Make Zombie chase player within a set range

Questions & Answers
1

So I have a zombie with a script that makes the zombie follow the player, but as I’m new with c# im not to sure how to make it so it will chase you within a certain range and stop chasing your when out of range.

currently all it does is follow you when close enough but when I out run it it still follows me. Thanks any help.

Pay most attention on the update method as that is what needs fixing.

Thanks and heres my script:

using UnityEngine;
using System.Collections;

public class EnemyAI : MonoBehaviour {
	public float deathDistance = 0.5f;
	public float distanceAway;
	public Transform thisObject;
	public Transform target;
	private NavMeshAgent navComponent;
	public float dist;

	void Start() 
	{
		target = GameObject.FindGameObjectWithTag("Player").transform;
		navComponent = this.gameObject.GetComponent<NavMeshAgent>();
	}

	void Update() 
	{

		dist = Vector3.Distance(target.position, transform.position);

		if(dist <= 30)
		{
			navComponent.SetDestination (target.position);

			if (dist >= 30) {
				target = null;
			}
		}

		else
		{
			if(target = null)
			{
				target = this.gameObject.GetComponent<Transform>();
			}
			else
			{
				target = GameObject.FindGameObjectWithTag("Player").transform;
			}
		}
	}
}
2

Hi :smiley:

you should use a Ray.

READ THIS PART ONLY IF YOU DON’T KNOW WHAT A RAY IS!!!
It kinda draws a line from a point to a direction. You can check how close something is and use your function with those distances.

here’s an quick example, it has a big collider on the enemy and this script would go on the enemy:

``<pre> private RaycastHit hit; void OnTriggerStay(Collider other) { Vector3 direction = other.transform.position - transform.position; if (Physics.Raycast(transform.position, direction.normalized, out hit)) { if (hit.collider.gameObject == player) { if (hit.distance &lt= 9 && hit.distance &gt 2.5f) { AttackThatBetch(); } else if (hit.distance &lt= 2.5f) { BiteThatHoe(); } else { ImmaGoLookAtThatTreeAndStandStill(); } } } } </pre>

Hope it helped :wink:

3

Your approach of using Vector3.Distance is correct. It should be quicker than using a RayCast, but a RayCast is better if you don’t want your enemy to try to chase you through walls. As a learning exercise though I’d recommend sticking to Vector3.Distance for now, and once it is working changing it to a RayCast.

Your problem is that you are setting your target to null, and then in the next execution of your app trying to determine a distance from the current game object to target.transform (you will probably see an error in the Console output tab).

public class Chase : MonoBehaviour
{
    public Transform player;

    void Update()
    {
        var direction = player.position - transform.position;
        var angle = Vector3.Angle(direction, this.transform.forward);
        if (angle < 180 && direction.magnitude < 10)
        {
            var rotation = Quaternion.Slerp(
                this.transform.rotation, Quaternion.LookRotation(direction), Time.deltaTime);
            rotation.x = 0;
            rotation.z = 0;
            transform.rotation = rotation;

            if (direction.magnitude > 5)
                transform.Translate(0, 0, Time.deltaTime * 1.5f);
        }
    }
}

This code is more or less from this tutorial Basic Artificial Intelligence for a Non-Player Character with Unity 5 - YouTube - It takes you through the logic of each step, and adds animation too.