As far as I understand: the new GPU API is notable because it should allow writing graphics code & shaders once and have it all work cross-platform (including on consoles) with minimal hassle - and previously that required Unity or Unreal, or your own custom solution.
WebGPU/WGSL is a similar "cross-platform graphics stack" effort but as far as I know nobody has written console backends for it. (Meanwhile the SDL3 GPU API currently doesn't seem to support WebGPU as a backend.)
1) SDL_gpu is a pure C library, heavily focused on extreme portability and no depedencies. And somehow it's also an order of magnitude less code than the other options. Or at least this is a difference from bgfx, maybe not so much sokol_gfx.
2) The SDL_gpu approach is a bit lower level. It exposes primitives like command buffers directly to your application (so you can more easily reason about multi-threading), and your software allocates transfer buffers, fills them with data, and kicks off a transfer to GPU memory explicitly rather than this happening behind the scenes. It also spawns no threads - it only takes action in response to function calls. It does take care of hard things such as getting barriers right, and provides the GPU memory allocator, so it is still substantially easier to use than something like Vulkan. But in SDL_gpu it is extremely obvious to see the data movements between CPU and GPU (and memory copies within the CPU), and to observe the asynchronous nature of the GPU work. I suspect the end result of this will be that people write far more efficient renderers on top of SDL_gpu than they would have on other APIs.
[1] https://bkaradzic.github.io/bgfx/overview.html
A good example demonstrating where the old SDL 2D API is too limited is with the 2D immediate mode GUI library, Nuklear. It has a few simple API stubs to fill in so it can be adapted to work with any graphics system. But for performance, it wants to batch submit all the vertices (triangle strip). But SDL's old API didn't support anything like that.
The reluctance was the SDL maintainers didn't want to create a monster and couldn't decide where to draw the line, so the line was held at the old 2D API. Then a few years ago, a user successfully changed the maintainers' minds after writing a demonstration showing how much could be achieved by just adding a simple batching API to SDL 2D. So that shifted the mindset and led to this current effort. I have not closely followed the development, but I think it still aims to be a simple API, and you will still be encouraged to pick a full blown 3D API if you go beyond 2D needs. But you no longer should need to go to one of the other APIs to do 2D things in modern ways on modern hardware.
Exposing a modern (in the sense of how self-proclaimed modern APIs like Vulkan, D3D12 and Metal work) GPU API that lets applications written against it to work with various backends (D3D11, D3D12, Vulkan, Metal, whatever Switch and PS5 uses, etc) fits perfectly with what SDL already does for every other aspect of making a game/game engine/framework/etc.
As if it was "needed", it was needed as much as any other of SDL's "subsystems": strictly speaking, not really as you could use some other library (but that could be said for SDL itself) but from the perspective of what the SDL wants to provide (an API to target so you wont have to target each underlying API separately) it was needed for the sake of completeness (previously OpenGL was used for this task if you wanted 3D graphics but that was when OpenGL was practically universally available for the platforms SDL itself officially supported - but nowadays this is not the case).
WebGPU has a couple of design decisions which were necessary to support Vulkan on mobile devices, which make it a very rigid API and even (desktop) Vulkan is moving away from that rigid programming model, while WebGPU won't be able to adapt so quickly because it still needs to support outdated mobile GPUs across all operating systems.
I've been going down the Vulkan rabbit hole. It's been fun/enlightening to learn, but the nature of Vulkan makes progress feel slow. I think if SDL3 were available when I started, I would have happily went that route and have more to show for the amount of time I've invested.
I’m also sceptical about their new bytecode for a shading language. Parsing shaders at runtime was not a concern with WebGPU - it’s very fast. Even producing native shaders is fast [1]. It’s the pipeline creation that’s slow, and this bytecode wouldn’t help here.
[1] http://kvark.github.io/naga/shader/2022/02/17/shader-transla...
There is a sister project for a cross-platform shading language [1] and another for translating existing ones between each other [2] , but they get done when they get done, and the rest of the API doesn't have to wait for them.
WebGPU was made by a committee of vendors and language-lawyers (standards-lawyers?) with politics and bureaucracy, and it shows. SDL_GPU is made by game developers who value pragmatism above all (and often are looked down upon from the ivory tower because of that).
[1]: https://github.com/libsdl-org/SDL_shader_tools [2]: https://github.com/flibitijibibo/SDL_gpu_shadercross
See also: Not supporting Vulkan or OpenXR at all, using USD instead of glTF for AR content even though it's less well suited for the task, etc. (Well, they probably don't mind that it helps maintain the walled garden either... There's more than one reason for everything)
0: https://docs.google.com/document/d/1F6ns6I3zs-2JL_dT9hOkX_25...
