[vtkusers] question about vtkAlgorithm::Update()

[Francois Bertel]

Hello,

vtkExecutive is an abstract class, Update() is overridden in concrete
subclasses. See the class hierarchy here:
http://www.vtk.org/doc/nightly/html/classvtkExecutive.html

On Fri, Jan 22, 2010 at 9:24 AM, dizou <di_zou at yahoo.com> wrote:
>
> vtkAlgorithm::Update() executes the following code:
>
> this->GetExecutive()->Update();
>
> So I looked at vtkExecutive::Update(). This is the code for
> vtkExecutive::Update():
>
>  if (this->Algorithm->GetNumberOfOutputPorts())
>    {
>    return this->Update(0);
>    }
>  return this->Update(-1);
>
> So vtkExecutive::Update(int) is:
>
> int vtkExecutive::Update(int)
> {
>  vtkErrorMacro("This class does not implement Update.");
>  return 0;
> }
>
> So does this mean that vtkAlgorithm::Update() will always have a return
> value of 0? So what exactly does vtkAlgorithm::Update() end up doing?
>
> this->Algorithm->GetNumberOfOutputPorts() returns 1
>
> This is the code I have:
>
> Geo = vtkGeometryFilter()
> Geo.SetInput(XReader.GetOutputDataObject(0))
> Normals = vtkPolyDataNormals()
> Normals.SetInput(Geo.GetOutput())
> Normals.Update()
>
> I get this error message when I get to Normals.Update():
> The instruction at "***" referenced memory at "***". The memory could not be
> "read"
>
> XReader.GetOutputDataObject(0) and Geo.GetOutput() all produce valid output.
> --
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>
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François Bertel, PhD  | Kitware Inc. Suite 204
1 (518) 371 3971 x113 | 28 Corporate Drive
                      | Clifton Park NY 12065, USA