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https://github.com/eliasstepanik/strudel-docker.git
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68 lines
2.8 KiB
JavaScript
68 lines
2.8 KiB
JavaScript
/*
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xen.mjs - <short description TODO>
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Copyright (C) 2022 Strudel contributors - see <https://github.com/tidalcycles/strudel/blob/main/packages/xen/xen.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, mod } from '@strudel.cycles/core';
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export function edo(name) {
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if (!/^[1-9]+[0-9]*edo$/.test(name)) {
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throw new Error('not an edo scale: "' + name + '"');
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}
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const [_, divisions] = name.match(/^([1-9]+[0-9]*)edo$/);
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return Array.from({ length: divisions }, (_, i) => Math.pow(2, i / divisions));
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}
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const presets = {
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'12ji': [1 / 1, 16 / 15, 9 / 8, 6 / 5, 5 / 4, 4 / 3, 45 / 32, 3 / 2, 8 / 5, 5 / 3, 16 / 9, 15 / 8],
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};
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function withBase(freq, scale) {
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return scale.map((r) => r * freq);
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}
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const defaultBase = 220;
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function getXenScale(scale, indices) {
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if (typeof scale === 'string') {
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if (/^[1-9]+[0-9]*edo$/.test(scale)) {
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scale = edo(scale);
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} else if (presets[scale]) {
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scale = presets[scale];
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} else {
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throw new Error('unknown scale name: "' + scale + '"');
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}
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}
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scale = withBase(defaultBase, scale);
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if (!indices) {
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return scale;
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}
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return scale.filter((_, i) => indices.includes(i));
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}
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function xenOffset(xenScale, offset, index = 0) {
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const i = mod(index + offset, xenScale.length);
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const oct = Math.floor(offset / xenScale.length);
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return xenScale[i] * Math.pow(2, oct);
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}
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// scaleNameOrRatios: string || number[], steps?: number
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Pattern.prototype._xen = function (scaleNameOrRatios, steps) {
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return this._asNumber()._withEvent((event) => {
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const scale = getXenScale(scaleNameOrRatios);
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steps = steps || scale.length;
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const frequency = xenOffset(scale, event.value);
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return event.withValue(() => frequency).setContext({ ...event.context, type: 'frequency' });
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});
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};
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Pattern.prototype.tuning = function (steps) {
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return this._asNumber()._withEvent((event) => {
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const frequency = xenOffset(steps, event.value);
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return event.withValue(() => frequency).setContext({ ...event.context, type: 'frequency' });
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});
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};
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Pattern.prototype.define('xen', (scale, pat) => pat.xen(scale), { composable: true, patternified: true });
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// Pattern.prototype.define('tuning', (scale, pat) => pat.xen(scale), { composable: true, patternified: false });
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