Rust+SDL3+OpenGL DIY Template

This is an extern "C"-heavy and unsafe template for getting started with OpenGL in Rust, using SDL3. The hope is that you will find value, and base your next project on it- unless the very design of it discourages you away.

What is the problem?

Rust gamedev is not quite mature, and some of the choices made here may turn out to be not the best ones as the ecosystem evolves:

• SDL3: I mainly chose raw SDL3 over GLFW or a Rust-native solutions because it has audio too. I reckon SDL2 will be maintained for quite some time but it will probably not get any new features.

  • sdl3-sys crate provides slightly more ergonomic bindings than a raw bindgen conversion.
  • sdl3 crate does not have feature-parity with sdl3-sys yet.

• C GLAD: There are a number of OpenGL wrappers for Rust, but unfortunately some have bitrotten and others have too little traction to be dependable. Taking the matters into your own hands may be a good idea.

  • Notably, not all bindings support 4.6 SPIR-V stuff.
  • Sticking to the standard is not a bad idea.

• OpenGL: Currently, I feel that Rust Vulkan ecosystem seems more mature than its OpenGL counterpart, so you may want to re-evaluate whether you really want OpenGL.

How to use it, then?

• Probably don't fork this repository! Copy the code over and start from scratch.
• Go to glad.dav1d.de and generate your own bindings with your favorite extensions, alongwith its loader.
• Replace my bindings in glad-sys/cc/ directory with yours.
  • Apologies for the dirtiness! A much better way would be to generate bindings directly from the Khronos spec but gl_generator not getting updates is this template's raison d'être!
• If in the far future, consider bumping some of the version numbers.
  • sdl3-sys is still in churn; specify an exact version number in sdl3-experiment/Cargo.toml instead of a wildcard if doing a more serious projects.
  • Repository lacks a Cargo.lock for similar reasons. Commit yours into your repo!
• Compile glad-sys, and modify build.rs for your use-case and/or fix errors. DIY!
  • There are some guardrails to avoid surprises, but not nearly enough!

Note

One interesting Rust quirk is that the equivalent C function pointer type is always wrapped in Option. This is unlike pointers to any other raw type. There is some helper code to unwrap everything before use. struct GL is a part of it and it contains unwrapped function pointers.

Unfortunately, this hits another quirk of Rust where a.B() only ever means calling method B impl ed on a and not invoking a function pointer. This leads to code that looks like:

let mut gl = GL::unwrap();
(gl.Clear)(GL_COLOR_BUFFER_BIT);

which is ugly. A better wrapper may come in the future.

License

This repository incorporates code from the following third-parties:

• SDL3 under zlib license
• sdl3-sys under zlib license
• GLAD under ??? (which include khrplatform.h that is under ???)

To stay in line with SDL, this repository is also licensed under Zlib license.