[vtk-developers] [vtkusers] vtkDataSetSurfaceFilter - Cell Picking

[David E DeMarle]

The input data should have a globalids array containing a unique value for
each cell. If it does, extract will preserve it. After the extraction, use
that array in the polydata to do the look up to the original cell in the
unstructured grid.
On Mar 5, 2013 6:00 PM, "Bhanu Hariharan" <bhanu at petrotel.com> wrote:

> Hi All,
>
> I need some help doing the following. Please could one of you guide me on
> how.
>
> I use a vtkDataSetSurfaceFilter on VTKUnstructuredGrid to render skin of
> that grid. That works fine and I can see the number of surfaces shown by
> grabbing the
> dataSetSurfaceFilter->GetOutput()->GetNumberOfCells().
>
>
> I need a way to map the surface back to the original cell id. That is if I
> have 2 cells and I render just skin, number of surfaces rendered are 10. I
> need to be able to pick on any of these 10 surfaces and map them back to
> either of the the 2 grid cells.
>
>
> http://www.vtk.org/doc says :
>
> If PassThroughCellIdsOn is 1, then the output polygonal dataset will have
> a celldata array that holds the cell index of the original 3D cell that
> produced each output cell. This is useful for cell picking.
> I turned the PassThroughCellIds On and I have UseStrips turned off.
>
> Then I did
> vtkPolyData *surfacePolyData = dataSetSurfaceFilter->GetOutput();
>
> But I do not see how I can access that celldata array that holds the
> original 3D cells for the surfaces.
>
> Please can anyone advise on how.
>
> Thanks in advance.
> Bhanu
>
>
>
>
>
>
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