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When validating IR, verify that all `Binding`s for vertex shader outputs and fragment shader inputs, whether directly in the argument or result, or applied to a struct member, has specified an interpolation and sampling, not `None`. This ensures that front ends explicitly state their policies, rather than coasting through on back ends' default behavior. In practice, all our front ends have very similar defaults, so provide a utility function on `Module` to apply these rules. Use this utility function in the SPIR-V and WGSL front ends; GLSL seems to already fill in interpolation as required.
Naga
This is an experimental shader translation library for the needs of gfx-rs project and WebGPU.
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 | |
| GLSL | 🆗 | glsl-in | Vulkan flavor is expected |
| Rust |
| Back-end | Status | Feature | Notes |
|---|---|---|---|
| SPIR-V | ✅ | spv-out | |
| WGSL | 🚧 | wgsl-out | |
| Metal | ✅ | msl-out | |
| HLSL | 🚧 | hlsl-out | |
| 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 "convert", which allows to test the conversion of different code paths.
cargo run --features spv-in -- my_shader.spv # dump the IR module to debug output
cargo run --features spv-in,msl-out -- 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 --features wgsl-in,glsl-out -- 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,
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