I'm on holidays since yesterday! I have a bit of time get back to side projects (and lifting weights). What better to celebrate this auspicious occasion than to bundle my OpenGL learning resources together in a sale.
You can get the Anton's OpenGL 4 Tutorials e-book, and Crongdor the Barbarian indie video game at discount on my itch.io page https://capnramses.itch.io/, or at an even higher bundled discount at https://itch.io/s/15742/antons-opengl-stuff-end-of-year-sale.
Crongdor the Barbarian is a game I wrote with OpenGL, and it ships with all the source code, so you can see how I did it, and maybe get some ideas for how to implement different effects, or how you can use the OpenGL API at scale beyond stand-alone demos, or just see how it bundles together so that it "runs on other peoples' computers". It's pretty straight-forward old-school C++ code ( arrays, loops, and structs ) so should be reasonably easy to follow. I'd of course do a few things differently now, and I'm always happy to chat about code or anything game development related if you want to ask questions.
If you're learning, or want to know where to start with computer graphics - these might be handy or interesting too.