Surface recognition by throwing rays

I am studying the textbook "Unity in action 2 edition" and trying to make surface recognition by throwing rays.
The code for unity 2019.4 produces:"
NullReferenceException: Object reference not set to an instance of an object
RelativeTarger.Update () (at Assets/RelativeTarger.cs:69"
Anyone can follow this tutorial and understand what the problem is?
I looked it 100 times and I can't understand

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class RelativeTarger : MonoBehaviour
6. {
7.     [SerializeField] private Transform target;
8.     public float rotSpeed = 15.0f;
9.     public float moveSpeed = 6.0f;
10.     private CharacterController _charController;
11.     public float jumpSpeed = 15.0f;
12.     public float gravity = -9.8f;
13.     public float terminalVelocity = -10.0f;
14.     public float minFall = -1.5f;
15.     private float _vertSpeed;
16.     //RAY//
17.     private ControllerColliderHit _contact;
18.  
19.     // Start is called before the first frame update
20.     void Start()
21.     {
22.         _vertSpeed = minFall;
23.         _charController = GetComponent<CharacterController>();
24.  
25.     }
26.  
27.     // Update is called once per frame
28.     void Update()
29.     {
30.         Vector3 movement = Vector3.zero;
31.         float horInput = Input.GetAxis("Horizontal");
32.         float vertInput = Input.GetAxis("Vertical");
33.         if (horInput != 0 || vertInput != 0) {
34.             movement.x = horInput * moveSpeed;
35.             movement.z = vertInput * moveSpeed;
36.             movement = Vector3.ClampMagnitude(movement, moveSpeed);
37.             Quaternion tmp = target.rotation;
38.             target.eulerAngles = new Vector3(0, target.eulerAngles.y, 0);
39.             movement = target.TransformDirection(movement);
40.             target.rotation = tmp;
41.             Quaternion direction = Quaternion.LookRotation(movement);
42.             transform.rotation = Quaternion.Lerp(transform.rotation, direction,
43.                 rotSpeed * Time.deltaTime);
44.  
45.         }
46.  
47.         bool hitGround = false;
48.         RaycastHit hit;
49.  
50.         if (_vertSpeed < 0 && Physics.Raycast(transform.position, Vector3.down, out hit)) {
51.             float check = (_charController.height + _charController.radius) / 1.9f;
52.             hitGround = hit.distance <= check;  
53.         }
54.  
55.  
56.  
57.         if (hitGround) {
58.             if (Input.GetButtonDown("Jump")) {
59.                 _vertSpeed = jumpSpeed;
60.             } else {
61.                 _vertSpeed = minFall;
62.             }
63.         } else {
64.             _vertSpeed += gravity * 5 * Time.deltaTime;
65.             if (_vertSpeed < terminalVelocity) {
66.                 _vertSpeed = terminalVelocity;
67.             }
68.             if (_charController.isGrounded) {
69.                 if (Vector3.Dot(movement, _contact.normal) < 0) {
70.                     movement = _contact.normal * moveSpeed;
71.                 } else {
72.                     movement += _contact.normal * moveSpeed;
73.                 }
74.             }
75.         }
76.         movement.y = _vertSpeed;
77.  
78.         movement *= Time.deltaTime;
79.         _charController.Move(movement);
80.         }
81.         void OnControllerColliderHit(ControllerColliderHit hit) {
82.                 _contact = hit;
83.         }
84. }

 

_contact isn't assigned anything until OnControllerColliderHit, that's why it's null reference. Try changing line 68 to this:

Code (CSharp):

1. if (_charController.isGrounded && (_contact != null)) {

 

Thank you, now the program starts, but the jump stopped working, and the character somehow barely moves

 

The hitGround condition does not pass, maybe something is wrong with the rays

 

This, probably:

Code (CSharp):

1. Physics.Raycast(transform.position, Vector3.down,

If the position is below the surface, it will not hit. Try either clamping the position passed in so it will never be underneath the surface (if floor is linear/flat that's easy),or even just something that will make sure the position is above surface..

Code (CSharp):

1. Physics.Raycast(transform.position + (Vector3.up * 100), Vector3.down,

Edit: note you will probably need to add a layerMask later to this Raycast so it's only testing what you're allowing to walk on.. you don't want it to be glitching out standing on top of projectiles flying by etc.

 

I did it as you said, but as far as I understand, it goes inside

Code (CSharp):

1. if (_vertSpeed <0 && Physics.Raycast (transform.position, Vector3.down, out hit))

, but it can't get through

Code (CSharp):

1. float check = (_charController.height + _charController.radius) / 1.9f;
2. hitGround = hit.distance <= check;

 

Could be that your Raycast is hitting something else (collider on the character most likely in this case, which you could fix by setting the collider .enabled = false before the Raycast then .enabled true again after), you can find out what's being hit, just add

Debug.Log("hit: " + hit.transform.name);

before the line starting with "float check". You can also

Debug.Log(hit.distance + "/" + check)

to see what the values are.

 

thanks, I will try to solve