[vtkusers] vtkUnstructuredGrid - how to detect if a cell as neighbors?
Teresa Azevedo
dce06003 at fe.up.pt
Fri Oct 30 12:53:25 EDT 2009
Hi all, again.
I made the suggested modifications (use the vtkMergePoints), and the
test code worked ok.
Then I performed the same modifications onto my project, I got a
strange behaviour when it hits the Render() function of the
vtkRenderWindow. The program crashes with the error "Unhandled
exception in Vol3D.exe (VTKCOMMON.dll)".
I searched the VTKlist and got similar posts, unfortunately with no
answers... does anybody knows what may be the problem?
Thank you,
Teresa
Quoting Wes Turner <wes.turner at kitware.com>:
> Look at:
>
> http://www.vtk.org/doc/nightly/html/classvtkMergePoints.html<http://www.vtk.org/doc/nightly/html/classvtkMergePoints.html#3cd8b8f48693148a6b5546c237aab78f>
>
> You can insert your points into a merge points class which will determine if
> the point is a duplicate and return the correct point id. At the end, you
> can do:
>
> aVoxelGrid->SetPoints(vMergePts->GetPoints());
>
> - Wes
>
> On Tue, Oct 27, 2009 at 11:16 AM, Teresa Azevedo <dce06003 at fe.up.pt> wrote:
>
>> Hi, Wes. Thank you so much for your quick answer!
>>
>> If I try your changes, I runs ok: I get two messages.
>> But my problem is: I have a set of voxels (with different sizes), from
>> which I build my grid. That is, I do not know which voxels share the same
>> face points.
>> Is there a way to check, on the point list, if a certain point is already
>> there?
>>
>> Teresa
>>
>>
>> Quoting Wes Turner <wes.turner at kitware.com>:
>>
>> Teresa,
>>>
>>> I didn't try to run this, so there may be more issues than just this one,
>>> but you are duplicating points not sharing them. Try the changes I marked
>>> below.
>>>
>>> - Wes
>>>
>>> On Tue, Oct 27, 2009 at 10:46 AM, Teresa Azevedo <dce06003 at fe.up.pt>
>>> wrote:
>>>
>>> Hi all.
>>>>
>>>> I would like to extract the boundary cells of an unstructured grid, that
>>>> is, those who have at least one face with no neighbors.
>>>> Here is a test code, that builds an unstructured grid, with two voxels
>>>> that
>>>> share one face. When I check if a cell of the grid has neighbors, the
>>>> code
>>>> prompts a message box. Unfortunately, when I run it, I never get the
>>>> message.
>>>> Can someone tell me what I am doing wrong?
>>>>
>>>> vtkUnstructuredGrid* aVoxelGrid = vtkUnstructuredGrid::New();
>>>> aVoxelGrid->Allocate(2, 2);
>>>>
>>>> vtkPoints* vPts = vtkPoints::New();
>>>> vPts->SetNumberOfPoints(16);
>>>> vPts->InsertPoint( 0, 0, 0, 0);
>>>> vPts->InsertPoint( 1, 1, 0, 0);
>>>> vPts->InsertPoint( 2, 0, 1, 0);
>>>> vPts->InsertPoint( 3, 1, 1, 0);
>>>> vPts->InsertPoint( 4, 0, 0, 1);
>>>> vPts->InsertPoint( 5, 1, 0, 1);
>>>> vPts->InsertPoint( 6, 0, 1, 1);
>>>> vPts->InsertPoint( 7, 1, 1, 1);
>>>>
>>>> vtkVoxel* vl = vtkVoxel::New();
>>>> vl->GetPointIds()->SetId(0, 0);
>>>> vl->GetPointIds()->SetId(1, 1);
>>>> vl->GetPointIds()->SetId(2, 2);
