A Vulkan layer to display information about the running application using an overlay.
Building
=======
The overlay layer will be built if :code:`overlay` is passed as a :code:`vulkan-layers` argument. For example:
.. code-block:: sh
meson -Dvulkan-layers=device-select,overlay builddir/
ninja -C builddir/
sudo ninja -C builddir/ install
See `docs/install.rst <https://gitlab.freedesktop.org/mesa/mesa/-/blob/master/docs/install.rst>`__ for more information.
Basic Usage
=======
Turn on the layer:
.. code-block:: sh
VK_INSTANCE_LAYERS=VK_LAYER_MESA_overlay /path/to/my_vulkan_app
List the available statistics:
.. code-block:: sh
VK_INSTANCE_LAYERS=VK_LAYER_MESA_overlay VK_LAYER_MESA_OVERLAY_CONFIG=help /path/to/my_vulkan_app
Turn on some statistics:
.. code-block:: sh
VK_INSTANCE_LAYERS=VK_LAYER_MESA_overlay VK_LAYER_MESA_OVERLAY_CONFIG=submit,draw,pipeline_graphics /path/to/my_vulkan_app
Position the overlay:
.. code-block:: sh
VK_INSTANCE_LAYERS=VK_LAYER_MESA_overlay VK_LAYER_MESA_OVERLAY_CONFIG=submit,draw,pipeline_graphics,position=top-right /path/to/my_vulkan_app
Logging Statistics
=======
Log statistics to a file:
.. code-block:: sh
VK_INSTANCE_LAYERS=VK_LAYER_MESA_overlay VK_LAYER_MESA_OVERLAY_CONFIG=output_file=/tmp/output.txt /path/to/my_vulkan_app
Logging is enabled for the entire lifecycle of the process unless a control socket is specified (see below).
**Note:** some statistics (e.g. :code:`frame_timing` and :code:`gpu_timing`) log values for the entire sample interval instead of per-frame.
For these statistics, logging the :code:`frame` statistic allows one to compute per-frame statistics after capture.
Log statistics to a file, controlling when such statistics will start to be captured:
.. code-block:: sh
VK_INSTANCE_LAYERS=VK_LAYER_MESA_overlay VK_LAYER_MESA_OVERLAY_CONFIG=output_file=/tmp/output.txt,control=mesa_overlay /path/to/my_vulkan_app
The command above will open a Unix socket with the abstract path :code:`mesa_overlay`. When a control socket is specified,
logging must be explicitly enabled through the control socket. :code:`mesa-overlay-control.py` provides a convenient CLI:
.. code-block:: sh
mesa-overlay-control.py start-capture
.. code-block:: sh
mesa-overlay-control.py stop-capture
Direct Socket Control
------
The Unix socket may be used directly if needed. Once a client connects to the socket, the overlay layer will immediately
send the following commands to the client:
.. code-block:: sh
:MesaOverlayControlVersion=1;
:DeviceName=<device name>;
:MesaVersion=<mesa version>;
The client connected to the overlay layer can enable statistics capturing by sending the command:
.. code-block:: sh
:capture=1;
And disable it by sending:
.. code-block:: sh
:capture=0;
.. _docs/install.rst: ../../docs/install.rst
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