[vtkusers] Modifying vtkPolyData

[David Gobbi]

David,

I've taken a closer look at your code, and this chunk of code here is
completely unnecessary:

 vtkSmartPointer<vtkPolyData> sphere =
      vtkSmartPointer<vtkPolyData>::New();
  sphere->ShallowCopy(sphereSource->GetOutput());

Inside your callback, the proper way to get the filter input data is this:

 filter->GetPolyDataInput();

In fact, your params struct is unnecessary too.  All that the
ProgrammableFilter callback needs is a pointer to the filter.   From
that, it can get the input data and the output data.

   David