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JamBuddy/src/lib/voicings.js
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vadimwit 8cd9b01941 edu panel
2026-03-18 01:26:51 +00:00

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// ─── Guitar voicing shapes ────────────────────────────────────────────────────
// Open string pitches (standard tuning): E A D G B e
const OPEN = [4, 9, 2, 7, 11, 4] // pitch class per string [s6 … s1]
// Barre shape: offsets[] are fret distances from the root fret, per string [s6…s1].
// 'x' = muted. rootStr = 1-indexed string that holds the root (6=low E, 5=A…).
// Open shape: frets[] are absolute fret numbers (0=open, 'x'=muted) for a specific root key.
const GUITAR_SHAPES = {
maj: [
{ label: 'E Barre', type: 'barre', rootStr: 6, offsets: [0,2,2,1,0,0], fingers: [1,3,4,2,1,1], barre: { fromStr: 1, toStr: 6, fo: 0 } },
{ label: 'A Barre', type: 'barre', rootStr: 5, offsets: ['x',0,2,2,2,0], fingers: [0,1,3,4,2,1], barre: { fromStr: 1, toStr: 5, fo: 0 } },
{ label: 'D Shape', type: 'barre', rootStr: 4, offsets: ['x','x',0,2,3,2], fingers: [0,0,1,3,4,2] },
{ label: 'G Shape', type: 'barre', rootStr: 6, offsets: [0,-1,-3,-3,-3,0], fingers: [4,3,1,1,1,4] },
{ label: 'Open E', type: 'open', onlyRoot: 4, frets: [0,2,2,1,0,0], fingers: [0,2,3,1,0,0] },
{ label: 'Open A', type: 'open', onlyRoot: 9, frets: ['x',0,2,2,2,0], fingers: [0,0,1,2,3,0] },
{ label: 'Open G', type: 'open', onlyRoot: 7, frets: [3,2,0,0,0,3], fingers: [2,1,0,0,0,3] },
{ label: 'Open C', type: 'open', onlyRoot: 0, frets: ['x',3,2,0,1,0], fingers: [0,3,2,0,1,0] },
{ label: 'Open D', type: 'open', onlyRoot: 2, frets: ['x','x',0,2,3,2], fingers: [0,0,0,1,3,2] },
],
min: [
{ label: 'E Barre', type: 'barre', rootStr: 6, offsets: [0,2,2,0,0,0], fingers: [1,3,4,1,1,1], barre: { fromStr: 1, toStr: 6, fo: 0 } },
{ label: 'A Barre', type: 'barre', rootStr: 5, offsets: ['x',0,2,2,1,0], fingers: [0,1,3,4,2,1], barre: { fromStr: 1, toStr: 5, fo: 0 } },
{ label: 'D Shape', type: 'barre', rootStr: 4, offsets: ['x','x',0,2,3,1], fingers: [0,0,1,3,4,2] },
{ label: 'Open Em', type: 'open', onlyRoot: 4, frets: [0,2,2,0,0,0], fingers: [0,2,3,0,0,0] },
{ label: 'Open Am', type: 'open', onlyRoot: 9, frets: ['x',0,2,2,1,0], fingers: [0,0,2,3,1,0] },
{ label: 'Open Dm', type: 'open', onlyRoot: 2, frets: ['x','x',0,2,3,1], fingers: [0,0,0,2,3,1] },
],
dom7: [
{ label: 'E7 Barre', type: 'barre', rootStr: 6, offsets: [0,2,0,1,0,0], fingers: [1,3,0,2,1,1], barre: { fromStr: 1, toStr: 6, fo: 0 } },
