CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

Could you check P.is_valid() returns true before calling compute_normals?

On 11/04/2016 03:58 PM, Iason Manolas wrote:
> This
> <https://github.com/IasonManolas/Thesis/blob/meshScene/mypolyhedron.h>
> is my code.
> Do you think there could be something wrong with my cgal distribution?
>
> Iason
>
>
> On 4 November 2016 at 16:17, Iason Manolas 
> <
> <mailto:>>
>  wrote:
>
>     CGAL::Polyhedron_3<CGAL::Exact_predicates_inexact_constructions_kernel>
>
>     On 4 November 2016 at 16:10, Sebastien Loriot (GeometryFactory)
>     
> <
>  
> <mailto:>>
>  wrote:
>
>         What is your polyhedron type?
>
>         Sebastien.
>
>         On 11/04/2016 02:59 PM, Iason Manolas wrote:
>
>             My program crashes when I call compute_vertex_normals.
>             The stack calling the function that crashes is:
>             4.In *compute_normal.h*at line 183: *(!is_border**(he,pmesh))*
>             3.In *helpers.h* at line 45: *face(hd,g)*
>             2.In *graph_traits_Polyhedron_3.h* at line: 420: *h->face();*
>             1.In H*alfedgeDS_halfedge_base.h* at line 327:*face()*
>
>             The error I get in Qt creator is SIGSEGV
>             
> <http://stackoverflow.com/questions/2454192/whats-sigsegv-segmentation-fault-in-qt
>             
> <http://stackoverflow.com/questions/2454192/whats-sigsegv-segmentation-fault-in-qt>>
>             which after searching found out that propably means: "Trying
>             to access
>             pointer with invalid value."
>             My guess was that I had not correctly initialized the
>             Polyhedron but
>             everything seems fine..
>
>             Any idea why this happens?
>
>             Best Regards,
>             Iason Manolas
>
>             On 1 November 2016 at 10:53, Andreas Fabri
>             
> <
>             
> <mailto:>
>             
> <mailto:
>             
> <mailto:>>>
>  wrote:
>
>                 You must
>                 #include <boost/property_map/property_map.hpp>
>
>                 and write
>
>             compute_vertex_normals(P,boost::make_assoc_property_map(normals))
>
>
>                 On 01/11/2016 09:45, Iason Manolas wrote:
>
>                     Thanks for your response Sebastien.
>
>                     After reading your code  I wrote:
>                     using
>             vd=boost::graph_traits<CGALPolyhedron>::vertex_descriptor;
>                     std::map<vd,Kernel::Vector_3>* normals;
>
>             CGAL::Polygon_mesh_processing::compute_vertex_normals(P,normals);
>             (since
>                     I want to compute vertex and not face normals)
>
>                     But I get:
>
>
>             /usr/include/CGAL/Polygon_mesh_processing/compute_normal.h:228:
>                     error:
>                     no matching function for call to
>
>             
> ‘put(std::map<CGAL::internal::In_place_list_iterator<CGAL::HalfedgeDS_in_place_list_vertex<CGAL::I_Polyhedron_vertex<CGAL::HalfedgeDS_vertex_base<CGAL::HalfedgeDS_list_types<CGAL::Epick,
>
>             CGAL::I_Polyhedron_derived_items_3<CGAL::Polyhedron_items_3>,
>                     std::allocator<int> >, CGAL::Boolean_tag<true>,
>                     CGAL::Point_3<CGAL::Epick> > > >,
>
>             
> std::allocator<CGAL::HalfedgeDS_in_place_list_vertex<CGAL::I_Polyhedron_vertex<CGAL::HalfedgeDS_vertex_base<CGAL::HalfedgeDS_list_types<CGAL::Epick,
>
>             CGAL::I_Polyhedron_derived_items_3<CGAL::Polyhedron_items_3>,
>                     std::allocator<int> >, CGAL::Boolean_tag<true>,
>                     CGAL::Point_3<CGAL::Epick> > > > > >,
>                     CGAL::Vector_3<CGAL::Epick> >&,
>                     CGAL::HDS_graph_traits<CGAL::Polyhedron_3<CGAL::Epick>
>
>                         ::vertex_descriptor&,
>
>
>             
> CGAL::Type_equality_wrapper<CGAL::Cartesian_base_no_ref_count<double,
>                     CGAL::Epick>, CGAL::Epick>::Vector_3&)’
>                          put(vnm, v, vec);
>                             ^
>                     That propably means that the put fuction cannot
>             recognize vnm ( I
>                     passed) as a valid argument?
