[vtkusers] How to set the scalars of points which come from vtkSource class?

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hi,all:
   I have a problem when I programmed with the vtkSource class.
   I wanted to produce a simple cube from vtkCubeSource and
then insert the scalars to its 8 points. It seems easy like 
this:
  

   vtkCubeSource  *cube=vtkCubeSource::New();

   for (int i=0; i<8; i++) scalarstemp->InsertTuple1(i,i);
   cube->GetOutput()->GetPointData()->SetScalars(scalarstemp);
   scalarstemp->Delete();


 


 But the codes always work not well.The method setscalars failed to set 
the scalars.

 Need your help. 
 Thank you in advance.

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