Unity AI Null-Reference Exception Error... ANY HELP APPRECIATED!

Hey guys,
I'm making a game in Unity 2017.2 and using the third person AI controller prefabs for now. The game involves a bad guy who patrols the maze and is searching for an object with tag player. I looked online for a tutorial on how to do such a task and found this tutorial(

). I followed the previous tutorial as well to perfectly execute this. The first scene that I used this it worked perfectly, the animations were spot on and everything. I went to copy paste this into the next scene(full copy paste nothing in the new scene except for everything in the other working scene), and baked the Navigation map. I play the game and the characters animations are not working properly (in idle mode), and the character moves to only one of the points and stays there (very slowly may I add). I have tried restarting unity many times, only to discover a null-exception error in the console. When I click on the error so that it shows me what the problem is, it takes me over to the standard assets Third person controller script on the last line. But that can't be the error as when I have the unity standard AI system in place I get no errors. I can only assume that the code used from the tutorial is trying to access the unity standard Third person script but is something is not executed properly in the code from the tutorial.

Here is the code from the tutorial:

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3. using UnityEngine.AI;
4.  
5. namespace UnityStandardAssests.Characters.ThirdPerson
6. {
7.     public class BasicAI : MonoBehaviour
8.     {
9.         public NavMeshAgent agent;
10.         public UnityStandardAssets.Characters.ThirdPerson.ThirdPersonCharacter character;
11.  
12.    public enum State
13.         {
14.             PATROL,
15.             CHASE
16.         }
17.         public State state;
18.         private bool alive;
19.  
20.         public GameObject[] waypoints;
21.         private int waypointInd;
22.         public float patrolSpeed = 0.5f;
23.  
24.         public float chaseSpeed = 1f;
25.         public GameObject target;
26.  
27.         private void Start()
28.         {
29.             agent = GetComponent<NavMeshAgent>();
30.             character = GetComponent<UnityStandardAssets.Characters.ThirdPerson.ThirdPersonCharacter>();
31.  
32.             agent.updatePosition = true;
33.             agent.updateRotation = false;
34.  
35.             waypoints = GameObject.FindGameObjectsWithTag("Briefcase spawn 1");
36.             waypointInd = Random.Range(0, waypoints.Length);
37.  
38.             state = BasicAI.State.PATROL;
39.  
40.             alive = true;
41.  
42.             StartCoroutine("FSM");
43.         }
44.  
45.         IEnumerator FSM()
46.         {
47.                 while (alive)
48.                 {
49.                     switch (state)
50.                     {
51.                     case State.PATROL:
52.                         Patrol();
53.                         break;
54.                     case State.CHASE:
55.                         Chase();
56.                         break;
57.                      }
58.                      yield return null;
59.                 }
60.             }
61.            
62.             void Patrol()
63.         {
64.             agent.speed = patrolSpeed;
65.             if (Vector3.Distance(this.transform.position, waypoints[waypointInd].transform.position) >=2)
66.             {
67.                 agent.SetDestination(waypoints[waypointInd].transform.position);
68.                 character.Move(agent.desiredVelocity, false, false);
69.             }
70.             else if (Vector3.Distance(this.transform.position, waypoints[waypointInd].transform.position)<=2)
71.             {
72.                 waypointInd = Random.Range(0, waypoints.Length);
73.             }
74.             else
75.             {
76.                 character.Move(Vector3.zero, false, false);
77.             }
78.         }
79.  
80.         void Chase()
81.         {
82.             agent.speed = chaseSpeed;
83.             agent.SetDestination(target.transform.position);
84.             character.Move(agent.desiredVelocity, false, false);
85.         }
86.  
87.         private void OnTriggerEnter(Collider coll)
88.         {
89.             if (coll.tag == "Player")
90.             {
91.                 state = BasicAI.State.CHASE;
92.                 target = coll.gameObject;
93.             }
94.             if (coll.tag == "Briefcase spawn 1")
95.             {
96.                 waypointInd = Random.Range(0, waypoints.Length);
97.             }
98.             if (coll.tag == "Death")
99.             {
100.                 Application.LoadLevel(13);
101.             }
102.         }
103.        
104.     }
105. }

