1

Code:

using UnityEngine;
using System.Collections;

public class enemyAI : MonoBehaviour
{
    private Rigidbody2D myRigidbody;
    private bool moveRight;
    private Vector2 moveLocation;
    [SerializeField]
    private float speed;
    [SerializeField]
    private Vector2 tra1;
    [SerializeField]
    private Vector2 tra2;
    // Use this for initialization
    void Start()
    {
        myRigidbody = GetComponent<Rigidbody2D>();
        moveRight = true;
        
    }

    // Update is called once per frame
    void FixedUpdate () {
        
        Debug.Log(moveRight);
        tra1 = transform.position;

        EmemyMovement();
        

        tra2 = transform.position;

        if (tra1.x == tra2.x)
        {
            moveRight = !moveRight;
        }
    }


    private void EmemyMovement()
    {
        if (moveRight == true)
        {
            moveLocation = new Vector2(transform.position.x + speed, transform.position.y);
            myRigidbody.MovePosition(moveLocation);
        }
        else
        {

            moveLocation = new Vector2(transform.position.x + -speed, transform.position.y);
            myRigidbody.MovePosition(moveLocation);
        }
    }
}

It should be that it moves right until it stops then it moves left but when I run it the variable moveRight changes between true and false every frame and bounces forwards and backwards. Any help?

2

You want the AI to move back and forth between two walls?
Here is a simplication of your script, with some comments:

using UnityEngine;
using System.Collections;

public class EnemyAI : MonoBehaviour
{

    // Note: public variables are serialize by default.
    public float speed = 1.0f;
    public Vector2 leftWall;
    public Vector2 rightWall;

    Vector3 direction;

    // Use this for initialization
    void Start()
    {
        direction = Vector3.right;
    }

    // Update is called once per frame
    void FixedUpdate()
    {
        Vector3 velocity = speed*direction;

        // Don't forget Time.Delta time to make the movement frame-rate independent.
        transform.position += velocity * Time.deltaTime; 

        if (transform.position.x > rightWall.x)
        {
            transform.position = rightWall;
            direction = Vector3.left;
        }

        if (transform.position.x < leftWall.x)
        {
            transform.position = leftWall;
            direction = Vector3.right;
        }
    }

}

If you want to make more advanced AI, I would suggest to have a look at Behaviour Tree. It’s an AI technique that simplifies the development of complex (or simple) AI. I’ve made a scripting framework based on Behaviour Tree ( see Panda BT: www.pandabehaviour.com ).

Developing AIs using this tool consist of defining “tasks” and use them from a BT script. For instance, to make an AI that move to arbitrary locations, you first need to make a “task” to handle the AI movement. This is implemented as a function on a MonoBehaviour:

using UnityEngine;
using Panda; // We are using Panda BT

public class EnemyAIBT : MonoBehaviour
{
    public float speed = 1.0f;

    public Transform[] locations; // Array of locations.

    Vector3 destination;

    [Task] // <-- This marks a function as a task.
    void MoveTo(int locationIndex)
    {
        // Set the destiantion when the task is starting.
        if (Task.current.isStarting)
            destination = locations[locationIndex].position;

        // Move towards the destination on each tick (Update).
        transform.position = Vector3.MoveTowards(transform.position, destination, speed * Time.deltaTime);

        // The task is done when we have reached the destination.
        if (transform.position == destination) 
            Task.current.Succeed();
    }
}

Once, you’ve defined some tasks, you can use them as building blocks from a BT script to define how your AI behaves. For instance, to make an AI that move back and forth between the first 2 locations, its BT script would be:

tree("Root")
	sequence
		MoveTo(0)
		MoveTo(1)

This is an extremely simple BT, but you can do much more with Behaviour Tree. The package contains several examples from simple to advanced.

If you have any question about using this tool you are welcome on this forum thread.