Logitech MX Ink stylus not detected as separate input in OpenXR on Quest Link (PCVR)

[altarfinch]

Hi,

I'm using the Logitech MX Ink stylus with Meta Quest 2/3 over Quest Link in PCVR, via OpenXR in Unreal Engine 5.4. The stylus defines its own interaction profile "/interaction_profiles/logitech/mx_ink_stylus" according to Logitech and OpenXR specs. However, when checking the interaction profile at runtime, only this is ever reported:

/interaction_profiles/oculus/touch_controller

The MX Ink is not distinguishable from a normal Touch controller in Meta’s OpenXR runtime. It is visible in OpenXR Explorer, so the profile is recognized — just never actually used.

Question:
Is this expected? Any way to detect the stylus separately in OpenXR on PCVR via Quest Link?

Thanks!

[maceochaidh]

See the MX Ink GitHub page here https://logitech.github.io/mxink/   As you can seem from that, it's possible to use MX Ink in PCVR for native OpenXR, Unity, WebXR ... but for Unreal there is limited support:

At this point there is no dedicated Unreal Plugin for MX Ink. However, MX Ink inputs also reports inputs in legacy mode as per a Touch Controller, i.e., the inputs can be read just as per a standard Touch Controller.  

[altarfinch]

From what I understand, the MX Ink has a dedicated OpenXR interaction profile (XR_LOGITECH_mx_ink_stylus_interaction). However, it seems that this profile either doesn't propagate correctly over Meta Quest Link, or Unreal's current OpenXR version doesn't support it yet (OpenXR 1.0). I can confirm that the extension is listed as enabled in OpenXR Explorer, but Unreal only reports the standard Oculus Touch interaction profile at runtime.

[maceochaidh]

To use it in Unreal (not as a controller, but as a stylus) you'd have to create a new plugin for MX Ink, i.e., use the Unreal OpenXR plugin interface to add the MX Ink Interaction Profile. An example of this is the HP Motion Controller Plugin which enables developers to target that hardware specifically (which is not directly supported by core Unreal offering).