>
>
>
>                     On 1 November 2016 at 09:50, Sebastien Loriot
>             (GeometryFactory)
>                     
> <
>  
> <mailto:>
>             
> <mailto:
>  
> <mailto:>>
>                     
> <mailto:
>             
> <mailto:>
>  
> <mailto:
>             
> <mailto:>>>>
>  wrote:
>
>                         A writable property map, as describe in the
>             concept of the
>                     boost web
>                         site is a mecanism that allow to generically
>             associate a
>                     property
>                         (the value type) to a given object (the key).
>
>                         If you want to associate a normal to a facet of a
>                     Polyhedron, here
>                         is a simple example (not tested):
>
>
>                         struct Poly_normal_map{
>
>                           typedef Polyhedron::Facet_handle key_type;
>                           typedef Kernel::Vector_3 value_type;
>                           typedef boost::writable_property_map_tag category;
>
>                           std::map<Polyhedron::Facet_handle,
>             Kernel::Vector_3>* normals;
>
>                           Poly_normal_map() : normals(NULL)
>                           {}
>
>                           Poly_normal_map(std::map<Polyhedron::Facet_handle,
>                                                    Kernel::Vector_3>& n)
>                             : normals(*n)
>                           {}
>
>                           friend void put(Poly_normal_map pnm,
>                                           Polyhedron::Facet_handle fh,
>                                           const Kernel::Vector_3& n
>                           {
>                             CGAL_assertion(pnm.normals!=0);
>                             pnm.normals.insert( std::make_pair(fh, n) );
>                           }
>                         };
>
>                         std::map<Polyhedron::Facet_handle,
>             Kernel::Vector_3> normals;
>                         Poly_normal_map vpm(normals); //vpm is you
>             writable property map
>
>
>                         If you want to make the property map read-write,
>             you can add
>                         a get function:
>
>                           friend const value_type& get(Poly_normal_map pnm,
>
>              Polyhedron::Facet_handle fh)
>                           {
>                             CGAL_assertion(pnm.normals!=0);
>                             return pnm.normals[fh];
>                           }
>
>                         and update the category tag.
>
>                         Note that the code I've written is roughly
>             equivalent to using a
>                         boost::associative_property_map
>
>
>             
> (http://www.boost.org/doc/libs/1_62_0/libs/property_map/doc/associative_property_map.html
>             
> <http://www.boost.org/doc/libs/1_62_0/libs/property_map/doc/associative_property_map.html>
>
>             
> <http://www.boost.org/doc/libs/1_62_0/libs/property_map/doc/associative_property_map.html
>             
> <http://www.boost.org/doc/libs/1_62_0/libs/property_map/doc/associative_property_map.html>>
>
>
>             
> <http://www.boost.org/doc/libs/1_62_0/libs/property_map/doc/associative_property_map.html
>             
> <http://www.boost.org/doc/libs/1_62_0/libs/property_map/doc/associative_property_map.html>
>
>             
> <http://www.boost.org/doc/libs/1_62_0/libs/property_map/doc/associative_property_map.html
>             
> <http://www.boost.org/doc/libs/1_62_0/libs/property_map/doc/associative_property_map.html>>>)
>                         :
>
>                         std::map<Polyhedron::Facet_handle,
>             Kernel::Vector_3> normals;
>                         boost::associative_property_map<
>                                  std::map<Polyhedron::Facet_handle,
>                                           Kernel::Vector_3> > vpm(normals);
>
>                         If you're not stuck with Polyhedron_3, you can
>             use class
>                         Surface_mesh that comes with its own property
>             mechanism
>                         as illustrated in this example:
>
>
>
>             
> http://doc.cgal.org/latest/Polygon_mesh_processing/Polygon_mesh_processing_2compute_normals_example_8cpp-example.html
>             
> <http://doc.cgal.org/latest/Polygon_mesh_processing/Polygon_mesh_processing_2compute_normals_example_8cpp-example.html>
>
>             
> <http://doc.cgal.org/latest/Polygon_mesh_processing/Polygon_mesh_processing_2compute_normals_example_8cpp-example.html
>             
> <http://doc.cgal.org/latest/Polygon_mesh_processing/Polygon_mesh_processing_2compute_normals_example_8cpp-example.html>>
>
>
>             
> <http://doc.cgal.org/latest/Polygon_mesh_processing/Polygon_mesh_processing_2compute_normals_example_8cpp-example.html
>             
> <http://doc.cgal.org/latest/Polygon_mesh_processing/Polygon_mesh_processing_2compute_normals_example_8cpp-example.html>
>
>             
> <http://doc.cgal.org/latest/Polygon_mesh_processing/Polygon_mesh_processing_2compute_normals_example_8cpp-example.html
>             
> <http://doc.cgal.org/latest/Polygon_mesh_processing/Polygon_mesh_processing_2compute_normals_example_8cpp-example.html>>>
>
>                         Sebastien.
