Development Notes

# The Mesa 3D Graphics Library

# Development Notes

## Adding Extensions

To add a new GL extension to Mesa you have to do at least the following.

- If glext.h doesn't define the extension, edit include/GL/gl.h and add code like this:

           #ifndef GL_EXT_the_extension_name
           #define GL_EXT_the_extension_name 1
           /* declare the new enum tokens */
           /* prototype the new functions */
           /* TYPEDEFS for the new functions */
           #endif

- In the src/mapi/glapi/gen/ directory, add the new extension functions and enums to the gl_API.xml file. Then, a bunch of source files must be regenerated by executing the corresponding Python scripts.
- Add a new entry to the `gl_extensions` struct in mtypes.h
- Update the `extensions.c` file.
- From this point, the best way to proceed is to find another extension, similar to the new one, that's already implemented in Mesa and use it as an example.
- If the new extension adds new GL state, the functions in get.c, enable.c and attrib.c will most likely require new code.
- The dispatch tests check_table.cpp and dispatch_sanity.cpp should be updated with details about the new extensions functions. These tests are run using 'make check'

## Coding Style

Mesa's code style has changed over the years. Here's the latest.

Comment your code! It's extremely important that open-source code be well documented. Also, strive to write clean, easily understandable code.

3-space indentation

If you use tabs, set them to 8 columns

Line width: the preferred width to fill comments and code in Mesa is 78 columns. Exceptions are sometimes made for clarity (e.g. tabular data is sometimes filled to a much larger width so that extraneous carriage returns don't obscure the table).

Brace example:

    	if (condition) {
    	   foo;
    	}
    	else {
    	   bar;
    	}

    	switch (condition) {
    	case 0:
    	   foo();
    	   break;

    	case 1: {
    	   ...
    	   break;
    	}

    	default:
    	   ...
    	   break;
    	}

Here's the GNU indent command which will best approximate my preferred style: (Note that it won't format switch statements in the preferred way)

    	indent -br -i3 -npcs --no-tabs infile.c -o outfile.c

Local variable name example: localVarName (no underscores)

Constants and macros are ALL_UPPERCASE, with _ between words

Global variables are not allowed.

Function name examples:

    	glFooBar()       - a public GL entry point (in glapi_dispatch.c)
    	_mesa_FooBar()   - the internal immediate mode function
    	save_FooBar()    - retained mode (display list) function in dlist.c
    	foo_bar()        - a static (private) function
    	_mesa_foo_bar()  - an internal non-static Mesa function

Places that are not directly visible to the GL API should prefer the use of `bool`, `true`, and `false` over `GLboolean`, `GL_TRUE`, and `GL_FALSE`. In C code, this may mean that `#include <stdbool.h>` needs to be added. The `try_emit_`* methods in src/mesa/program/ir_to_mesa.cpp and src/mesa/state_tracker/st_glsl_to_tgsi.cpp can serve as examples.

## Submitting patches

You should always run the Mesa Testsuite before submitting patches. The Testsuite can be run using the 'make check' command. All tests must pass before patches will be accepted, this may mean you have to update the tests themselves.

Patches should be sent to the Mesa mailing list for review. When submitting a patch make sure to use git send-email rather than attaching patches to emails. Sending patches as attachments prevents people from being able to provide in-line review comments.

When submitting follow-up patches you can use --in-reply-to to make v2, v3, etc patches show up as replies to the originals. This usually works well when you're sending out updates to individual patches (as opposed to re-sending the whole series). Using --in-reply-to makes it harder for reviewers to accidentally review old patches.

## Marking a commit as a candidate for a stable branch

If you want a commit to be applied to a stable branch, you should add an appropriate note to the commit message.

Here are some examples of such a note:

- CC: <mesa-stable@lists.freedesktop.org>
- CC: "9.2 10.0" <mesa-stable@lists.freedesktop.org>
- CC: "10.0" <mesa-stable@lists.freedesktop.org>

Simply adding the CC to the mesa-stable list address is adequate to nominate the commit for the most-recently-created stable branch. It is only necessary to specify a specific branch name, (such as "9.2 10.0" or "10.0" in the examples above), if you want to nominate the commit for an older stable branch. And, as in these examples, you can nominate the commit for the older branch in addition to the more recent branch, or nominate the commit exclusively for the older branch. This "CC" syntax for patch nomination will cause patches to automatically be copied to the mesa-stable@ mailing list when you use "git send-email" to send patches to the mesa-dev@ mailing list. Also, if you realize that a commit should be nominated for the stable branch after it has already been committed, you can send a note directly to the mesa-stable@lists.freedesktop.org where the Mesa stable-branch maintainers will receive it. Be sure to mention the commit ID of the commit of interest (as it appears in the mesa master branch). The latest set of patches that have been nominated, accepted, or rejected for the upcoming stable release can always be seen on the Mesa Stable Queue page.

## Cherry-picking candidates for a stable branch

Please use `git cherry-pick -x <commit>` for cherry-picking a commit from master to a stable branch.

## Making a New Mesa Release

These are the instructions for making a new Mesa release.

### Get latest source files

Use git to get the latest Mesa files from the git repository, from whatever branch is relevant.

### Verify and update version info in VERSION

Create a docs/relnotes/x.y.z.html file. The bin/bugzilla_mesa.sh and bin/shortlog_mesa.sh scripts can be used to create the HTML-formatted lists of bugfixes and changes to include in the file. Link the new docs/relnotes/x.y.z.html file into the main relnotes.html file.

Update docs/index.html.

Tag the files with the release name (in the form mesa-x.y) with: `git tag -s mesa-x.y -m "Mesa x.y Release"` Then: `git push origin mesa-x.y`

### Make the tarballs

Make the distribution files. From inside the Mesa directory:

    	./autogen.sh
    	make tarballs

After the tarballs are created, the md5 checksums for the files will be computed. Add them to the docs/relnotes/x.y.html file.

Copy the distribution files to a temporary directory, unpack them, compile everything, and run some demos to be sure everything works.

### Update the website and announce the release

Make a new directory for the release on annarchy.freedesktop.org with:
`mkdir /srv/ftp.freedesktop.org/pub/mesa/x.y`

Basically, to upload the tarball files with:
`rsync -avP -e ssh MesaLib-x.y.* USERNAME@annarchy.freedesktop.org:/srv/ftp.freedesktop.org/pub/mesa/x.y/`

Update the web site by copying the docs/ directory's files to /home/users/b/br/brianp/mesa-www/htdocs/ with:
`sftp USERNAME,mesa3d@web.sourceforge.net`

Make an announcement on the mailing lists: mesa-dev@lists.freedesktop.org, mesa-users@lists.freedesktop.org and mesa-announce@lists.freedesktop.org