协程仅发射一次

Question

I'm trying to run a script that will generate a "ramps" upon touch between point a and b. This code receives a list of where the elements of the ramps should be and then instanciates and places them on the screen.

However the coroutine is only running once and I can't understand why. Can anyone give me some advice?

Thank you very much in advance

public IEnumerator CreateRamp(List<Vector3> lP, float angle)
{

    int i = 1;
    while (i <= lP.Count)
    {
        Debug.Log("Iteration " + i + " of " + lP.Count + " position is " + lP[i]);
        GameObject item = Instantiate(Resources.Load("floor")) as GameObject;


        item.transform.position = current_Position;
        item.transform.eulerAngles = new Vector3(0, 0, UnityEngine.Random.Range(0f, 360f));

        item.GetComponent<Ramp>().strtPos = item.transform.position;
        item.GetComponent<Ramp>().strtRot = item.transform.eulerAngles;
        item.GetComponent<Ramp>().strtScale = new Vector3(0.4f, 0.4f, 1);

        item.GetComponent<Ramp>().tgtRot = new Vector3(0, 0, angle);
        item.GetComponent<Ramp>().tgtPos = lP[i-1];
        i += 1;
        yield return new WaitForSeconds(0.2f);
    }
}

Answer 1

I suspect your condition i <= lP.Count is true only once. (Maybe lP.Count == 1 , I think).

The way co-routine works is that, the code inside the CreateRamp function is executed across multiple frames.

When you StartCoroutine(CreateRamp(...)) , it is immediately run until it hits yield statement. It will wait there for 0.2 seconds and will be run again from the statement right after the yield.

In the second execution, it evaluates the condition i <= lP.Count again and see that it is False => it jumps out of the loop and because it hits the end of the function, that co-routine will be stopped, no more execution in the future.

Answer 2

Since this function is an IEnumerable it should be treated by other code as a list of Ramp objects. I suspect (there isn't enough of your code to know), that the way you are calling this function is incorrect.

On a side note, with your yield returning a waitforX, It would be better in the long term to either perform the wait outside of this function (where you are calling it from) or at the very least add the wait period as a parameter to the function. Hard coded values like that will end up biting you later on, especially if your game's code-base grows. I recommend it be exposed as a setting on your GameObject, so it can be tweaked from the editor.

One other thing, How do you destroy these Ramp objects when you are done with them? It might be good to consider storing references to them as you create them so you can destroy them later.