Here is the Unity standard code which it seems to be accessing :

Code (CSharp):

1. using UnityEngine;
2.  
3. namespace UnityStandardAssets.Characters.ThirdPerson
4. {
5.     [RequireComponent(typeof(Rigidbody))]
6.     [RequireComponent(typeof(CapsuleCollider))]
7.     [RequireComponent(typeof(Animator))]
8.     public class ThirdPersonCharacter : MonoBehaviour
9.     {
10.         [SerializeField] float m_MovingTurnSpeed = 360;
11.         [SerializeField] float m_StationaryTurnSpeed = 180;
12.         [SerializeField] float m_JumpPower = 12f;
13.         [Range(1f, 4f)][SerializeField] float m_GravityMultiplier = 2f;
14.         [SerializeField] float m_RunCycleLegOffset = 0.2f; //specific to the character in sample assets, will need to be modified to work with others
15.         [SerializeField] float m_MoveSpeedMultiplier = 1f;
16.         [SerializeField] float m_AnimSpeedMultiplier = 1f;
17.         [SerializeField] float m_GroundCheckDistance = 0.1f;
18.  
19.         Rigidbody m_Rigidbody;
20.         Animator m_Animator;
21.         bool m_IsGrounded;
22.         float m_OrigGroundCheckDistance;
23.         const float k_Half = 0.5f;
24.         float m_TurnAmount;
25.         float m_ForwardAmount;
26.         Vector3 m_GroundNormal;
27.         float m_CapsuleHeight;
28.         Vector3 m_CapsuleCenter;
29.         CapsuleCollider m_Capsule;
30.         bool m_Crouching;
31.  
32.  
33.         void Start()
34.         {
35.             m_Animator = GetComponent<Animator>();
36.             m_Rigidbody = GetComponent<Rigidbody>();
37.             m_Capsule = GetComponent<CapsuleCollider>();
38.             m_CapsuleHeight = m_Capsule.height;
39.             m_CapsuleCenter = m_Capsule.center;
40.  
41.             m_Rigidbody.constraints = RigidbodyConstraints.FreezeRotationX | RigidbodyConstraints.FreezeRotationY | RigidbodyConstraints.FreezeRotationZ;
42.             m_OrigGroundCheckDistance = m_GroundCheckDistance;
43.         }
44.  
45.  
46.         public void Move(Vector3 move, bool crouch, bool jump)
47.         {
48.  
49.             // convert the world relative moveInput vector into a local-relative
50.             // turn amount and forward amount required to head in the desired
51.             // direction.
52.             if (move.magnitude > 1f) move.Normalize();
53.             move = transform.InverseTransformDirection(move);
54.             CheckGroundStatus();
55.             move = Vector3.ProjectOnPlane(move, m_GroundNormal);
56.             m_TurnAmount = Mathf.Atan2(move.x, move.z);
57.             m_ForwardAmount = move.z;
58.  
59.             ApplyExtraTurnRotation();
60.  
61.             // control and velocity handling is different when grounded and airborne:
62.             if (m_IsGrounded)
63.             {
64.                 HandleGroundedMovement(crouch, jump);
65.             }
66.             else
67.             {
68.                 HandleAirborneMovement();
69.             }
70.  
71.             ScaleCapsuleForCrouching(crouch);
72.             PreventStandingInLowHeadroom();
73.  
74.             // send input and other state parameters to the animator
75.             UpdateAnimator(move);
76.         }
77.  
78.  
79.         void ScaleCapsuleForCrouching(bool crouch)
80.         {
81.             if (m_IsGrounded && crouch)
82.             {
83.                 if (m_Crouching) return;
84.                 m_Capsule.height = m_Capsule.height / 2f;
85.                 m_Capsule.center = m_Capsule.center / 2f;
86.                 m_Crouching = true;
87.             }
88.             else
89.             {
90.                 Ray crouchRay = new Ray(m_Rigidbody.position + Vector3.up * m_Capsule.radius * k_Half, Vector3.up);
91.                 float crouchRayLength = m_CapsuleHeight - m_Capsule.radius * k_Half;
92.                 if (Physics.SphereCast(crouchRay, m_Capsule.radius * k_Half, crouchRayLength, Physics.AllLayers, QueryTriggerInteraction.Ignore))
93.                 {
94.                     m_Crouching = true;
95.                     return;
96.                 }
97.                 m_Capsule.height = m_CapsuleHeight;
98.                 m_Capsule.center = m_CapsuleCenter;
99.                 m_Crouching = false;
100.             }
101.         }
102.  
103.         void PreventStandingInLowHeadroom()
104.         {
105.             // prevent standing up in crouch-only zones
106.             if (!m_Crouching)
107.             {
108.                 Ray crouchRay = new Ray(m_Rigidbody.position + Vector3.up * m_Capsule.radius * k_Half, Vector3.up);
109.                 float crouchRayLength = m_CapsuleHeight - m_Capsule.radius * k_Half;
110.                 if (Physics.SphereCast(crouchRay, m_Capsule.radius * k_Half, crouchRayLength, Physics.AllLayers, QueryTriggerInteraction.Ignore))
111.                 {
112.                     m_Crouching = true;
113.                 }
114.             }
115.         }
116.  
117.  
