[vtk-developers] Generated normals not present in the polydata from unknown reason.

[Jana Sefcikova]

Hi Bill,
thanks for response, but normalGenerator is updated before assignement in
original code as you propose.

On 20 April 2012 16:34, Bill Lorensen <bill.lorensen at gmail.com> wrote:

> Oops...
> Try
> normalGenerator->Update();
>  before
> polydata = normalGenerator->GetOutput();
>
>
> On Fri, Apr 20, 2012 at 10:33 AM, Bill Lorensen <bill.lorensen at gmail.com>
> wrote:
> > Try
> > normalGenerator-Update();
> > before
> > polydata = normalGenerator->GetOutput();
> >
> >
> > On Fri, Apr 20, 2012 at 10:30 AM, Jana Sefcikova <neollie at gmail.com>
> wrote:
> >> Dear Users,
> >> I tested vtk example PolyDataExtractNormals
> >> (
> http://www.vtk.org/Wiki/VTK/Examples/Cxx/PolyData/PolyDataExtractNormals)
> >> code that tries to detect whether normals are present in input polydata
> >> structure and if not it will generate them. I made small change to code
>  at
> >> the end of the main function in order to run TestPointNormal twice so I
> have
> >> :
> >>
> >>   std::cout << "PolyData address: " << polydata << std::endl;
> >>   TestPointNormals(polydata);
> >>
> >>   TestPointNormals(polydata);
> >>
> >> I expected that after first round the polydata will be changed and will
> >> contain new array for "Normals"  because output of normal generator is
> >> assigned to input polydata in the first round / polydata =
> >> normalGenerator->GetOutput(); /
> >> so second  test round should pass directly without normal generation.
> >> But after the firt test, polydata normals are not present any more so
> second
> >> Test generate them  again .
> >> So my question is : Why normals dissapeared ?
> >> The same confusion for me occured when I enabled splitting on normal
> >> generator (normalGenerator->SetSplitting(1);).  Inside first
> >> TestPointNormals polydata had more points as before at the end (due to
> >> splitting), but second test again work on likely unchanged polydata.
> >>
> >> Why two functions working on the same pointer that is changed inside
> each
> >> call looks unchanged ?
> >>
> >> Thanks for any advice.
> >>
> >>
> >>
> >>
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> > --
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