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

[Riccardo Corsi]

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

[Robert Osfield]

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.

set OSG_GL_ERROR_CHECKING=ON

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

Robert.

Post by Riccardo Corsi
Hi all,
when using my application with the Oculus I get the following GL error at
*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
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[Riccardo Corsi]

Hi Robert,

the error I've reported is what I get with the env var already ON.
Unfortunately it doesn't add any more details.
Riccardo

Post by Robert Osfield
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.
set OSG_GL_ERROR_CHECKING=ON
This will hopefully give you a more precise location of the error.
Robert.

Post by Riccardo Corsi
Hi all,
when using my application with the Oculus I get the following GL error at
*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
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osg-users mailing list
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org

_______________________________________________
osg-users mailing list
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org

[Robert Osfield]

Post by Riccardo Corsi
the error I've reported is what I get with the env var already ON.
Unfortunately it doesn't add any more details.

Try adding GL checks around any of the Oculus related code.

Robert.

[Riccardo Corsi]

I've tracked the issue down to the fact that it is necessary to call
viewer.setReleaseContextAtEndOfFrameHint(false);
for the Oculus to work properly.

Thanks,
Riccardo

Post by Robert Osfield

Post by Riccardo Corsi
the error I've reported is what I get with the env var already ON.
Unfortunately it doesn't add any more details.

Try adding GL checks around any of the Oculus related code.
Robert.
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osg-users mailing list
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org

[Robert Osfield]

Hi Riccardo,

Post by Riccardo Corsi
I've tracked the issue down to the fact that it is necessary to call
viewer.setReleaseContextAtEndOfFrameHint(false);
for the Oculus to work properly.

Is it running single context, single threading and then using GL calls in
the main thread?

Robert.

[Riccardo Corsi]

Hi Robert,

yes, it's single context, single thread, all GL calls are done by osg and
osgOculusViewer in the various camera draw callbacks.

Post by Robert Osfield
Hi Riccardo,

Post by Riccardo Corsi
I've tracked the issue down to the fact that it is necessary to call
viewer.setReleaseContextAtEndOfFrameHint(false);
for the Oculus to work properly.

Is it running single context, single threading and then using GL calls in
the main thread?
Robert.
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