QOpenGLContext::swapBuffers() called with non-exposed window, behavior is undefined

[kantaki]

Hello,

I want to use Qt5 with OpenGL. I saw the talk from Sean Harmer on youtube.

Someone was able to recreate the code from the talk.
https://github.com/advancingu/Qt5OpenGL

But if I try to execute it I get the following error message " QOpenGLContext::swapBuffers() called with non-exposed window, behavior is undefined ", and a transparent window appears.

The code that is causing this error is probably:

@void Window::paintGl()
{
mContext->makeCurrent(this);
mScene->render();
mContext->swapBuffers(this);
}@

Any idea why I get this error?

The main problem is that the window is transparent. My guess is that this problem is related to the error message.

[1313]

Where in code you said that you are using DoubleBuffer? SwapBuffer Only works when you use doubleBuffer.

[kane]

The problem is, if the window is shown in the application but it is not in the window management system, it is a non exposed window. You cant swap the buffer on it.

You have to do the first draw after exposeEvent occurs or check if( !isExposed ) on window before you draw.