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# Vello Sparse Shaders

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This crate contains the WESL programs and linked WGSL output, plus optionally generated GLSL
shader programs, used by the Vello Hybrid renderer.

## Features
- Single source of truth authored as [WESL](https://wesl-lang.dev/) programs.
- Automated build step for linking WESL to WGSL and compiling GLSL shaders using
  [naga](https://github.com/gfx-rs/wgpu/tree/trunk/naga).

## Usage
This crate provides linked WGSL programs and the build step for GLSL programs used by the optimized
hybrid rendering engine.

Whenever the WESL shaders are updated, the build script automatically relinks the WGSL and
regenerates the GLSL programs used by the crate itself.

If you want to inspect the generated WebGL GLSL output directly, you can also create a "local copy" that is
easier to inspect by running:

```sh
cargo run -p vello_sparse_shaders --features glsl
```

After doing so, the WebGL shaders will be written into the `generated_glsl` folder.

## Minimum supported Rust Version (MSRV)

This version of Vello Hybrid Shaders has been verified to compile with **Rust 1.88** and later.

Future versions of Vello Hybrid might increase the Rust version requirement.
It will not be treated as a breaking change and as such can even happen with small patch releases.

<details>
<summary>Click here if compiling fails.</summary>

As time has passed, some of Vello Hybrid's dependencies could have released versions with a higher Rust requirement.
If you encounter a compilation issue due to a dependency and don't want to upgrade your Rust toolchain, then you could downgrade the dependency.

```sh
# Use the problematic dependency's name and version
cargo update -p package_name --precise 0.1.1
```

</details>

## Community

Discussion of Vello Hybrid development happens in the [Linebender Zulip](https://xi.zulipchat.com/), specifically the [#vello channel](https://xi.zulipchat.com/#narrow/channel/197075-vello).
All public content can be read without logging in.

Contributions are welcome by pull request.
The [Rust code of conduct] applies.

## License

Licensed under either of

- Apache License, Version 2.0 ([LICENSE-APACHE](LICENSE-APACHE) or <http://www.apache.org/licenses/LICENSE-2.0>)
- MIT license ([LICENSE-MIT](LICENSE-MIT) or <http://opensource.org/licenses/MIT>)

at your option.

[Rust code of conduct]: https://www.rust-lang.org/policies/code-of-conduct
[Vello]: https://github.com/linebender/vello
[the changelog]: https://github.com/linebender/vello/tree/main/CHANGELOG.md
