// title: Hymn #15 - generative melody by array rewriting
// author: madamdata
// description:
// This composition uses a task to read an array of durations and pitches. Every certain number of cycles, the functions scrambRand and octRand are called. scrambRand reverses a random sub-segment of the array. octRand randomly transposes a note up or down an octave. Every so often, all pitches are transposed according to the transp array. 
// 
// Two instances of this process are run simultaneously, one left and one right.
// code:
(
SynthDef(\ping, {
	arg freq = 440, pan = 0;
	var sig;
	sig = SinOsc.ar(freq, 0, 0.3);
	sig = sig * EnvGen.ar(Env.perc(0.01, 1), doneAction:2);
	sig = Pan2.ar(sig, pan);
	Out.ar(0, sig)
}).add;
)

(
~scramb = {|pan|
var notes = [0,4,7,14,9,12,4,7,9,7];
var dur = [1,1,2,3,6,3,4,5,2,1,13];
var transp = [0, 5, 7, 3, 2];
var scrambRand = {|array|
	var rand = rrand(0, array.size-3);
	var end = rand + rrand(1,2);
	var range = (rand..end);
	var reverseRange = range.reverse;
	var temp = array.copy;
	range.postln;
	range.do({|item, index|
		array[item] = temp[reverseRange[index]];
	});
	array;
};
var octRand = {|array|
		var rand = rrand(0, array.size-1);
		array[rand] = array[rand] + [-12,0,12].choose;
	};
var task = Task {
	var step = 0;
	var transpStep = 0;
	loop {
		var freq = (notes.wrapAt(step) + 60 + transp.wrapAt(transpStep)).midicps;
		Synth(\ping, [\freq, freq, \pan, pan]);
		(dur.wrapAt(step) * 0.15).wait;
		step = step + 1 % (notes.size * 12;);
		if (step%32 == 0, {scrambRand.value(notes)});
		if (step%20 == 0, {scrambRand.value(dur)});
		if (step%66 == 0, {transpStep = transpStep + 1 % (transp.size)});
		if (step%24 == 0, {notes = notes.rotate(rrand(-1, 1))});
		if (step%56 ==0, {octRand.value(notes)});
	}
}.play;
};
)

(
~scramb.value(-0.7);~scramb.value(0.7);
)