CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

The following is working for me:

#include <CGAL/Simple_cartesian.h>
#include <CGAL/Surface_mesh.h>
#include <boost/iterator/transform_iterator.hpp>
#include <CGAL/convex_hull_3.h>

typedef CGAL::Simple_cartesian<double> K;
typedef CGAL::Surface_mesh<K::Point_3> Mesh;
typedef Mesh::Property_map<Mesh::Vertex_index, K::Point_3> Vpm;

int main()
{
  Mesh m1, m2;
  CGAL::convex_hull_3(
    boost::make_transform_iterator(m1.vertices().begin(),

CGAL::Property_map_to_unary_function<Vpm>(m1.points())),
    boost::make_transform_iterator(m1.vertices().end(),

CGAL::Property_map_to_unary_function<Vpm>(m1.points())),
    m2);
}

Side note: you should use exact predicates with the convex hull
algorithm.

Sebastien.

On 03/05/2018 11:05 AM, Riedel, Torge wrote:
> Hi,
>
> I tried to compute a convex hull of a mesh, but I get compilation errors 
> and do not know how to fix. Here is my code:
>
>     typedefCGAL::Simple_cartesian<double> K;
>
>    typedefCGAL::Surface_mesh<K::Point_3> Mesh;
>
>     std::vector< CGAL::cpp11::array<double, 3> > points;
>
>     std::vector< CGAL::cpp11::array<int, 3> > triangles;
>
>     CGAL::read_STL(input, points, triangles);
>
>     CGAL::Polygon_mesh_processing::orient_polygon_soup(points, triangles);
>
> Meshm;
>
>     CGAL::Polygon_mesh_processing::polygon_soup_to_polygon_mesh(points, 
> triangles, m);
>
> Meshsm_convex;
>
>     CGAL::convex_hull_3(m.vertices_begin(), m.vertices_end(), sm_convex);
>
>     std::cout <<" i Points: "<<sm_convex.number_of_vertices() <<" 
> Triangles: "<<sm_convex.number_of_faces() <<std::endl;
>
> I get the following compilation errors:
>
> 1>C:\Evaluation\MeshFW\cgal.org\CGAL-4.11.1\include\CGAL/convex_hull_3.h(903): 
> error C2976: 
> 'CGAL::internal::Convex_hull_3::Default_traits_for_Chull_3': too few 
> template arguments
>
> 1>  
> C:\Evaluation\MeshFW\cgal.org\CGAL-4.11.1\include\CGAL/convex_hull_3.h(72): 
> note: see declaration of 
> 'CGAL::internal::Convex_hull_3::Default_traits_for_Chull_3'
>
> 1>  main.cpp(114): note: see reference to function template 
> instantiation 'void 
> CGAL::convex_hull_3<CGAL::Surface_mesh<CGAL::Point_3<Kernel_>>::Index_iterator<CGAL::Surface_mesh<CGAL::Point_3<Kernel_>>::Vertex_index>,Mesh>(InputIterator,InputIterator,Polyhedron_3 
> &)' being compiled
>
> 1>          with
>
> 1>          [
>
> 1>              Kernel_=CGAL::Epick,
>
> 1>              
> InputIterator=CGAL::Surface_mesh<CGAL::Point_3<CGAL::Epick>>::Index_iterator<CGAL::Surface_mesh<CGAL::Point_3<CGAL::Epick>>::Vertex_index>,
>
> 1>              Polyhedron_3=Mesh
>
> 1>          ]
>
> 1>  
> C:\Evaluation\MeshFW\cgal.org\boost_1_66_0\boost/bind/placeholders.hpp(54): 
> note: see reference to class template instantiation 'boost::arg<9>' 
> being compiled
>
> 1>  
> C:\Evaluation\MeshFW\cgal.org\boost_1_66_0\boost/bind/placeholders.hpp(53): 
> note: see reference to class template instantiation 'boost::arg<8>' 
> being compiled
>
> 1>  
> C:\Evaluation\MeshFW\cgal.org\boost_1_66_0\boost/bind/placeholders.hpp(52): 
> note: see reference to class template instantiation 'boost::arg<7>' 
> being compiled
>
> 1>  
> C:\Evaluation\MeshFW\cgal.org\boost_1_66_0\boost/bind/placeholders.hpp(51): 
> note: see reference to class template instantiation 'boost::arg<6>' 
> being compiled
>
> 1>  
> C:\Evaluation\MeshFW\cgal.org\boost_1_66_0\boost/bind/placeholders.hpp(50): 
> note: see reference to class template instantiation 'boost::arg<5>' 
> being compiled
>
> 1>  
> C:\Evaluation\MeshFW\cgal.org\boost_1_66_0\boost/bind/placeholders.hpp(49): 
> note: see reference to class template instantiation 'boost::arg<4>' 
> being compiled
>
> 1>  
> C:\Evaluation\MeshFW\cgal.org\boost_1_66_0\boost/bind/placeholders.hpp(48): 
> note: see reference to class template instantiation 'boost::arg<3>' 
> being compiled
>
> 1>  
> C:\Evaluation\MeshFW\cgal.org\boost_1_66_0\boost/bind/placeholders.hpp(47): 
> note: see reference to class template instantiation 'boost::arg<2>' 
> being compiled
>
> 1>  
> C:\Evaluation\MeshFW\cgal.org\boost_1_66_0\boost/bind/placeholders.hpp(46): 
> note: see reference to class template instantiation 'boost::arg<1>' 
> being compiled
>
> 1>C:\ 
> Evaluation\MeshFW\cgal.org\CGAL-4.11.1\include\CGAL/convex_hull_3.h(903): error 
> C2955: 'CGAL::internal::Convex_hull_3::Default_traits_for_Chull_3': use 
> of class template requires template argument list
>
> 1>  
> C:\Evaluation\MeshFW\cgal.org\CGAL-4.11.1\include\CGAL/convex_hull_3.h(72): 
> note: see declaration of 
> 'CGAL::internal::Convex_hull_3::Default_traits_for_Chull_3'
>
> In my understanding this is because I passed the vertex iterators to the 
> convex hull function. If I pass iterators of an std::vector of points 
> like the example in the cgal docs does it, it compiles without problems. 
> I was not able to find a way to get iterators to the points of a surface 
> mesh. My challenge is, that the mesh “m” has to be the input source for 
> the complex hull operation. A separate list/vector of the points is not 
> available. So my question is: How to do this? Hopefully without the need 
> to build an extra list of points.
>
> Kind regards
>
> Torge
>
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