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<!--beginarticle-->Hello all,<br>
<pre>
I have been playing with some of the vtk source classes
(vtkSphereSource, vtkCubeSource, etc..) for generating simple meshes. I
have noticed some issues when i use the vtkCubeSource.
Let's focus on this example:
<a href="http://www.vtk.org/Wiki/VTK/Examples/GeometricObjects/Cube">http://www.vtk.org/Wiki/VTK/Examples/GeometricObjects/Cube</a>
The output file cube.vtp, contains 24 points, not 8. Every point is
repeated 3 times. Is that ok?
"cube.vtp"
...
<DataArray type="Float32" Name="Points" NumberOfComponents="3"
format="ascii" RangeMin="0.43301270189" RangeMax="0.43301270189">
-0.25 -0.25 -0.25 -0.25 -0.25 0.25
-0.25 0.25 -0.25 -0.25 0.25 0.25
0.25 -0.25 -0.25 0.25 -0.25 0.25
0.25 0.25 -0.25 0.25 0.25 0.25
-0.25 -0.25 -0.25 -0.25 -0.25 0.25
0.25 -0.25 -0.25 0.25 -0.25 0.25
-0.25 0.25 -0.25 -0.25 0.25 0.25
0.25 0.25 -0.25 0.25 0.25 0.25
-0.25 -0.25 -0.25 0.25 -0.25 -0.25
-0.25 0.25 -0.25 0.25 0.25 -0.25
-0.25 -0.25 0.25 0.25 -0.25 0.25
-0.25 0.25 0.25 0.25 0.25 0.25
</DataArray>
...
With this output file i generate an unstructured grid, applying
vtkDelaunay3d class.
#######
vtkSmartPointer<vtkDelaunay3D> del = vtkSmartPointer<vtkDelaunay3D>::New();
del->SetInput(cubeSource->GetOutput());
del->Update();
vtkSmartPointer<vtkXMLUnstructuredGridWriter> gridWriter =
vtkSmartPointer<vtkXMLUnstructuredGridWriter>::New();
gridWriter->SetInputConnection(del->GetOutputPort());
gridWriter->SetDataModeToAscii();
gridWriter->SetFileName("cube.vtu");
gridWriter->Write();
#######
Whenever i try to look deeper in to the resulting mesh ("cube.vtu"), i
have noticed that not every point of the resulting mesh is interconnected.
"cube.vtu"
...
<DataArray type="Int32" Name="connectivity" format="ascii" RangeMin="0"
RangeMax="7">
2 1 0 4 3 1
2 4 4 3 1 5
3 4 2 6 5 4
3 6 5 6 3 7
</DataArray>
...
I mean, iterating through the grid, using grid->GetPointCells() method,
points with id:
* 0, 7: only 1 cell.
* 1, 2, 5, 6: 3 cells.
* 3, 4: 5 cells.
* [8-23]: 0 cells. No connectivity.
Some questions arises:
- Why there are 16 isolated points [8-23]?
- Why points [0-7] do not have the same connectivity?
Hope someone could help me on this!
Thanks in advance,
Jorge.
</pre>
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