mirror of
https://github.com/9x/sheetmusictrainer.git
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535 lines
23 KiB
TypeScript
535 lines
23 KiB
TypeScript
/**
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* Arpeggio generator (Phrase Mode material).
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*
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* Diatonic triads (I, ii, iii, IV, V, vi, vii°) built from the selected
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* key/mode; each practice run arpeggiates ONE chord — the user picks the
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* degree, the pattern (up / down / up-down / 1-2-3-5) and the coverage
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* (one or two octaves). Chord tones are spelled via the key's degree
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* spelling (same machinery as melody/scale generators), so spelling and
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* validation match the Phrase Mode invariants exactly.
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*
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* Arpeggio mode is ALWAYS eighths (240 ticks per note). Meter is auto-derived
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* from the pattern length — the user no longer picks rhythm or meter.
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*/
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import { PPQ, validateScore, type Result, type Score, type ScoreEvent } from '../score/model';
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import { keyFor, type KeyContext, type ModeId } from './scales';
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import { STEP_LETTERS, LETTER_PC, type StepLetter } from '../score/model';
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import { makeRng } from './melodyGenerator';
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export type ArpeggioDegree = 'I' | 'ii' | 'iii' | 'IV' | 'V' | 'vi' | 'vii0';
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export type ArpeggioPattern =
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| 'up' | 'down' | 'updown' | '1235'
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// Giuliani-style right-hand figures over one chord (indices into the
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// chord cycle per note; 1=root 2=third 3=fifth 4=octave):
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| '1321' // root-fifth-third-root
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| '1325' // root-fifth-third-octave
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| '1535' // root-octave-fifth-octave
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| '12353' // root-third-fifth-octave-fifth
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| '121321' // rolling thirds (root-third-root-fifth-third-root)
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| '1353' // root-third-fifth-third
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| '15453' // root-octave-fifth-octave-fifth-octave
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| '132532' // long broken-chord wave
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| 'custom' // user-defined pattern from customPattern digits
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| 'random'; // one broken-chord figure, chosen randomly per exercise (seed)
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export type ArpeggioCoverage = 'one-octave' | 'two-octave';
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/** How the chord per bar is chosen in sequence mode. */
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export type ArpeggioProgression = 'random' | 'functional' | 'diatonic-cycle';
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export interface ArpeggioConfig {
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readonly keyTonic: string;
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readonly keyMode: ModeId;
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readonly degree: ArpeggioDegree;
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readonly pattern: ArpeggioPattern;
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readonly coverage: ArpeggioCoverage;
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/** Sequence mode: bars > 1 with chord progression selection. */
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readonly bars?: number;
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readonly progression?: ArpeggioProgression;
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/** Restrict progression chords to these degrees (empty = all 7).
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* The first bar always uses `degree` if it is in the selection. */
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readonly chordSelection?: readonly ArpeggioDegree[];
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/** Seed for progression selection (deterministic). */
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readonly seed?: number;
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/** User-defined custom pattern digits (1-indexed: 1=root, 2=third, 3=fifth,
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* 4=octave, 5=fifth-above-octave). Only used when pattern === 'custom'. */
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readonly customPattern?: string;
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}
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/** Degree index (0-based) into the scale for each arpeggio degree label. */
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const DEGREE_INDEX: Record<ArpeggioDegree, number> = {
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I: 0, ii: 1, iii: 2, IV: 3, V: 4, vi: 5, 'vii0': 6,
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};
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export const ARPEGGIO_DEGREE_LABELS: Record<ArpeggioDegree, string> = {
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I: 'I', ii: 'ii', iii: 'iii', IV: 'IV', V: 'V', vi: 'vi', 'vii0': 'vii°',
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};
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export const PATTERN_LABELS: Record<ArpeggioPattern, string> = {
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up: 'Up', down: 'Down', updown: 'Up & down', '1235': '1-2-3-5',
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'1321': '1-3-2-1',
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'1325': '1-3-2-5(8)',
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'1535': '1-5-3-5(8)',
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'12353': '1-2-3-5-3',
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'121321': '1-2-1-3-2-1',
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'1353': '1-3-5-3',
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'15453': '1-5-4-5-3-5',
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'132532': '1-3-2-5-3-2',
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'custom': 'Custom…',
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'random': 'Random',
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};
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/**
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* Broken-chord figures — NOTE sequences (not fingerings): the bass takes the
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* root, the remaining notes ride the upper chord tones.
