[Development] OpenGL Support in Qt5

[BRM]

> From: Sean Harmer <sean.harmer at kdab.com>

> On Monday 16 July 2012 07:21:23 Thiago Macieira wrote:
>>  On segunda-feira, 16 de julho de 2012 15.12.15, Sean Harmer wrote:
>>  > On Monday 16 July 2012 07:08:38 Thiago Macieira wrote:
>>  > > I'm asking for Qt 5.0: what should we tell Linux distributors 
> to
>>  > > configure
>>  > > qtbase with? Considering what requirements qtwayland has, I think 
> it
>>  > > needs
>>  > > to be -opengl es2.
>>  > > 
>>  > > Correct?
>>  > 
>>  > If using wayland then yes I believe so.
>>  > 
>>  > If using xcb backend then -opengl desktop works fine.
>> 
>>  There's only one build of Qt. The choice is made at compile-time of 
> qtbase,
>>  not at run-time like the platform plugin.
>> 
>>  So everyone should use OpenGL ES 2.
> 
> Unless they want to support applications that use legacy OpenGL calls or 
> develop new applications that use modern desktop GL.
> 
> There seems to be a dependency issue here that needs resolving. Qtbase itself 
> has a configure time switch for OpenGL ES vs Desktop whereas the QPA plugins 
> can be decided upon at runtime. Is there some way we can move the GL decision 
> to be runtime too I wonder?
> 
> I don't like how even building the wayland QPA plugin means that we limit Qt 
> 
> and the apps built with it to OpenGL ES. I really don't want to get into a 
> situation where we can build modern OpenGL apps for the desktop that work fine 
> on Windows and Mac but not on Linux just because Qt for Linux has the wayland 
> qpa plugin built.

Quite agreed.

> 
> Ideas welcome.
> 

Just $0.02, but perhaps this would be good functionality to provide for developers for 5.0/5.1, and we instruct distributions not to provide it by default for the time being.
Once the world has caught up a bit, then that can be changed, but those that are using the functionality, etc can do so and build/provide their own libs if necessary.

Yes, it may mean that app developers might have to provide their own install of the Qt libs ( or distributions provide two version that can be simultaneously installed - that's up to them) for a while, but why hinder the progress of Qt apps?

And, btw, I'm thinking of some of the larger Qt-based applications like AutoDesk's AutoCAD. (No, I don't work for AutoDesk or work on AutoCAD itself; I'm just aware that they do use Qt.)
Or VLC, or other video intensive applications.

$0.02, for whatever it is worth.

Ben