euclid.mjs
mjs
/*euclid.mjs - Bjorklund/Euclidean/Diaspora rhythmsCopyright (C) 2023 Rohan Drape and strudel contributorsSee <https://codeberg.org/uzu/strudel/src/branch/main/packages/core/euclid.mjs> for authors of this file.The Bjorklund algorithm implementation is ported from the Haskell Music Theory Haskell module by Rohan Drape -https://rohandrape.net/?t=hmtThis 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/>.*/import { timeCat, register, silence, stack, pure, _morph } from './pattern.mjs';import { rotate, flatten, splitAt, zipWith } from './util.mjs';import Fraction, { lcm } from './fraction.mjs';const left = function (n, x) { const [ons, offs] = n; const [xs, ys] = x; const [_xs, __xs] = splitAt(offs, xs); return [ [offs, ons - offs], [zipWith((a, b) => a.concat(b), _xs, ys), __xs], ];};const right = function (n, x) { const [ons, offs] = n; const [xs, ys] = x; const [_ys, __ys] = splitAt(ons, ys); const result = [ [ons, offs - ons], [zipWith((a, b) => a.concat(b), xs, _ys), __ys], ]; return result;};const _bjorklund = function (n, x) { const [ons, offs] = n; return Math.min(ons, offs) <= 1 ? [n, x] : _bjorklund(...(ons > offs ? left(n, x) : right(n, x)));};export const bjorklund = function (ons, steps) { const inverted = ons < 0; const absOns = Math.abs(ons); const offs = steps - absOns; const ones = Array(absOns).fill([1]); const zeros = Array(offs).fill([0]); const result = _bjorklund([absOns, offs], [ones, zeros]); const pattern = flatten(result[1][0]).concat(flatten(result[1][1])); return inverted ? pattern.map((x) => 1 - x) : pattern;};/** * Changes the structure of the pattern to form an Euclidean rhythm. * Euclidean rhythms are rhythms obtained using the greatest common * divisor of two numbers. They were described in 2004 by Godfried * Toussaint, a Canadian computer scientist. Euclidean rhythms are * really useful for computer/algorithmic music because they can * describe a large number of rhythms with a couple of numbers. * * @memberof Pattern * @name euclid * @param {number} pulses the number of onsets/beats * @param {number} steps the number of steps to fill * @returns Pattern * @example * // The Cuban tresillo pattern. * note("c3").euclid(3,8) *//** * Like `euclid`, but has an additional parameter for 'rotating' the resulting sequence. * @memberof Pattern * @name euclidRot * @param {number} pulses the number of onsets/beats * @param {number} steps the number of steps to fill * @param {number} rotation offset in steps * @returns Pattern * @example * // A Samba rhythm necklace from Brazil * note("c3").euclidRot(3,16,14) *//** * @example // A thirteenth-century Persian rhythm called Khafif-e-ramal. * note("c3").euclid(2,5) * @example // The archetypal pattern of the Cumbia from Colombia, as well as a Calypso rhythm from Trinidad. * note("c3").euclid(3,4) * @example // Another thirteenth century Persian rhythm by the name of Khafif-e-ramal, as well as a Rumanian folk-dance rhythm. * note("c3").euclidRot(3,5,2) * @example // A Ruchenitza rhythm used in a Bulgarian folk dance. * note("c3").euclid(3,7) * @example // The Cuban tresillo pattern. * note("c3").euclid(3,8) * @example // Another Ruchenitza Bulgarian folk-dance rhythm. * note("c3").euclid(4,7) * @example // The Aksak rhythm of Turkey. * note("c3").euclid(4,9) * @example // The metric pattern used by Frank Zappa in his piece titled Outside Now. * note("c3").euclid(4,11) * @example // Yields the York-Samai pattern, a popular Arab rhythm. * note("c3").euclid(5,6) * @example // The Nawakhat pattern, another popular Arab rhythm. * note("c3").euclid(5,7) * @example // The Cuban cinquillo pattern. * note("c3").euclid(5,8) * @example // A popular Arab rhythm called Agsag-Samai. * note("c3").euclid(5,9) * @example // The metric pattern used by Moussorgsky in Pictures