The team behind OpenHMD have now officially announced version 0.3.0, which comes with a huge amount of changes and new hardware support.
What exactly is OpenHMD? Its aim is to provide a FOSS API and drivers for hardware like Virtual Reality Headsets and Controllers. They're hoping to support as many devices as they possibly can, while also being cross-platform.
From this release they now support: 3Glasses D3 (first-party support from 3Glasses), Oculus Rift CV1 (rotational), HTC Vive and HTC Vive Pro (rotational), NOLO VR (Positional including Controller support), Windows Mixed Reality HMD support (rotational), Deepoon E2, GearVR Gen1. Sadly PSVR is currently disabled due to issues, sounds like it may return later though.
As of this update, they have also now finalized their Controller API, making it clear they're not aiming to support all game controllers as there's already stuff out there to do that. They're focusing directly on controllers that "are directly part of VR ecosystems".
They also upgraded their OpenGL example to use SDL2 for "more debug functions, controller support, and convenience". Sounds like a lot of impressive work goes into OpenHMD! They're also working to release more often on a new schedule.