Formlet

A FOF-like resonant filter UGen. Its impulse response is like that of a sine wave with a Decay2 envelope over it. It is possible to control the attack and decay times.

Formlet is equivalent to:

Ringz(in, freq, decay) - Ringz(in, freq, attack)

The great advantage to this filter over FOF (Fonction d'onde formantique) is that there is no limit to the number of overlapping grains since the grain is just the impulse response of the filter.

''Note'': Ringz and derived UGens Klank and Formlet produce output RMS depending on the server's sampling rate. This is to achieve the same amplitude for single-sample impulse inputs.

===Examples===

// modulated formant frequency
play {
 val in = Blip.ar(SinOsc.kr(5,0).mulAdd(20, 300), 1000) * 0.1
 Formlet.ar(in, XLine.kr(1500, 700, 8), 0.005, 0.04)
}

// mouse control of frequency and decay time
play {
 val in    = Blip.ar(SinOsc.kr(5,0).mulAdd(20, 300), 1000) * 0.1
 val freq  = MouseY.kr(700, 2000, 1)
 val decay = MouseX.kr(0.01, 0.2, 1)
 Formlet.ar(in, freq, attack = 0.005, decay = decay)
}