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To develop the desired application, Unity and Visual Studio will be your primary tools. It’s recommended to use Unity 2021.3 LTS and Visual Studio 2022.
For information on using QR code tracking, please refer to QR code tracking overview - Mixed Reality | Microsoft Learn.
Currently, there’s no official solution for Web-RTC feature. You can use Media Capture API to implement real-time audio and video communication.
To get head, hand and eye tracking data, you can refer to the following links:
Eye Tracking Eye Gaze Provider - MRTK 2 | Microsoft Learn
IMixedRealityHand Interface (Microsoft.MixedReality.Toolkit.Input) | Microsoft Learn
For the issue on implementing the multi-user feature over a local network, you can refer to Is it possible to create a multi-user app for HoloLens without internet connection (offline mode) ? - Microsoft Q&A.
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