3440e89437
Some GPUs are able to render more efficiently when all channels of a
color attachment are written, since whole pixels are being overwritten,
rather than hitting a read-modify-write cycle where newly written data
has to be combined with existing unmodified image data.
When faking GL_RGB as RGBA (in case RGB/RGBX isn't color renderable),
we introduce an extra channel that doesn't exist from the application
point of view. With such a format, a color mask of 0x7 (RGB) would mean
to write all channels. But because we've added an alpha channel behind
their back, this becomes a partial write. We are free to write whatever
garbage we want to the alpha channel, however. So we can enable alpha
writes, making this a more efficient full pixel write again.
This is done unconditionally as it's expected to address a problem
common to many drivers and isn't expected to be harmful, even on GPUs
where it may not help much.
Improves WebGL Aquarium performance on Alderlake GT1 by around 2.4x, in
the Chromium, using Wayland (the --enable-features=UseOzonePlatform and
--ozone-platform=wayland flags).
v2: Don't require PIPE_CAP_RGB_OVERRIDE_DST_ALPHA_BLEND (Marek)
v3: Fix independent blending enables (Emma) - now set when needed,
skipped when not needed, and PIPE_CAP_INDEP_BLEND_ENABLE is no
longer a requirement. We just optimize where we can.
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/7864
Reviewed-by: Matt Turner <mattst88@gmail.com> [v1]
Reviewed-by: Marek Olšák <marek.olsak@amd.com> [v2]
Reviewed-by: Emma Anholt <emma@anholt.net> [v3]
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/20290>
`Mesa <https://mesa3d.org>`_ - The 3D Graphics Library ====================================================== Source ------ This repository lives at https://gitlab.freedesktop.org/mesa/mesa. Other repositories are likely forks, and code found there is not supported. Build & install --------------- You can find more information in our documentation (`docs/install.rst <https://mesa3d.org/install.html>`_), but the recommended way is to use Meson (`docs/meson.rst <https://mesa3d.org/meson.html>`_): .. code-block:: sh $ mkdir build $ cd build $ meson .. $ sudo ninja install Support ------- Many Mesa devs hang on IRC; if you're not sure which channel is appropriate, you should ask your question on `OFTC's #dri-devel <irc://irc.oftc.net/dri-devel>`_, someone will redirect you if necessary. Remember that not everyone is in the same timezone as you, so it might take a while before someone qualified sees your question. To figure out who you're talking to, or which nick to ping for your question, check out `Who's Who on IRC <https://dri.freedesktop.org/wiki/WhosWho/>`_. The next best option is to ask your question in an email to the mailing lists: `mesa-dev\@lists.freedesktop.org <https://lists.freedesktop.org/mailman/listinfo/mesa-dev>`_ Bug reports ----------- If you think something isn't working properly, please file a bug report (`docs/bugs.rst <https://mesa3d.org/bugs.html>`_). Contributing ------------ Contributions are welcome, and step-by-step instructions can be found in our documentation (`docs/submittingpatches.rst <https://mesa3d.org/submittingpatches.html>`_). Note that Mesa uses gitlab for patches submission, review and discussions.