Reprojection mode override on OpenXR does not allow for the focus point to be set

[ChristopherManthei]

Describe the bug

When using OpenXR, there is an MRTK camera setting that lets you override the reprojection mode. However, when setting it to Planar Manual, there is no way to set the focus point.

To reproduce

Steps to reproduce the behavior:

1. Use any MRTK project on HoloLens2 that was set up to use OpenXR and the legacy renderer (URP doesn't work due to another bug).
2. Goto MRTK Settings > Camera > Camera Settings Providers > OpenXR Camera Settings
3. Set HoloLens 2 Reprojection Method to Planar Manual.
4. Search everywhere how to set the focus point. The documentation is unfortunately out of date.

Expected behavior

There should be an API to also set the focus point. The documentation is unfortunately incorrect: "Planar Reprojection: On every frame, applications tell the system the location of a plane to stabilize. Unity applications call SetFocusPointForFrame and should have Shared Depth Buffer disabled."

1. Disabling Shared Depth Buffer is not necessary. This was only true before the reprojection settings existed.
2. The fuction SetFocusPointForFrame does not exist in OpenXR.

Screenshots

If applicable, add screenshots to help explain your problem.

Your setup (please complete the following information)

• Unity Version 2020.3.13f1
• MRTK Version 2.7.2
• OpenXR Plugin 1.0.3

Target platform (please complete the following information)

• HoloLens 2

Additional context

The MRTK's OpenXRReprojectionUpdater calls SetReprojectionSettings every frame with a cleared struct with no focus point data in it so even if a user manually calls it MRTK will clobber it over.

[stale[bot]]

This issue has been marked as stale by an automated process because it has not had any recent activity. It will be automatically closed in 30 days if no further activity occurs. If this is still an issue please add a new comment with more recent details and repro steps.

[IssueSyncBot]

We appreciate your feedback and thank you for reporting this issue.

Microsoft Mixed Reality Toolkit version 2 (MRTK2) is currently in limited support. This means that Microsoft is only fixing high priority security issues. Unfortunately, this issue does not meet the necessary priority and will be closed. If you strongly feel that this issue deserves more attention, please open a new issue and explain why it is important.

Microsoft recommends that all new HoloLens 2 Unity applications use MRTK3 instead of MRTK2.

Please note that MRTK3 was released in August 2023. It features an all-new architecture for developing rich mixed reality experiences and has a minimum requirement of Unity 2021.3 LTS. For more information about MRTK3, please visit https://www.mixedrealitytoolkit.org.

Thank you for your continued support of the Mixed Reality Toolkit!