>
>
>
>                         On 10/31/2016 12:46 PM, Iason Manolas wrote:
>
>                             Hi,
>
>                             I am new to CGAL. I have constructed a
>                     CGAL::Polyhedron_3 and
>                             now I want
>                             to compute the normal vector for each of its
>             vertices. So I
>                             found the
>                             Polygon Mesh Processing package which
>             happens to have a
>                     function
>
>
>             
> <http://doc.cgal.org/latest/Polygon_mesh_processing/group__PMP__normal__grp.html#gad46aaf003999b2939f3f9e4f6fa58d0e
>             
> <http://doc.cgal.org/latest/Polygon_mesh_processing/group__PMP__normal__grp.html#gad46aaf003999b2939f3f9e4f6fa58d0e>
>
>             
> <http://doc.cgal.org/latest/Polygon_mesh_processing/group__PMP__normal__grp.html#gad46aaf003999b2939f3f9e4f6fa58d0e
>             
> <http://doc.cgal.org/latest/Polygon_mesh_processing/group__PMP__normal__grp.html#gad46aaf003999b2939f3f9e4f6fa58d0e>>
>
>
>             
> <http://doc.cgal.org/latest/Polygon_mesh_processing/group__PMP__normal__grp.html#gad46aaf003999b2939f3f9e4f6fa58d0e
>             
> <http://doc.cgal.org/latest/Polygon_mesh_processing/group__PMP__normal__grp.html#gad46aaf003999b2939f3f9e4f6fa58d0e>
>
>             
> <http://doc.cgal.org/latest/Polygon_mesh_processing/group__PMP__normal__grp.html#gad46aaf003999b2939f3f9e4f6fa58d0e
>             
> <http://doc.cgal.org/latest/Polygon_mesh_processing/group__PMP__normal__grp.html#gad46aaf003999b2939f3f9e4f6fa58d0e>>>>
>                             doing exactly what I want . In the above
>             link I found
>                     out that the
>                             second argument was of type  VertexNormalMap
>             which is a
>                     model of
>                             WritablePropertyMap. There was a link
>
>
>             
> <http://www.boost.org/doc/libs/1_62_0/libs/property_map/doc/WritablePropertyMap.html
>             
> <http://www.boost.org/doc/libs/1_62_0/libs/property_map/doc/WritablePropertyMap.html>
>
>             
> <http://www.boost.org/doc/libs/1_62_0/libs/property_map/doc/WritablePropertyMap.html
>             
> <http://www.boost.org/doc/libs/1_62_0/libs/property_map/doc/WritablePropertyMap.html>>
>
>
>             
> <http://www.boost.org/doc/libs/1_62_0/libs/property_map/doc/WritablePropertyMap.html
>             
> <http://www.boost.org/doc/libs/1_62_0/libs/property_map/doc/WritablePropertyMap.html>
>
>             
> <http://www.boost.org/doc/libs/1_62_0/libs/property_map/doc/WritablePropertyMap.html
>             
> <http://www.boost.org/doc/libs/1_62_0/libs/property_map/doc/WritablePropertyMap.html>>>>
>                             to boost libraries explaining(?) what
>             writable property
>                     map is .
>
>                             Unfortunately this is my first encounter
>             with property
>                     maps and
>                             consequently I am a bit confused..
>                             I also had a look at cgal's explanation of
>             property maps
>                     page
>
>             <http://doc.cgal.org/latest/Property_map/index.html
>             <http://doc.cgal.org/latest/Property_map/index.html>
>                     <http://doc.cgal.org/latest/Property_map/index.html
>             <http://doc.cgal.org/latest/Property_map/index.html>>
>
>             <http://doc.cgal.org/latest/Property_map/index.html
>             <http://doc.cgal.org/latest/Property_map/index.html>
>                     <http://doc.cgal.org/latest/Property_map/index.html
>             <http://doc.cgal.org/latest/Property_map/index.html>>> >, but I
>                             did not
>                             understand much..
>
>                             Could anyone suggest a way of creating the
>             property map
>                     I need?
>
>                             Best Regards,
>                             Iason
>
>
>
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>
>
>
>
>                 --
>                 Andreas Fabri, PhD
>                 Chief Officer, GeometryFactory
>                 Editor, The CGAL Project
>
>                 phone: +33.492.954.912 <tel:%2B33.492.954.912>
>             <tel:%2B33.492.954.912>    skype: andreas.fabri
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