[vtkusers] vtkAppendPolyData delete the scalars

Tue Aug 7 11:34:14 EDT 2012

2012/8/7 Alex Malyushytskyy <alexmalvtk at gmail.com>

> If both polydata have exactly the same scalars (type, dimensions )
> output should have a scalar field.
> If it does not , it is a bug.
>

myPolyData->GetNumberOfPoints() = 2421
myPolyData->GetNumberOfCells()   = 3010 (so the scalar array for this
polydata is the same length)

otherPolyData->GetNumberOfPoints() = 574
otherPolyData->GetNumberOfCells()   = 524

>
> But I doubt it. You do not show all significant code, so
> I am not sure these 2 scalars are compatible.
>

What additional information do you need?

>
> Did you want 1 scalar value per cell?
> If so, could you try to replace
>
>     vtkIntArray* scalars = vtkIntArray::New();
>     scalars->SetNumberOfComponents(1);
>     scalars->SetNumberOfValues(myPolyData->GetNumberOfCells());
>     scalars->SetNumberOfTuples(myPolyData->GetNumberOfCells());
>
>  with
>
>    vtkIntArray* scalars = vtkIntArray::New();
>    scalars->SetNumberOfValues( myPolyData->GetNumberOfCells());
>

Yes, I want 1 scalar per cell, I tried this but didn't work.

>
> if this does not help, or it is not what you want check what value (
> if not null, what type of array ) the following line would return
>
> vtkDataArray * pA =finalPolyData->GetCellData()->GetScalars();
>
> // replace the following line with line above
>   vtkIntArray* scalarArray =
> static_cast<vtkIntArray*>(finalPolyData->GetCellData()->GetScalars());
>
>
This make the program crash, so there is nothng there.

> Alex
>
> On Mon, Aug 6, 2012 at 2:18 AM, Gonzalo Amadio <gonzaloamadio at gmail.com>
> wrote:
> > Yes, what I wanted to mean with "is Strange" is that letting the input
> > without appending works fine, so it means that it has its scalars.
> > In other words, I printed the scalars of "otherPolyData" and "myPolyData"
> > before appending, and I obtain desired results. So it means that they
> have
> > scalars.
> >
> > So I don't know what is happening here. Maybe I have to add something
> more
> > to satisfy conditions for using the filter, but I don't know.
> > Some help?
> >
> > Thank you!
> >
> >
> >
> > 2012/8/3 Alex Malyushytskyy <alexmalvtk at gmail.com>
> >>
> >> >> appendGreenSubdAndRedBlue->AddInput(otherPolyData);   // what is
> >> >> extrange is that if I comment this line, it works fine
> >> >> appendGreenSubdAndRedBlue->AddInput(myPolyData);
> >>
> >> there is nothing strange, if you comment this line there is no
> >> modification were made,
> >> so output is the same as input.
> >>
> >> why it removes scalar?
> >> otherPolyData probably does not the same scalar. From documentation:
> >>
> >> "All geometry is extracted and appended, but point and cell attributes
> >> (i.e., scalars, vectors, normals) are extracted and appended only if
> >> all datasets have the point and/or cell attributes available. (For
> >> example, if one dataset has point scalars but another does not, point
> >> scalars will not be appended.)"
> >>
> >> Regards,
> >>   Alex
> >>
> >>
> >> On Thu, Aug 2, 2012 at 4:25 AM, Gonzalo Amadio <gonzaloamadio at gmail.com
> >
> >> wrote:
> >> > Hello everyone. Is there some reason whereby vtkAppendPolyData delete
> >> > the
> >> > scalars when I append 2 polydatas?
> >> >
> >> > Here is my code.
> >> >
> >> >> myPolyData->ShallowCopy(otherPolyData);
> >> >>         SubdividePolyData(myPolyData);   /// Here I modified the
> >> >> polydata,
> >> >> so I need to assign it again the scalar array.
> >> >>
> >> >>
> >> >>
> >> >>         // The problem I think is here in this lines, where I assign
> >> >> the
> >> >> scalar array
> >> >> vtkIntArray* scalars = vtkIntArray::New();
> >> >> scalars->SetNumberOfComponents(1);
> >> >> scalars->SetNumberOfValues(myPolyData->GetNumberOfCells());
> >> >> scalars->SetNumberOfTuples(myPolyData->GetNumberOfCells());
> >> >>
> >> >>
> >> >>
> >> >> for (int i = 0; i < myPolyData->GetNumberOfCells(); i++)
> >> >> scalars->SetValue(i, 1);
> >> >>
> >> >>
> >> >>
> >> >> myPolyData->GetCellData()->SetScalars(scalars);
> >> >>
> >> >>
> >> >>
> >> >>         vtkSmartPointer<vtkAppendPolyData> appendGreenSubdAndRedBlue
> =
> >> >> vtkSmartPointer<vtkAppendPolyData>::New();
> >> >> appendGreenSubdAndRedBlue->AddInput(otherPolyData);   // what is
> >> >> extrange
> >> >> is that if I comment this line, it works fine
> >> >> appendGreenSubdAndRedBlue->AddInput(myPolyData);
> >> >> appendGreenSubdAndRedBlue->Update();
> >> >>
> >> >>
> >> >>
> >> >> vtkPolyData * finalPolyData = appendGreenSubdAndRedBlue->GetOutput();
> >> >>
> >> >>
> >> >>
> >> >>         vtkIntArray* scalarArray =
> >> >>
> static_cast<vtkIntArray*>(finalPolyData->GetCellData()->GetScalars());
> >> >>         std::cout  << scalarArray->GetNumberOfTuples() << std::endl;
> >> >> //This line gives me an error
> >> >
> >> >
> >> >
> >> > The error that I obtain is the following :
> >> >
> >> > File :     vtkAbstractArray.h -  line 104
> >> >
> >> >   vtkIdType GetNumberOfTuples()
> >> >     {return (this->MaxId + 1)/this->NumberOfComponents;}
> >> >
> >> > error:
> >> >
> >> > name               type                          value
> >> > this        vtkAbstractArray * const           0x0
> >> >
> >> >
> >> > I can assign "manually" again the scalars to the finalPolyData, but it
> >> > is
> >> > suppose that the scalars remains when I append them.
> >> >
> >> > Thank you!
> >> >
> >> > --
> >> > --------
> >> > Gonzalo
> >> >
> >> > _______________________________________________
> >> > Powered by www.kitware.com
> >> >
> >> > Visit other Kitware open-source projects at
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> >> >
> >> > Please keep messages on-topic and check the VTK FAQ at:
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> >> >
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> >> >
> >> _______________________________________________
> >> Powered by www.kitware.com
> >>
> >> Visit other Kitware open-source projects at
> >> http://www.kitware.com/opensource/opensource.html
> >>
> >> Please keep messages on-topic and check the VTK FAQ at:
> >> http://www.vtk.org/Wiki/VTK_FAQ
> >>
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> >
> >
> >
> >
> > --
> > --------
> > Gonzalo Amadio
> >
> _______________________________________________
> Powered by www.kitware.com
>
> Visit other Kitware open-source projects at
> http://www.kitware.com/opensource/opensource.html
>
> Please keep messages on-topic and check the VTK FAQ at:
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-- 
--------
Gonzalo Amadio
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