vtkStructuredPoints-->vtkExtractVOI-->vtkMarchingCubes-->vtkPolyDataNormals-->
                                         -->vtkPolyDataMapper-->vtkActor-->vtkXRenderWindow

and uses the vtkXRenderWindowInteractor to manipulate the 3D object.

I also have 3 additional X windows (which can accept GL commands).

My problem is this: I use the same vtkStructuredPoints object to read the original data for the 3D window and the 3
2D GL windows. The GL windows just read from teh structured points scalar array to display the 2D slices (along
all 3 axial planes). The problem is, in the process, it invalidates the pipeline. Thus, when I come back to the 3D
window, the entire pipeline is executed  again, tremendously slowing down interaction. I have carefully looked
at the code; all I am doing is GetScalar () on the scalars array to get at the attribute data. I wouldnt think
this would cause a Modified signal to be sent (I am definitely not sending this) to the structured points scalars array.

I verified this, by copying the scalars to a separate array and using this to  update the 2D windows - no problem,
everthing works as it should and the pipeline doesnt re-execute. Obviously, I dont like this solution, as it
doubles the storage.

I would like to know under what conditions could the pipeline be invalidated (I mean from an execution standpoint)
by the above pipeline automatically, without an explicit Modified() signal from the application.

Could this be some bug in the pipeline update function? I am  using a nightly version from 9/15/99. Has vtk changed
enought that it might be worth an upgrade?

Thanks.

    -- krs

-- 
K.R.Subramanian                           Phone: (704) 547-4872
Department of Computer Science            FAX:   (704) 547-3516
UNC Charlotte                             Email: krs@cs.uncc.edu
9201 Univ. City Blvd.                     WWW: http://www.cs.uncc.edu/~krs
Charlotte, NC 28223-0001