How do I get my AI to chase the player?,How do I go from patrolling to chasing the player?

Questions & Answers
1

I am new to Unity and Scripting. So far I have a code to where my AI makes a patrol around my Nav Mesh. I want to have it chase the player and attack the player when the player comes into a certain range, but return to patrolling once the player gets out of that range. This is for an Oculus project. Any help is greatly appreciated. Here is the code I have so far:

using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.AI;

public class NPCSimplePatrol : MonoBehaviour
{
    //Dictates whether the agent waits on each node
    [SerializeField]
    bool _patrolWaiting;

    //The total time we wait at each node
    [SerializeField]
    float _totalWaitTime = 3f;

    //The probability of switching direction
    [SerializeField]
    float _switchProbability = 0.2f;

    //The list of all patrol nodes to visit
    [SerializeField]
    List<Waypoint> _patrolPoints;

    //Private variables for base behaviour
    NavMeshAgent _navMeshAgent;
    int _currentPatrolIndex;
    bool _travelling;
    bool _waiting;
    bool _patrolForward;
    float _waitTimer;
    public Transform player;
    static Animator anim;

    //Use this for initialization
    public void Start()
    {
        anim = GetComponent<Animator>();
        _navMeshAgent = this.GetComponent<NavMeshAgent>();

        if(_navMeshAgent == null)
        {
            Debug.LogError("The nav mesh agent component is not attached to " + gameObject.name);
        }
        else
        {
            if(_patrolPoints != null && _patrolPoints.Count >= 2)
            {
                _currentPatrolIndex = 0;
                SetDestination();
            }
            else
            {
                Debug.Log("Insufficient patrol points for basic patrolling behaviour.");
            }
        }
    }

    public void Update()
    {
        
            //Check if we're close to destination
            if (_travelling && _navMeshAgent.remainingDistance <= 1.0f)
            {
                _travelling = false;

                //If we're going to wait, then wait
                if (_patrolWaiting)
                {

                    _waiting = true;
                    _waitTimer = 0f;
                }
                else
                {

                    ChangePatrolPoint();
                    SetDestination();
                }
            }

            //Instead if we're waiting
            if (_waiting)
            {
                anim.SetBool("IsIdle", true);
                anim.SetBool("IsWalking", false);
                anim.SetBool("IsAttacking", false);
                _waitTimer += Time.deltaTime;
                if (_waitTimer >= _totalWaitTime)
                {

                    _waiting = false;

                    ChangePatrolPoint();
                    SetDestination();

                    anim.SetBool("IsIdle", false);
                    anim.SetBool("IsWalking", true);
                    anim.SetBool("IsAttacking", false);
                }
            }
    }       

    private void SetDestination()
    {
        if (_patrolPoints != null)
        {

            Vector3 targetVector = _patrolPoints[_currentPatrolIndex].transform.position;
            _navMeshAgent.SetDestination(targetVector);
            _travelling = true;
        }
    }

    /// <summary>
    /// Selects a new patrol point in the available list but
    /// also with a small probability allows for us to move forward or backwards
    /// </summary>
    private void ChangePatrolPoint()
    {
        if(UnityEngine.Random.Range(0f, 1f) <= _switchProbability)
        {
            _patrolForward = !_patrolForward;
        }

        if (_patrolForward)
        {
            _currentPatrolIndex = (_currentPatrolIndex + 1) % _patrolPoints.Count;
        }
        else
        {
            if(--_currentPatrolIndex < 0)
            {
                _currentPatrolIndex = _patrolPoints.Count - 1;
            }
        }
    }
}
2

I can’t write out code to help you, because I’m on my phone but you’ll want to setup a trigger, when a player enters it, in the update function or late update function start setting the nav mesh agent destination to the player’s position.

