[vtkusers] clean way to replace polydata

[Marius Erdt]

Hi vtk-users,

I've got a function that should recompute the normals of a vtkPolyData. 
However, if I try to delete the input poly by calling Delete and assign 
the output of the filter to its variable, the program chrashes.

void computeNormals( vtkPolyData* &poly ){

     vtkPolyDataNormals* normalsGen = vtkPolyDataNormals::New();
     normalsGen->SetInput( poly );
     normalsGen->Update();

     poly->Delete();
     poly = NULL;
     poly = vtkPolyData::New();
     poly->DeepCopy( normalsGen->GetOutput() );

     normalsGen->Delete();
}

The codes works if I don't delete the input PolyData. However, then I 
got a memory leak since the data of the original poly is not released.

Does anyone knows a solution?

Thanks,
Marius