BotNavHelper.cs

using UnityEngine;
using System.Collections;
using System.Collections.Generic;
using System.Linq;

public class BotNavHelper : MonoBehaviour
{
    public float DiscoveryRadius;
    public float WalkableRadius;

    BotNavHelper[] _siblings;

    public Vector3 GetRandomPoint ()
    {
        return transform.position + (Vector3)Random.insideUnitCircle * WalkableRadius;
    }
    
    public BotNavHelper GetSiblingClosestTo (Vector3 point)
    {
        return _siblings.OrderBy(nav => (nav.transform.position - point).magnitude).FirstOrDefault();
    }
    
    void OnDrawGizmos ()
    {
        Gizmos.color = new Color(1,0.5f,1,0.2f);
        Gizmos.DrawWireSphere(transform.position, WalkableRadius);
        Gizmos.color = new Color(1,1,1,0.2f);
        Gizmos.DrawWireSphere(transform.position, DiscoveryRadius);
    }
    
    void Awake ()
    {
        _siblings = FindObjectsOfType<BotNavHelper>()
            .Where(nav => nav != this)
            .Where(nav => IsTouching(nav, this))
            .ToArray();
    }
    
    public static bool IsTouching (BotNavHelper n0, BotNavHelper n1)
    {
        // p0 is a point in the direction of n0 to n1 with a magnitude of n0.Radius
        Vector3 p0 = n0.transform.position + (n1.transform.position - n0.transform.position).normalized * n0.DiscoveryRadius;
        return ((n1.transform.position - p0).magnitude < n1.DiscoveryRadius);
    }
}