Re: [vtkusers] the New QVTKOpenGLWidget

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Re: [vtkusers] the New QVTKOpenGLWidget

Jean-Christophe Fillion-Robin-2
Hi All,

Thanks for the feedback.

Based on feedback, we will keep the widget QVTKOpenGLWidget and only rename QVTKOpenGLSimpleWidget to QVTKOpenGLNativeWidget
The corresponding change can be found at

> unless it's somehow possible to make a widget that will work well in both scenarios

That is the idea, ultimately we would like the QVTKOpenGLWidget to be smarter.


On Tue, Aug 28, 2018 at 1:28 AM Elvis Stansvik <[hidden email]> wrote:
2018-08-28 0:12 GMT+02:00 Jean-Christophe Fillion-Robin <[hidden email]>:
> Hi All,
> To follow up on Mathieu email, we are in in the process of integrating this
> merge request [1] (and the equivalent in paraview [2]) that will add/rename
> the following classes:
> * QVTKOpenGLAlienWidget  (equivalent to QVTKOpenGLWidget class described in
> the previous email)
> * QVTKOpenGLNativeWidget (equivalent to QVTKOpenGLSimpleWidget class
> described in the previous email)
> * QVTKOpenGLWidget will:
>    - behave as it was before the introduction of the "new QVTKOpenGLWidget"
> and will instead derive from QVTKOpenGLNativeWidget.
>    - only be available if VTK_LEGACY_REMOVE is OFF
>    - will most likely be removed in VTK 10
> We anticipate that this clearer naming convention will facilitate update of
> user code.
> Let us know what you think,

I think this naming is the best one possible, unless it's somehow
possible to make a widget that will work well in both scenarios of
course :)

Much better naming than the "Simple" suffix, so +1.


> Thanks
> Jc
> [1]
> [2]
> On Thu, Aug 23, 2018 at 5:07 AM Mathieu Westphal
> <[hidden email]> wrote:
>> Hello list,
>> If you are working on a VTK/Qt application this information should
>> interest you.
>> Sometime ago, a new QVTKOpenGLWidget implementation has been added to VTK,
>> while the old one has been moved to QVTKOpenGLSimpleWidget.
>> The last fixes for this change have just been merged, so make sure to use
>> VTK master to test this.
>> 1. Why is there a new widget and what does it do ?
>> We have been having some issues reported for the old widget, and the old
>> widget could not support quad buffer stereo rendering by design.
>> Has it is a needed feature in ParaView, a reimplementation was necessary.
>> This new widget fix most of the reported issues with the old widget as well
>> as adding stereo support.
>> 2. Why keeping the old widget around then ?
>> Due to Qt limitations, this new implementation does not support very well
>> being a native widget.
>> But native widget are sometimes mandatory, for example within QScrollArea
>> and QMDIArea, so the QVTKOpenGLSimpleWidget should be used when in needs of
>> VTK rendering in the contact of Qt native widget.
>> Also it allows users to switch back to the old widget if necessary.
>> 3. I'm not sure what native widgets are, what should I do in my
>> application ?
>> Here are the different situation :
>> Your Qt application only uses a central QVTKOpenGLWidget for rendering:
>> -> Nothing to do, just build with last master and make sure all is working
>> well
>> Your Qt application only uses QVTKOpenGLWidget within QScrollArea or
>> QMDIArea, or manually set widgets to be native and you are not interested by
>> stereo rendering.
>>  -> Change all your QVTKOpenGLWidget to QVTKOpenGLSimpleWidget and you are
>> good to go
>> Your application uses a non-native QVTKOpenGLWidget for rendering as well
>> as native QVTKOpenGLWidget for rendering (eg: ParaView, with the central
>> rendering widget and the color map editor rendering widget in scroll areas)
>> :
>>  -> Use QVTKOpenGLWidget for non-native widgets and QVTKOpenGLSimpleWidget
>> for native ones. The later will never support stereo.
>> 4. I followed your recommendation but I see some strange
>> stuff/bugs/rendering issues
>> Even if this new class has been tested extensively and will be used in the
>> next ParaView release, It may still contains some issues. Feel free to
>> discuss them in this mailing list or on our gitlab.
>> Best regards,
>> Mathieu Westphal
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