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* Indices into the octave cycle [0=root, 1=third, 2=fifth, 3=octave].
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*/
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const BROKEN_FIGURES: Record<string, number[]> = {
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'1321': [0, 2, 1, 0],
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'1325': [0, 2, 1, 3],
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'1535': [0, 3, 2, 3],
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'12353': [0, 1, 2, 3, 2],
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'121321': [0, 1, 0, 2, 1, 0],
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'1353': [0, 1, 2, 1],
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'15453': [0, 3, 2, 3, 2, 3],
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'132532': [0, 2, 1, 3, 2, 1],
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};
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/**
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* Renderable note durations — subset of VexFlow duration codes the
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* PhraseSheetMusic renderer accepts. ALL generated durations MUST be in this
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* set, otherwise the renderer produces ghost slots and crashes or misaligns.
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*/
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const RENDERABLE_NOTE_TICKS = new Set([120, 240, 360, 480, 720, 960, 1440, 1920]);
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/** Descending renderable durations for rest fills (largest first). */
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const REST_FILL_TICKS = [1920, 1440, 960, 720, 480, 240];
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/** pc of a spelled degree (step letter + alter). */
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const degreePc = (d: { step: StepLetter; alter: number }): number =>
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(LETTER_PC[STEP_LETTERS.indexOf(d.step)] + d.alter + 144) % 12;
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/** Chord symbol name for a diatonic degree, e.g. "C", "Am", "Bdim". */
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function chordNameFor(key: KeyContext, degreeIndex: number): string {
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const d = key.degrees[degreeIndex];
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const third = key.degrees[(degreeIndex + 2) % 7];
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const fifth = key.degrees[(degreeIndex + 4) % 7];
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const root = d.step + (d.alter < 0 ? 'b'.repeat(-d.alter) : '#'.repeat(d.alter));
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const thirdInterval = (degreePc(third) - degreePc(d) + 12) % 12;
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const fifthInterval = (degreePc(fifth) - degreePc(d) + 12) % 12;
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let suffix = '';
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if (thirdInterval === 3 && fifthInterval === 7) suffix = 'm';
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else if (thirdInterval === 3 && fifthInterval === 6) suffix = 'dim';
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return root + suffix;
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}
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/**
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* Chord-tone midi notes of the diatonic triad on `degreeIndex` (0-based),
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* intersected with the playable pool, ascending.
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*/
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function chordTonesInPool(key: KeyContext, degreeIndex: number, pool: number[]): number[] {
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const steps = [0, 2, 4].map(offset => (degreeIndex + offset) % 7);
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const pcs = new Set(steps.map(i => degreePc(key.degrees[i])));
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return pool.filter(midi => pcs.has(((midi % 12) + 12) % 12));
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}
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/** Spelling (step, alter) for a midi note in the key — via scale degrees. */
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function spellInKey(key: KeyContext, midi: number): { step: StepLetter; alter: number; octave: number } | null {
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const pc = ((midi % 12) + 12) % 12;
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const d = key.degrees.find(deg => degreePc(deg) === pc);
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if (!d) return null;
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const octave = (midi - pc) / 12 - 1;
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return { step: d.step, alter: d.alter, octave };
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}
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/**
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* Auto-derive a meter (3/4 or 4/4) from the number of eighths in the phrase.
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* Always returns 3/4 or 4/4 — 6/8 is never used for arpeggios since it can
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* produce non-renderable tick sizes with some pattern lengths.
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*
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* For N notes at 240 ticks each:
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* Try 4/4: bars4 = ceil(N*240 / 1920), remainder4 = bars4*1920 - N*240
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* Try 3/4: bars3 = ceil(N*240 / 1440), remainder3 = bars3*1440 - N*240
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* Pick the one with smaller remainder (fewer bars as tiebreaker).
