CGAL users discussion list

["FEYEL Frederic." <>]

Humm, under which form could I send this datas to the list. Two vrml files ?


Peter Hachenberger a écrit :
> Can you also sent the input data for which the program crashed.
>
> Peter
>
> On Wed, 2006-12-13 at 10:23 +0100, FEYEL Frederic. wrote:
>   
>> First of all, thank you very much for your help. It is a real pleasure
>> to see this reactivity !
>>
>> My program is really simple:
>>
>>   to_cgal(mesh1,P1); to_cgal(mesh2,P2);
>>
>>   if (!P1.is_closed() || !P2.is_closed() ) ERROR("Supplied meshes are
>> not closed");
>>
>>   Nef_polyhedron N1(P1);
>>   Nef_polyhedron N2(P2);
>>
>>   Nef_polyhedron N3;
>>
>>   N3=N1-N2;
>>   if (!N3.is_simple()) ERROR("Resulting shape is not a 2-manifold");
>>   N3.convert_to_Polyhedron(P3);
>>
>>  
>>
>> The to to_cgal(...) methods allows the conversion from  my own data
>> structure: it constructs the Polyhedron, knowing the surface mesh,
>> using the following piece of code:
>>
>>   Build_poly_from_utility_mesh<HalfedgeDS> builder(mesh);
>>   P.delegate(builder);
>>
>>
>> where the Build_poly_from_utility_mesh contains (all UTILITY_xxxxx
>> classes are my datastructures, containing nodes, elements, etc...
>> In the test, all those UTILITY_ELEMENT are made of 3-nodes shell elements) 
>> :
>>
>>    void operator()( HDS& hds) {
>>       CGAL::Polyhedron_incremental_builder_3<HDS> B(hds);
>>
>>       B.begin_surface(mesh->nodes.size(),mesh->elements.size());
>>
>>       for (int inode=0;inode<mesh->nodes.size();inode++) {
>>         VECTOR &pos=mesh->nodes[inode]->position;
>>         Point p(pos[0],pos[1],pos[2]);
>>         B.add_vertex(p);
>>       }
>>
>>       for (int ielem=0;ielem<mesh->elements.size();ielem++) {
>>         UTILITY_ELEMENT &an_elem=*mesh->elements[ielem];
>>
>>         B.begin_facet();
>>         for (int inode=0;inode<an_elem.nodes.size();inode++)
>>           B.add_vertex_to_facet(an_elem.nodes[inode]->give_rank());
>>         B.end_facet();
>>       }
>>
>>       B.end_surface();
>>     }
>>
>>
>> I think that the creation of the Polyhedron works well, because the VRML
>> exported file looks ok in an
>> independent VRML viewer.
>>
>> Once again, thank you very much for your help.
>>
>> Frédéric.
>>
>>
>>
>> Andreas Fabri a écrit :
>>     
>>> Please post your test program if it is short.
>>>
>>> andreas
>>>
>>> Frédéric FEYEL wrote:
>>>       
>>>> Thank you for your advice.
>>>>
>>>> I changed my closed surface so that it contains only 3-nodes
>>>> facets, so that all facets are obviously planar.
>>>>
>>>> However, the same problem is still there:
>>>>
>>>> CGAL error: assertion violation!
>>>> Expr: pe_prev->facet()->plane().
>>>> has_on(pe_prev->opposite()->vertex()->point())
>>>> File: ./cgal_build/CGAL-3.2.1/include/CGAL/Nef_3/polyhedron_3_to_nef_3.h
>>>>
>>>> Does anyone has some extra clues ?
>>>>
>>>> Thank you very much for your help,
>>>>
>>>> Best Regards,
>>>>
>>>> Frederic.
>>>>
>>>> Andreas Fabri a écrit :
>>>>         
>>>>> Hello,
>>>>>
>>>>> When you have facets with more than three vertices they must be
>>>>> coplanar, which might not be given if their coordinates are doubles.
>>>>> The solution is to either make them coplanar, or to triangulate
>>>>> the faces.
>>>>>
>>>>> best regards,
>>>>>
>>>>> andreas
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> 
>>>>>  wrote:
>>>>>           
>>>>>> Hello,
>>>>>>
>>>>>> I am very new to CGAL, and I am wondering if it is possible to do
>>>>>> solid/solid intersections.
>>>>>>
>>>>>> It is funny to see that infact, I have the same question as Cedric
>>>>>> Le Maitre (he sent a mail today)...
>>>>>>
>>>>>> More precisely, I have two solids described by two closed Polyhedra
>>>>>> (using 3 and 4 nodes faces).
>>>>>>
>>>>>> I would like to get the Polyhedra that represents the difference
>>>>>> between
>>>>>> the two solids.
>>>>>>
>>>>>> I tried using the Nef_polyhedron_3 classes :
>>>>>>
>>>>>> 1- construct two Polyhedron
>>>>>> 2- construct the Nef_polyhedron from the 2 polyhedron
>>>>>> 3- intersect the 2 Nef_polyhedron
>>>>>> 4- convert the result back to a Polyhedron
>>>>>>
>>>>>> When I construct the nef associated with one of the Polyhedrons, I
>>>>>> get the following error :
>>>>>>
>>>>>> CGAL error: assertion violation!
>>>>>> Expr: pe_prev->facet()->plane().
>>>>>> has_on(pe_prev->opposite()->vertex()->point())
>>>>>> File:
>>>>>> ./cgal_build/CGAL-3.2.1/include/CGAL/Nef_3/polyhedron_3_to_nef_3.h
>>>>>> Line: 151
>>>>>>
>>>>>> I had a look in this file, but the error is not so obvious, at
>>>>>> least for
>>>>>> a 'CGAL-beginner' like me.
>>>>>>
>>>>>>
>>>>>> Could anyone guide me, and tell me if such operation is available in
>>>>>> CGAL, and if yes, how to achieve it ? Any help would be greatly
>>>>>> appreciated.
>>>>>>
>>>>>>
>>>>>> Best Regards,
>>>>>>
>>>>>> Frederic.
>>>>>>
>>>>>>
>>>>>>             
>>>>
>>>>
>>>>         
>
>
>