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.
  • The main C header for the WebGPU API.
  • Definition of a structure of all function pointers for this specific Dawn version (called "proctable").
  • A C++ wrapper for the C header.
• 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, Android and Fuchsia 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
• A Dawn proc-table backend implementation of WebGPU for applications what want to be able to switch at runtime between native or client-server mode.

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.

On Linux you need to have the pkg-config command:

# Install pkg-config on Ubuntu
sudo apt-get install pkg-config

Then get the source as follows:

# Clone the repo as "dawn"
git clone https://dawn.googlesource.com/dawn 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. 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.

If you find issues with Dawn, please feel free to report them on the bug tracker. For other discussions, please post to Dawn's mailing list.

License

Please see LICENSE.

Disclaimer

This is not an officially supported Google product.