Unfortunately, OpenGL is anything but "quite simple" and is very complex.
Fortunately, you can find frameworks built on top of OpenGL that make things a lot easier for the developer. If you're interested in C++, you should check out these:
Note that Unity is the only proprietary software of these 3. The basic version is free and limited, but enough to discover how it works. However for any substantial professional work, you'll need to by the Pro edition that is expensive (1500USD or 75USD/month for a minimum of 12 months).
I have limited experience with Panda (although I used to Python bindings not the C++ ones, for sanity's sake...). If you have questions, I could maybe help out there.