Question by Negidnyk · Feb 03 at 01:23 PM · ienumerator

How can I pass parameters into IEnumerator method?

I am trying to pass Ray as a parameter of IEnumerator method, but it doesn't change passed object. I would be grateful if someone explain to me why. I thought if variable is reference type it should be changed wherever it is called.

 public class Rays : MonoBehaviour
 {
     private Ray rayR;
     private Ray rayL;
     void Start()
     {
         rayR = new Ray(transform.position + new Vector3(0, -0.8f, 0), transform.up);
         rayL = new Ray(transform.position + new Vector3(0, -0.8f, 0), transform.up);
     }
     void Update()
     {
         Debug.DrawRay(rayR.origin, rayR.direction * 2, Color.blue);
         Debug.DrawRay(rayL.origin, rayL.direction * 2, Color.blue);
         if (Input.GetKeyDown(KeyCode.D))
         {
             rayR.direction = transform.forward;
             StartCoroutine(RayBack(rayR));
         }
         else if (Input.GetKeyDown(KeyCode.A))
         {
             rayL.direction = -transform.forward;
             StartCoroutine(RayBack(rayL));
         }
         if (Physics.Raycast(rayR,2))
         {
             RotateCylinder.rotateRight = false;
         }
         if (Physics.Raycast(rayL, 2))
         {
             RotateCylinder.rotateRight = true;
         }
     }
     IEnumerator RayBack(Ray ray)
     {
         yield return new WaitForSeconds(1);
         Debug.Log("kdv");
         ray.direction = transform.up;
         rayR.direction = transform.up;
     }
 }

Add comment · Show 4

andrew-lukasik · Feb 03 at 01:51 PM 0

Ray is a struct and structs are passed by copy. This means that ray.direction = transform.up; modifies a copy (to no consequence outside of this method scope) meanwhile rayR.direction = transform.up; does something opposite - it modifies a struct that is allocated in memory inside this Rays class.

Negidnyk · Feb 03 at 02:01 PM 0

@andrew-lukasik , thank you . I just thought that Ray is class therefore reference type . Sorry for disturbing . But how can I pass parameter to IEnumerator be reference , because when I put modifier "ref" it gives an error?

andrew-lukasik Negidnyk · Feb 03 at 02:28 PM 0

Struct must be contained in some kind of memory allocation object to pass it here. But you can do something different and use System.Action parameter with inlined method (lambda expression)

 StartCoroutine( ExecuteAfterDelay( () => rayR.direction = transform.up , 1f ) );

 IEnumerator ExecuteAfterDelay ( System.Action action , float seconds )
 {
     yield return new WaitForSeconds(seconds);
     action();
 }