[osg-users] OpenGL viewport error (with Oculus)

Robert Osfield robert.osfield at gmail.com
Wed Oct 17 03:56:20 PDT 2018

Hi Riccardo,

The OSG doesn't do fine grained GL error checking by default so when it
does check for a GL error this error may have occurred many GL operations
before, so while the error may have been reported just after a viewport is
set it could well be prior operations that are the cause.

You can enable finer grained GL error checking by setting the
OSG_GL_ERROR_CHECKING env var to ON i.e.


This will hopefully give you a more precise location of the error.


On Wed, 17 Oct 2018 at 11:43, Riccardo Corsi <riccardo.corsi at kairos3d.it>

> Hi all,
> when using my application with the Oculus I get the following GL error at
> every frame:
> *Warning: detected OpenGL error 'invalid operation' after applying
> attribute Viewport *
> This error is coming from the call RenderStage::drawImplementation()
> <https://github.com/openscenegraph/OpenSceneGraph/blob/master/src/osgUtil/RenderStage.cpp#L1333> but
> the _viewport is valid. I'm not so familiar with the backend to understand
> where this error might come from.
> Any hint to debug this?
> Note: I'm using the Oculus through osgOculusViewer
> <https://github.com/bjornblissing/osgoculusviewer>.
> The sample Oculus viewer works fine without GL errors.
> My app is setup the same way, I cannot spot any sensible difference.
> I'm using win10, osg 3.6.3
> Thanks,
> Riccardo
> _______________________________________________
> osg-users mailing list
> osg-users at lists.openscenegraph.org
> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
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