In that sense the WebGPU project is an extremely valuable resource for other wrapper APIs, and saves those other APIs a ton of time.
When I went looking for a cross-platform gaming library, SDL and its API struck the right balance for me. I just wanted a C (++) library I could call to create windows and graphical contexts — a fast sprite rendering framework. I didn't need a whole IDE or a bloated library, didn't want to learn a new language, etc.
But if you want to support Apple's operating systems then you're stuck with OpenGL 4.1 (officially deprecated by Apple 5 years ago) - so no modern GPU features like compute shaders.
You can go the Vulkan route and use MoltenVK for Apple systems, but Vulkan is quite a step up in complexity from OpenGL ("1000 lines of code for a triangle" as people like to say). The goal for SDL3's GPU API is to give you a more approachable (but still plenty flexible) alternative to that.
And similar story for consoles, presumably.
Apparently lots of people asked for "SDL_render but can you add shader support that works for all platforms", so that's the origin story.
SDL3 does also add a higher level audio API - I don't know much about its merits.
> But this is terrible advice in 2021, because OpenGL, for all intents and purposes, is a deprecated API. It still works, it's still got some reasonably modern features, but even if you add up the 22 years Microsoft spent trying to kill it with Apple's seven-or-maybe-twenty, it doesn't change the fact that the brains behind OpenGL would rather you migrate to Vulkan, which is also terrible advice.
> It seems bonkers to tell people "write these three lines of code to make a window, and then 2000 more to clear it," but that's the migration funnel--and meat grinder--that SDL users are eventually going to get shoved into, and that's unacceptable to me.
Also, SDL2 has evolved considerably since 2.0.0, and SDL3 continues that evolution while allowing API-breaking changes. SDL3 is not a from-scratch re-write and as an SDL user I dont anticipate migrating from SDL2 to SDL3 will be that difficult.
[edit] And SDL1/2 was never so "thin" that it didn't have its own high-level graphics system, which is useful to have out-of-the-box so that new/basic users can get stuff on screen right away.
[edit2] As ahefner points out, SDL1 was pretty "thin" by modern standards, but it still gave you enough to draw basic stuff on screen without writing your own pixel math, which was pretty helpful back in the 90's.
Very small teams are able to show games running the latest UE5.x engine on native elf/linux, vulkan ("vein", "shmaragon" something).
But the steam client... is still 32bits and x11/GL hard dependent...
I still plan to code my own wayland compositor once the steam client is ELF64 and does proper wayland->x11/vulkan->CPU fallbacks. It will feel weird to have a clean 64bits system.
This abstraction at least has the potential to fulfil the needs of anything more than simple 2D games while allowing you to target the sadly increasingly fragmented graphics API ecosystem (RIP dreams of an universal OpenGL(Next) future). Looks like the hardest part (shader translation) isn't there yet though.
The grimfang4/sdl-gpu was one good way to take advantage of modern GPUs in a simple way and workaround the holes/limitations of the old SDL 2D API. The new SDL 3 GPU API will likely make the need for things like grimfang4/sdl-gpu redundant.
See for yourself: https://github.com/libsdl-org/SDL_shader_tools/blob/main/doc...
Deviations from C-language families, such as "Flow control statements don't need parentheses." are completely unnecessary, I think. Same goes for "Flow control statements must use braces."
One of the developers made an interesting blog post motivating this decision [2] (although some of the finer details have changed since that was written).
There is also a "third party" solution [3] by another one of the developers that enables cross-platform use of SPIR-V or HLSL shaders using SPIRV-Cross and FXC/DXC, respectively (NB: It seems this currently wouldn't compile against SDL3 master).
[1] https://github.com/libsdl-org/SDL/blob/d1a2c57fb99f29c38f509...
I did find an example of using the GPU API, but I didn't see any mention of selecting a backend (Vk, etc.) in the example - is this possible or is the backend selected e.g. based on the OS?
The convention itself IS the thing that stops you from fucking that up. It's the kind of thing you do once 2 days into a 30 year career and never again.
I still think it's dumb in Javascript, where you could be using the language on day 2 of learning programming. But in a GPU shader language that it would be almost impossible to understand with no programming experience? It's actually insane.
Having said that everything else about this project looks pretty good, so I guess they can get a pass lol.
