[Paraview] Is there a way to reuse the preivous DataSet from RequestData

[Gonzalo Brito Gadeschi]

Thanks, that solves it.

On Mon, Feb 2, 2015 at 8:03 PM, Utkarsh Ayachit <utkarsh.ayachit at kitware.com
> wrote:

> The only way is to cache it in the reader itself. Create a new
> vtkUnstructuredGrid and ShallowCopy the contents of your "output" to
> it at the end of your RequestData().
>
> Utkarsh
>
> On Mon, Feb 2, 2015 at 2:00 PM, Gonzalo Brito Gadeschi
> <g.brito at aia.rwth-aachen.de> wrote:
> > In a reader plugin for unstructured grids, after the plugin opens a file,
> > and paraview calls RequestData for the first time, I initialize the grid
> > like:
> >
> >  vtkInformation* outInfo = outputVector->GetInformationObject(0);
> >  vtkDataSet* output = vtkDataSet::GetData(outInfo);
> >  vtk_grid = vtkUnstructuredGrid::SafeDownCast(output);
> >
> >   vtk_grid->Initialize();
> >   vtk_grid->Allocate(0);
> >   vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New();
> >   vtk_grid->SetPoints(points);
> >   // create grid points, cells..
> >   // load cell data fields (the user can control this via the plugin
> > interface)
> >
> > If the user then decides to load/unload some fields, I would like to
> reuse
> > the loaded points and cells, and just update/add/remove fields.
> >
> > The problem comes when in subsequent calls to RequestData:
> >
> >   vtkInformation* outInfo = outputVector->GetInformationObject(0);
> >   vtkDataSet* output = vtkDataSet::GetData(outInfo);
> >
> >   // this asserts works:
> >   assert(old_vtk_grid == vtkUnstructuredGrid::SafeDownCast(output));
> >  // this assert fails: the number of points is 0..
> >   assert(old_number_of_points == vtk_grid->GetNumberOfPoints());
> >   // this produces a segmentation fault
> >   assert(old_number_of_cells ==
> vtk_grid->GetCells()->GetNumberOfCells());
> >
> > That is, even tho the grid pointer that gets passed to RequestData
> points to
> > the same memory as before, it seems that the grid is "empty" (number of
> > points is 0).
> >
> > Is there a way to preserve the grid state between calls to RequestData?
> >
> > Bests,
> > Gonzalo
> >
> > --
> > Dipl.-Ing. Gonzalo Brito Gadeschi
> > Institute of Aerodynamics and Chair of Fluid Mechanics
> > RWTH Aachen University
> > Wuellnerstraße 5a
> > D-52062 Aachen
> > Germany
> > Phone: ++49-(0)241-80-94821
> > Fax: ++49-(0)241-80-92257
> > E-mail:  g.brito at aia.rwth-aachen.de
> > Internet: www.aia.rwth-aachen.de
> >
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>



-- 
Dipl.-Ing. Gonzalo Brito Gadeschi
Institute of Aerodynamics and Chair of Fluid Mechanics
RWTH Aachen University
Wuellnerstraße 5a
D-52062 Aachen
Germany
Phone: ++49-(0)241-80-94821
Fax: ++49-(0)241-80-92257
E-mail:  g.brito at aia.rwth-aachen.de
Internet: www.aia.rwth-aachen.de
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