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*/
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export function autoArpeggioMeter(noteCount: number): { numerator: 4 | 3; denominator: 4 } {
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const totalTicks = noteCount * 240;
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const bars4 = Math.ceil(totalTicks / 1920);
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const remainder4 = bars4 * 1920 - totalTicks;
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const bars3 = Math.ceil(totalTicks / 1440);
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const remainder3 = bars3 * 1440 - totalTicks;
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if (remainder3 < remainder4) return { numerator: 3, denominator: 4 };
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if (remainder4 < remainder3) return { numerator: 4, denominator: 4 };
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// equal remainders → prefer fewer bars
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return bars3 <= bars4 ? { numerator: 3, denominator: 4 } : { numerator: 4, denominator: 4 };
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}
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/**
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* Build the arpeggio path: chord tones ascending from the lowest available
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* root (degree tone) that allows a full one/two-octave cycle in the pool.
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* Pattern up/down/updown/1235 is applied to one octave cycle.
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*/
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function buildPath(key: KeyContext, degreeIndex: number, pool: number[], coverage: ArpeggioCoverage, pattern: ArpeggioPattern): number[] | null {
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const tones = chordTonesInPool(key, degreeIndex, pool);
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if (tones.length < 3) return null; // need at least one full triad
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const rootPc = degreePc(key.degrees[degreeIndex]);
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const octaveCycle = (startMidi: number): number[] => {
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// chord tones >= startMidi within one octave, INCLUDING the octave
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// of the root (an arpeggio cycle conventionally ends on the octave)
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const cycle: number[] = [];
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for (const midi of tones) {
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if (midi >= startMidi && midi <= startMidi + 12) cycle.push(midi);
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}
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if (!cycle.includes(startMidi + 12) && pool.includes(startMidi + 12)) {
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cycle.push(startMidi + 12);
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}
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return cycle.sort((a, b) => a - b);
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};
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const cycles: number[][] = [];
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// candidate roots: chord-tone midis with pc == rootPc, ascending
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const roots = tones.filter(m => ((m % 12) + 12) % 12 === rootPc);
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const octavesWanted = coverage === 'one-octave' ? 1 : 2;
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for (const root of roots) {
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const first = octaveCycle(root);
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if (first.length < 3 || first[0] !== root) continue;
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// second octave: tones one octave above `root`
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const second = first.map(m => m + 12).filter(m => pool.includes(m));
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if (octavesWanted === 2 && second.length < 4) continue;
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cycles.push(first);
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break; // lowest fitting root
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}
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if (cycles.length === 0) return null;
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const base = cycles[0];
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const up = octavesWanted === 2
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// base already ends on the octave of the root — the second octave
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// continues from there (drop the duplicated turning root)
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? [...base, ...base.map(m => m + 12).slice(1)]
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: base;
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switch (pattern) {
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case 'up': return up;
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case 'down': return [...up].reverse();
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case 'updown': {
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// ascend then descend, dropping the duplicated turning note
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const desc = [...up].reverse().slice(1);
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return [...up, ...desc];
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}
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case '1235': {
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// root, third, fifth, octave (of the root) — repeated per octave
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const path: number[] = [];
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for (let oct = 0; oct < octavesWanted; oct++) {
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path.push(base[0] + 12 * oct);
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path.push(base[1] + 12 * oct);
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path.push(base[2] + 12 * oct);
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path.push(base[0] + 12 * (oct + 1));
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}
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return path;
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}
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default: {
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// Broken-chord figure: cycle [root, third, fifth, octave] with the
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// figure selecting cycle positions per note; the octave wraps so
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// e.g. 1321 over C-E-G becomes C G E C' ... (ascending octave
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// register shift every figure repetition).
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const figure = BROKEN_FIGURES[pattern];
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// 4-note cycle per octave: root, third, fifth, octave
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const cycleOct = (oct: number): number[] => [
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base[0] + 12 * oct, base[1] + 12 * oct, base[2] + 12 * oct, base[0] + 12 * (oct + 1),
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];
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const path: number[] = [];
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for (let oct = 0; oct < octavesWanted; oct++) {
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const c = cycleOct(oct);
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for (const idx of figure) {
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const note = c[idx];
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if (note !== undefined && (oct === 0 || pool.includes(note))) path.push(note);
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}
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}
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return path;
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}
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}
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}
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/**
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* Parse custom pattern digits into cycle indices (0-based).
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* Digits are 1-indexed: 1=root, 2=third, 3=fifth, 4=octave, 5=fifth-above-octave.
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* Returns null for empty/invalid input.
