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

[Bhanu Hariharan]

David,
Thanks for replying. However I have a doubt.
Are you suggesting the VTKUnstructuredgrid should have an globalids array?
Is that what the member is called - globalIds? I actually pass
VTKUnstructuredgrid  to a VTKThreshold filter and then pass that filter to
VTKdatasetsurfacefilter.

Perhaps you can post a couple lines of code. That would be very helpful.
Thanks,
Bhanu


On Tue, Mar 5, 2013 at 6:55 PM, David E DeMarle <dave.demarle at kitware.com>wrote:

> 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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