CGAL users discussion list

["FEYEL Frederic." <>]

Ok, I will generate off files, and send them tonight.

Peter Hachenberger a écrit :
> If they are small. I personally would prefer off files. 
>
> On Wed, 2006-12-13 at 13:14 +0100, FEYEL Frederic. wrote:
>   
>> 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.
>>>>>>>>
>>>>>>>>
>>>>>>>>             
>>>>>>>>                 
>>>>>>         
>>>>>>             
>>>   
>>>       
>
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