Muddling through SDL GPU - The Plan

13 Jul 2025

Ok, so. I want to learn how to use a modern GPU API, and since SDL3 was just released with a new GPU API abstraction over the major 3 GPU APIS (Direct3D 12, Vulkan, and Metal), it seems like a good time! Except, it’s maybe a little too new: the documentation on it is great, but it feels like it assumes you already know how to work with one of the big 3 APIs. I don’t. I never really moved beyond OpenGL 1.2. Maybe 1.1? Either way, my graphics programming knowledge is more than 20 years out of date.

The tutorials I’ve been able to find are good, if you already understand the concepts. Moonside Games in particular has some good information, and there’s an example repository, but I need something a little more basic. I’ve never written a shader or assembled a pipeline; I don’t even think I’ve used vertex buffers.

So I started trying to learn how to do all of this. I was mostly interested in Metal (I use macOS 99% of the time) so I started by translating Metal by Example by Warren Moore to SDL’s GPU API and trying to get it working on macOS, Windows, and Linux. I started writing down some notes as I went, and that ballooned into “I should blog this”, and here we are.

Anyway, I have a general outline in mind, which is:

1. Part 1 - Getting Started. How to initialize SDL, get a window on screen, hook it up to the GPU subsystem, and clear the window to a solid color.
2. Part 2 - Drawing Primitives. Set up a basic GPU pipeline with shaders that do almost nothing, draw a single triangle to the window.
3. Part 2.5 - Compiling Shaders. What shader languages and formats we need and how to compile them.
4. Part 3 - Uniforms. Pass extra parameters to your shaders, use them to animate and change things on the fly.
5. Part 4 - Texturing. Load a texture, paint your geometry with it.
6. Part 5 - Text rendering with SDL_ttf. Take the previous parts and put them together to draw something meaningful. Maybe add in an extra render target?
7. Part 6 - Lighting
8. Part 7 - Load and render a model, with some sort of animation done in the vertex shader.

There’s a repository to go along with this series available at mohiji/gpu-by-example on Github. I’m going to organize it into one example project per part (except the Compiling Shaders one) and provide projects to run on Windows, macOS, and Linux.

I do want to stress again: I’m learning as I go. Let’s have fun with it!