[vtkusers] How to back tracing the data pipeline

[Xiaofeng Zhao]

I would like to know if it is possible to back track a data pipeline.  For 
example, for the sphere example in the following:

  // create sphere geometry
  vtkSphereSource *sphere = vtkSphereSource::New();

  // map to graphics library
  vtkPolyDataMapper *map = vtkPolyDataMapper::New();
  map->SetInput(sphere->GetOutput());

I'd like to know if it's possible to get to the vtkSphereSource object from 
the vtkPolyDataMapper object.

Thanks in advance.

Xiaofeng Zhao