adding falloff to an expression

[Dan Ebberts]

Play around with this:

decayTime = 1; // decay time (seconds)
mult = 5;
audLev = thisComp.layer(“Audio Amplitude”).effect(“Both Channels”)(“Slider”);

k = 4.605/decayTime;
currFrame = Math.round(time/thisComp.frameDuration);
decayFrames = Math.round(decayTime/thisComp.frameDuration);
sampleFrame = Math.max(0, currFrame – decayFrames);
decayTime = 0;
curMax = 0;

while (sampleFrame <= currFrame){ sampleVal = audLev.valueAtTime(sampleFrame * thisComp.frameDuration) * mult; curVal = curMax/ Math.exp(decayTime * k); if (sampleVal >= curVal){
curMax = sampleVal;
decayTime = 0;
}else{
decayTime += thisComp.frameDuration;
}
sampleFrame++;
}
curVal

Dan

[Michael Duff]

thanks Dan! I’ll study through that when I have a big coffee ….. in the meantime I have another, hopefully much simpler, question …

i just want to grab the Y-position of a layer but at a different point in time .. so something like transform.position[1].valueAtTime(time-1)

does that makes sense?

thanks!

[Dan Ebberts]

Sure, but it would be like this:

transform.position.valueAtTime(time-1)[1]

Dan

[Michael Duff]

thanks! i knew it would be something simple like that …