Question Looking for ai path finding without using nav mesh agent, is there any tutorial/s ?

This script is attached to a transform and the transform is moving towards a target.

Code (csharp):

1.  
2. using System;
3. using System.Collections;
4. using System.Collections.Generic;
5. using System.Linq;
6. using UnityEngine;
7. using UnityEngine.UI;
8.  
9. public class Follow : MonoBehaviour
10. {
11.     public Transform targetToFollow;
12.     public Transform missionTarget;
13.     public GameObject naviParent;
14.     public Text textDistance;
15.     public Text textSpeed;
16.     public float lookAtRotationSpeed;
17.     public float moveSpeed;
18.     public float followRadius = 1.5f;
19.     public float fastRadius = 5f;
20.     public float speedBoost = 0.5f;
21.  
22.     private bool isNaviChild = false;
23.  
24.     void Start()
25.     {
26.        
27.     }
28.  
29.     // Update is called once per frame
30.     void FixedUpdate()
31.     {
32.         Vector3 lTargetDir = targetToFollow.position - transform.position;
33.  
34.         lTargetDir.y = 0.0f;
35.  
36.         transform.rotation = Quaternion.RotateTowards(transform.rotation,
37.             Quaternion.LookRotation(lTargetDir), Time.time * lookAtRotationSpeed);
38.  
39.         float ms = moveSpeed;
40.         var distance = Vector3.Distance(transform.position, targetToFollow.position);
41.         // Compute a position no further than followRadius away from our target.
42.         Vector3 fromTarget = Vector3.ClampMagnitude(
43.             -lTargetDir, followRadius);
44.         Vector3 stopPoint = targetToFollow.position + fromTarget;
45.  
46.         // Compute a speed that's faster when far away and slower when close.
47.         float speedBlend = Mathf.Clamp01((distance - followRadius) / (fastRadius - followRadius));
48.  
49.         ms = moveSpeed + speedBlend * speedBoost;
50.  
51.         // Move as far as we can at our speed ms to reach the stopPoint, without overshooting.
52.         transform.position = Vector3.MoveTowards(transform.position,
53.             stopPoint, Time.deltaTime * ms);
54.  
55.         var dist = Vector3.Distance(transform.position, targetToFollow.position);
56.         if(dist < 0.1f && isNaviChild == false)
57.         {
58.             transform.parent = targetToFollow;
59.             transform.localPosition = new Vector3(0, 0, 0);
60.             transform.localRotation = Quaternion.identity;
61.             transform.localScale = new Vector3(0.001f, 0.001f, 0.001f);
62.  
63.             isNaviChild = true;
64.         }
65.     }
66.  
67.     private void Mission()
68.     {
69.  
70.     }
71. }
72.  

The problem will be if there is any obstacles and how to avoid them ?
For example :

Simple wall, How to find the shortest way ? Or if the wall sides are equal then how to decide what direction path to move ?

Or if for example the player was walking around a cave or around a house and the transform by accident went inside the house or the cave how will the transform know to find the way back out and continue moving towards the player ?

What about a rock that have some shapes ? Trees and other obstacles.

The player has "forgotten" the transform the player doing his own stuff in the game and the transform should find a way and sometime somehow to reach the player. This is the main logic.


The reason that I don't want to use nav mesh agent is because the nav mesh agent is more relevant to terrain/s and I want something to cover also the terrain area but also areas that are not terrain like just a simple plane with many obstacles.

I want to start thinking of some logic ai path finding system. It's not have to be 100% accurate but it should do the work in most of the situations.