Comment by dahart

Unfortunately, the goal with OpengGL is not to teach graphics and rendering concepts. Same goes for DirectX, Vulkan, WebGL, etc. These APIs are being designed primarily for performance, not for ease of learning. For teaching and learning, it’s a great idea to start with rasterization & ray tracing in software first! That can teach you the graphics concepts first, and also provide good motivation to learn a graphics API if you want it to go faster.