GPU driver for SDL_render #192

Akaricchi · 2024-08-17T18:21:27Z

A basic GPU driver for SDL_render. Mostly based on the GL driver with some reference to the Vulkan one.

I threw most of the stuff from the test directory at it and it all seems to work, including testautomation. This is by no means comprehensive and I have yet to test it with a more serious program (probably through the sdl2-compat layer), or on anything that isn't Vulkan on Linux.

Some known issues:

YUV support is missing. The implementation would probably have to be similar to that of the GL backend. The Vulkan backend uses some fancy extensions for this.
All the colorspace conversion stuff found in the Vulkan backend is missing.
Presentation code could be improved/stolen from FNA3D as per @thatcosmonaut's suggestion.
I've made an effort to support all GPU backends, but this is untested. D3D11 and D3D12 are supported with DXBC shaders (no DXIL), and Metal with text-form MSL. The shaders are rebuildable on any OS; DXBC output was tested with https://github.com/mozilla/fxc2 on Linux.
Because we have to support synchronous readback for ReadPixels, everything is rendered into a faux-backbuffer and copied into the swapchain at present time. The Vulkan backend doesn't need this workaround.
A few random TODOs and FIXMEs throughout the code.
The code is only known to compile with GCC and Clang, and will probably have to be disfigured by someone who cares, in order to compile with VS and conform to whatever prehistoric version of C that SDL follows. I do hate myself and love pain, but not enough to maintain that, sorry. Thank me later for not using designated initializers absolutely everywhere.

Closes #12

flibitijibibo

At a high level this looks great so far - we may change the shader pipeline to be more like testgpu but the core is what's most important and it's in good shape. I may defer to @icculus for some of the FIXMEs/TODOs since a lot of it depends on what SDL_Render prefers at a high level, and I'm not as familiar with that as I should be.

flibitijibibo · 2024-08-17T21:15:27Z

src/render/sdlgpu/SDL_shaders_gpu.c

+    SDL_GpuShaderFormat format;
+} GPU_ShaderModuleSource;
+
+// FIXME Please fix this in the build system!


These will have to be #ifdef rather than just #if, since that's how cmakedefines come out https://github.com/thatcosmonaut/SDL/blob/gpu/include/build_config/SDL_build_config.h.cmake#L447

Looks like SDL defines a bunch of undefined macros as 0s here, at least for the render backends: https://github.com/libsdl-org/SDL/blob/a7bed810b3499d157655ae6dcc7cd5e8a34fa549/src/SDL_internal.h#L194

GPU also uses #if checks on its backend defines, which is technically not correct (clang throws a warning).

Maybe we could do something similar for GPU backends. I like them being 1/0 macros because it makes the implementation of GPU_FillSupportedShaderFormats neat, but it's not a big deal.

Oh, good catch - we can do the same for GPU.

Akaricchi · 2024-08-17T21:31:07Z

I'm personally not a fan of the testgpu shader builder because it requires running on at least two different proprietary operating systems in order to rebuild all the shaders. I tried to make it reasonably portable, but it's your call.

Lots of missing and broken stuff, but it's a start

Shouldn't change the behavior, just makes the intent a little more clear.

We have to render everything into a faux-backbuffer to support this, because swapchain readback is pain and synchronous swapchain readback is gigapain.

I hate this but CI must pass

flibitijibibo

Latest should be good enough for the first round of Beta reviews - they may complain about util.h and pipeline.c/h but that's an easy fix if it comes up.

thatcosmonaut

Thanks for doing this. There's some significant performance issues here that we should address before ship but the SDL_render tests are functional and the busywork is done, so that's good enough for now. Will squash and then commit a patch on top that fixes a sampler creation issue and notes some performance FIXMEs.

icculus · 2024-08-29T19:59:27Z

Yeah, I'm super-thrilled someone just jumped in to work on this, as it's going to be quite important, so thanks for that!

flibitijibibo reviewed Aug 17, 2024

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Akaricchi force-pushed the gpu_render branch 2 times, most recently from 66aaf8e to c5fafed Compare August 19, 2024 22:46

flibitijibibo force-pushed the gpu_next branch from 8d15a6f to 95bf26e Compare August 23, 2024 13:53