{ label: 'A7 Barre', type: 'barre', rootStr: 5, offsets: ['x',0,2,0,2,0], fingers: [0,1,2,0,3,0] },
{ label: 'D Shape', type: 'barre', rootStr: 4, offsets: ['x','x',0,2,1,2], fingers: [0,0,1,3,2,4] },
{ label: 'Open E7', type: 'open', onlyRoot: 4, frets: [0,2,0,1,0,0], fingers: [0,2,0,1,0,0] },
{ label: 'Open A7', type: 'open', onlyRoot: 9, frets: ['x',0,2,0,2,0], fingers: [0,0,2,0,3,0] },
{ label: 'Open G7', type: 'open', onlyRoot: 7, frets: [3,2,0,0,0,1], fingers: [3,2,0,0,0,1] },
{ label: 'Open D7', type: 'open', onlyRoot: 2, frets: ['x','x',0,2,1,2], fingers: [0,0,0,2,1,3] },
{ label: 'Open B7', type: 'open', onlyRoot: 11, frets: ['x',2,1,2,0,2], fingers: [0,2,1,3,0,4] },
],
maj7: [
{ label: 'E Barre', type: 'barre', rootStr: 6, offsets: [0,2,1,1,0,0], fingers: [1,3,2,2,1,1], barre: { fromStr: 1, toStr: 6, fo: 0 } },
{ label: 'A Barre', type: 'barre', rootStr: 5, offsets: ['x',0,2,1,2,0], fingers: [0,1,3,2,4,1], barre: { fromStr: 1, toStr: 2, fo: 0 } },
{ label: 'D Shape', type: 'barre', rootStr: 4, offsets: ['x','x',0,2,2,2], fingers: [0,0,1,2,3,4], barre: { fromStr: 1, toStr: 3, fo: 2 } },
{ label: 'Open Cmaj7', type: 'open', onlyRoot: 0, frets: ['x',3,2,0,0,0], fingers: [0,3,2,0,0,0] },
{ label: 'Open Amaj7', type: 'open', onlyRoot: 9, frets: ['x',0,2,1,2,0], fingers: [0,0,2,1,3,0] },
{ label: 'Open Emaj7', type: 'open', onlyRoot: 4, frets: [0,2,1,1,0,0], fingers: [0,2,1,1,0,0] },
],
min7: [
{ label: 'E Barre', type: 'barre', rootStr: 6, offsets: [0,2,0,0,0,0], fingers: [1,3,1,1,1,1], barre: { fromStr: 1, toStr: 6, fo: 0 } },
{ label: 'A Barre', type: 'barre', rootStr: 5, offsets: ['x',0,2,0,1,0], fingers: [0,1,3,1,2,1], barre: { fromStr: 1, toStr: 5, fo: 0 } },
{ label: 'D Shape', type: 'barre', rootStr: 4, offsets: ['x','x',0,2,1,1], fingers: [0,0,1,3,2,2] },
{ label: 'Open Em7', type: 'open', onlyRoot: 4, frets: [0,2,0,0,0,0], fingers: [0,2,0,0,0,0] },
{ label: 'Open Am7', type: 'open', onlyRoot: 9, frets: ['x',0,2,0,1,0], fingers: [0,0,2,0,1,0] },
{ label: 'Open Dm7', type: 'open', onlyRoot: 2, frets: ['x','x',0,2,1,1], fingers: [0,0,0,3,1,2] },
],
dim: [
{ label: 'A Barre', type: 'barre', rootStr: 5, offsets: ['x',0,1,2,1,'x'], fingers: [0,1,2,4,3,0] },
{ label: 'Compact', type: 'barre', rootStr: 4, offsets: ['x','x',0,1,3,1], fingers: [0,0,1,2,4,3] },
],
dim7: [
{ label: 'Movable Box', type: 'barre', rootStr: 5, offsets: ['x',0,1,2,1,2], fingers: [0,1,2,4,3,4] },
{ label: 'Compact', type: 'barre', rootStr: 4, offsets: ['x','x',0,1,0,1], fingers: [0,0,1,2,3,4] },
],
aug: [
{ label: 'E Barre', type: 'barre', rootStr: 6, offsets: [0,3,2,1,1,0], fingers: [1,4,3,2,2,1] },
