[vtkusers] normal vectors on streamlines

[Yifei Li]

Hi all,

I retrieved the normal vectors by

vtkFloatArray* normals =
static_cast<vtkFloatArray*>(streamer->GetOutput()->GetPointData()->GetArray("Normals"));
        float normal[3];
for (int i = 0; i < normals->GetNumberOfTuples(); i++)
  {
    normals->GetTupleValue(i, normal);
    vtkMath::Normalize(normal);
    cout << normal[0] << ", " << normal[1] << ", " << normal[2] << endl;
  }


However, I saw in the output from above many zero vectors (0, 0, 0), and
also (nan, nan, nan).

So it seems there exists bugs in vtkStreamTracer's normal computation
routine.  Is there anyone who had this problem?

Yifei
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