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*/
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function parseCustomPattern(digits: string): number[] | null {
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if (!digits || digits.trim().length === 0) return null;
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const result: number[] = [];
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for (const ch of digits.trim()) {
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const n = parseInt(ch, 10);
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if (isNaN(n) || n < 1 || n > 5) return null;
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// Map 1→0 (root), 2→1 (third), 3→2 (fifth), 4→3 (octave), 5→4 (fifth above octave)
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result.push(n - 1);
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}
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return result.length > 0 ? result : null;
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}
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/**
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* Build a custom path from 0-based digit indices using the one-octave cycle
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* [root, third, fifth, octave] (index 4 = fifth above the octave).
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*/
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function buildCustomPath(
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base: number[],
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pattern: number[],
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octavesWanted: number,
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pool: number[],
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): number[] | null {
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const cycleOct = (oct: number): number[] => [
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base[0] + 12 * oct, base[1] + 12 * oct, base[2] + 12 * oct, base[0] + 12 * (oct + 1),
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];
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const path: number[] = [];
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for (let oct = 0; oct < octavesWanted; oct++) {
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const c = cycleOct(oct);
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// Extend the cycle for digit 5: fifth above the octave (+7 semitones).
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const extended = [...c, c[3] + 7];
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for (const idx of pattern) {
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const note = extended[idx];
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if (note === undefined) continue;
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if (oct > 0 && !pool.includes(note)) continue;
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path.push(note);
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}
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}
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return path.length > 0 ? path : null;
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}
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/**
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* Build the path for one chord (degree), honouring built-in patterns and the
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* user-defined custom pattern. Returns null when the chord cannot be voiced
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* in the playable pool.
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*/
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function pathForChord(
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key: KeyContext,
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degreeIndex: number,
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pool: number[],
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coverage: ArpeggioCoverage,
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pattern: ArpeggioPattern,
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customDigits: number[] | null,
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): number[] | null {
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if (pattern === 'custom') {
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if (!customDigits) return null;
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const tones = chordTonesInPool(key, degreeIndex, pool);
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if (tones.length < 3) return null;
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const rootPc = degreePc(key.degrees[degreeIndex]);
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const roots = tones.filter(m => ((m % 12) + 12) % 12 === rootPc);
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const octavesWanted = coverage === 'one-octave' ? 1 : 2;
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for (const root of roots) {
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// chord tones >= root within one octave, including the octave
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const cycle: number[] = [];
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for (const midi of tones) {
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if (midi >= root && midi <= root + 12) cycle.push(midi);
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}
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if (!cycle.includes(root + 12) && pool.includes(root + 12)) cycle.push(root + 12);
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cycle.sort((a, b) => a - b);
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if (cycle.length < 3 || cycle[0] !== root) continue;
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const p = buildCustomPath(cycle, customDigits, octavesWanted, pool);
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if (p) return p;
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}
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return null;
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}
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return buildPath(key, degreeIndex, pool, coverage, pattern);
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}
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/**
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* Emit one eighth-note event with key-aware spelling.
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* Returns false when the midi note cannot be spelled in this key.
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*/
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function pushNote(
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events: ScoreEvent[],
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key: KeyContext,
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midi: number,
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startTick: number,
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id: string,
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): boolean {
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const spelled = spellInKey(key, midi);
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if (!spelled) return false;
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events.push({
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id,
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startTick,
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durationTicks: 240,
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pitch: { midi, ...spelled },
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});
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return true;
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}
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/**
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* Fill the tail of the material (after the last note) with rests built from
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* RENDERABLE durations only. Splits the gap greedily, largest duration first.
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*/
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function pushRestFill(events: ScoreEvent[], fromTick: number, untilTick: number): void {
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let cursor = fromTick;
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while (cursor < untilTick) {
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const gap = untilTick - cursor;
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const dur = REST_FILL_TICKS.find(d => d <= gap);
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if (!dur) break; // gap smaller than an eighth — should not happen
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events.push({
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id: `r${events.length}`,
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startTick: cursor,
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durationTicks: dur,
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pitch: null, // rest
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});
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cursor += dur;
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}
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}
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/**
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* Resolve the effective broken-chord figure for this exercise. 'random'
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* picks one deterministic figure per seed so every auto-continued run gets
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* a fresh broken-chord pattern while remaining reproducible.
