[vtkusers] Depth peeling and Qt

[Shawn Waldon]

Hi Ignacio,

IIRC, VTK 6.2 was before VTK had real support for Qt5 and there were still
some major issues with VTK + Qt5 (as you have noticed).  You will either
have to backport changes or update to a newer VTK.  I think VTK 8.1 may be
the first release since QVTKOpenGLWidget (full Qt5 support) was added,
although it may have been in 8.0.  You could try backporting
QVTKOpenGLWidget, but I'm not sure how difficult that will be (it requires
Qt 5.5 or 5.6 minimum I think).  Also, QVTKOpenGLWidget only works with the
newer "OpenGL2" rendering backend which was still experimental in VTK 6.2.
So you may have trouble with that too.  Your easiest approach would
probably be to use a newer VTK.

HTH,
Shawn

On Fri, Jan 12, 2018 at 8:48 AM, Sankhesh Jhaveri <
sankhesh.jhaveri at kitware.com> wrote:

> Hi Ignacio,
>
> In general, depth peeling is known to work with VTK and Qt5.
> Are you using the QVTKOpenGLWidget
> <https://www.vtk.org/doc/nightly/html/classQVTKOpenGLWidget.html>?
> Could you post your modifications somewhere for us to see?
>
> Thanks,
> Sankhesh
> ​
>
> On Fri, Jan 12, 2018 at 7:45 AM Ignacio Fernández Galván via vtkusers <
> vtkusers at vtk.org> wrote:
>
>> Hi all,
>>
>> I'm trying to get depth peeling and Qt interface to work together with
>> VTK 6.2.0 (Ubuntu 16.04) and python, and I'm not having much success.
>>
>> Depth peeling with "plain" VTK works fine
>> (http://vtk.1045678.n5.nabble.com/Enable-depth-peeling-
>> after-initialization-td5746070.html),
>> but then problems start
>>
>> I can't try PyQt4 because "import vtk" crashes (see
>> https://gitlab.kitware.com/vtk/vtk/issues/16009).
>>
>> So I modified
>> https://www.vtk.org/Wiki/VTK/Examples/Python/Widgets/EmbedPyQt to work
>> with PyQt5. I also modified QVTKRenderWindowInteractor to use PyQt5 and
>> configure the RenderWindow with:
>>
>> self._RenderWindow.SetMultiSamples(0)
>> self._RenderWindow.SetAlphaBitPlanes(1)
>>
>> but (a): the sphere looks weird, like some facets being inside out and
>> not being rendered, and (b): depth peeling is not enabled with the
>> translucent object that works without Qt.
>>
>> If I use an external (non-Qt) render window, it works fine, but then the
>> event loop conflicts with Qt and I get a working VTK window and a frozen
>> Qt interface.
>>
>> I would appreciate some help or a working example, or even the assertion
>> that it will never work.
>>
>> Thanks,
>> Ignacio
>> _______________________________________________
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>>
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>> Please keep messages on-topic and check the VTK FAQ at:
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>>
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>
>
> --
> Sankhesh Jhaveri *Sr. Research & Development Engineer* | Kitware
> <http://www.kitware.com/> | (518) 881-4417
> ​
>
> _______________________________________________
> Powered by www.kitware.com
>
> Visit other Kitware open-source projects at http://www.kitware.com/
> opensource/opensource.html
>
> Please keep messages on-topic and check the VTK FAQ at:
> http://www.vtk.org/Wiki/VTK_FAQ
>
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>
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