117 lines
2.2 KiB
Racket
117 lines
2.2 KiB
Racket
#lang scribble/manual
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@(require (for-label racket))
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@title{Sweep}
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Triggered linear ramp@section{categories}
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UGens>Triggers
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@section{description}
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Starts a linear raise by rate/sec from zero when trig input crosses from
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non-positive to positive.
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When rate == 1, Sweep may be used to get a continually-updating measurement
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of the time (in seconds) since the last trigger.
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@section{classmethods}
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@section{private}
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categories
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@section{method}
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ar, kr
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@section{argument}
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trig
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triggers when trig input crosses from non-positive to positive.
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@section{argument}
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rate
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rate/sec raise rate
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@section{Examples}
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@racketblock[
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// using sweep to modulate sine frequency
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(
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{ var trig;
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trig = Impulse.kr(MouseX.kr(0.5, 20, 1));
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SinOsc.ar(Sweep.kr(trig, 700) + 500, 0, 0.2)
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}.play;
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)
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// using sweep to index into a buffer
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b = Buffer.read(s, Platform.resourceDir +/+ "sounds/a11wlk01.wav");
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(
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{ var trig;
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trig = Impulse.kr(MouseX.kr(0.5, 10, 1));
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BufRd.ar(1, b, Sweep.ar(trig, BufSampleRate.ir(0)))
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}.play;
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)
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// backwards, variable offset
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(
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{ var trig, pos, rate;
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trig = Impulse.kr(MouseX.kr(0.5, 10, 1));
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rate = BufSampleRate.ir(0);
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pos = Sweep.ar(trig, rate.neg) + (BufFrames.ir(0) * LFNoise0.kr(0.2));
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BufRd.ar(1, b, pos)
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}.play;
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)
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// raising rate
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(
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{ var trig, rate;
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trig = Impulse.kr(MouseX.kr(0.5, 10, 1));
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rate = Sweep.kr(trig, 2) + 0.5;
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BufRd.ar(1, b, Sweep.ar(trig, BufSampleRate.ir(0) * rate))
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}.play;
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)
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b.free
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::
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Sweep can be used as a resettable link::Classes/Phasor:: or link::Classes/Line:: - one that can start, pause, resume and stop. To get a resettable link::Classes/XLine:: behavior change the ]
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@racketblock[linlin:: to ]
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@racketblock[linexp:: in the SynthDef below.
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]
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@racketblock[
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(
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SynthDef(\lineReset, {|start= 0, end= 1, dur= 1, t_trig= 1, run= 1|
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var phasor= (Sweep.ar(t_trig, 1/dur*run)).linlin(0, 1, start, end, \minmax);
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phasor.poll;
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Out.ar(0, SinOsc.ar(phasor, 0, 0.2));
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}).add;
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)
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a= Synth(\lineReset, [\start, 400, \end, 800, \dur, 2])
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a.set(\t_trig, 1)
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a.set(\run, 0)
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a.set(\run, 1)
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a.set(\t_trig, 1)
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a.free
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//shorter duration and downwards...
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a= Synth(\lineReset, [\start, 1000, \end, 500, \dur, 0.5])
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a.set(\t_trig, 1)
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a.set(\run, 0)
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a.set(\run, 1)
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a.set(\t_trig, 1)
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a.free
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::
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]
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