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*/
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function resolveRandomPattern(pattern: ArpeggioPattern, seed: number): ArpeggioPattern {
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if (pattern !== 'random') return pattern;
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const figures = Object.keys(BROKEN_FIGURES);
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const rng = makeRng(seed * 7919 + 13);
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return figures[Math.floor(rng() * figures.length)] as ArpeggioPattern;
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}
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export function generateArpeggio(
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config: ArpeggioConfig,
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eligiblePitches: number[],
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): Result<Score> {
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const key = keyFor(config.keyTonic, config.keyMode);
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const pool = Array.from(new Set(eligiblePitches.filter(m => Number.isInteger(m)))).sort((a, b) => a - b);
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if (pool.length === 0) return { ok: false, error: 'No playable notes in the selected range — widen the note set.' };
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const bars = config.bars ?? 1;
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const pattern = resolveRandomPattern(config.pattern, config.seed ?? 0);
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const coverage = config.coverage;
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// ---- Chord sequence ----------------------------------------------------
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const degreeIndices: number[] = [];
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const sel = (config.chordSelection ?? []).filter(d => d in DEGREE_INDEX).map(d => DEGREE_INDEX[d as ArpeggioDegree]);
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const pool7 = sel.length > 0 ? Array.from(new Set(sel)).sort((a, b) => a - b) : [0, 1, 2, 3, 4, 5, 6];
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if (bars === 1) {
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degreeIndices.push(DEGREE_INDEX[config.degree]);
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} else {
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const rng = makeRng(config.seed ?? 1);
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const pick = <T,>(arr: T[]): T => arr[Math.floor(rng() * arr.length)];
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for (let b = 0; b < bars; b++) {
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if (b === 0) {
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degreeIndices.push(pool7.includes(DEGREE_INDEX[config.degree]) && rng() < 0.34
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? DEGREE_INDEX[config.degree]
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: pick(pool7));
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continue;
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}
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const prev = degreeIndices[b - 1];
|
|
if (config.progression === 'diatonic-cycle') {
|
|
let next = (prev + 1) % 7;
|
|
for (let tries = 0; tries < 7 && !pool7.includes(next); tries++) next = (next + 1) % 7;
|
|
degreeIndices.push(next);
|
|
} else if (config.progression === 'functional') {
|
|
const NEXT: Record<number, number[]> = {
|
|
0: [3, 4, 5],
|
|
1: [4],
|
|
2: [3, 5],
|
|
3: [0, 4],
|
|
4: [0, 5],
|
|
5: [1, 3],
|
|
6: [0],
|
|
};
|
|
const targets = (NEXT[prev] ?? [0]).filter(d => pool7.includes(d));
|
|
degreeIndices.push(pick(targets.length > 0 ? targets : pool7.filter(d => d !== prev)));
|
|
} else {
|
|
const candidates = pool7.filter(d => d !== prev);
|
|
degreeIndices.push(pick(candidates.length > 0 ? candidates : pool7));
|
|
}
|
|
}
|
|
}
|
|
|
|
// ---- Custom pattern digits (only for pattern === 'custom') --------------
|
|
const customDigits = pattern === 'custom' ? parseCustomPattern(config.customPattern ?? '') : null;
|
|
if (pattern === 'custom' && !customDigits) {
|
|
return { ok: false, error: 'Custom pattern is empty or invalid — enter digits like "1321" (1=root, 2=third, 3=fifth, 4=octave).' };
|
|
}
|
|
|
|
// ---- Build the path for the first chord ----------------------------------
|
|
// All bars share the same pattern, so the path length (and thus meter) is
|
|
// derived from the first chord's voicing. Sequence mode repeats the path
|
|
// within each bar, so the meter also derives from the path length itself.
