3 ms·

There's no need for transpilers these days, you can just compile HLSL to SPIR-V bytecode with dxc. https://github.com/microsoft/DirectXShaderCompiler https://g

by TillE 3y ago

There's no need for transpilers these days, you can just compile HLSL to SPIR-V bytecode with dxc. https://github.com/microsoft/DirectXShaderCompiler https://github.com/microsoft/DirectXShaderCompiler

sylware 3y ago
I would even advise to author the shaders directly in SPIR-V with a basic SSA checker and text to binary translater. That, very conservatively to avoid any drivers incompatibility (aka nothing fancy). I wonder if there is an open source HLSL to spir-v compiler written in simple and plain C... but I am ready to work a bit more to avoid to depend on a complex HLSL compiler.
novagameco 3y ago
Can WebGL run SPIR-V? That was my main issue
- tadfisher 3y ago
  I'm pretty sure you have to transpile SPIR-V shaders to GLSL first. WebGPU has its own Rust-inspired language as well.
  - slimsag 3y ago
    It's worth noting that SPIR-V isn't really compiled for the target ISA, it's not even guaranteed to be in a particular optimized form already.. so when the GPU driver loads it, it may or may not decide to spend a lot of time running optimization passes before translating it to the actual machine code the GPU needs. In contrast, Metal shaders can be pre-compiled to the actual ARM binary code the GPU runs. And DirectX shader bytecode, DXIL, is (poorly) defined to be a low-level IR that LLVM spits out right before it would be translated to machine code, rather than a high-level IR like SPIR-V is. i.e. it is guaranteed to be in an optimized form already, so drivers do not expect to run any optimizations at load time. SPIR-V seems a bit of a mess here, because you don't really know what the target GPU is going to do - and what you can expect in terms of time the GPU spends on optimizing the SPIR-V when loading it varies on mobile and non-mobile GPUs, depending basically on what the GPU manufacturer felt behaved the best based on how random people making games distribute optimized or unoptimized SPIR-V. Valve even maintains a fancy database of (SPIRV, GPU driver) pairings which map to _actual_ precompiled shaders for all games distributed on their platform, so that they aren't affected by this. Whew, what a mess shaders are.
    - pjmlp 3y ago
      Which is really how the experience with portable APIs from Khronos goes, most people that claim they are portable never really did any serious cross platform, cross device programming with them. At the end of the day there are so many if this, if that, load this extension, load that extension, do this workaroud, do that workaround, that it could just be another API for all pratical purposes.
slimsag 3y ago
The quantity and type of SPIR-V issues which DirectXShaderCompiler has makes me believe it is not really used in serious settings. Microsoft also directly states in the README it is a community contribution, which seems an intentional choice of language. I'd love to be proven wrong, though

by TillE 3y ago

sylware 3y ago

I would even advise to author the shaders directly in SPIR-V with a basic SSA checker and text to binary translater. That, very conservatively to avoid any drivers incompatibility (aka nothing fancy). I wonder if there is an open source HLSL to spir-v compiler written in simple and plain C... but I am ready to work a bit more to avoid to depend on a complex HLSL compiler.

novagameco 3y ago

Can WebGL run SPIR-V? That was my main issue

tadfisher 3y ago
I'm pretty sure you have to transpile SPIR-V shaders to GLSL first. WebGPU has its own Rust-inspired language as well.
- slimsag 3y ago
  It's worth noting that SPIR-V isn't really compiled for the target ISA, it's not even guaranteed to be in a particular optimized form already.. so when the GPU driver loads it, it may or may not decide to spend a lot of time running optimization passes before translating it to the actual machine code the GPU needs. In contrast, Metal shaders can be pre-compiled to the actual ARM binary code the GPU runs. And DirectX shader bytecode, DXIL, is (poorly) defined to be a low-level IR that LLVM spits out right before it would be translated to machine code, rather than a high-level IR like SPIR-V is. i.e. it is guaranteed to be in an optimized form already, so drivers do not expect to run any optimizations at load time. SPIR-V seems a bit of a mess here, because you don't really know what the target GPU is going to do - and what you can expect in terms of time the GPU spends on optimizing the SPIR-V when loading it varies on mobile and non-mobile GPUs, depending basically on what the GPU manufacturer felt behaved the best based on how random people making games distribute optimized or unoptimized SPIR-V. Valve even maintains a fancy database of (SPIRV, GPU driver) pairings which map to _actual_ precompiled shaders for all games distributed on their platform, so that they aren't affected by this. Whew, what a mess shaders are.
  - pjmlp 3y ago
    Which is really how the experience with portable APIs from Khronos goes, most people that claim they are portable never really did any serious cross platform, cross device programming with them. At the end of the day there are so many if this, if that, load this extension, load that extension, do this workaroud, do that workaround, that it could just be another API for all pratical purposes.

slimsag 3y ago

The quantity and type of SPIR-V issues which DirectXShaderCompiler has makes me believe it is not really used in serious settings. Microsoft also directly states in the README it is a community contribution, which seems an intentional choice of language. I'd love to be proven wrong, though