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Why multiply on Pi
Hi, everybody, I noticed some pro artists do multiplication on Pi. Can you, please, explain what sense in that?
For example in this expression, which gives you scale hesitation on each marker.look at “angle” variable, expression will work without “Math.PI” as well.
n = 0;
t = 0;
if (marker.numKeys > 0){
n = marker.nearestKey(time).index;
if (marker.key(n).time > time) n–;
}
if (n > 0) t = time – marker.key(n).time;
amp = 15;
freq = 5;
decay = 3.0;
angle = freq * 2 * Math.PI * t;
scaleFact = (100 + amp * Math.sin(angle) / Math.exp(decay * t)) / 100;
[value[0] * scaleFact, value[1] / scaleFact];
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2 Replies
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Multiplying by 2*pi allows you to express your frequency (freq) in cycles per second. So in your expression, the damped sine wave will oscillate at 5 cycles per second. Without the 2*pi, it will still oscillate, just a frequency that’s harder to predict. It’s just convenience (and convention) mainly.
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God, bless internet, Dan, thank you so much for explaining things, really appreciate this.
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