at an Exhibition. * note("c3").euclid(5,11) * @example // The Venda clapping pattern of a South African children’s song. * note("c3").euclid(5,12) * @example // The Bossa-Nova rhythm necklace of Brazil. * note("c3").euclid(5,16) * @example // A typical rhythm played on the Bendir (frame drum). * note("c3").euclid(7,8) * @example // A common West African bell pattern. * note("c3").euclid(7,12) * @example // A Samba rhythm necklace from Brazil. * note("c3").euclidRot(7,16,14) * @example // A rhythm necklace used in the Central African Republic. * note("c3").euclid(9,16) * @example // A rhythm necklace of the Aka Pygmies of Central Africa. * note("c3").euclidRot(11,24,14) * @example // Another rhythm necklace of the Aka Pygmies of the upper Sangha. * note("c3").euclidRot(13,24,5) */const _euclidRot = function (pulses, steps, rotation) { const b = bjorklund(pulses, steps); if (rotation) { return rotate(b, -rotation); } return b;};export const euclid = register('euclid', function (pulses, steps, pat) { return pat.struct(_euclidRot(pulses, steps, 0));});export const bjork = register('bjork', function (euc, pat) { if (!Array.isArray(euc)) { euc = [euc]; } const [pulses, steps = pulses, rot = 0] = euc; return pat.struct(_euclidRot(pulses, steps, rot));});export const { euclidrot, euclidRot } = register(['euclidrot', 'euclidRot'], function (pulses, steps, rotation, pat) { return pat.struct(_euclidRot(pulses, steps, rotation));});/** * Similar to `euclid`, but each pulse is held until the next pulse, * so there will be no gaps. * @name euclidLegato * @memberof Pattern * @param {number} pulses the number of onsets/beats * @param {number} steps the number of steps to fill * @param rotation offset in steps * @param pat * @example * note("c3").euclidLegato(3,8) */const _euclidLegato = function (pulses, steps, rotation, pat) { if (pulses < 1) { return silence; } const bin_pat = _euclidRot(pulses, steps, 0); const gapless = bin_pat .join('') .split('1') .slice(1) .map((s) => [s.length + 1, true]); return pat.struct(timeCat(...gapless)).late(Fraction(rotation).div(steps));};export const euclidLegato = register(['euclidLegato'], function (pulses, steps, pat) { return _euclidLegato(pulses, steps, 0, pat);});/** * Similar to `euclid`, but each pulse is held until the next pulse, * so there will be no gaps, and has an additional parameter for 'rotating' * the resulting sequence * @name euclidLegatoRot * @memberof Pattern * @param {number} pulses the number of onsets/beats * @param {number} steps the number of steps to fill * @param {number} rotation offset in steps * @example * note("c3").euclidLegatoRot(3,5,2) */export const euclidLegatoRot = register(['euclidLegatoRot'], function (pulses, steps, rotation, pat) { return _euclidLegato(pulses, steps, rotation, pat);});/** * A 'euclid' variant with an additional parameter that morphs the resulting * rhythm from 0 (no morphing) to 1 (completely 'even'). For example * `sound("bd").euclidish(3,8,0)` would be the same as * `sound("bd").euclid(3,8)`, and `sound("bd").euclidish(3,8,1)` would be the * same as `sound("bd bd bd")`. `sound("bd").euclidish(3,8,0.5)` would have a * groove somewhere between. * Inspired by the work of Malcom Braff. * @name euclidish * @synonyms eish * @memberof Pattern * @param {number} pulses the number of onsets * @param {number} steps the number of steps to fill * @param {number} groove exists between the extremes of 0 (straight euclidian) and 1 (straight pulse) * @example * sound("hh").euclidish(7,12,sine.slow(8)) * .pan(sine.slow(8)) */export const { euclidish, eish } = register(['euclidish', 'eish'], function (pulses, steps, perc, pat) { const morphed = _morph(bjorklund(pulses, steps), new Array(pulses).fill(1), perc); return pat.struct(morphed).setSteps(steps);});
No comments yet.