# Dawn, a WebGPU implementation

Dawn (formerly NXT) is an open-source and cross-platform implementation of the work-in-progress WebGPU standard.
It exposes a C/C++ API that maps almost one-to-one to the WebGPU IDL and can be managed as part of a larger system such as a Web browser.

Dawn provides several WebGPU building blocks:
 - **WebGPU C/C++ headers** that applications and other building blocks use.
 - **A "native" implementation of WebGPU** using platforms' GPU APIs:
   - **D3D12** on Windows 10
   - **Metal** on OSX (and eventually iOS)
   - **Vulkan** on Windows, Linux (eventually ChromeOS and Android too)
   - OpenGL as best effort where available
 - **A client-server implementation of WebGPU** for applications that are in a sandbox without access to native drivers

## Directory structure

- `dawn.json`: description of the API used to drive code generators.
- `examples`: examples showing how Dawn is used.
- `generator`: code generator for files produces from `dawn.json`
  - `templates`: Jinja2 templates for the generator
- `scripts`: scripts to support things like continuous testing, build files, etc.
- `src`: 
  - `common`: helper code shared between core Dawn libraries and tests/samples
  - `dawn_native`: native implementation of WebGPU, one subfolder per backend
  - `dawn_wire`: client-server implementation of WebGPU
  - `include`: public headers for Dawn
  - `tests`: internal Dawn tests
    - `end2end`: WebGPU tests performing GPU operations
    - `unittests`: unittests and by extension tests not using the GPU
      - `validation`: WebGPU validation tests not using the GPU (frontend tests)
  - `utils`: helper code to use Dawn used by tests and samples
- `third_party`: directory where dependencies live as well as their buildfiles.

## Building Dawn

Dawn uses the Chromium build system and dependency management so you need to [install depot_tools] and add it to the PATH.
Then get the source as follows:

[install depots_tools]: http://commondatastorage.googleapis.com/chrome-infra-docs/flat/depot_tools/docs/html/depot_tools_tutorial.html#_setting_up

```sh
# Clone the repo as "dawn"
git clone https://github.com/google/nxt-standalone.git dawn && cd dawn

# Bootstrap the gclient configuration
cp scripts/standalone.gclient .gclient

# Fetch external dependencies and toolchains with gclient
gclient sync
```

Then generate build files using `gn args out/Debug` or `gn args out/Release`.
A text editor will appear asking build options, the most common option is `is_debug=true/false`; otherwise `gn args out/Release --list` shows all the possible options.

Then use `ninja -C out/Release` to build dawn and for example `./out/Release/dawn_end2end_tests` to run the tests.

## Contributing

Please read and follow [CONTRIBUTING.md](/CONTRIBUTING.md).
Dawn doesn't have a formal coding style yet, except what's defined by our clang format style.
Overall try to use the same style and convention as code around your change.

## License

Please see [LICENSE](/LICENSE).

## Disclaimer

This is not an officially supported Google product.