118.         void UpdateAnimator(Vector3 move)
119.         {
120.             // update the animator parameters
121.             m_Animator.SetFloat("Forward", m_ForwardAmount, 0.1f, Time.deltaTime);
122.             m_Animator.SetFloat("Turn", m_TurnAmount, 0.1f, Time.deltaTime);
123.             m_Animator.SetBool("Crouch", m_Crouching);
124.             m_Animator.SetBool("OnGround", m_IsGrounded);
125.             if (!m_IsGrounded)
126.             {
127.                 m_Animator.SetFloat("Jump", m_Rigidbody.velocity.y);
128.             }
129.  
130.             // calculate which leg is behind, so as to leave that leg trailing in the jump animation
131.             // (This code is reliant on the specific run cycle offset in our animations,
132.             // and assumes one leg passes the other at the normalized clip times of 0.0 and 0.5)
133.             float runCycle =
134.                 Mathf.Repeat(
135.                     m_Animator.GetCurrentAnimatorStateInfo(0).normalizedTime + m_RunCycleLegOffset, 1);
136.             float jumpLeg = (runCycle < k_Half ? 1 : -1) * m_ForwardAmount;
137.             if (m_IsGrounded)
138.             {
139.                 m_Animator.SetFloat("JumpLeg", jumpLeg);
140.             }
141.  
142.             // the anim speed multiplier allows the overall speed of walking/running to be tweaked in the inspector,
143.             // which affects the movement speed because of the root motion.
144.             if (m_IsGrounded && move.magnitude > 0)
145.             {
146.                 m_Animator.speed = m_AnimSpeedMultiplier;
147.             }
148.             else
149.             {
150.                 // don't use that while airborne
151.                 m_Animator.speed = 1;
152.             }
153.         }
154.  
155.  
156.         void HandleAirborneMovement()
157.         {
158.             // apply extra gravity from multiplier:
159.             Vector3 extraGravityForce = (Physics.gravity * m_GravityMultiplier) - Physics.gravity;
160.             m_Rigidbody.AddForce(extraGravityForce);
161.  
162.             m_GroundCheckDistance = m_Rigidbody.velocity.y < 0 ? m_OrigGroundCheckDistance : 0.01f;
163.         }
164.  
165.  
166.         void HandleGroundedMovement(bool crouch, bool jump)
167.         {
168.             // check whether conditions are right to allow a jump:
169.             if (jump && !crouch && m_Animator.GetCurrentAnimatorStateInfo(0).IsName("Grounded"))
170.             {
171.                 // jump!
172.                 m_Rigidbody.velocity = new Vector3(m_Rigidbody.velocity.x, m_JumpPower, m_Rigidbody.velocity.z);
173.                 m_IsGrounded = false;
174.                 m_Animator.applyRootMotion = false;
175.                 m_GroundCheckDistance = 0.1f;
176.             }
177.         }
178.  
179.         void ApplyExtraTurnRotation()
180.         {
181.             // help the character turn faster (this is in addition to root rotation in the animation)
182.             float turnSpeed = Mathf.Lerp(m_StationaryTurnSpeed, m_MovingTurnSpeed, m_ForwardAmount);
183.             transform.Rotate(0, m_TurnAmount * turnSpeed * Time.deltaTime, 0);
184.         }
185.  
186.  
187.         public void OnAnimatorMove()
188.         {
189.             // we implement this function to override the default root motion.
190.             // this allows us to modify the positional speed before it's applied.
191.             if (m_IsGrounded && Time.deltaTime > 0)
192.             {
193.                 Vector3 v = (m_Animator.deltaPosition * m_MoveSpeedMultiplier) / Time.deltaTime;
194.  
195.                 // we preserve the existing y part of the current velocity.
196.                 v.y = m_Rigidbody.velocity.y;
197.                 m_Rigidbody.velocity = v;
198.             }
199.         }
200.  
201.  
202.         void CheckGroundStatus()
203.         {
204.             RaycastHit hitInfo;
205. #if UNITY_EDITOR
206.             // helper to visualise the ground check ray in the scene view
207.             Debug.DrawLine(transform.position + (Vector3.up * 0.1f), transform.position + (Vector3.up * 0.1f) + (Vector3.down * m_GroundCheckDistance));
208. #endif
209.             // 0.1f is a small offset to start the ray from inside the character
210.             // it is also good to note that the transform position in the sample assets is at the base of the character
211.             if (Physics.Raycast(transform.position + (Vector3.up * 0.1f), Vector3.down, out hitInfo, m_GroundCheckDistance))
212.             {
213.                 m_GroundNormal = hitInfo.normal;
214.                 m_IsGrounded = true;
215.                 m_Animator.applyRootMotion = true;
216.             }
217.             else
218.             {
219.                 m_IsGrounded = false;
220.                 m_GroundNormal = Vector3.up;
221.                 m_Animator.applyRootMotion = false;
222.             }
223.         }
224.     }
225. }
226.  