3

So I created a script to chase, and the AI does. The only problem is that it won’t patrol, but just sit there idle here is my code that I have. Thanks for the quick reply by the way.

    using System.Collections;
    using System;
    using System.Collections.Generic;
    using UnityEngine;
    using UnityEngine.AI;
    
    public class Chase : MonoBehaviour
    {
        //Dictates whether the agent waits on each node
        [SerializeField]
        bool _patrolWaiting;
    
        //The total time we wait at each node
        [SerializeField]
        float _totalWaitTime = 3f;
    
        //The probability of switching direction
        [SerializeField]
        float _switchProbability = 0.2f;
    
        //The list of all patrol nodes to visit
        [SerializeField]
        List<Waypoint> _patrolPoints;
    
        //Private variables for base behaviour
        public Transform player;
        static Animator anim;
        NavMeshAgent _navMeshAgent;
        int _currentPatrolIndex;
        bool _travelling;
        bool _waiting;
        bool _patrolForward;
        bool player_detected;
        float _waitTimer;
    
        // Start is called before the first frame update
        void Start()
        {
            anim = GetComponent<Animator>();
            _navMeshAgent = this.GetComponent<NavMeshAgent>();
    
            if (_navMeshAgent == null)
            {
                Debug.LogError("The nav mesh agent component is not attached to " + gameObject.name);
            }
            else
            {
                if (_patrolPoints != null && _patrolPoints.Count >= 2)
                {
                    _currentPatrolIndex = 0;
                    //SetDestination();
                }
                else
                {
                    Debug.Log("Insufficient patrol points for basic patrolling behaviour.");
                }
            }
        }
    
        // Update is called once per frame
        void Update()
        {
            Vector3 direction = player.position - this.transform.position;
            float angle = Vector3.Angle(direction, this.transform.forward);
            // this affects radius
            if(Vector3.Distance(player.position, this.transform.position) < 20 && angle < 30)
            {
    
                direction.y = 0;
    
                this.transform.rotation = Quaternion.Slerp(this.transform.rotation, Quaternion.LookRotation(direction), 0.1f);
    
               anim.SetBool("IsIdle", false);
                if(direction.magnitude > 2)
                {
                    this.transform.Translate(0, 0, 0.05f);
                   anim.SetBool("IsWalking", true);
                   anim.SetBool("IsAttacking", false);
                }
                else
                {
                   anim.SetBool("IsAttacking", true);
                   anim.SetBool("IsWalking", false);
                }
            }
            else
            {
              anim.SetBool("IsIdle", true);
              anim.SetBool("IsWalking", false);
              anim.SetBool("IsAttacking", false);
            }
    
            //Check if we're close to destination
            if (_travelling && _navMeshAgent.remainingDistance <= 1.0f)
            {
                _travelling = false;
    
                //If we're going to wait, then wait
                if (_patrolWaiting)
                {
    
                    _waiting = true;
                    _waitTimer = 0f;
                }
                else
                {
    
                    ChangePatrolPoint();
                    SetDestination();
                }
            }
    
            //Instead if we're waiting
            if (_waiting)
            {
                anim.SetBool("IsIdle", true);
                anim.SetBool("IsWalking", false);
                anim.SetBool("IsAttacking", false);
                _waitTimer += Time.deltaTime;
                if (_waitTimer >= _totalWaitTime)
                {
    
                    _waiting = false;
    
                    ChangePatrolPoint();
                    SetDestination();
    
                    anim.SetBool("IsIdle", false);
                    anim.SetBool("IsWalking", true);
                    anim.SetBool("IsAttacking", false);
                }
            }
    
            void SetDestination()
            {
                if (_patrolPoints != null)
                {
    
                    Vector3 targetVector = _patrolPoints[_currentPatrolIndex].transform.position;
                    _navMeshAgent.SetDestination(targetVector);
                    _travelling = true;
                }
            }
    
            /// <summary>
            /// Selects a new patrol point in the available list but
            /// also with a small probability allows for us to move forward or backwards
            /// </summary>
            void ChangePatrolPoint()
            {
                if (UnityEngine.Random.Range(0f, 1f) <= _switchProbability)
                {
                    _patrolForward = !_patrolForward;
                }
    
                if (_patrolForward)
                {
                    _currentPatrolIndex = (_currentPatrolIndex + 1) % _patrolPoints.Count;
                }
                else
                {
                    if (--_currentPatrolIndex < 0)
                    {
                        _currentPatrolIndex = _patrolPoints.Count - 1;
                    }
                }
            }
        }
    }
4

make a public float
example
public float lookRadius = 10f;

then create a method now you can see the lookRadius
private void OnDrawGizmosSelected()
{
Gizmos.color = Color.red;
Gizmos.DrawWireSphere(transform.position, lookRadius);
}
then simply write it in your code for the SetDestination

float distance = Vector3.Distance(target.position, transform.position);
if (distance <= lookRadius)
{
pathfinder.SetDestination(targetPosition);
}

so if you are in the look radius the enemy will come after you and if not he wont
i hope this helps