How to Contribute to Vulkan Source Repositories

The Repository

The source code for the Vulkan Loader component is sponsored by Khronos and LunarG.

The Vulkan Ecosystem Needs Your Help

There are a couple of methods to identify areas of need:

  • Examine the issues list in this repository and look for issues that are of interest
  • If you have your own work in mind, please open an issue to describe it and assign it to yourself.

Please feel free to contact any of the developers that are actively contributing should you wish to coordinate further.

Repository Issue labels:

  • Bug: These issues refer to invalid or broken functionality and are the highest priority.
  • Enhancement: These issues refer to ideas for extending or improving the loader.

It is the maintainers goal for all issues to be assigned within one business day of their submission. If you choose to work on an issue that is assigned, simply coordinate with the current assignee.

How to Submit Fixes

  • Ensure that the bug was not already reported or fixed by searching on GitHub under Issues and Pull Requests.
  • Use the existing GitHub forking and pull request process. This will involve forking the repository, creating a branch with your commits, and then submitting a pull request.
  • Please read and adhere to the style and process guidelines enumerated below.
  • Please base your fixes on the master branch. SDK branches are generally not updated except for critical fixes needed to repair an SDK release.
  • The resulting Pull Request will be assigned to a repository maintainer. It is the maintainer's responsibility to ensure the Pull Request passes the Google/LunarG internal CI processes. Once the Pull Request has been approved and is passing internal CI, a repository maintainer will merge the PR.

Coding Conventions and Formatting

  • Use the Google style guide for source code with the following exceptions:

    • The column limit is 132 (as opposed to the default value 80). The clang-format tool will handle this. See below.
    • The indent is 4 spaces instead of the default 2 spaces. Again, the clang-format tool will handle this.
    • If you can justify a reason for violating a rule in the guidelines, then you are free to do so. Be prepared to defend your decision during code review. This should be used responsibly. An example of a bad reason is “I don't like that rule.” An example of a good reason is “This violates the style guide, but it improves type safety.”

  • Run clang-format on your changes to maintain consistent formatting

    • There are .clang-format files present in the repository to define clang-format settings which are found and used automatically by clang-format.
    • clang-format binaries are available from the LLVM orginization, here: LLVM. Our CI system (Travis-CI) currently uses clang-format version 5.0.0 to check that the lines of code you have changed are formatted properly. It is recommended that you use the same version to format your code prior to submission.
    • A sample git workflow may look like:
   # Make changes to the source.
   $ git add -u .
   $ git clang-format --style=file
   # Check to see if clang-format made any changes and if they are OK.
   $ git add -u .
   $ git commit
  • Commit Messages
    • Limit the subject line to 50 characters -- this allows the information to display correctly in git/Github logs
    • Begin subject line with a one-word component description followed by a colon (e.g. loader, layers, tests, etc.)
    • Separate subject from body with a blank line
    • Wrap the body at 72 characters
    • Capitalize the subject line
    • Do not end the subject line with a period
    • Use the body to explain what and why vs. how
    • Use the imperative mode in the subject line. This just means to write it as a command (e.g. Fix the sprocket)

Strive for commits that implement a single or related set of functionality, using as many commits as is necessary (more is better).

Please ensure that the repository compiles and passes tests without error for each commit in your pull request. Note that to be accepted into the repository, the pull request must pass all tests on all supported platforms. The automatic Github Travis and AppVeyor continuous integration features will assist in enforcing this requirement.*

Generated Source Code

The loader/generated directory contains source code that is created by several generator scripts in the scripts directory. All changes to these scripts must be submitted with the corresponding generated output to keep the repository self-consistent. This requirement is enforced by both Travis CI and AppVeyor test configurations. Regenerate source files after modifying any of the generator scripts and before building and testing your changes. More details can be found in BUILD.md.

Testing Your Changes

  • Run the existing tests in the tests directory of the repository before and after each of your commits to check for any regressions.

    • Linux: run_all_tests.sh
    • Windows: run_all_tests.ps1

  • Run tests that explicitly exercise your changes.

  • Feel free to subject your code changes to other tests as well!

Coding Conventions for CMake files

  • When editing configuration files for CMake, follow the style conventions of the surrounding code.
    • The column limit is 132.
    • The indent is 4 spaces.
    • CMake functions are lower-case.
    • Variable and keyword names are upper-case.
  • The format is defined by cmake-format using the .cmake-format.py file in the repository to define the settings. See the cmake-format page for information about its simple markup for comments.
  • Disable reformatting of a block of comment lines by inserting a # ~~~ comment line before and after that block.
  • Disable any formatting of a block of lines by surrounding that block with # cmake-format: off and # cmake-format: on comment lines.
  • To install: sudo pip install cmake_format
  • To run: cmake-format --in-place $FILENAME
  • IMPORTANT (June 2018) cmake-format v0.3.6 has a bug that can corrupt the formatting of comment lines in CMake files. A workaround is to use the following command before running cmake-format: sed --in-place='' 's/^ *#/#/' $FILENAME

Contributor License Agreement (CLA)

You will be prompted with a one-time “click-through” CLA dialog as part of submitting your pull request or other contribution to GitHub.

License and Copyrights

All contributions made to the Vulkan-Loader repository are Khronos branded and as such, any new files need to have the Khronos license (Apache 2.0 style) and copyright included. Please see an existing file in this repository for an example.

All contributions made to the LunarG repositories are to be made under the Apache 2.0 license and any new files need to include this license and any applicable copyrights.

You can include your individual copyright after any existing copyrights.