如何重新启动协程？

Question

I am trying to implement a coroutine that moves an object to a specific point and then comes back to the origin (specified by me) as a coroutine in Unity, but the coroutine is not executed after returning to the origin. What's wrong?

public class LineManager : MonoBehaviour
{
    public Vector3 positionToGo = new Vector3(0, -4, 0);
    IEnumerator coroutine;
    void Start()
    {
        coroutine = MoveToPosition(transform, positionToGo, 2f);
    }

    void Update()
    {
        if(transform.position.y == 4)
        {
            StartCoroutine(coroutine);
        }
    }

    public IEnumerator MoveToPosition(Transform transform, Vector3 position, float timeToMove)
    {
        var currentPos = transform.position;
        var t = 0f;
        while (t < 1 && currentPos.y > position.y)
        {
            t += Time.deltaTime / timeToMove;
            transform.position = Vector3.Lerp(currentPos, position, t);
            yield return null;
        }
            transform.position = new Vector3(0, 4, 0);
            StopCoroutine(coroutine);
    }
}

Answer 1

You don't really need to restart your routine for that.

But first things first:

transform.position.y == 4

is risky as it is a direct float comparison and might fail. See Is floating point math broken?

Anyways, back to the coroutine restarting. Why not simply move without a routine at all

public Vector3 positionToGo = new Vector3(0, -4, 0);
public float timeToMove = 2f;

private Vector3 originalPosition;
private float factor;

private void Awake()
{
    originalPosition = transform.position;
}

private void Update()
{
    if(factor >= 1)
    {
        factor = 0;
        transform.position = originalPosition;
    }
    else
    {
        factor += Time.deltaTime / timeToMove;
        transform.position = Vector3.Lerp(originalPosition, positionToGo, factor);
    }
}

---

As an alternative if you want to use the routine you can always simply make it loop

public Vector3 positionToGo = new Vector3(0, -4, 0);
public float timeToMove = 2f;

private IEnumerator Start()
{
    var originalPosition = transform.position;

    while(true)
    {
        for(var factor = 0f; factor < 1f; factor += Time.deltaTime / timeToMove)
        {
            transform.position = Vector3.Lerp(originalPosition, position, factor);
            yield return null;
        }

        transform.position = originalPosition;
    }
}

Answer 2

call the Coroutine in that IEnumerator with waitforseconds