AI movement in certain range

Questions & Answers
1

I have created the code to make a cube move towards a ball.
Now I want the cube to move towards the ball when the ball is within a certain distance from the cube, and the cube will not go out of range when chasing the ball.

How do I define the distance and range?
Thanks!

Following is my code.

using UnityEngine;
using System.Collections;

public class EnemyAI : MonoBehaviour {
	
	public Transform target;
	public float moveSpeed = 3f;
	public float rotationSpeed = 5f;
	
	private Transform myTransform;
	
	void Awake ()
	{
		myTransform = transform;
	}
	
	void Start()
	{
		GameObject  go = GameObject.FindGameObjectWithTag("Ball");
		//select the target
		target = go.transform;
	}
	
	void Update()
	{
		Debug.DrawLine(target.position, myTransform.position, Color.yellow);

		myTransform.rotation = Quaternion.Slerp(myTransform.rotation,  Quaternion.LookRotation(target.position - myTransform.position), rotationSpeed * Time.deltaTime);
		
		myTransform.position += myTransform.forward * moveSpeed * Time.deltaTime;
	}
	
}
2

put your all update into :

public float range = 10;

if(Vector3.Distance(myTransform.position, target.position) < range)
{
    // Movement
}

This is for 10 units.