Apex seems to be using the wrong delta time

  • February 7, 2018 at 23:14 #22766
    EmanTs
    Participant

    When first starting the scene with both a game window and a scene window open, I have half a second lag spike, during which my units massively overshoot their patrol targets (some actually commit suicide).
    I noticed in the SteerableUnitComponent’s Fixed update, that deltaTime was being used instead of fixedDeltaTime. After fixing this, I noticed a small improvement, however, the problem still persists – is it possible that there is a similar issue somewhere else?

    February 8, 2018 at 10:38 #22769
    Rami
    Keymaster

    Hi Emants,

    Thanks for posting.

    Using deltaTime or fixedDeltaTime should not make any difference. According to the Unity docs:

    “When called from inside MonoBehaviour’s FixedUpdate, returns the fixed framerate delta time.”

    Thus it seems unlikely that you would see any difference in using deltaTime or fixedDeltaTime – unless, of course, Unity’s documentation is misleading.

    As far as I know we haven’t encountered such an issue before. The easiest fix I can see off the top of my head is to simply delay their movement until you can ensure that the game will run smoothly. Simply Stop() or Wait() them as soon as possible (e.g. in Awake) and start them again when appropriate. Wait() has the option to pass how many seconds it should wait for, so that would be the easiest to use probably.

    February 12, 2018 at 16:27 #22788
    EmanTs
    Participant

    Thank you – well, maybe it could be a coincidence, but a certain enemy would fall off a ledge after overshooting ~80% of the time, and after changing the delta time, I hadn’t seen him do it anymore.
    Regardless though, if fixeddeltatime is being used one way or another, we should not have any overshooting, but I do. I would like to address this problem because – although I would like the game to run without lag – I would also like to prepare for the case where it does – so enemies don’t go killing themselves because of a framerate dip

    February 13, 2018 at 10:27 #22799
    Rami
    Keymaster

    That is of course a serious issue that should be fixed. I don’t know why it happens or why we haven’t ever seen it in the various products and projects where we have used similar functionality. So unfortunately I wouldn’t know where to begin. When our lead developer returns from sickness I will address this with him, so hopefully we can bring you a fix as soon as possible.

    February 14, 2018 at 11:26 #22809
    Geminior
    Keymaster

    That Time.deltaTime works as Rami describes, is easily verified by a Debug.Log(Time.deltaTime) in fixed update.
    So given that, it would appear your issue has a different cause.

    Are you sure you start your units only after the game world has properly initialized?
    Have your stepped frame by frame with an attached debugger to check the state of things?

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