Set a minimum and maximum for rotation expression

Question

Need to modify the attached code to include a minimum and maximum rotation in the wiggle expression. Say for example the VU meter needle will never rotate less than 2 and more than 100.

//Smooth wiggle

freq = effect("Speed")("Slider");

amp = effect("Range")("Slider");

n = freq.numKeys;

if (n > 0 && freq.key(1).time < time){

accum = freq.key(1).value*(freq.key(1).time - inPoint);

for (i = 2; i <= n; i++){

if (freq.key(i).time > time) break;

k1 = freq.key(i-1);

k2 = freq.key(i); accum += (k1.value + k2.value)*(k2.time - k1.time)/2; }

accum += (freq.value + freq.key(i-1).value)*(time - freq.key(i-1).time)/2;

}else{

accum = freq.value*(time - inPoint);

}

wiggle(1,amp,1,.5,accum)

Rick Gerard · Accepted Answer

You could tie rotation to opacity for your red light layer. Something like this:r = thisComp.layer("VU Dial");if (r > 90)    100else    0

Rick Gerard · Answer

That expression creates the changing values based on keyframes and slider values. You have several options. One of them would be to define the output wiggle value as "t" and then use a linear interpolation method to limit the output from 2 to 100. You would have to know what the minimum and maximum values that wiggle would generate, and those values are based on keyframes and sliders.

A linear interpolation looks like this:

t = wiggle(freq, amp, octaves = 1, amp_mult = .5, t = time);
r = linear(t, tMin, tMax, 2, 100)

Without setting a bunch of keyframes and adding some sliders, I have no idea what tMin or tMax would be.

If you just want a random rotation wiggle from 2 to 100 that happens 8 times a second, all you need in the rotation property is:

t = wiggle(8, 100);
linear(t, -100, 100, 2, 100)

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