#lang scribble/manual
@(require (for-label racket))

@title{LocalIn}
 Define and read from buses local to a synth.@section{related}
  Classes/LocalOut
@section{categories}
   UGens>InOut

@section{description}


LocalIn defines buses that are local to the enclosing synth. These are
like the global buses, but are more convenient if you want to implement a
self contained effect that uses a feedback processing loop.

There can only be one audio rate and one control rate LocalIn per
SynthDef. The audio can be written to the bus using
link::Classes/LocalOut:: .

@section{warning}
 
Audio written to a  link::Classes/LocalOut::  will not be read by a
corresponding LocalIn until the next cycle, i.e. one block size of
samples later. Because of this it is important to take this additional
delay into account when using LocalIn to create feedback delays with
delay times shorter than the threshold of pitch (i. e. < 0.05
seconds or > 20Hz), or where sample accurate alignment is required.
See the resonator example below.
::

@section{classmethods}
 

@section{method}
 ar, kr

@section{argument}
 numChannels

The number of channels (i.e. adjacent buses) to read in. You
cannot modulate this number by assigning it to an argument in a
SynthDef.

@section{argument}
 default

The initial value written to the bus once, so that it can be used before overwriting it with LocalOut. An array can be passed in to specify different values for each channel.


@section{Examples}
 


@racketblock[
(
{
	var source, local;

	source = Decay.ar(Impulse.ar(0.3), 0.1) * WhiteNoise.ar(0.2);
	local = LocalIn.ar(2) + [source, 0]; // read feedback, add to source
	local = DelayN.ar(local, 0.2, 0.2); // delay sound

	// reverse channels to give ping pong effect, apply decay factor
	LocalOut.ar(local.reverse * 0.8);

	local
}.play;
)

(
{
	var local, in;

	in = Mix.fill(12, {
		Pan2.ar(
			Decay2.ar(Dust.ar(0.05), 0.1, 0.5, 0.1)
				* FSinOsc.ar(IRand(36,84).midicps).cubed.max(0),
			Rand(-1,1))
	});
	in = in + Pan2.ar(Decay2.ar(Dust.ar(0.03), 0.04, 0.3) * BrownNoise.ar, 0);

	4.do { in = AllpassN.ar(in, 0.03, {Rand(0.005,0.02)}.dup, 1); };

	local = LocalIn.ar(2) * 0.98;
	local = OnePole.ar(local, 0.5);

	local = Rotate2.ar(local[0], local[1], 0.23);
	local = AllpassN.ar(local, 0.05, {Rand(0.01,0.05)}.dup, 2);

	local = DelayN.ar(local, 0.3, [0.19,0.26]);
	local = AllpassN.ar(local, 0.05, {Rand(0.03,0.15)}.dup, 2);

	local = LeakDC.ar(local);
	local = local + in;

	LocalOut.ar(local);

	local

}.play;
)

(
{
	var local, in, amp;

	in = SoundIn.ar([0, 1]);

	amp = Amplitude.kr(Mix.ar(in));
	in = in * (amp > 0.02); // noise gate

	local = LocalIn.ar(2);
	local = OnePole.ar(local, 0.4);
	local = OnePole.ar(local, -0.08);

	local = Rotate2.ar(local[0], local[1], 0.2);

	local = DelayN.ar(local, 0.25, 0.25);

	local = LeakDC.ar(local);
	local = ((local + in) * 1.25).softclip;

	LocalOut.ar(local);
	local * 0.1;
}.play;
)

// Resonator, must subtract blockSize for correct tuning
(
{
	var in, imp, sound;

	in = LocalIn.ar(1);
	imp = Impulse.ar(1);
	sound = DelayC.ar(imp + (in * 0.995), 1, 440.reciprocal - ControlRate.ir.reciprocal);
	LocalOut.ar(sound); // for feedback
	in
}.play;

// compare pitch
{
	SinOsc.ar(440, 0, 0.2)
}.play(s, 1);
)
::

]