>>>> vl->GetPointIds()->SetId(3, 3);
>>>> vl->GetPointIds()->SetId(4, 4);
>>>> vl->GetPointIds()->SetId(5, 5);
>>>> vl->GetPointIds()->SetId(6, 6);
>>>> vl->GetPointIds()->SetId(7, 7);
>>>>
>>>> aVoxelGrid->InsertNextCell(VTK_VOXEL, vl->GetPointIds());
>>>>
>>>> vPts->InsertPoint( 8, 0, 0, 1);
>>>> vPts->InsertPoint( 9, 1, 0, 1);
>>>> vPts->InsertPoint( 10, 0, 1, 1);
>>>> vPts->InsertPoint( 11, 1, 1, 1);
>>>> vPts->InsertPoint( 12, 0, 0, 2);
>>>> vPts->InsertPoint( 13, 1, 0, 2);
>>>> vPts->InsertPoint( 14, 0, 1, 2);
>>>> vPts->InsertPoint( 15, 1, 1, 2);
>>>>
>>>> vtkVoxel* v2 = vtkVoxel::New();
>>>>
>>>
>>> v2->GetPointIds()->SetId(0, 8);
>>>
>>>> v2->GetPointIds()->SetId(1, 9);
>>>> v2->GetPointIds()->SetId(2, 10);
>>>> v2->GetPointIds()->SetId(3, 11);
>>>>
>>>>
>>> v2->GetPointIds()->SetId(0, 4);
>>> v2->GetPointIds()->SetId(1, 5);
>>> v2->GetPointIds()->SetId(2, 6);
>>> v2->GetPointIds()->SetId(3, 7);
>>>
>>>
>>> v2->GetPointIds()->SetId(4, 12);
>>>> v2->GetPointIds()->SetId(5, 13);
>>>> v2->GetPointIds()->SetId(6, 14);
>>>> v2->GetPointIds()->SetId(7, 15);
>>>>
>>>> aVoxelGrid->InsertNextCell(VTK_VOXEL, v2->GetPointIds());
>>>> aVoxelGrid->SetPoints(vPts);
>>>> aVoxelGrid->Update();
>>>>
>>>> vtkGenericCell* cell = vtkGenericCell::New();
>>>> for( int i = 0; i < aVoxelGrid->GetNumberOfCells(); i++ )
>>>> {
>>>> aVoxelGrid->GetCell( i, cell );
>>>> vtkIdList* cellNeighbors = vtkIdList::New();
>>>> int numFaces = cell->GetNumberOfFaces();
>>>> for ( int j = 0; j < numFaces; j++ )
>>>> {
>>>> vtkCell* face = cell->GetFace( j );
>>>> aVoxelGrid->GetCellNeighbors( i, face->PointIds,
>>>> cellNeighbors);
>>>> if ( cellNeighbors->GetNumberOfIds() > 0 )
>>>> {
>>>> MessageBox(NULL, "Cell has neighbors!",
>>>> NULL, MB_OK);
>>>> }
>>>> }
>>>> }
>>>>
>>>>
>>>> Thank you all.
>>>> Teresa
>>>>
>>>> _______________________________________________
>>>> Powered by www.kitware.com
>>>>
>>>> Visit other Kitware open-source projects at
>>>> http://www.kitware.com/opensource/opensource.html
>>>>
>>>> Please keep messages on-topic and check the VTK FAQ at:
>>>> http://www.vtk.org/Wiki/VTK_FAQ
>>>>
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>>>>
>>>>
>>>
>>>
>>> --
>>> Wesley D. Turner, Ph.D.
>>> Kitware, Inc.
>>> Technical Leader
>>> 28 Corporate Drive
>>> Clifton Park, NY 12065-8662
>>> Phone: 518-881-4920
>>>
>>>
>>
>> _______________________________________________
>> Powered by www.kitware.com
>>
>> Visit other Kitware open-source projects at
>> http://www.kitware.com/opensource/opensource.html
>>
>> Please keep messages on-topic and check the VTK FAQ at:
>> http://www.vtk.org/Wiki/VTK_FAQ
>>
>> Follow this link to subscribe/unsubscribe:
>> http://www.vtk.org/mailman/listinfo/vtkusers
>>
>
>
>
> --
> Wesley D. Turner, Ph.D.
> Kitware, Inc.
> Technical Leader
> 28 Corporate Drive
> Clifton Park, NY 12065-8662
> Phone: 518-881-4920
>
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