[vtk-developers] BUG: vtkImageActor - set of ComputedDisplayExtent variable.

[john Tourtellott]

May I suggest adding a brief /* comment */ to the code indicating why
the line in question is not a typo or copy-paste error, so that others
won't suspect it's a bug.

john



On Wed, 2010-07-14 at 10:28 -0400, vtk-developers-request at vtk.org wrote:
> Date: Wed, 14 Jul 2010 10:27:57 -0400
> From: Dave Partyka <dave.partyka at kitware.com>
> Subject: Re: [vtk-developers] BUG: vtkImageActor - set of
> 	ComputedDisplayExtent variable.
> To: Karthik Krishnan <karthik.krishnan at kitware.com>
> Cc: vtk-developers at vtk.org, David Gobbi <david.gobbi at gmail.com>,
> 	"Pokutnev,	Pavel \(GE EntSol, SensInsp\)" <Pavel.Pokutnev at ge.com>
> Message-ID:
> 	<AANLkTimJBBjcu39LagffURBl6wB5XZsuWo8J5ZhI5a4l at mail.gmail.com>
> Content-Type: text/plain; charset="iso-8859-1"
> 
> I apologize for hastily committing this. I have reverted it back.
> 
> On Wed, Jul 14, 2010 at 10:23 AM, Karthik Krishnan <
> karthik.krishnan at kitware.com> wrote:
> 
> > This behaviour has always existed in vtkImageActor - due to the way VTK
> > deals with point data and cell data and the fact that the tips of the render
> > window delineate the available screen pixels for display. What this means is
> > that the tips of the clipped rectangle you are seeing (and the centers of
> > any other rectangle) correspond to the positions of the centers of
> > vtkImageData voxels. Because the display extent, in word coordinates runs
> > from the Word position of the left edge voxel center to the world position
> > of the right edge voxel center, you end up with clipping.
> >
> > This has been the topic of discussion on the list before.
> >
> > I don't believe that the fix you proposed can resolve that. Does it ? It
> > would simply cause one to update the whole input needlessly leading to
> > slowness when one renders a vtkImageActor for the very first time, without
> > setting the DisplayExtent.
> >
> > Thanks
> > --
> > karthik
> >
> >
> >