Quad Buffer Unity - Stereo Display

QuadBuffer used to be supported in Unity (up to 2019) through the Stereo Display (non-head-mounted) option, allowing 3D visuals to be sent directly to the GPU for systems like CAVE environments and 3D projectors.

Since its removal, many of us have been stuck using older Unity versions to keep these setups working.

These systems are still widely used for immersive applications like research, simulations, and training. Bringing back QuadBuffer support would enable developers to use Unity’s modern features while still supporting these specialized devices.

Here is a CAVE System:

https://www.youtube.com/watch?v=VqDGBmYYkz4

There are commercial solutions like MiddleVR or even Unreal Engine’s nDisplay, which support this feature. There is also an open-source solution, UniCAVE, but it only works with Unity versions up to 2019.

I’m exploring ways to recreate this functionality. Two possible options I’ve identified are:

  1. Writing a custom XR plugin using the Unity XR SDK (but I’m unsure how difficult this would be or whether it would get access to the plugin).
  2. Using Unity APIs (OpenGL or DirectX) directly for stereo rendering.

Has anyone tried something similar? Which approach would you recommend, or is there another way to achieve this?