Viewport HMD integration using OpenHMD
This adds basic support for controlling the viewport view using a head mounted display (HMD).
To use it, go to the Properties Editor, Render Layers context. Enable Views, select "HMD View". You can then open a new HMD Window from there and start a HMD session.
- Move HMD options to a better place, they are not Render Layer related (maybe properties region?). This also involves separating HMD usage from RenderData.views_format.
- Zoom and pan don't work in HMD window while in camera view
- View streched vertically in HMD window while not in camera view
- TODOs/XXXs marked in code (esp. WM_ calls in BKE_)
- Apply D1350 for better mouse interaction while in HMD view