public class PlayerAttack : MonoBehaviour {
public GameObject target;
public float AttackTimer;
public float CoolDown;

// Use this for initialization
void Start () {
AttackTimer = 0;
CoolDown = 2.0f;
}

// Update is called once per frame
void Update () {
if(AttackTimer > 0)
AttackTimer -=Time.deltaTime;

if(AttackTimer < 0)
AttackTimer = 0;

if(Input.GetKeyUp(KeyCode.F)) {
if(AttackTimer == 0) {
Attack();
AttackTimer = CoolDown;

}
}
}

private void Attack() {

float distance = Vector3.Distance(target.transform.position, transform.position);

Vector3 dir = (target.transform.position - transform.position).normalized;

float direction = Vector3.Dot(dir, transform.forward);

Debug.Log(direction);

if(distance < 2.5f) {
if(direction > 0){
EnemyHealth eh = (EnemyHealth)target.GetComponent("EnemyHealth");
eh.AddjustCurrentHealth(-10);

}
}
}
}

using System.Collections;

public class EnemyHealth : MonoBehaviour {

public int MaxHealth = 100;

public int curHealth = 100;

public int Health = 100;

public float Screenwidth;

// Use this for initialization

void Start () {

}

// Update is called once per frame

void Update () {

AddjustCurrentHealth(0);

Screenwidth = Screen.width / 2;

}

void OnGUI(){

GUI.Box(new Rect(10, 40, Screenwidth, 20), curHealth + "/" + MaxHealth);

}

public void AddjustCurrentHealth(int adj){

curHealth += adj;

if (curHealth < 0){

curHealth = 0;

}

if (curHealth > MaxHealth){

curHealth = MaxHealth;

}

if (MaxHealth < 1){

MaxHealth = 1;

}

Screenwidth = (Screen.width / 2) * ( curHealth / (float)MaxHealth);

}

}