Can't figure out how to stop zombie from dealing damage when no longer colliding with player - unity3d

Question

I am creating a top down zombie shooter and I have made the zombie do damage to the player when it is touching the player. However when the player backs away from the zombie after taking damage, the players health will continue to drop. Any ideas on how to fix this would be appreciated.
public float moveSpeed= 5f;
public Rigidbody2D rb;
public Camera cam;
public float playerHealth = 100;
public float enemyDamage = 25;
public GameObject gameOverScreen;
Vector2 movement;
Vector2 mousePos;
// Update is called once per frame
void Update()
{
movement.x = Input.GetAxisRaw("Horizontal");
movement.y = Input.GetAxisRaw("Vertical");
mousePos = cam.ScreenToWorldPoint(Input.mousePosition);
if(playerHealth == 0)
{
gameOverScreen.SetActive(true);
}
}
void FixedUpdate()
{
rb.MovePosition(rb.position + movement * moveSpeed * Time.fixedDeltaTime);
Vector2 lookDir = mousePos - rb.position;
float angle = Mathf.Atan2(lookDir.y, lookDir.x) * Mathf.Rad2Deg - 90f;
rb.rotation = angle;
}
void OnCollisionEnter2D(Collision2D collision)
{
if (collision.gameObject.CompareTag("Enemy"))
{
StartCoroutine(DamagePlayer());
}
else
{
StopCoroutine(DamagePlayer());
}
}
IEnumerator DamagePlayer()
{
while(true)
{
yield return new WaitForSeconds(1);
playerHealth -= enemyDamage;
}
}

Answer 1

First of all for doing something if it is not colliding anymore you should use OnCollisionExit2D
Then you can either use it the way you did using
StopCoroutine(DamagePlayer());
Or if want to be sure you could either store a reference to your routine
private Coroutine routine;
void OnCollisionEnter2D(Collision2D collision)
{
if (collision.gameObject.CompareTag("Enemy"))
{
if(routine == null)
{
routine = StartCoroutine(DamagePlayer());
}
}
else
{
if(routine != null) StopCoroutine(routine);
}
}
private void OnCollisionEnter2D(Collision2D collision)
{
if(routine != null) StopCoroutine (routine);
}
or use a bool flag in order to terminate it
private bool cancelRoutine = true;
void OnCollisionEnter2D(Collision2D collision)
{
if (collision.gameObject.CompareTag("Enemy"))
{
if(cancelRoutine) routine = StartCoroutine(DamagePlayer());
}
else
{
cancelRoutine = true;
}
}
private void OnCollisionEnter2D(Collision2D collision)
{
cancelRoutine = true;
}
IEnumerator DamagePlayer()
{
cancelRoutine = false;
while(! cancelRoutine)
{
yield return new WaitForSeconds(1);
playerHealth -= enemyDamage;
}
}
In general you could solve this without a routine by directly using OnCollisionStay2D like e.g.
void OnCollisionEnter2D(Collision2D collision)
{
if (collision.gameObject.CompareTag("Enemy"))
{
timer = 1;
}
}
void OnCollisionStay2D(Collision2D collision)
{
if (collision.gameObject.CompareTag("Enemy"))
{
timer -= Time.deltaTime;
if(timer <= 0)
{
timer = 1;
playerHealth -= enemyDamage;
}
}
}