|
|
const firstPath = pathForChord(key, degreeIndices[0], pool, coverage, pattern, customDigits);
|
|
if (!firstPath || firstPath.length === 0) {
|
|
return {
|
|
ok: false,
|
|
error: 'The arpeggio does not fit the playable range — widen the range (strings/fret window) or pick another degree.',
|
|
};
|
|
}
|
|
const meter = autoArpeggioMeter(firstPath.length);
|
|
const notesPerBar = meter.numerator * 2; // 2 eighths per beat
|
|
const barLength = meter.numerator * PPQ;
|
|
const noteDur = 240; // always eighths
|
|
|
|
// ---- Events: single-chord vs sequence mode --------------------------------
|
|
const events: ScoreEvent[] = [];
|
|
const chordSymbols: (string | null)[] = [];
|
|
|
|
if (bars === 1) {
|
|
// Single-chord mode: the path plays once; any remaining ticks in the
|
|
// final bar(s) become rests (renderable durations only). The path is
|
|
// NEVER stretched — durations stay at 240 ticks.
|
|
const barCount = Math.max(1, Math.ceil((firstPath.length * noteDur) / barLength));
|
|
chordSymbols.push(chordNameFor(key, degreeIndices[0]));
|
|
|
|
let cursor = 0;
|
|
for (let slot = 0; slot < firstPath.length; slot++) {
|
|
pushNote(events, key, firstPath[slot], cursor, `a0-${slot}`);
|
|
cursor += noteDur;
|
|
}
|
|
const totalTicks = barCount * barLength;
|
|
if (cursor < totalTicks) pushRestFill(events, cursor, totalTicks);
|
|
} else {
|
|
// Sequence mode: one chord per bar, each bar holds exactly
|
|
// `notesPerBar` eighths (the path cycles if it is shorter, and is
|
|
// truncated if longer — with two-octave coverage the auto-derived
|
|
// meter always gives enough room).
|
|
let cursor = 0;
|
|
for (let b = 0; b < bars; b++) {
|
|
const di = degreeIndices[b];
|
|
chordSymbols.push(chordNameFor(key, di));
|
|
const barPath = pathForChord(key, di, pool, coverage, pattern, customDigits);
|
|
if (!barPath || barPath.length === 0) {
|
|
return { ok: false, error: `Cannot voice arpeggio for chord ${chordNameFor(key, di)}.` };
|
|
}
|
|
for (let n = 0; n < notesPerBar; n++) {
|
|
pushNote(events, key, barPath[n % barPath.length], cursor, `a${b}-${n}`);
|
|
cursor += noteDur;
|
|
}
|
|
}
|
|
}
|
|
|
|
// ---- Validate all durations are renderable -----------------------------
|
|
for (const e of events) {
|
|
if (!RENDERABLE_NOTE_TICKS.has(e.durationTicks)) {
|
|
return { ok: false, error: `Internal arpeggio error: non-renderable duration ${e.durationTicks} at ${e.id}.` };
|
|
}
|
|
}
|
|
|
|
const chordName = `${key.tonic} ${ARPEGGIO_DEGREE_LABELS[config.degree]}`;
|
|
const patternLabel = PATTERN_LABELS[pattern];
|
|
const totalMeasures = Math.max(1, Math.ceil(events.reduce((s, e) => Math.max(s, e.startTick + e.durationTicks), 0) / barLength));
|
|
const title = bars === 1
|
|
? `Arpeggio — ${chordName} (${patternLabel}, ${coverage})`
|
|
: `Arpeggio — ${key.tonic}: ${bars} bars (${config.progression ?? 'functional'})`;
|
|
const score: Score = {
|
|
version: 1,
|
|
id: `arpeggio-${config.keyTonic}-${config.keyMode}-${config.degree}-${config.pattern}-${config.coverage}-${bars}b-${config.progression ?? 'single'}-${config.seed ?? 0}`,
|
|
title,
|
|
meter,
|
|
key: { tonic: config.keyTonic, mode: config.keyMode, signature: key.signature },
|
|
measures: Array.from({ length: totalMeasures }, (_, i) => ({
|
|
number: i + 1,
|
|
startTick: i * barLength,
|
|
durationTicks: barLength,
|
|
})),
|
|
chordSymbols: bars === 1
|
|
// repeat the single chord symbol across the overflow bars
|
|
? Array.from({ length: totalMeasures }, () => chordSymbols[0])
|
|
: chordSymbols,
|
|
voices: [{ id: 'melody', events }],
|
|
};
|
|
const problems = validateScore(score);
|
|
if (problems.length > 0) return { ok: false, error: `Internal arpeggio error: ${problems[0]}` };
|
|
return { ok: true, value: score };
|
|
} |