I’m experiencing Unity editor crashes with which FMOD may have something to do.
Using EventInstance::setCallback, I wrote a delegate which lets the UI element pulse via Animator.
public StudioEventEmitter bgmEvent;
[SerializeField] private Animator uiAnimator;
private EVENT_CALLBACK beatPulseCallback;
private void Start() {
beatPulseCallback = StudioEventCallBack;
bgmEvent.EventInstance.setCallback(
beatPulseCallback, EVENT_CALLBACK_TYPE.TIMELINE_BEAT
);
}
private RESULT StudioEventCallBack(EVENT_CALLBACK_TYPE type, EventInstance eventInstance, IntPtr parameters)
{
Debug.Log("CB");
if (uiAnimator != null)
{
uiAnimator.SetTrigger("PulseTriggered");
}
return RESULT.OK;
}
Note that the callback references an Animator during the procedure. This code appears to work until I exit the PlayMode when Unity editor crashes.
If I trigger the same code using other means (e.g. KeyDown,) I cannot observe any crashes.
The project that has this code is quite big, and the FMOD integration takes time to shut down when exiting the PlayMode, so I did some experiments.
When I move this code to a new empty project and try to reproduce it:
- 70% of the time it doesn’t fail
- 20% of the time it freezes the Unity editor, and
- 10% of the time the code crashes it.
When it freezes the editor, it usually leaves a NullReferenceException before its demise. The funny thing is that the exception occurs at if (uiAnimator != null) part - the null check itself is returning an NRE, which should not happen.
Then I added an OnDestroy() method to remove the callback before quitting:
private void OnDestroy() {
bgmEvent.EventInstance.setCallback(null);
bgmEvent.Stop();
}
And this code seems to mitigate the crash altogether (and that’s what I currently do to avoid it.) However, when I stop the event before removing callbacks, the editor crashes.
Based on the observations, I suspect that the callback can be being triggered after the Unity context is destroyed - and if the callback happens to reference GameObjects, everything goes haywire since the underlying reference is gone.
Can you confirm if my suspicion is correct? If it is, I consider this issue a bug (or at least should be documented somehow? AFAIR there is no mention of the danger of referencing GameObjects in callbacks - this example does not seem to clear callbacks in OnDestroy method.)
OS: macOS Catalina 10.15.3.
Unity version: 2019.3.3f1.
FMOD Studio/Unity Integration version: 2.00.07.