Of course, I already messed a lot with the Quake source, and learned a lot of stuff with it (read: I know/understand the basic math behind OpenGL, and I already messed with a number of "draw your first textured cube" tutorials). Problem is, nowadays Quake cannot be considered a good starting point regarding best practices for the more recent OpenGL incarnations (specially the older and simpler engines, like my Q2K4 engine - PLEASE, DON'T USE THAT AS REFERENCE!). And if you try to find in the internet something as comprehensive as Nehe's tutorials to OpenGL 3+ you'll have a hard time ahead.
So, I am asking to our more experienced engine coders if you guys can recommend online tutorials, manuals and even books that could help me to learn more about the last OpenGL resources and how to correctly use them. And, why not ? Any material covering DirectX essentials would be good, too. Thanks in advance.