To understand Vulkan, Metal or Direct3D 12, you first need to understand modern high-level APIs like OpenGL 4 or Direct3D 11. The fixed-function pipeline is not

To understand Vulkan, Metal or Direct3D 12, you first need to understand modern high-level APIs like OpenGL 4 or Direct3D 11. The fixed-function pipeline is nothing like the new way of doing things. Then you can move to low-level ones, if you really want to spend a few weeks on it! But if it is a hobby, I suggest you stay with a high-level one.