CGAL users discussion list

[Andreas Fabri <>]

Hi Maarten,

As a workaround you might try to add
#define CGAL_DONT_USE_LAZY_KERNEL 1

It should compile.

andreas


Maarten Moesen wrote:
> Hello,
>
> When trying a 2D mesher example of CGAL together with the exact
> constructions kernel I noticed that it doesn't compile on my PC  (CGAL
> 3.3.1 / linux32 / g++ 4.0) giving error messages summarized by:
>
> test.cpp:52: instantiated from here
> /usr/local/CGAL-3.3/include/CGAL/Lazy.h:368: error: no matching function
> for call to ‘exact(CGAL::Null_tag&)’
> /usr/local/CGAL-3.3/include/CGAL/Lazy.h:83: note: candidates are: const
> double& CGAL::exact(const double&) 
> ... and so on.
>
> This is only when using Exact_predicates_exact_constructions_kernel. For
> Exact_predicates_inexact_constructions_kernel and
> Exact_predicates_exact_constructions_kernel_with_sqrt it compiles (and
> works :)
>
> Is this OK? I'd like to use the
> Exact_predicates_exact_constructions_kernel because I'm planning to make
> some constructions using NEF polyhedra earlier on in the process and
> found out that exact_..._with_sqrt doesn't work together with these.
> (Maybe a second mail)
>
> Thanks,
>
> Maarten Moesen
>
> Here's the code:
>
> #include <CGAL/Exact_predicates_exact_constructions_kernel.h>
> #include <CGAL/Constrained_Delaunay_triangulation_2.h>
> #include <CGAL/Delaunay_mesher_2.h>
> #include <CGAL/Delaunay_mesh_face_base_2.h>
> #include <CGAL/Delaunay_mesh_size_criteria_2.h>
>
> #include <iostream>
>
> struct K : public CGAL::Exact_predicates_exact_constructions_kernel {};
> typedef CGAL::Triangulation_vertex_base_2<K> Vb;
> typedef CGAL::Delaunay_mesh_face_base_2<K> Fb;
> typedef CGAL::Triangulation_data_structure_2<Vb, Fb> Tds;
> typedef CGAL::Constrained_Delaunay_triangulation_2<K, Tds> CDT;
> typedef CGAL::Delaunay_mesh_size_criteria_2<CDT> Criteria;
> typedef CGAL::Delaunay_mesher_2<CDT, Criteria> Mesher;
>
> typedef CDT::Vertex_handle Vertex_handle;
> typedef CDT::Point Point;
>
> int main()
> {
>   CDT cdt;
>
>   Vertex_handle va = cdt.insert(Point(-4,0));
>   Vertex_handle vb = cdt.insert(Point(0,-1));
>   Vertex_handle vc = cdt.insert(Point(4,0));
>   Vertex_handle vd = cdt.insert(Point(0,1));
>   cdt.insert(Point(2, 0.6));
>
>   cdt.insert_constraint(va, vb);
>   cdt.insert_constraint(vb, vc);
>   cdt.insert_constraint(vc, vd);
>   cdt.insert_constraint(vd, va);
>
>   std::cout << "Number of vertices: " << cdt.number_of_vertices() <<
> std::endl;
>
>   std::cout << "Meshing the triangulation with default criterias..."
>       << std::endl;
>
>   Mesher mesher(cdt);
>   mesher.refine_mesh();
>
>   std::cout << "Number of vertices: " << cdt.number_of_vertices() <<
> std::endl;
>
>   std::cout << "Meshing with new criterias..." << std::endl;
>   // 0.125 is the default shape bound. It corresponds to abound 20.6
> degree.
>   // 0.5 is the upper bound on the length of the longuest edge.
>   // See reference manual for Delaunay_mesh_size_traits_2<K>.
>   mesher.set_criteria(Criteria(0.125, 0.5));
>   mesher.refine_mesh();
>
>   std::cout << "Number of vertices: " << cdt.number_of_vertices() <<
> std::endl;
> }