[Interest] compiling qt with eglfs

[pritam.ghanghas at gmail.com]

On Wed, Nov 7, 2012 at 10:50 PM, Thomas Senyk
<thomas.senyk at pelagicore.com>wrote:

> On Wed, November 07, 2012 06:16:39 PM pritam.ghanghas at gmail.com wrote:
> > On Wed, Nov 7, 2012 at 5:29 PM, Thomas Senyk
> <thomas.senyk at pelagicore.com>wrote:
> > > On Wed, November 07, 2012 05:29:00 PM pritam.ghanghas at gmail.com wrote:
> > > > Hi
> > > >
> > > > I was trying to get qt working with eglfs + opengles.
> > > > I am able to compile but when I try to run hellogl_es2. I get this.
> > > >
> > > > ./hellogl_es2 -qws
> > >
> > > No no no! :) No! :)
> > > I can't stretch that enough: eglfs doesn't support this application!
> > >
> > > Those plugins (eglfs, simplegl, minimalegl, kms,...) only support
> one(!)
> > > fullscreen opengl-surface..
> > > Therefor one can't mix QWidget-classes with QGLWidget (as it's the case
> > > for
> > > hellogl_es2)
> > >
> > > How do I get the mix(QWidget + some QGLWidgets) working then? I need
> the
> >
> > mix. I have a lot of
> > code that is in QWidgets and I would like to use QGLWIdget incremently as
> > and when I need it.
> > I was previously using directfb. I enabled opengl without changing
> anything
> > else, hellogl_es2 lauched
> > but glWidget showed nothing, just some garbage probably due to not
> clearing
> > the surface.
> > So I swtiched to eglfs that resulted in the current scenario.
>
> This is a hard limitation of eglfs.
> It can't handle/composit multiple egl-surfaces and as the QGLWidget needs a
> egl-surface and you also having QWidgets around the QGLWidget which also
> need
> a surface you can forget about eglfs.
>
>
> You need a proper windowing system for that kind of approach.
> The 3 I know of:
> - X11       (not embedded)
> - directfb (not clue about the current state of the different directfb
> pluings)
> - wayland (properly not available on your board)
>
>
>
> Another long-term solution would be to switch to QtQuick(2.0)   ;)
>

Thank you for great explanation. We would switch to QtQuick ultimately.
But for now I need to see opengl performance. I have not yet reached to the
point where I get
a simple gl application running.


>
> >
> > > Take qmlviewer or similar and use QGLWidget as viewport for the
> > > QGraphicsView/QDeclarativeView
> > > (-opengl as argument for qmlviewer)
> > >
> > > > QScreenLinuxFb::connect: No such file or directory
> > > > Error opening framebuffer device /dev/fb0
> > > >
> > > > : driver cannot connect
> > > >
> > > > Aborted
> > > >
> > > > I don't understand why it needs  /dev/fb0.
> > >
> > > QWS != QPA
> > >
> > > They are different, independent Qt ports.
> > > They can't co-exist! You have to take one or the other!
> > >
> > >
> > > eglfs is a platform plugin for QPA
> > > Their is simplegl for QWS, but I got no clue about it's current state.
> > >
> > > Me advice is to try QPA and eglfs as I know it's working.
> >
> > So if I supply -qpa while configuring qt and copy my mkspec from qws to
> qpa
> > dir, will i get working QPA?
>
> Yes most likely!
>  ... as long as you keep in mind that the plugins are also two distinct
> sets!
> One set of plugins for QWS
> Another set of plugins for QPA
>
> >
> > > > Any Ideas what is wrong. This is with Qt 4.8.3.
> > > > configure argument and output can be found here.
> > > > http://pastebin.kde.org/598940/
> > > >
> > > > I am comiling qt5 in parallel but results from that will take some
> time.
> > > > Any ideas what is going wrong here.
> > >
> > > You will not have that problem with qt5, as qws is gone ;)
> > >
> > > great, lesser confusion :-).
>



-- 
pritam
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