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

   public class TestFollow : MonoBehaviour {

    private Transform _bullet;
    private Vector2 _screenSize;
    private float _interval = 10;
    public Sprite sp1,sp2;
    SpriteRenderer sr;
    bool mouseClicked = false;
    public float moveSpeed = 10f;
    public float speed;


    // Use this for initialization

    void Start ()
    {
        sr = gameObject.GetComponent<SpriteRenderer> ();

        if (sr.sprite == null) // if the sprite on spriteRenderer is null then
            sr.sprite = sp1; // set the sprite to sprite1

        _bullet = transform;
        _screenSize = new Vector2(Screen.width, Screen.height);


    }

    public void Update ()
{

    transform.position = Vector2.Lerp (transform.position, Camera.main.ScreenToWorldPoint (Input.mousePosition), moveSpeed);

    Vector3 difference = Camera.main.ScreenToWorldPoint (Input.mousePosition) - transform.position;
    difference.Normalize ();

    {
        if (Input.GetMouseButtonDown (0)) {
            Debug.Log ("Left Mouse Button was pressed");
            moveSpeed = 0f;
            if (sr.sprite == sp1) { // if the spriteRenderer sprite = sprite1 then change to sprite2
                sr.sprite = sp2;

            }
            mouseClicked = true; //register that the mouse has been clicked and the sprite is changed to sprite2
        }
    }


    if (mouseClicked) {        //checks if sprite has already been changed

        // Check for every 10 frames, reduce _interval if you want to check more often.
        if (Time.frameCount % _interval == 0) {
            // Use debug to learn mouse position, you can disable this if you want.
            Debug.Log (Input.mousePosition);

            // Mouse on Top Right screen
            _bullet.localEulerAngles = Vector3.zero;

            // Mouse on Bottom Right, else Mouse on Bottom Left else Mouse on Top Left
            if (Input.mousePosition.x > _screenSize.x / 2 && Input.mousePosition.y < _screenSize.y / 2)
                _bullet.Rotate (Vector3.forward, -90, Space.Self);
            else if (Input.mousePosition.x < _screenSize.x / 2 && Input.mousePosition.y < _screenSize.y / 2)
                _bullet.Rotate (Vector3.forward, -180, Space.Self);
            else if (Input.mousePosition.x < _screenSize.x / 2 && Input.mousePosition.y > _screenSize.y / 2)
                _bullet.Rotate (Vector3.forward, 90, Space.Self);
        }
    }

    {

        if (Input.GetMouseButton(1)) {
            Debug.Log ("Pressed secondary button.");

            _bullet.transform.position += (transform.right + _bullet.transform.up).normalized * speed * Time.deltaTime;
        }
    }
}
}