This solves a problem where OpenXR timestamps could become invalid
(negative) in certain circumstances:
The timestamps that the OpenXR state tracker returned were offset such
that they appeared to start at OpenXR application startup time.
However monado-service is a long running service using system timestamps.
Because of this, if monado-service started work using a system timestamp
acquired before an OpenXR application started, then this system timestamp
could not be converted into an OpenXR without becoming invalid.
With this change, the OpenXR timestamps for OpenXR applications are offset
such that they appear to start at monado-service startup time instead.
As a side effect, all OpenXR applications connected to the same
monado-service instance will receive timestamps from the same domain.
Includes fixes from Christoph Haag:
```
st/gui: Fix segfault when starting monado-gui without arguments
```
```
st/gui: Run gui_prober_select only in the modules that need a prober
This also speeds up starting up the monado-gui main menu.
```
Co-authored-by: Moses Turner <moses@collabora.com>
Co-authored-by: Jakob Bornecrantz <jakob@collabora.com>
Co-authored-by: Christoph Haag <christoph.haag@collabora.com>
The overrides didn't do anything unless Monado was compiled for
in-process, and even then the device might return a differnt fov.
The todo was for a driver and shouldn't be in the state tracker.
Usually renderdoc captures frames by hooking the present functions to
recognize when an application is finished rendering a frame.
OpenXR applications might not present to a window. Therefore use the
renderdoc API to capture application frames between xrBeginFrame and
and xrEndFrame.
This allows renderdoc to capture application frames without the need
to modify the application.
It was necessary to add a list of xdevs to oxr_sdl2_hack_start and to
populate such list from its callees.
That includes sdl2_program.gui_program->xdevs which was not being filled
for the monado-service target.
This commit is a band aid until a more proper room setup is implemented.
It allows moving the tracking offset for the device roles head, left and right by a fixed value.
A y tracking offset OXR_TRACKING_ORIGIN_OFFSET_Y=1.0 would tell monado that the current tracking
origin is 1 meter above the desired tracking origin, e.g. when the headset was calibrated to a
(0,0,0) position while sitting on table 1 meter above the floor.
This environment variable affects STAGE space, but not LOCAL space.
