Overlapped Worlds for VR [WIP]

This demo shows a Unity plugin, which makes possible the creation and configuration of doors/portals between overlapping worlds. The plugin is under development and is intended for virtual reality apps.

The purpose of this demo is to show the possibilities offered by the plugin and to collect user feedback on the interest and relevance of a plugin able to build overlapping spaces for virtual reality.

What's the point?

Navigate only by natural walking, in a virtual area larger than the physical area.

No loading between 2 spaces / worlds.

Virtual movements and physical movements are always sync (no passive movements needed such as moving platform, vehicle, ...)

Why?

One of the major constraints of VR is the restricted physical area of play. It limits the user's movements, often compensated by the use of navigation metaphors such as teleportation or "sliding".

Natural walking brings many advantages over other current navigation methods: greater sense of presence (see references below), better spatial orientation and concentration (see references below), intuitive and without additional hardware.

Current state

Done

(Not production ready)

• Transition between 2 worlds
• Up to 5 doors per world
• Simple "recursion" (see a door through another door)
• Basic management of dynamic objects across worlds (visibility and collisions)

To do

• Real-time light and shadow support (A lot of artifacts due to the technique used for worlds transition)
• Collisions and detection physics improvements
• SRPs compatibility (URP and HDRP)
• Easier integration for custom shaders
• Smooth texture transition between worlds

Unwanted features (aka bugs)

• You can cross portals on both sides in all rooms (it should not be possible in the white room for example)
• It is possible to make a manipulable object disappear by making it go through a portal and then come out without going through the portal again. (The player remains in the same world) 

Installation

1. Make a 3m x 3m play area
2. Start SteamVR and make sure your HMD is running it
3. Unzip downloaded file
   
4. Run "OverlappedWorlds.exe"
5. Have fun :)

References

"Walking > walking-in-place > flying, in virtual environments" by Usoh et al

"Locomotion Mode Affects the Updating of Objects Encountered During Travel: The Contribution of Vestibular and Proprioceptive Inputs to Path Integration" by Chance et al

"Impossible Spaces: Maximizing Natural Walking in Virtual Environments with Self-Overlapping Architecture" by Suma et al