Slow over time on collision with a FrostBullet

Question

I'm new at Unity and C#. I started this 2D game few weeks ago.

So basically what I want to do is when the player is hit by "FrostBullet", it should deal the damage and slow that player over time. In my script the player is hit by FrostBullet, it deals the damage and the slow is constant, not over time. I want it to be like, when the player is hit by FrostBullet, the player should be slowed for 2 sec and than his movement speed is back to normal.

So this is how my code look like:

public class FrostHit : MonoBehaviour 
{
float maxS = 40f;
float slowSpeed = 20f;
public Rigidbody2D rb;
int damage = -5;
int timeOfReducedSpeed = 2;
bool isHit = false;


void Start()
{
    rb.velocity = transform.right * slowSpeed;
}
void OnTriggerEnter2D(Collider2D other)
{
    if (other.gameObject.tag == "Player_Njinja")
    {
       HealthNjinja healthNjinja = other.gameObject.GetComponent<HealthNjinja>();
       healthNjinja.ModifyHealth(damage);

       PlayerMovementNjinja reduceMoveSpeed = other.gameObject.GetComponent<PlayerMovementNjinja>();
       reduceMoveSpeed.runSpeed = slowSpeed;

       Destroy(gameObject);
    }

      PlayerMovementKnight maxSpeed = other.gameObject.GetComponent<PlayerMovementKnight>();
      maxSpeed.runSpeed = maxS;
      HealthKnight healthKnight = other.gameObject.GetComponent<HealthKnight>();

     if (other.gameObject.tag == "Player_Knight")
      {
        isHit = true;
        healthKnight.ModifyHealth(damage);
        StartCoroutine(speedTime());

        Destroy(gameObject);
     }
     IEnumerator speedTime()
     {
        while (isHit == true)
        {
            slowPlayer();
            yield return new WaitForSeconds(timeOfReducedSpeed);
            revertSpeed();
        }
      }
     void slowPlayer()
     {
        maxSpeed.runSpeed = slowSpeed;
     }
     void revertSpeed()
     {
        maxSpeed.runSpeed = maxS;
     }
}

}

Also my PlayerMovement code:

public class PlayerMovementKnight : MonoBehaviour
{
public CharacterController2D controller;
public Animator animator;

public float runSpeed = 40f;
float horizontalMove = 0f;
bool jump = false;
bool crouch = false;

public WeaponKnight Bullet;
public bool grounded;

void Update()
{
    horizontalMove = Input.GetAxisRaw("Horizontal") * runSpeed;
    animator.SetFloat("Speed", Mathf.Abs(horizontalMove));

    if (Input.GetButtonDown("Jump"))
    {
        jump = true;
        animator.SetBool("IsJumping", true);
    }
    if (Input.GetButtonDown("Crouch"))
    {
       crouch = true;
    }

   else if (Input.GetButtonUp("Crouch"))
   {
       crouch = false;
   }
   if (grounded && GetComponent<Bullet>().knockBack == false)
   {
       GetComponent<Rigidbody2D>().velocity = new Vector2(0, 0);
   }

}
public void OnLanding()
{
    animator.SetBool("IsJumping", false);
}
public void OnCrouching(bool isCrouching)
{
    animator.SetBool("IsCrouching", isCrouching);
}
void FixedUpdate()
{
    controller.Move(horizontalMove * Time.fixedDeltaTime, crouch, jump);
    jump = false;
}

}

Answer 1

The issue seems to be that your bool isHit, that is set to true before calling the Coroutine, is never reset to false.

So the loop:

while (isHit == true)
    {
        slowPlayer();
        yield return new WaitForSeconds(timeOfReducedSpeed);
        revertSpeed();
    }

is really an infinite loop. You might want to reset the bool to false somewhere.

Edit:

Following to comments, I see now that your script is attached to the bullet GameObject. After starting the Coroutine, and slowing down the player, you Destroy(gameObject); After that, the script gets destroyed too, and the Coroutine is therefore stopped...and nothing remains to restore player’s speed back to normal.

You should move the Coroutine to the player’s script, and start it when needed. This way, it would still exist after you destroy the bullet.