arfoundation-samples/Assets/Scenes/ARCollaborationData/AnchorInfoManager.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using UnityEngine.XR.ARFoundation;

namespace UnityEngine.XR.ARFoundation.Samples
{
    /// <summary>
    /// Displays information about each reference point including
    /// whether or not the reference point is local or remote.
    /// The reference point prefab is assumed to include a GameObject
    /// which can be colored to indicate which session created it.
    /// </summary>
    [RequireComponent(typeof(ARSessionOrigin))]
    [RequireComponent(typeof(ARAnchorManager))]
    public class AnchorInfoManager : MonoBehaviour
    {
        [SerializeField]
        ARSession m_Session;

        public ARSession session
        {
            get { return m_Session; }
            set { m_Session = value; }
        }

        void OnEnable()
        {
            GetComponent<ARAnchorManager>().anchorsChanged += OnAnchorsChanged;
        }

        void OnDisable()
        {
            GetComponent<ARAnchorManager>().anchorsChanged -= OnAnchorsChanged;
        }

        void OnAnchorsChanged(ARAnchorsChangedEventArgs eventArgs)
        {
            foreach (var referencePoint in eventArgs.added)
            {
                UpdateAnchor(referencePoint);
            }

            foreach (var referencePoint in eventArgs.updated)
            {
                UpdateAnchor(referencePoint);
            }
        }

        unsafe struct byte128
        {
            public fixed byte data[16];
        }

        void UpdateAnchor(ARAnchor referencePoint)
        {
            var canvas = referencePoint.GetComponentInChildren<Canvas>();
            if (canvas == null)
                return;

            canvas.worldCamera = GetComponent<ARSessionOrigin>().camera;

            var text = canvas.GetComponentInChildren<Text>();
            if (text == null)
                return;

            var sessionId = referencePoint.sessionId;
            if (sessionId.Equals(session.subsystem.sessionId))
            {
                text.text = $"Local";
            }
            else
            {
                text.text = $"Remote";
            }

            var cube = referencePoint.transform.Find("Scale/SessionId Indicator");
            if (cube != null)
            {
                var renderer = cube.GetComponent<Renderer>();
                {
                    // Generate a color from the sessionId
                    Color color;
                    unsafe
                    {
                        var bytes = *(byte128*)&sessionId;
                        color = new Color(
                            bytes.data[0] / 255f,
                            bytes.data[4] / 255f,
                            bytes.data[8] / 255f,
                            bytes.data[12] / 255f);
                    }
                    renderer.material.color = color;
                }
            }
        }
    }
}