在while循环列表中，协程有时无法正常工作-C＃Unity3D Rhythm Game

Question

I'm going to make a rhythm game.

music playing time is variable which change by music playing in millisecond

List is a float list which have the time(float second) I filled , let me to access it and use for compare with music playing time to instance object .

when list time = music time then instant object.

but sometimes will missing(not found value in list but value is really exist in list).

Here is my assumption.

I think List.indexOf performance are not good and thread have some delay.

Music playing time change every millisecond , a little delay from unity or others will cause missing(doesn't entering if statement)

I don't know if it's correct.

Could any one help me.

Here is my code.

IEnumerator Execute(MethodDelegate Start,MethodDelegate Stop)
    {
        while (true) {
            int res = result.IndexOf ((float)System.Math.Round (GameObject.Find ("Music").GetComponent<AudioSource> ().time, DigitalAdjust)-TimeAdjust);
            if (res!=-1) {
                if (res == result.Count-2) {
                    Stop.Invoke ();
                    print ("CoroutineStop");
                    StopCoroutine (_Execute);
                }
                //execute
                num=Positoin[res];
                print (res);
                Start.Invoke();
            }
            yield return null;
        }
    }

Thanks.

Answer 1

Chances are that you are correct. You might miss some if statement because you don't match the millisecond exactly. Here are some things that could help:

It you game reaches 60 FPS (the usual rate for a smooth rendering), each frame will take around 16 milliseconds. If you have events that must trigger at exact milliseconds you will miss some because your Execute function calls are separated by around 16ms (a coroutine is called once per frame).

A solution to this is remember the last time the Execute function was called and check everything in between:

private float _lastTime;

IEnumerator Execute(MethodDelegate Start,MethodDelegate Stop)
{
    while (true) {            
        // here your code must check all the event between _lastTime and Time.time
        var lastTimeMilliseconds = (int)(_lastTime*1000);
        var currentTimeMilliseconds = (int)(Time.time*1000);
        for(int time = lastTimeMilliseconds+1; time <= currentTimeMillisedons; time++)
        {
            // let's say last frame was at time 1000ms
            // This frame occurs at time 1016ms
            // we have to check your list for events that have occured since last frame (at time 1001, 1002, 1003, ...) 
            // so we have a for loop starting at 1001 until 1016 and check the list
            int res = result.IndexOf ((float)System.Math.Round (time, DigitalAdjust)-TimeAdjust);
            if (res!=-1) 
            {
                if (res == result.Count-2) 
                {
                    Stop.Invoke ();
                    print ("CoroutineStop");
                    StopCoroutine (_Execute);
                }
                //execute
                num=Positoin[res];
                print (res);
                Start.Invoke();
            }
        }            

       // At the end, remember the time:
       _lastTime = Time.time;

        yield return null;
    }
}

Check the Time class, you also have access to Time.deltaTime to know the time elapsed between two frames, if that helps.

EDIT : As you requested in comment, I added some bit of code from your example to explain better this idea. Note that I don't know what your variables do so you will have to adapt. For instance, Time.time gives that time since app start. You will likely need to adapt this use the time since you started the audio

Another important thing:

• GameObject.Find must look in all the objects. It is really slow and shouldn't be used every frame

• GetComponent looks for all your scripts and is slow as well. It shouldn't be used every frame.

Instead, do this:

private AudioSource _audioSource;

private void Start()
{
     _audioSource = GameObject.Find ("Music").GetComponent<AudioSource> ();
}

This will retrieve the source only once. Then in your code you simply call

_audioSource.time;