Picky mathematical points with vtkCamera

[David Gobbi]

Hi All,

Yesterday I rewrote much of the geometrical transformation
code in VTK camera, in order to move the mathematics into
vtkProjectionTransform.  I also changed the behaviour a little,
and would like to gather peoples opinion.

Using vtkCamera::SetWindowCenter() in conjunction with
ParallelProjection.  The code used to shear the view volume,
I changed it so that it translates the view volume instead.
This seemed much more in line with what happens when 
SetWindowCenter is used with with perspective views.

However, I think that SetWindowCenter was originally meant
as a counter-intuitive (IMHO) method for creating oblique
projections.  So what I thought was an error in the VTK code
probably wasn't.

So, any opinions?  Should the result of using
vtkCamera::SetWindowCenter() with a parallel projection
be to shift the view volume, or to shear it?  


It also looks like I've broken the stereo-3D viewing code, that
will be fixed shortly. 

 - David

--
  David Gobbi, MSc                    dgobbi at irus.rri.on.ca
  Advanced Imaging Research Group
  Robarts Research Institute, University of Western Ontario

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