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105 lines
4.4 KiB
JavaScript
105 lines
4.4 KiB
JavaScript
/*
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euclid.mjs - <short description TODO>
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Copyright (C) 2022 Strudel contributors - see <https://github.com/tidalcycles/strudel/blob/main/packages/core/euclid.mjs>
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This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more details. You should have received a copy of the GNU Affero General Public License along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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import { Pattern, timeCat } from './pattern.mjs';
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import bjork from 'bjork';
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import { rotate } from './util.mjs';
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import Fraction from './fraction.mjs';
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const euclid = (pulses, steps, rotation = 0) => {
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const b = bjork(steps, pulses);
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if (rotation) {
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return rotate(b, -rotation);
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}
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return b;
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};
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/**
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* Changes the structure of the pattern to form an euclidean rhythm.
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* Euclidian rhythms are rhythms obtained using the greatest common divisor of two numbers.
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* They were described in 2004 by Godfried Toussaint, a canadian computer scientist.
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* Euclidian rhythms are really useful for computer/algorithmic music because they can accurately
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* describe a large number of rhythms used in the most important music world traditions.
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*
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* @memberof Pattern
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* @name euclid
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* @param {number} pulses the number of onsets / beats
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* @param {number} steps the number of steps to fill
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* @param {number} rotation (optional) offset in steps
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* @returns Pattern
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* @example
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* // The Cuban tresillo pattern.
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* n("c3").euclid(3,8).out()
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*/
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/**
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* @example // A thirteenth century Persian rhythm called Khafif-e-ramal.
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* n("c3").euclid(2,5)
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* @example // The archetypal pattern of the Cumbia from Colombia, as well as a Calypso rhythm from Trinidad.
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* "c3".euclid(3,4)
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* @example // Another thirteenth century Persian rhythm by the name of Khafif-e-ramal, as well as a Rumanian folk-dance rhythm.
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* "c3".euclid(3,5,2)
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* @example // A Ruchenitza rhythm used in a Bulgarian folk-dance.
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* "c3".euclid(3,7)
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* @example // The Cuban tresillo pattern.
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* "c3".euclid(3,8)
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* @example // Another Ruchenitza Bulgarian folk-dance rhythm.
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* "c3".euclid(4,7)
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* @example // The Aksak rhythm of Turkey.
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* "c3".euclid(4,9)
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* @example // The metric pattern used by Frank Zappa in his piece titled Outside Now.
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* "c3".euclid(4,11)
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* @example // Yields the York-Samai pattern, a popular Arab rhythm.
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* "c3".euclid(5,6)
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* @example // The Nawakhat pattern, another popular Arab rhythm.
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* "c3".euclid(5,7)
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* @example // The Cuban cinquillo pattern.
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* "c3".euclid(5,8)
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* @example // A popular Arab rhythm called Agsag-Samai.
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* "c3".euclid(5,9)
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* @example // The metric pattern used by Moussorgsky in Pictures at an Exhibition.
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* "c3".euclid(5,11)
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* @example // The Venda clapping pattern of a South African children’s song.
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* "c3".euclid(5,12)
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* @example // The Bossa-Nova rhythm necklace of Brazil.
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* "c3".euclid(5,16)
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* @example // A typical rhythm played on the Bendir (frame drum).
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* "c3".euclid(7,8)
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* @example // A common West African bell pattern.
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* "c3".euclid(7,12)
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* @example // A Samba rhythm necklace from Brazil.
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* "c3".euclid(7,16,14)
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* @example // A rhythm necklace used in the Central African Republic.
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* "c3".euclid(9,16)
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* @example // A rhythm necklace of the Aka Pygmies of Central Africa.
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* "c3".euclid(11,24,14)
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* @example // Another rhythm necklace of the Aka Pygmies of the upper Sangha.
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* "c3".euclid(13,24,5)
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*/
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Pattern.prototype.euclid = function (pulses, steps, rotation = 0) {
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return this.struct(euclid(pulses, steps, rotation));
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};
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/**
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* Similar to `.euclid`, but each pulse is held until the next pulse, so there will be no gaps.
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* @name euclidLegato
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* @memberof Pattern
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* @example
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* n("g2").decay(.1).sustain(.3).euclidLegato(3,8).out()
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*/
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Pattern.prototype.euclidLegato = function (pulses, steps, rotation = 0) {
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const bin_pat = euclid(pulses, steps, rotation);
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const firstOne = bin_pat.indexOf(1);
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const gapless = rotate(bin_pat, firstOne)
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.join('')
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.split('1')
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.slice(1)
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.map((s) => [s.length + 1, true]);
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return this.struct(timeCat(...gapless)).late(Fraction(firstOne).div(steps));
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};
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export default euclid;
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