[vtkusers] Find reason for exclusion of vtkGUISupportQtOpenGL in build output?

[Marcus D. Hanwell]

On Wed, Jun 29, 2016 at 10:43 AM, Elvis Stansvik
<elvis.stansvik at orexplore.com> wrote:
> 2016-06-29 16:37 GMT+02:00 Sankhesh Jhaveri <sankhesh.jhaveri at kitware.com>:
>>
>> vtkGUISupportQtOpenGL module hasn't been ported to the OpenGL2 backend
>> yet.
>>
>> See:
>> https://github.com/Kitware/VTK/commit/e58ca401466f9af4c542c085f7b599b6bde939c8
>>
>> For now, it just works with the OpenGL backend.
>
> Aha. That explains it. Thanks.
>
> Are there any big downsides to using the OpenGL backend? What are the main
> benefits of the OpenGL2 backend?
>
I would echo Sankhesh's comments - are there any applications using
the classes in vtkGUISupportQtOpenGL? There are not many I am aware
of, and the classes in that module use a deprecated Qt class. The vast
majority make use of QVTKWidget in vtkGUISupportQt

Things changed quite a bit in Qt, and I think if you are
packaging/using this in general builds skipping vtkGUISupportQtOpenGL
is normally the correct thing to do unless you have a compelling user
of the classes in there. If you do it would be great to learn what is
using it in the wild.

We will hopefully have a replacement for OpenGL2 soon, but it should
likely derive from the newer QOpenGL* classes, and as such may not
precisely match the previous API.

Marcus