Akaricchi force-pushed the gpu_render branch from c5fafed to db5a864 Compare August 28, 2024 21:16

flibitijibibo force-pushed the gpu_next branch from 3b02992 to 3856fbc Compare August 28, 2024 23:02

Akaricchi force-pushed the gpu_render branch from fd69fab to 3e3d178 Compare August 28, 2024 23:22

flibitijibibo force-pushed the gpu_next branch from 3856fbc to 7ef675e Compare August 28, 2024 23:25

Akaricchi force-pushed the gpu_render branch from 3e3d178 to 1dbd3e5 Compare August 28, 2024 23:31

Akaricchi marked this pull request as ready for review August 28, 2024 23:36

Akaricchi and others added 19 commits August 29, 2024 02:26

Begin implementation of GPU backend for SDL_Render

870dcc4

Lots of missing and broken stuff, but it's a start

render_gpu: Make buildable on msvc

325e790

render_gpu: Add pipeline cache

c787d5a

render_gpu: Don't keep the vertex transfer buffer mapped permanently

802f285

render_gpu: Release transfer buffer after texture upload

b820f87

render_gpu: Yes, we do need an RGB shader

5c6bb47

render_gpu: Fix clip rect

b0b98d3

render_gpu: Get offset before drawcall merge when rendering geometry

c04ad7a

Shouldn't change the behavior, just makes the intent a little more clear.

render_gpu: Fix line/point rendering

7153453

render_gpu: Fix swapchain being invalid on the first frame

898a4ac

render_gpu: Hook up vsync

d3eb41b

render_gpu: Implement ReadPixels

e0d5652

We have to render everything into a faux-backbuffer to support this, because swapchain readback is pain and synchronous swapchain readback is gigapain.

render_gpu: Dynamically resize vertex buffer

0fb7031

render_gpu: remove GL leftovers

d06fc11

render_gpu: Clean up unused texture fields

6225c94

render_gpu: Optimize SPIR-V for size

1e75b72

render_gpu: Hook up shaders for other backends (untested)

8957902

render_gpu: Fix vsync

bd26dd8

render_gpu: Mark shader headers as generated code

fa76f5b

Akaricchi added 17 commits August 29, 2024 02:26

render_gpu: Remove nonsense comment

2fb10d7

render_gpu: Fix SDL_GpuBlit assertion failure after window resize

b7ec3f6

render_gpu: Fix GPU_RenderReadPixels

63ef65f

render_gpu: Switch D3D12 shaders to DXIL

87c98a9

render_gpu: Add hints for debug and low-power preference

b5dc9d5

render_gpu: Fix SDL_GpuDrawPrimitives() call

19d3e9f

render_gpu: post-rebase fixups

531b19d

render_gpu: Fix viewport and scissor handling

da3fc56

render_gpu: Handle clears more efficiently

9c907dd

render_gpu: Clean up shader macros

9cf0feb

render_gpu: Don't check mailbox twice if it succeeds

1bb1090

render_gpu: Fix bogus maybe-uninitialized warning

e6e7e08

render_gpu: Don't rely on { 0 } for initialization

1edd206

I hate this but CI must pass

render_gpu: Fix MSVC warnings

f7b6fa9

render_gpu: Deal with post-rebase fallout

ebc8e4a

render_gpu: Appease MSVC again

dd95143

render_gpu: Banish it to the shadow realm

c021268

Akaricchi force-pushed the gpu_render branch from ec68b78 to c021268 Compare August 29, 2024 00:26

render_gpu: Banish it to the shadowest realm

0a6a122

flibitijibibo approved these changes Aug 29, 2024

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thatcosmonaut approved these changes Aug 29, 2024

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thatcosmonaut merged commit 80dad09 into thatcosmonaut:gpu_next Aug 29, 2024
39 checks passed

thatcosmonaut mentioned this pull request Aug 29, 2024

Implement gpu backend for SDL_Render #12

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GPU driver for SDL_render #192

GPU driver for SDL_render #192

Akaricchi commented Aug 17, 2024 •

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icculus commented Aug 29, 2024

GPU driver for SDL_render #192

GPU driver for SDL_render #192

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icculus commented Aug 29, 2024

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