Naga

The shader translation library for the needs of wgpu.

Supported end-points

Front-end	Status	Feature	Notes
SPIR-V (binary)	✅	spv-in
WGSL	✅	wgsl-in	Fully validated
GLSL	🆗	glsl-in	GLSL 440+ and Vulkan semantics only

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	GLSL 330+ and GLSL ES 300+
AIR
DXIL/DXIR
DXBC
DOT (GraphViz)	🆗	dot-out	Not a shading language

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

Conversion tool

Naga can be used as a CLI, which allows to test the conversion of different code paths.

First, install naga-cli from crates.io or directly from GitHub.

# release version
cargo install naga-cli

# development version
cargo install naga-cli --git https://github.com/gfx-rs/naga.git

Then, you can run naga command.

naga my_shader.wgsl # validate only
naga my_shader.spv my_shader.txt # dump the IR module into a file
naga 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`
naga my_shader.wgsl my_shader.vert --profile es310 # convert the WGSL to GLSL vertex stage under ES 3.20 profile

As naga includes a default binary target, you can also use cargo run without installation. This is useful when you develop naga itself, or investigate the behavior of naga at a specific commit (e.g. wgpu might pin a different version of naga than the HEAD of this repository).

cargo run my_shader.wgsl

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-dxc # for HLSL shaders via DXC
make validate-hlsl-fxc # for HLSL shaders via FXC
# Note: HLSL Make targets make use of the "sh" shell. This is not the default shell in Windows.