I need to change my projects rendering environment with better one. At the moment i am using company's old - not supported one.

I searched and found- Openscenegraph and ogre3d ( implemented with c++) api's. I need them to achieve simple modeling editing things like combining meshes etc.

So which one of those:
- quick to learn
- quick to implement
- easy to control
- support custom file extensions - i wish to embed my custom model files.

I will use qt5 as application environment.