{ label: 'Compact', type: 'barre', rootStr: 5, offsets: ['x',0,3,2,2,'x'], fingers: [0,1,4,2,3,0] },
],
sus4: [
{ label: 'E Barre', type: 'barre', rootStr: 6, offsets: [0,2,2,2,0,0], fingers: [1,2,3,4,1,1], barre: { fromStr: 1, toStr: 6, fo: 0 } },
{ label: 'A Barre', type: 'barre', rootStr: 5, offsets: ['x',0,2,2,3,0], fingers: [0,1,2,3,4,0] },
{ label: 'D Shape', type: 'barre', rootStr: 4, offsets: ['x','x',0,2,3,3], fingers: [0,0,1,2,3,4] },
{ label: 'Open Asus4', type: 'open', onlyRoot: 9, frets: ['x',0,2,2,3,0], fingers: [0,0,1,2,4,0] },
{ label: 'Open Dsus4', type: 'open', onlyRoot: 2, frets: ['x','x',0,2,3,3], fingers: [0,0,0,1,2,3] },
],
sus2: [
{ label: 'E Barre', type: 'barre', rootStr: 6, offsets: [0,2,4,4,0,0], fingers: [1,2,4,4,1,1], barre: { fromStr: 1, toStr: 6, fo: 0 } },
{ label: 'A Barre', type: 'barre', rootStr: 5, offsets: ['x',0,2,4,0,0], fingers: [0,1,2,4,1,1], barre: { fromStr: 1, toStr: 2, fo: 0 } },
{ label: 'D Shape', type: 'barre', rootStr: 4, offsets: ['x','x',0,2,3,0], fingers: [0,0,1,2,3,0] },
{ label: 'Open Asus2', type: 'open', onlyRoot: 9, frets: ['x',0,2,2,0,0], fingers: [0,0,1,2,0,0] },
{ label: 'Open Dsus2', type: 'open', onlyRoot: 2, frets: ['x','x',0,2,3,0], fingers: [0,0,0,1,3,0] },
],
half_dim: [
{ label: 'A Barre', type: 'barre', rootStr: 5, offsets: ['x',0,1,0,1,'x'], fingers: [0,1,2,0,3,0] },
{ label: 'E Barre', type: 'barre', rootStr: 6, offsets: [0,1,2,0,0,'x'], fingers: [1,2,3,1,1,0], barre: { fromStr: 2, toStr: 6, fo: 0 } },
],
maj6: [
{ label: 'E Barre', type: 'barre', rootStr: 6, offsets: [0,2,2,1,2,0], fingers: [1,3,4,2,4,1], barre: { fromStr: 1, toStr: 6, fo: 0 } },
{ label: 'A Barre', type: 'barre', rootStr: 5, offsets: ['x',0,2,2,2,2], fingers: [0,1,2,3,4,4], barre: { fromStr: 1, toStr: 2, fo: 2 } },
],
min6: [
{ label: 'E Barre', type: 'barre', rootStr: 6, offsets: [0,2,2,0,2,0], fingers: [1,3,4,1,4,1], barre: { fromStr: 1, toStr: 6, fo: 0 } },
],
add9: [
{ label: 'E Barre', type: 'barre', rootStr: 6, offsets: [0,2,4,1,0,2], fingers: [1,2,4,3,1,1], barre: { fromStr: 1, toStr: 6, fo: 0 } },
{ label: 'Open Cadd9', type: 'open', onlyRoot: 0, frets: ['x',3,2,0,3,0], fingers: [0,3,2,0,4,0] },
{ label: 'Open Gadd9', type: 'open', onlyRoot: 7, frets: [3,2,0,2,3,3], fingers: [2,1,0,3,4,4] },
{ label: 'Open Dadd9', type: 'open', onlyRoot: 2, frets: ['x','x',0,2,3,0], fingers: [0,0,0,1,3,0] },
],
}
// ─── Piano techniques ─────────────────────────────────────────────────────────
// Each technique has intervals for left hand (LH) and right hand (RH) in semitones above root.
