[Paraview-developers] Replacement of SetInput with SetInputData (VTK5 vs. 6)

[Berk Geveci]

Replace that Update() with cp->Update().

The rule for internal filters is that you should never use
SetInputConnection() to connect anything to an external filter from within
RequestData(). You don't want internal pipeline executions to propagate to
external filters as it may cause all kinds of problems. SetInputData() does
not create a pipeline connection so it is safe to use in such
circumstances. SetInputConnection() is safe to connect internal filters to
each other.

Best,
-berk

On Tue, Apr 28, 2015 at 2:54 AM, Schlottke, Michael <
M.Schlottke at aia.rwth-aachen.de> wrote:

> Hi Utkarsh,
>
> Thank you very much for this answer, it clears things up a lot. Am I right
> to sum this up as a rule of thumb to
>
> “use SetInputConnection whenever possible, resort to SetInputData where it
> isn’t”
>
> for most use cases?
>
> On a related note, I’ve encountered a few filters with code like this:
>
> //////////////////////////////////////////////////////////////
> vtkMyFilter::RequestData(….)
> {
>   …
>   vtkCellDataToPointData* cp = vtkCellDataToPointData::New();
>   ...
>   vtkUnstructuredGrid* pdata = cp->GetUnstructuredGridOutput();
>   pdata->GetPointData()->RemoveArray(“arrayname");
>   pdata->GetPointData()->Update();
>   pdata->Update(); // will not compile with VTK6 (******)
>
>   vtkInformation *outInfo = outputVector->GetInformationObject(0);
>   vtkUnstructuredGrid *output =
> vtkUnstructuredGrid::SafeDownCast(outInfo->Get(vtkDataObject::DATA_OBJECT()));
>   output->SetPoints(pdata->GetPoints());
>   output->CopyStructure(pdata);
>   output->GetCellData()->PassData(pdata->GetCellData());
>
>   return 1;
> }
> //////////////////////////////////////////////////////////////
>
> I am wondering about the line marked with (******). Is it obsolete with
> VTK6 (as there is no Update() method for non-vtkAlgorithm objects), should
> I call cp->Update() instead, or is there something entirely different to do
> to make this code work properly?
>
> Regards,
>
> Michael
>
> > On 27 Apr 2015, at 19:53 , Utkarsh Ayachit <utkarsh.ayachit at kitware.com>
> wrote:
> >
> >> Now I am wondering: ifinside the RequestData method of a filter, do I
> *ever*
> >> need  to use SetInputConnection, and if yes, how?
> >
> >
> > Here's an example:
> >
> > vtkMyFilter::RequestData(....)
> > {
> >   vtkDataSet* myinput = vtkDataSet::GetData(inputInformation[0], 0);
> >
> >   vtkNew<vtkSomeFilter> filter1;
> >   filter1->SetInputData(myinput);
> >
> >   vtkNew<vtkSomeFilter> filter2;
> >   filter2->SetInputConnection(filter1->GetOutputPort());
> >   ...
> >
> >   filter2->Update()
> > }
> >
> > Thus, for internal pipelines, it makes sense to use SetInputConnection.
> >
> >> It seems like all filters
> >> I’ve had a look at always access the input data object (which I can only
> >> pass on using SetInputData, not SetInputConnection), not the input port.
> >> However, as a user with little VTK experience it seems like this might
> >> “break” the aforementioned pipeline?
> >
> > It the example I gave, for example, if you use SetInputData() to pass
> > the output of filter1 to filter2, you'll need to call
> > filter1->Update() before doing that. Otherwise, filter1 has not
> > execute and hence doesn't have valid data to pass to filter2. Unlike
> > the old SetInput(), setting the dataset using SetInputData() doesn't
> > preserve the pipeline information i.e. filter2 will not update filter1
> > just because you called filter2->Update() if SetInputData() is used to
> > pass the data.
> >
> > Hope that clarifies it a little.
>
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