3 Replies Latest reply on Jun 17, 2012 8:03 AM by Mylenium

    Wiggle Expression Random Values' Persistence?

    Matt Maxwell Level 1

      I am using the wiggle expression extensively in a project, and I am starting to notice that if I render a part of my render one day, then render the rest again another day, the set of wiggle values are different each time and the animation jumps undesireably. I am doing stereo 3D and I have to render the right eye, then the left, but keep the wiggle values right for each eye.

       

      My question is, how long do the random values chosen by the wiggle expression persist? By session? If I save my document and quit, then open it again and render another, will I now get different random wiggle values? How can I count on the chosen random values chosen by wiggle to stay the same? What event causes the expression to go through and choose a set of new random values?

       

      I would prefer not to "bake" the values into Keyframes. I just want to understand the persistence rules so I know what I'm up against.

        • 1. Re: Wiggle Expression Random Values' Persistence?
          Mylenium Most Valuable Participant

          Random seed is persistent. It doesn't randomly change on a day to day basis. The automatic seeding is of course different for every layer and every comp and also responds to time, so it changes when you change layer order or move the in point or anything like that. Also there may be differences for legacy projects when opened in CS6, because the randomization algorithm has changed. Anyway, you can always pin a specific random seed using seedRandom(value,true) preceeding your wiggle.

           

          Mylenium

          • 2. Re: Wiggle Expression Random Values' Persistence?
            Matt Maxwell Level 1

            Thank you! I haven't had much success finding help on the web.

             

            So, like this?

             

            seedRandom(value,true);

            wiggle(10,20);

             

            So, this locks the seed forever regardless of how I rearrange layer stacking and in/out points? Is there still a chance that it will ever reseed? What actions on my part would trigger a reseed when the above expression is present?

             

            What exactly does seedRandom do in this specific case? I have found a few articles on the web but they are overcomplicated and aren't directly related to wiggle.

            • 3. Re: Wiggle Expression Random Values' Persistence?
              Mylenium Most Valuable Participant

              Just fill in any numeric value in place of "value". It will never change. That's the whole point of it. It determines the base seed for the internal noise algorithm and if that is consistent, so is the output.

               

              Mylenium