MusicTheory.ts•5.01 kB
export class MusicTheory {
private scales = {
major: [0, 2, 4, 5, 7, 9, 11],
minor: [0, 2, 3, 5, 7, 8, 10],
dorian: [0, 2, 3, 5, 7, 9, 10],
phrygian: [0, 1, 3, 5, 7, 8, 10],
lydian: [0, 2, 4, 6, 7, 9, 11],
mixolydian: [0, 2, 4, 5, 7, 9, 10],
aeolian: [0, 2, 3, 5, 7, 8, 10],
locrian: [0, 1, 3, 5, 6, 8, 10],
pentatonic: [0, 2, 4, 7, 9],
blues: [0, 3, 5, 6, 7, 10],
chromatic: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11],
wholetone: [0, 2, 4, 6, 8, 10],
harmonic_minor: [0, 2, 3, 5, 7, 8, 11],
melodic_minor: [0, 2, 3, 5, 7, 9, 11]
};
private chordProgressions = {
pop: ['I', 'V', 'vi', 'IV'],
jazz: ['IIM7', 'V7', 'IM7'],
blues: ['I7', 'I7', 'I7', 'I7', 'IV7', 'IV7', 'I7', 'I7', 'V7', 'IV7', 'I7', 'V7'],
folk: ['I', 'IV', 'I', 'V'],
rock: ['I', 'bVII', 'IV', 'I'],
classical: ['I', 'IV', 'V', 'I'],
modal: ['i', 'bVII', 'IV', 'i'],
edm: ['i', 'VI', 'III', 'VII']
};
generateScale(root: string, scaleName: keyof typeof this.scales): string[] {
const noteNames = ['C', 'C#', 'D', 'D#', 'E', 'F', 'F#', 'G', 'G#', 'A', 'A#', 'B'];
const rootIndex = noteNames.indexOf(root.toUpperCase());
if (rootIndex === -1) {
throw new Error(`Invalid root note: ${root}`);
}
const scale = this.scales[scaleName];
if (!scale) {
throw new Error(`Invalid scale: ${scaleName}`);
}
return scale.map(interval => {
const noteIndex = (rootIndex + interval) % 12;
return noteNames[noteIndex];
});
}
generateChordProgression(key: string, style: keyof typeof this.chordProgressions): string {
const progression = this.chordProgressions[style];
if (!progression) {
throw new Error(`Invalid progression style: ${style}`);
}
const chordMap: Record<string, string> = {
'I': `"${key}"`,
'I7': `"${key}7"`,
'i': `"${key.toLowerCase()}m"`,
'ii': `"${this.getNote(key, 2)}m"`,
'IIM7': `"${this.getNote(key, 2)}m7"`,
'iii': `"${this.getNote(key, 4)}m"`,
'III': `"${this.getNote(key, 4)}"`,
'IV': `"${this.getNote(key, 5)}"`,
'IV7': `"${this.getNote(key, 5)}7"`,
'V': `"${this.getNote(key, 7)}"`,
'V7': `"${this.getNote(key, 7)}7"`,
'vi': `"${this.getNote(key, 9)}m"`,
'VI': `"${this.getNote(key, 9)}"`,
'VII': `"${this.getNote(key, 11)}"`,
'bVII': `"${this.getNote(key, 10)}"`,
'IM7': `"${key}maj7"`
};
return progression
.map(chord => chordMap[chord] || `"${key}"`)
.join(' ');
}
getNote(root: string, semitones: number): string {
const noteNames = ['C', 'C#', 'D', 'D#', 'E', 'F', 'F#', 'G', 'G#', 'A', 'A#', 'B'];
const rootIndex = noteNames.indexOf(root.toUpperCase());
if (rootIndex === -1) return root;
return noteNames[(rootIndex + semitones) % 12];
}
generateEuclideanRhythm(hits: number, steps: number): string {
if (hits > steps) {
throw new Error('Hits cannot exceed steps');
}
const pattern: boolean[] = new Array(steps).fill(false);
const interval = steps / hits;
for (let i = 0; i < hits; i++) {
const index = Math.floor(i * interval);
pattern[index] = true;
}
return pattern.map(hit => hit ? '1' : '~').join(' ');
}
generatePolyrhythm(pattern1: number, pattern2: number, length: number = 16): string {
const rhythm1 = this.generateEuclideanRhythm(pattern1, length);
const rhythm2 = this.generateEuclideanRhythm(pattern2, length);
return `[${rhythm1}], [${rhythm2}]`;
}
getScaleNotes(root: string, scaleName: keyof typeof this.scales, octave: number = 3): string[] {
const scale = this.generateScale(root, scaleName);
return scale.map(note => `${note.toLowerCase()}${octave}`);
}
generateArpeggio(chord: string, pattern: string = 'up'): string {
const patterns: Record<string, number[]> = {
'up': [0, 1, 2, 3],
'down': [3, 2, 1, 0],
'updown': [0, 1, 2, 3, 2, 1],
'random': [0, 2, 1, 3, 0, 3, 1, 2]
};
const arpPattern = patterns[pattern] || patterns['up'];
const notes = this.getChordNotes(chord);
return arpPattern
.map(index => notes[index % notes.length])
.join(' ');
}
private getChordNotes(chord: string): string[] {
// Simplified chord parsing - would need more sophisticated implementation
const root = chord.replace(/[^A-G#]/g, '');
const type = chord.replace(/[A-G#]/g, '');
const intervals: Record<string, number[]> = {
'': [0, 4, 7], // major
'm': [0, 3, 7], // minor
'7': [0, 4, 7, 10], // dominant 7
'maj7': [0, 4, 7, 11], // major 7
'm7': [0, 3, 7, 10], // minor 7
'dim': [0, 3, 6], // diminished
'aug': [0, 4, 8] // augmented
};
const chordIntervals = intervals[type] || intervals[''];
return chordIntervals.map(interval => {
const note = this.getNote(root, interval);
return `${note.toLowerCase()}3`;
});
}
}