But why does the GPU API need to be in mainline SDL? Couldn't it be a separate project like SDL_net, SDL_mixer, SDL_image, and SDL_ttf? I would think that as a separate project "SDL_gpu" could be versioned independently, evolve independently, and not be obligated to support every platform SDL itself supports. In fact if "SDL_gpu" only required a windowing context, then it could presumably integrate with SDL2 and non-SDL applications!
AFAICT, if you don't want to use it then you don't have to - just like you didn't have to use SDL_render in SDL2. That is what was pitched by maintainer Ryan Gordon[0][1] at least.
[0]: https://github.com/libsdl-org/SDL_shader_tools/blob/main/doc... , though the approach that ended up getting merged was an initially-competing approach implemented by FNA folks instead and they seem to have made some different decisions than what was outlined in that markdown doc.
While using SDL for drawing is optional (and seldom done if you're doing 3D) I would like to add that its drawing API is useful to have out-of-the-box so that new/basic users can get stuff on screen right away without having to write their own high-level graphics engine first.
SDL needs to be able to render graphics efficiently, but the SDL2 way is no longer sufficient. Since SDL3 is a major version change, it makes sense to overhaul it while a variety of other API-breaking improvements are being made.
