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wiggle bias?
Need some help with a puzzling result. I’m trying to simulate the behavior of an unusual light I spotted in the night sky. It changed in size both horizontally and vertically, in a flickering kinda way, but remained generally circular. Been trying to duplicate that with wiggle. Here’s my code:
WH = wiggle(random(0.1,0.2),1); // horizontal wiggle value in percent
WV = wiggle(random(0.1,0.2),1); // vertical wiggle value in percent
[WH[0],WV[1]] // this expression assigns separate values to the horizontal and vertical scalesThe object being wiggled is a circle that starts at a scale of 3% in both dimensions. At the start of the animation this generates scale values that differ only slightly from the original [3,3], like [2.8,3.2]. But the difference steadily increases as time goes by, and after 25 seconds I’m getting values like [3.8,4.1]. Something is definitely causing an asymmetry in the wiggle variation.
Any insights greatly appreciated, thx.
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2 Replies
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Animating wiggle frequency that way can give you unpredictable results. This may help:
http://www.motionscript.com/articles/speed-control.html#wiggle
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Thanks for the tips. You have an incredibly valuable website for learning expressions. Been there often. After reading your comments about frequency I tried the following:
FH = random(1,3); // assigns random horizontal frequency
FV = random(1,3); // assigns random vertical frequency
WH = value + wiggle(FH,1); // horizontal wiggle value in percent
WV = value + wiggle(FV,1); // vertical wiggle value in percent
[WH[0],WV[1]] // this line assigns separate values to the horizontal and vertical scalesThat fixed the problem, and the shape is now fluctuating in scale in a way that simulates what I saw in the sky. No more divergence from original size near the end of the comp.
I suspect what happened originally might have been a “random walk” away from the original values that somehow accumulated positive changes. Perhaps in a longer comp things may have eventually returned to normal. Not sure. But what I have now does the trick. And I didn’t need to integrate. Thanks again!
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