and the error I get :

NullReferenceException: Object reference not set to an instance of an object
UnityStandardAssets.Characters.ThirdPerson.ThirdPersonCharacter.CheckGroundStatus () (at Assets/Standard Assets/Characters/ThirdPersonCharacter/Scripts/ThirdPersonCharacter.cs:221)
UnityStandardAssets.Characters.ThirdPerson.ThirdPersonCharacter.Move (Vector3 move, Boolean crouch, Boolean jump) (at Assets/Standard Assets/Characters/ThirdPersonCharacter/Scripts/ThirdPersonCharacter.cs:54)
UnityStandardAssests.Characters.ThirdPerson.BasicAI.Patrol () (at Assets/MY SCPRIPTS/BasicAI.cs:69)
UnityStandardAssests.Characters.ThirdPerson.BasicAI+<FSM>c__Iterator0.MoveNext () (at Assets/MY SCPRIPTS/BasicAI.cs:53)
UnityEngine.SetupCoroutine.InvokeMoveNext (IEnumerator enumerator, IntPtr returnValueAddress) (at C:/buildslave/unity/build/Runtime/Export/Coroutines.cs:17)
UnityEngine.MonoBehaviour:StartCoroutine(String)
UnityStandardAssests.Characters.ThirdPerson.BasicAI:Start() (at Assets/MY SCPRIPTS/BasicAI.cs:43)

I have some basic understanding of coding but this is beyond grade 11 coding class


I REALLY REALLY appreciate any help I can get!

Thank YOU!

 

Moving this code from Start to Awake seems to help:

Code (CSharp):

1.  void Awake()
2.       {
3.          go = this.gameObject;
4.        
5.          m_Animator = go.GetComponent<Animator>();
6.          m_Rigidbody = go.GetComponent<Rigidbody>();
7.          m_Capsule = go.GetComponent<CapsuleCollider>();
8.          m_CapsuleHeight = m_Capsule.height;
9.          m_CapsuleCenter = m_Capsule.center;
10.        
11.          m_Rigidbody.constraints = RigidbodyConstraints.FreezeRotationX | RigidbodyConstraints.FreezeRotationY | RigidbodyConstraints.FreezeRotationZ;
12.          m_OrigGroundCheckDistance = m_GroundCheckDistance;
13.       }

 

Thankyou! solved my same problem aswell