[vtk-developers] vtkDepthSortPolyData modernization

[Will Schroeder]

Go for it you'll never go back ;-)

--
Sent from mobile phone please excuse typos and terseness
On Nov 13, 2015 12:00 PM, "Burlen Loring" <burlen.loring at gmail.com> wrote:

> Hi Will,
>
> Your recent post mentioning changing std::sort to vtkSMPTools::Sort() had
> me thinking about that, and also about giving the gift of code. In the
> algorithm there are 3 distinct parts, computing the depths, sorting, and
> building the output. Each of of those could be parallelized. I'm willing to
> try it. Thanks for the suggestion!
>
> Burlen
>
> On 11/12/2015 10:20 AM, Will Schroeder wrote:
>
> Burlen I would use vtkSMPTools::Sort(). Under the hood it uses std::sort
> when VTK is built in VTK_SMP_IMPLEMENTATION_TYPE=Sequential mode (default).
> But when built with VTK_SMP_IMPLEMENTATION_TYPE=TBB, etc. you'll see
> significant parallelization benefits.
>
> W
>
> On Wed, Nov 11, 2015 at 12:04 PM, Burlen Loring <burlen.loring at gmail.com>
> wrote:
>
>> Hi All,
>>
>> Would anyone be willing to review this patch?
>> https://gitlab.kitware.com/vtk/vtk/merge_requests/844
>>
>> I was profiling VisIt and noticed that vtkDepthSortPolyData (in spite of
>> its limitations it is used by VisIt for transparent rendering) made use of
>> qsort and about 1/2 the time was spent by qsort. std::sort is known to be
>> faster because of the possibility of the compiler to inline the
>> comparisons. Updating qsort to std::sort seemed like an easy way to make it
>> faster. As I worked the profiler pointed out a number of other fairly easy
>> things to improve and overall the class is now ~3x faster for two of the
>> modes and ~2x faster for the other. I enumerated the changes in the commit
>> message and have added a cxx test to improve the test coverage.
>>
>> If you have the time, please take a look, and let me know if you have any
>> feedback on it.
>>
>> Thanks
>> Burlen
>>
>>
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>
>
> --
> William J. Schroeder, PhD
> Kitware, Inc.
> 28 Corporate Drive
> Clifton Park, NY 12065
> will.schroeder at kitware.com
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> (518) 881-4902
>
>
>
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