PlaceObjectsLine.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using ARLocation;
using System;

public class PlaceObjectsLine : MonoBehaviour
{
    [Serializable]
    public class Entry
    {
        public LocationData ObjectLocation;
        public OverrideAltitudeData OverrideAltitude = new OverrideAltitudeData();
    }

    [Tooltip("The locations where the objects will be instantiated.")]
    public List<PlaceAtLocation.LocationSettingsData> Locations;

    public PlaceAtLocation.PlaceAtOptions PlacementOptions;

    /// <summary>
    /// The game object that will be instantiated.
    /// </summary>
    [Tooltip("The game object that will be instantiated.")]
    public GameObject Prefab;

    [Space(4.0f)]

    private readonly List<Location> locations = new List<Location>();
    private readonly List<GameObject> instances = new List<GameObject>();

    private void Start()
    {
        foreach (var entry in Locations)
        {
            var newLoc = entry.GetLocation();

            AddLocation(newLoc);
        }
    }

    public void AddLocation(Location location)
    {
        var instance = PlaceAtLocation.CreatePlacedInstance(Prefab, location, PlacementOptions, true);

        instance.name = $"{gameObject.name} - {locations.Count}";

        locations.Add(location);
        instances.Add(instance);
    }

    public void Update()
    {
        float currentDist = 1000000;
        GameObject closest = null;
        foreach(var instance in instances)
        {
            var dist = Vector3.Distance(instance.transform.position, ARLocationManager.Instance.MainCamera.transform.position);

            if (dist < currentDist)
            {
                currentDist = dist;
                closest = instance;
            }
        }


        foreach(var instance in instances)
        {
            var deb = instance.GetComponent<ARLocation.UI.DebugDistance>();

            if (deb != null)
            {
                if (closest == instance)
                {
                    deb.enabled = true;
                }
                else
                {
                    deb.enabled = false;
                }

            }
        }

    }
}