ovrplugin-openxr-shim

A from-scratch reimplementation of Meta's libOVRPlugin.so on top of OpenXR, so legacy VrApi/OVRPlugin-based Meta Quest titles can run on standard OpenXR runtimes (Monado, and eventually Valve's Steam Frame under Lepton).

Status: Resident Evil 4 VR boots and is playable on a Quest 2 through this shim — stereo rendering, head + controller tracking, buttons, grips, haptics, and save loading all work. (Developed as a preservation / interoperability experiment.)

What it is

Quest's libOVRPlugin.so is the C shim Unreal/Unity games call to talk to Meta's VR runtime. Meta deprecated the underlying VrApi in 2022 and the whole modern stack (incl. Steam Frame's Monado) is OpenXR-only, so VrApi-era titles have no runtime on non-Meta OpenXR platforms. This project re-exports the ovrp_* C API backed by OpenXR instead, as a drop-in replacement libOVRPlugin.so:

game (libUE4.so) ──ovrp_* C API──> [THIS SHIM] ──OpenXR──> runtime (Monado / Meta / …)

It implements the OpenXR instance/session lifecycle, the Vulkan graphics binding, the frame loop + swapchains, layer compositing, and action-based input — mapping all of it to the ovrp_* ABI the game expects.

Legal / scope

• This repo contains only original code. It does not include or redistribute any game, the Meta runtime, Meta's headers, or Epic's UnrealEngine source. You must build the shim yourself and apply it to a copy of a game you legally own and dump yourself (patch-only, dump-your-own — like ROM-hack patches).
• Reimplementing an API for interoperability is the goal here; no proprietary binaries or decompiled source are published.
• Entitlement/ownership checks are out of scope: this project ships no circumvention code and circumvents nothing. On Quest the platform's real entitlement check runs unchanged (you own the title). Running on hardware with no Meta backend requires a valid entitlement by other means — that is the user's responsibility and not provided here.
• Not affiliated with or endorsed by Meta, Capcom, Epic Games, or Valve. All trademarks belong to their owners.
• Provided as-is, no warranty. You are responsible for compliance with applicable law and the terms of any software you use it with, in your jurisdiction.

Build

scripts/fetch_deps.sh          # OpenXR + Vulkan headers (Apache-2.0), Android NDK
shim/build_android.sh          # -> shim/build/arm64/libOVRPlugin.so

Needs: Android NDK (r27c), a JDK, and the OpenXR/Vulkan headers (the fetch script gets them). A host x86-64 build is also supported for compile-validation.

Use (with your own dumped game)

packaging/repack.sh /path/to/your/base.apk   # swap the shim in, re-sign
adb install -r packaging/out/<game>-shim.apk
# push your own dumped OBB, then launch on a dev-mode Quest

See packaging/README.md and TESTING.md for the full flow.

Layout

• shim/src/ — the implementation: xr_runtime (session/frame loop/swapchains), vk_session (Vulkan binding + ext), layers, xr_input (action sets), core (the ovrp_* entry points), android_init, generated stubs.
• shim/include/ovrplugin_shim.h — the ovrp_* C ABI (clean-room from observed ABI).
• packaging/ — repack/sign tooling.
• docs/ — research notes + session handoffs (docs/README.md narrates how the frame-pacing "ghost" was solved); TESTING.md/HOST.md at root.

Acknowledgements

Built against the OpenXR and Vulkan specs and the Khronos OpenXR loader.