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Random opacity that varies over time?
Hey guys,
Just a quick question – this is probably something very simple, but I can’t get my head around it at the moment.
I have a layer that is using a the ‘random’ expression to vary it’s opacity. However, I want this random opacity to get ‘less random’ over a set time, until it reaches a point at which it is entirely visible/the opacity is locked at a defined point.
Does that make sense?
So basically, at frame 0, the expression will have the effect of:
random(0,100)But by frame 200, the expression will have the effect of:
random(99,100)Or something similar. Is there a way to do this? If possible, I need user-definable variables for the length of transition, as well as adjustable stand and end values for the random-ness. Any help would be most appreciated!
Many thanks,
Geraint Abbott. -
8 Replies
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t = Math.exp(time) random(t,100)
Try something like this..
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t = timeToFrames(time) random(t,100)
…or actually even better, this one is more literal, tacking the exact number of the frame up to 100 for the random generator.
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t = timeToFrames(time)/2 random(t,100)
sorry, i just saw the part that you want it to be visible at 200 frames…so just divide the time by 2
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That’s pretty cool! Thanks 🙂
But what if I don’t want the end opacity to be 100%? I’ve tried altering the expression to say something like
t = timeToFrames(time)/2
random(t,50)
And that works fine up to frame 200 – but then it goes rather odd, going more than 50% transparent after that point. I suppose I could just cut the layer and have a second one set permanently at 50% transparency starting at 200 frames in… but it would be nice to keep the number of layers down! Is that possible at all?
Cheers,
Geraint. -
Try changing it to this:
t = Math.min(50,timeToFrames(time)/2);
random(t,50)Dan
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t = timeToFrames(time)/2 r = random(t,100) if(t<100){ r }else{ 50}You can use a conditional statement(if/else)..try this.
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Spot on!
Thanks guys, this worked perfectly.
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What if you want the opacity to be random but be cued not by random time but a varying number from soundkeys output?
Motion Designer / DJ / Father
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