[vtk-developers] Marking data modified

[David Cole]

I don't specifically know the answer to this one, but in general,
these sorts of things are on purpose for performance in VTK.

If you want to replace 100 (or even more) cells, you'd want
ReplaceCell NOT to call Modified, and just do it once at the end of
your bulk replacement. I'd be surprised if somebody chimed in and
contradicted this... so I would think just fixing the docs is the
right way to go here.


HTH,
David C.


On Mon, Aug 15, 2016 at 11:59 AM, Shawn Waldon <shawn.waldon at kitware.com> wrote:
> Hi all,
>
> I have been tracking down a bug in the vtkBoxRepresentation where the
> selected face never updated.  The issue was that the widget was calling
> ReplaceCell on the vtkCellArray for the selected face polydata, but never
> calling Modified() on the cell array (though it did call Modified() on the
> polydata).  With the new OpenGL backend this matters.  The documentation for
> ReplaceCell doesn't say that you have to do this afterward and the writer of
> vtkBoxRepresentation used that documentation.
>
> So my question is this: why doesn't ReplaceCell mark the cell array as
> modified? Is this a bug or on purpose for performance reasons?  I will
> update the docs or fix ReplaceCell once I know which is wrong.
>
> Thank you,
> Shawn
>
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