Development updates and news about PsychXR between releases.
It's been a while since the last release of PsychXR, however version 0.2.4 is
almost and introduces substantial changes such as OpenHMD support and color
space management to LibOVR.
PsychXR has finally gotten a new driver interface, this one using OpenHMD
which provides FOSS drivers for HMDs and VR peripherals. While this isn't the
OpenXR interface everyone wanted (more on that later), it's something that work
began on almost two years ago. The OpenHMD extension module isn't a simple
wrapper around the library. Effort is being made to make it function similarly
to LibOVR to make it easier to integrate into existing apps using the LibOVR
interface.
OpenXR support is the next major development target. The specification seems
mature enough now to include and has been seeing considerable adoption in
industry. OpenXR is a big deal since it will provide a standardized interface
for a wide variety of HMDs. OpenXR shares a lot in common with LibOVR (which
make sense considering how much Facebook contributed to that standard), so the
resulting extension may closely resemble the existing one. The inclusion of
OpenXR will mark the end of the 0.2.x series of PsychXR. No timeline has
been decided for when OpenXR will be added, but it's looking very likely to be
included near the end of 2021.
You may have noticed a bit of a slow down in PsychXR's development in recent months. I've been busy with other projects and PsychXR has been "good enough" for tasks I've been running in the lab, so there isn't any incentive for me to spend time adding features to it which detracts from my other work. Particularly since testing new features requires lots of time to ensure things are working as advertised.
I don't track usage statistics directly, but I've received e-mails from users indicating to me that PsychXR has considerable use in multiple labs. Knowing this gives me motivation to continue development for quite some time, even after my own research ceases.
I plan to get back into development soon. There are a few things planned for upcoming releases I'll list here:
- Bump LIBOVR support to the latest version of the Oculus Rift SDK.
- Add the ability to reference LIBOVR timestamps to an external clock source.
- Add a generic VR math library. This library can be built without the
Oculus SDK, providing similar features to
LibOVRPoseandLibOVRPoseStatethat can be used with other VR systems. - Split PsychXR drivers off into separate packages which are loaded as plugins. This will make adding additional drivers easier in the future, allowing PsychXR to build on platforms where a particular driver is not supported.
I've also received numerous messages asking whether other HMDs will eventually be supported. I've looked into possible drivers to support next (OpenVR, OpenHMD, OpenXR, etc.) but I haven't committed to anything yet. It's looking likely that OpenXR will be the next driver to be added which should support a large range of hardware, but there is no timeline for when work will begin on it. If additional HMD support is something you need, I'm open to accepting PRs to expedite the process.
I'm also looking into integrating OptiTrack support into PsychXR, possibly as a plugin. I've already written the library to do so that integrates well with PsychXR classes and have used it in experiments to date. However, I haven't packaged it up nicely to be included yet. I feel the math library needs to be added beforehand since data coming off NatNet needs to be formatted in a way that can be passed around between drivers more easily.
Lastly, PsychoPy seems to be the most common route for using PsychXR for many. One thing planned for PsychoPy is the introduction of extended off-screen rendering support. This will allow PsychoPy to better support stereoscopic rendering in general, but will greatly improve integration with VR hardware. Notably, you will be able to run the same code across different types of stereoscopic displays and HMDs without significant modification to your experiment's code. There are also tools currently in PsychoPy that can do VR specific things like lens correction (i.e. barrel distortion) which permits labs to create their own HMD-like displays. The introduction of the generic VR math library in PsychXR will aid in the doing so.