[vtkusers] Fwd: Bug in vtkPolyData

[Paul Edwards]

BTW there would be a problem with your implementation if
vtkPolyData::InsertNextCell was called after a call to
vtkPolyData::DeleteCell (and before vtkPolyData::RemoveDeletedCells)
as it would not append to vtkPolyData::CellsCopy.  I'm not sure if
that is allowed but your implementation would result in a index out of
bounds.

On 27 November 2014 at 11:23, Paul Edwards <paul.m.edwards at gmail.com> wrote:
> Hi Andy,
>
> I've attached a patch that uses a slightly different approach which
> only changes vtkPolyData::RemoveDeletedCells.  The code looks simpler
> and it passes your new test although I am assuming it is ok to
> ShallowCopy the vtkPolyData at the top of the function.  I'll let you
> decide if it is better!
>
> Note: the patch is for the VTK with the current ParaView master
> (v6.1.0-2506-g2e5a3c9)
>
> Best regards,
> Paul
>
> On 23 November 2014 at 17:37, Andy Bauer <andy.bauer at kitware.com> wrote:
>> Hi Paul,
>>
>> I have a potential fix for this bug at
>> http://review.source.kitware.com/#/t/5040/. It feels like a hack but I
>> couldn't figure out a better way to do it yet. I also modified a test to
>> verify that the proper cells were getting removed, based on the cell's
>> points.
>>
>> If you see a better way to do this, please let me know.
>>
>> Thanks,
>> Andy
>>
>> On Mon, Nov 17, 2014 at 5:37 PM, Andy Bauer <andy.bauer at kitware.com> wrote:
>>>
>>> Hi Paul,
>>>
>>> Thanks for the input. I'm at SC14 right now so I won't be able to look at
>>> this until I get back.
>>>
>>> Cheers,
>>> Andy
>>>
>>> On Mon, Nov 17, 2014 at 4:26 AM, Paul Edwards <paul.m.edwards at gmail.com>
>>> wrote:
>>>>
>>>> Hi Andy,
>>>>
>>>> I've attached a sample program demonstrating the issue.  The example
>>>> just loads the sphere.vtk file, removes all cells where the "Result"
>>>> value is not 0 and writes the result to output.vtk.  The tar file also
>>>> contains the correct and incorrect output.
>>>>
>>>> Best regards,
>>>> Paul
>>>>
>>>> On 15 November 2014 02:59, Andy Bauer <andy.bauer at kitware.com> wrote:
>>>> > Hi Paul,
>>>> >
>>>> > I was part of that fix and I think it's correct. There may have been
>>>> > more to
>>>> > that fix though since it took a couple of shots before getting it
>>>> > correct so
>>>> > the git history may not be as pristine as desired. If you can give me
>>>> > more
>>>> > specifics on the bug though I can try to see what's going on with it.
>>>> > If I
>>>> > remember correctly though, that fix had to do with the fact that some
>>>> > places
>>>> > thought that the order of iterating through cells in a vtkPolyData was
>>>> > first
>>>> > through all vertex cells, then all line cells, then all polys and
>>>> > finally
>>>> > through all triangle strips, irregardless of the order that cells got
>>>> > inserted in (i.e. using InsertNextCell()). The reality is that for
>>>> > polydata
>>>> > that cells are indeed iterated through in their insertion order. The
>>>> > test
>>>> > that was added for those changes hopefully shows the proper
>>>> > functionality
>>>> > along with associated cell data manipulations as well.
>>>> >
>>>> > Regards,
>>>> > Andy
>>>> >
>>>> >
>>>> >
>>>> > On Thu, Nov 13, 2014 at 1:55 PM, Paul Edwards
>>>> > <paul.m.edwards at gmail.com>
>>>> > wrote:
>>>> >>
>>>> >> Hi,
>>>> >>
>>>> >> I've just noticed an issue with vtkPolyData.  I had been calling
>>>> >> vtkPolyData::DeleteCell to remove the unwanted cells, followed by a
>>>> >> call to vtkPolyData::RemoveDeletedCells.  The result is not as it
>>>> >> should be in the latest version.  To fix I just started reverting
>>>> >> previous commits.  I tracked it down to the following:
>>>> >>
>>>> >> bugfix 14459: Iterating through polydata cells incorrectly.
>>>> >> commit: 44131c6d05375692af8b6b38cf4291983bdd8f45
>>>> >>
>>>> >> Sorry but I do not have time to provide a test case or track where in
>>>> >> this commit lies the problem.  I just thought I would give details
>>>> >> here in case anyone else notices the same problem and is searching for
>>>> >> a solution.
>>>> >>
>>>> >> Best regards,
>>>> >> Paul
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>>>> >
>>>
>>>
>>