[GB-175] Research feasibility of displaying OpenXR in Game Bridge

[BramTeurlings]

Read the description of the parent epic and see if such a program is feasible to make. The outcome of this ticket should describe:

• If we can communicate with the Hydra Service for the following:
  • Stopping it from opening the Hydra UI
  • Changing camera settings (convergence/separation/perspective)
• If it’s possible to copy buffer pointers between processes and present them in ReShade.
• If there are any performance concerns about this method of copying buffers.
• If OpenXR’s camera will move alongside the in-game camera.

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Originally reported by , imported from: Research feasibility of displaying OpenXR in Game Bridge

• assignee:
• status: Done
• priority: Medium
• resolution: Complete
• resolved: 2024-01-19T08:03:01-08:00
• imported: 2024-04-04

[BramTeurlings]

Subtask of parent task GB-174

[BramTeurlings]

712020:c26664a4-c3de-4473-a0b4-5a76804d5628:

OpenXR is now officially supported in ReShade 6.0.0 so this saves us a ton of work!

[BramTeurlings]

607809585759fb0069a89817:

I have looked a little bit into the reshade implementation of OpenXR. It looks like it hooks some graphics pipeline functions of an application that supports OpenXR.

Two things:

• To enable this with UEVR, I suspect reshade would have to hook the OpenXR functions of UEVR, which sounds very horrible, but might be possible. The only problem is that UEVR is injected on runtime and reshade is not, and you want reshade to load later. This is rather hard to do, haven’t found a way to do this yet.
• An OpenXR device will have to be created, if we want to create this in the addon itself it means it needs to create it before the game connects to the runtime. This might be a big challenge if possible at all. That would mean an external service is still necessary I assume. After that it might probably work. We should be able to get the buffers from reshade.

Maybe it’s possible to force the game to search for devices again, that would enable us to create a device in reshade.

It might be good to continue this ticket with the original ideas, the support for OpenXR in Reshade will probably help a lot.

[BramTeurlings]

607809585759fb0069a89817:

Looked into the reshade implementation of OpenXR, I suggest we continue with the original idea and use reshade functions.

[BramTeurlings]

712020:c26664a4-c3de-4473-a0b4-5a76804d5628:

We would have to see if we can initialize some connection to OpenXR in our addon after the game is launched and injected with UEVR. Not sure is this is possible.

[BramTeurlings]

712020:f91dd24e-5296-4a9d-90d9-b287c639e252:

So we decided to look at OpenXR and making a UEVR plugin instead of making a native version of UEVR. It can have several benefits in the end. Also it would not be necessary for us to use the Compositor (Hydra application) or the SR Hydra background service. We will use the code from the hydra runtime dll and modify it to be loaded by UEVR and have it render to the game window with SR. This would become a very minimal program and does not need multiple programs to interact with each other. Also there would be no need for ReShade.

[BramTeurlings]

712020:f91dd24e-5296-4a9d-90d9-b287c639e252:

Investigated while working on the program

[BramTeurlings]

712020:c26664a4-c3de-4473-a0b4-5a76804d5628:

Investigation was done on both UEVR and ReShade. This is satisfactory.

[BramTeurlings]

[Epic: OpenXR in GameBridge]