In 2026: Please don't learn this; it's obsolete. Learn Vulkan (Or another modern API; or how to build engines on top of them; or how to write shaders; or how to do GPU compute using CUDA etc)
Relatedly: could someone recommend a Vulkan introduction for people who don't "just want to make it work"? I understand the fact that Vulkan abstracts away a lot less of the rendering device than OpenGL does – that may be a strength or a weakness, but either way I'd like to understand. It seems a lot of introductions just skip over it all while apologizing for the boilerplate. I think I once bookmarked an article whi…
Khronos has a tutorial that walks you through getting a triangle on the screen, to rendering a glTF model, all the way up to how you go about making a simple engine.
But I'm not sure what you mean by "understand". If you want to understand the graphics theory, Vulkan tutorials aren't going to teach you that.