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Opacity decay over time?
I’ve been trying to write an expression that will cause the opacity of a layer to decay to zero over time after any keyframe. The idea is to make a flashing effect on a layer that can be controlled just by a series of keyframes for max opacity values. I originally set out to have it ramp up as well, but that was even farther beyond my expression abilities. This is what I’ve been working with, but I’m stuck. Any ideas?
It seems like it could be an interesting effect on any number of parameters.
Thanks!
decay = 1.0;
n = 0;
if (numKeys > 0){
n = nearestKey(time).index;
if (key(n).time > time){
n--;
}}
if (n == 0){ t = 0;
}else{
t = time - key(n).time;
}
if (n > 0 && t < 1){
P = (key(n).time - thisComp.frameDuration/10);
value - P/Math.exp(decay*t);
}else{value} -
2 Replies
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Maybe something like this would help:
if (numKeys > 0){
n = nearestKey(time).index;
rampUpTime = .1;
rampDownTime = .2;
if (time < key(n).time)
ease(time,key(n).time-rampUpTime,key(n).time,0,value)
else
ease(time,key(n).time,key(n).time+rampDownTime,value,0);
}else
value
Dan
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Oh wow–way better strategy!
Thank you again, Sensei.
I have this wired up to some sliders and it is working great!
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