Lemon Pass Through

Wireless PC VR for Meta Quest on Linux, with a window to the real world: a circle in the room where the game is cut away and the headset's passthrough cameras show through. Put it over your sim-racing wheel and you can see your hands, wheel and buttons while you race.

It's a fork of WiVRn, so it streams any OpenXR game the same way WiVRn does.

Features

• Room-anchored passthrough circle. It stays over your wheel as you move your head.
• Set up in the headset with the controllers. No config files or numbers to type.
• Saved between sessions.
• Everything else from WiVRn: wireless streaming, hardware video encoding, foveation, and controller and hand tracking.

Quick start

git clone https://github.com/j99-droid/LemonPassThrough.git
cd LemonPassThrough
./install.sh

Then:

1. In Steam, set the game's launch options to PRESSURE_VESSEL_FILESYSTEMS_RW=$XDG_RUNTIME_DIR/wivrn/comp_ipc %command%.
2. Open Lemon Pass Through on the PC, then in the headset, and connect. Then start the game.
3. Look at your wheel and press Right B. Adjust with the left thumbstick (hold the left trigger to resize), and press Right A to save.

The full walkthrough, controls and troubleshooting are in GUIDE.md.

Controls

Control	Action
Right B	Place the circle in front of you
Left thumbstick	Move it
Left trigger + left thumbstick up/down	Resize it
Right thumbstick up/down	Resize it
Right A	Save

Requirements

• Linux PC: Ubuntu 24.04, Pop!_OS 24.04 or newer for the installer; other distributions can build from source/ by hand.
• A Meta Quest with passthrough and developer mode on. Tested on the Quest 3.
• PC and headset on the same network.

Tested with Assetto Corsa EVO on Pop!_OS 24.04 with an NVIDIA RTX 4080 SUPER and a Quest 3.

How it works

The server makes part of each eye's image transparent and asks the headset to blend the stream over passthrough. The circle is a real position in the room: every frame, the server projects it into each eye using that frame's head pose and field of view. The game itself is unchanged.

The changes from WiVRn are in source/server/compositor/ (compositor.cpp, foveation.h and shaders/foveation.comp). The headset app is WiVRn's, renamed, with a new icon.

Building by hand

cmake -S source -B build -G Ninja -DWIVRN_BUILD_CLIENT=OFF -DCMAKE_BUILD_TYPE=RelWithDebInfo
cmake --build build

On Ubuntu 24.04, add -DVulkan_INCLUDE_DIR=<path to Vulkan-Headers 1.4>/include. install.sh handles this for you. See source/docs/building.md for the headset app.

Credits and license

Based on WiVRn by Patrick Nicolas and contributors, which builds on Monado. Licensed under GPL-3.0, see COPYING. Changes in this fork are under the same license.

Not affiliated with WiVRn, Meta or Kunos Simulazioni.