Hello Paulo,
Thank you for your response.
Unfortunately if the vtkProperty objects are automatically created by vtkActor::GetProperty(), they contain uninitialized values (garbage values that are different each time I run the program), so they could have shading set to Flat or Gouraud randomly. So I need to know if a vtkProperty object for this vtkActor does not exist before I call vtkActor::GetProperty() or if someone else has already created a vtkProperty object for this vtkActor.
Thanks,
Matthias