gecko-dev/third_party/rust/naga

Naga

The shader translation library for the needs of wgpu and gfx-rs projects.

Supported end-points

Everything is still work-in-progress, but some end-points are usable:

Front-end	Status	Feature	Notes
SPIR-V (binary)	✅	spv-in
WGSL	✅	wgsl-in	Fully validated
GLSL	🆗	glsl-in

Back-end	Status	Feature	Notes
SPIR-V	✅	spv-out
WGSL	🆗	wgsl-out
Metal	✅	msl-out
HLSL	🆗	hlsl-out	Shader Model 5.0+ (DirectX 11+)
GLSL	🆗	glsl-out
AIR
DXIL/DXIR
DXBC
DOT (GraphViz)	🆗	dot-out	Not a shading language

✅ = Primary support — 🆗 = Secondary support — 🚧 = Unsupported, but support in progress

Conversion tool

Naga includes a default binary target, which allows to test the conversion of different code paths.

cargo run my_shader.wgsl # validate only
cargo run my_shader.spv my_shader.txt # dump the IR module into a file
cargo run my_shader.spv my_shader.metal --flow-dir flow-dir # convert the SPV to Metal, also dump the SPIR-V flow graph to `flow-dir`
cargo run my_shader.wgsl my_shader.vert --profile es310 # convert the WGSL to GLSL vertex stage under ES 3.20 profile

Development workflow

The main instrument aiding the development is the good old cargo test --all-features --workspace, which will run the unit tests, and also update all the snapshots. You'll see these changes in git before committing the code.

If working on a particular front-end or back-end, it may be convenient to enable the relevant features in Cargo.toml, e.g.

default = ["spv-out"] #TEMP!

This allows IDE basic checks to report errors there, unless your IDE is sufficiently configurable already.

Finally, when changes to the snapshots are made, we should verify that the produced shaders are indeed valid for the target platforms they are compiled for. We automate this with Makefile:

make validate-spv # for Vulkan shaders, requires SPIRV-Tools installed
make validate-msl # for Metal shaders, requires XCode command-line tools installed
make validate-glsl # for OpenGL shaders, requires GLSLang installed
make validate-dot # for dot files, requires GraphViz installed
make validate-wgsl # for WGSL shaders
make validate-hlsl # for HLSL shaders. Note: this Make target makes use of the "sh" shell. This is not the default shell in Windows.

MSRV

The naga codebase's MSRV is 1.43. However some newer versions of our dependencies have newer MSRVs than that. Here are a list of all known MSRV breaking dependencies and the versions that hold to MSRV.

• bitflags: >1.3 have an MSRV of 1.46. <=1.2 has an MSRV of 1.43 or earlier.

If you want to use naga with 1.43 add the following to your Cargo.toml dependency list even if you don't use bitflags yourself:

bitflags = "<1.3"