QOpenGL on Mac - QCocoaGLContext: Falling back to unshared context

njbrown

I'm working on a opengl-based application in qt. It renders scenes fine on linux and windows, but on mac I end up with a black window. I used QOpenGLDebugLogger to give me some clarity on the issue and it outputs this error:

QCocoaGLContext: Falling back to unshared context

What does it mean and is this the cause of my scene not being rendered on mac specifically? If so how can i fix the issue?

The source for the project is here:
https://github.com/jahshaka/VR

Thanks in advance.

mrjj

Hi
200% mac noob but it seems to come from

http://code.qt.io/cgit/qt/qtbase.git/tree/src/plugins/platforms/cocoa/qcocoaglcontext.mm

// retry without sharing on context creation failure.
if (!m_context && m_shareContext) {
m_shareContext = nil;
m_context = [[NSOpenGLContext alloc] initWithFormat:pixelFormat shareContext:nil];
if (m_context)
qWarning("QCocoaGLContext: Falling back to unshared context.");
}

and its just a warning.

Did you check that openGL do work on the mac?

https://forum.qt.io/topic/70082/qt-5-7-opengl-core-profile-2-1-on-os-x-functions-don-t-work

njbrown

You were right, it's just a warning @mrjj .

I fixed the issue by setting the default surface format in the main function before the gui is created.

QSurfaceFormat format;
format.setDepthBufferSize(32);
format.setMajorVersion(3);
format.setMinorVersion(2);
format.setProfile(QSurfaceFormat::CoreProfile);

QSurfaceFormat::setDefaultFormat(format);

Maybe this is needed so the UI and the QOpenGLWidget has the same version opengl contexts so they play nice. I'm not entirely sure what goes on the background.