that it uses:
>
> "A typedef to a kernel which has the following properties:
>
>     * It uses Cartesian representation.
>     * It supports constructions of points from double Cartesian
>       coordinates.
>     * It provides exact geometric predicates, but inexact geometric
>       constructions."
>
> This indicates to me that I am using the right one... What am I doing wrong?

Every bird is an animal, but not every animal is a bird.

It opnly says that the Point_2 of an 
Exact_predicates_inexact_constructions_kernel
is constructible from double, that is the following should work:

typedef CGAL::Exact_predicates_inexact_constructions_kernel K;
typedef K::Point_2 Point_2;

double x=3.1415;

Point_2 p(x,0);



> Thanks.
>
> On Sat, Mar 13, 2010 at 4:15 AM, Michael Hemmer
> <
>  
> <mailto:>>
> wrote:
>
>     Hi Ian,
>
>     seem that you have not chosen the right point type. Chose the one
>     from the same Kernel that you use.
>
>     Michael
>
>
>     Ian Bentley wrote:
>
>              Hello , new to CGAL, and struggling with some basic concepts.
>
>         I create a std::vector< CGAL::Point_2< CGAL::Cartesian<double> >
>         and fill it with a series of points often generated at random,
>         but sometimes specified.  Anyways, the exact location of these
>         points is not particularly important, and as long as they are
>         accurate to an epsilon of 0.001, Everything that I am concerned
>         with will be fine.  This is why I chose Cartesian<double> for my
>         kernel, and that seems to work just fine.
>
>         Later however, I was looking to use this vector to create a
>         delaunay triangulation of these points.  Looking at the
>         examples:
>         
> http://www.cgal.org/Manual/last/doc_html/cgal_manual/Triangulation_2/Chapter_main.html
>         there, I put together the following code:
>
>         #include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
>         #include <CGAL/Delaunay_triangulation_2.h>
>
>         typedef CGAL::Exact_predicates_inexact_constructions_kernel K;
>
>         void network::buildDelaunayTriangulation(){
>                 CGAL::Delaunay_triangulation_2<K> l_delaunayTriangulation;
>                 std::vector<point >::iterator it;
>                 for(it=m_locations.begin(); it < m_locations.end(); it++){
>                         l_delaunayTriangulation.insert((*it));
>                 }
>         }
>
>         where m_locations is the vector of points created earlier.
>
>         When I run this code however I receive the error:
>
>         model/network.cc:29: error: no matching function for call to
>         
> ‘CGAL::Delaunay_triangulation_2<CGAL::Filtered_kernel<CGAL::Simple_cartesian<double>
>          >,
>         
> CGAL::Triangulation_data_structure_2<CGAL::Triangulation_vertex_base_2<CGAL::Filtered_kernel<CGAL::Simple_cartesian<double>
>          >, CGAL::Triangulation_ds_vertex_base_2<void> >,
>         CGAL::Triangulation_ds_face_base_2<void> >
>          >::insert(CGAL::Point_2<CGAL::Cartesian<double> >&)’
>
>         With a series of suggestions.
>
>         I suspect this is because I use the
>         Exact_predicates_inexact_constructions_kernel to build the
>         delaunay, but I'm not sure.  How can I fix this code?
>
>         --
>         Ian Bentley
>         M.Sc. Student
>         Queen's University
>         Kingston, Ontario
>
>
>         --
>         Ian Bentley
>         M.Sc. Student
>         Queen's University
>         Kingston, Ontario
>
>
>
>     --
>     You are currently subscribed to cgal-discuss.
>     To unsubscribe or access the archives, go to
>     https://lists-sop.inria.fr/wws/info/cgal-discuss
>
>
>
>
> --
> Ian Bentley
> M.Sc. Student
> Queen's University
> Kingston, Ontario