@julienchz
Hi
I have created some opengl tutorials check here: https://bitbucket.org/joaodeusmorgado/opengltutorials/src/master/
I am using QOpenGLWidget, but I use mostly raw opengl, you could easily create a abstract render class, and then reuse it to QOpenGLWidget, or any other frame work of your choice render class.
Hope it helps

i tried to use as many Gl functions instead of qt to use my old working code. But there is still nothing displayed. That's driven my crazy.

https://git.rwth-aachen.de/carstenf/OpenGL/tree/master/MeshViewerQt

Is there any way to see the content of the buffer while runtime???