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Particle systems seem to 'ignore' seed when at high speeds/noise

Discussion in 'General Graphics' started by Nitrousek, Nov 26, 2021.

  1. Nitrousek

    Nitrousek

    Joined:
    Jan 31, 2016
    Posts:
    38
    I've been trying to create a semi-beliveable lightning effect in Unity, by using a high speed particle with a trail and noise. After a little bit of work visuals were finally pleasing, I've selected a seed that looks very nice, but unfortunately, in game view, the seed seems to not work properly.

    When I play the effect in scene view, every time it looks exactly the same. Once I hit play button, and I play the effect by using play button (or any other method I've tried, like turning the effect on and off), the effect seems to ignore the seed. I have tested this for a while, and it seems, that this only happens when particles move at high speeds, or when noise frequency/strength is high. Once I set it to much lower value, it was fine, but the effect no longer works as it's supposed to.

    So far I have found no work-around other than having to re-create the whole effect using linerenderer, which is unfortunate. Posting this here because maybe there's something I've missed. Is this expected behaviour? If so, why does it play exactly the same in editor view?
     
  2. richardkettlewell

    richardkettlewell

    Unity Technologies

    Joined:
    Sep 9, 2015
    Posts:
    2,281
    I think it’s be a use the fps in game mode isn’t 100% deterministic.

    If you’re able to, you could do the simulation yourself in FixedUpdate by calling ParticleSystem.Simulate. That ought to be 100% deterministic.
     
    Nitrousek and karl_jones like this.