// Negative values go one octave below root. Labels appear on the keys.
export const PIANO_TECHNIQUES = {
maj: [
{
name: 'Full Chord',
desc: 'Classic voicing — root in left, triad in right',
tip: 'Anchor the root alone in your left hand, lock into the rhythm, let right hand sing.',
lh: [0],
rh: [0, 4, 7],
},
{
name: 'Root + 5th',
desc: 'Open, powerful — ambiguous major/minor quality',
tip: 'Stack octave + fifth in left hand. Works over major or minor — great for tense moments.',
lh: [0, 7],
rh: [0, 4, 7, 12],
},
{
name: 'Root + Octave',
desc: 'Thunderous low end — fills space in a band',
tip: 'Octave doubles in left hand, full chord in right. Huge sound in lower registers.',
lh: [0, 12],
rh: [4, 7, 12],
},
{
name: 'Spread Voicing',
desc: 'Wide, orchestral — two octaves apart',
tip: 'Split the chord wide: 5th in left, 3rd + 5th above the octave in right. Very cinematic.',
lh: [0, 7],
rh: [12, 16, 19],
},
{
name: 'Suspended Approach',
desc: 'Play sus4 → resolve to major — creates motion',
tip: 'Hit sus4 (replace 3rd with 4th) then release to the major 3rd. Works great in slow ballads.',
lh: [0],
rh: [0, 5, 7],
},
],
min: [
{
name: 'Full Chord',
desc: 'Classic minor voicing — dark and rich',
tip: 'The minor 3rd is everything. Let it ring — do not rush to resolve.',
lh: [0],
rh: [0, 3, 7],
},
{
name: 'Root + 5th',
desc: 'Open ambiguity — dramatic without the sadness',
tip: 'Power chord in both hands. Hides the minor quality — use when you want tension without gloom.',
lh: [0, 7],
rh: [0, 7, 12],
},
{
name: 'Root + Octave',
desc: 'Deep anchor — gives bass player space',
tip: 'Octave in left only. Right hand plays the minor chord high up for contrast.',
lh: [0, 12],
rh: [3, 7, 12],
},
{
name: 'Spread Minor',
desc: 'Atmospheric and wide — film score territory',
tip: 'Wide spacing on minor chords feels melancholic and vast. Popular in ambient and cinematic styles.',
lh: [0, 7],
rh: [12, 15, 19],
},
{
name: 'Minor + Add9',
desc: 'Add the 9th (2nd) — aching, bittersweet quality',
tip: 'Replace or add the 9th to minor. Radiohead, Portishead, modern soul — this interval is gold.',
lh: [0],
rh: [0, 3, 7, 14],
},
],
dom7: [
{
name: 'Full Dom7',
desc: 'Classic dominant — loaded with tension',
tip: 'The tritone between the 3rd and ♭7th creates all the tension. Let it ring before resolving.',
lh: [0],
rh: [0, 4, 7, 10],
},
{
name: 'Shell Voicing (1-3-♭7)',
desc: 'Skip the 5th — lean, jazz-approved',
tip: 'Root + major 3rd + ♭7th. The tritone is intact, 5th is redundant. Classic jazz comp technique.',
lh: [0],
rh: [4, 10],
},
{
name: 'Rootless Voicing',
desc: 'Advanced comping — let bass hold the root',
tip: 'No root in your hands at all. 3rd in left, upper structure in right. Very sophisticated sound.',
lh: [4],
rh: [7, 10, 14],
},
{
name: 'Blues Stomp',
desc: 'Root + 5th left, add ♭7 right — R&B classic',
tip: 'Left hand pumps root-5th pattern, right hand stabs the dominant 7th chord. Classic gospel/blues.',
lh: [0, 7],
rh: [0, 4, 10],
},
{
name: 'Tritone Sub',
desc: 'Replace with the chord a tritone away',
tip: 'G7 can be replaced with Db7 — they share the same tritone (F and B). Mind-bending jazz move.',
lh: [6],
rh: [10, 14, 16],
},
],
maj7: [
{
name: 'Full Maj7',
desc: 'Dreamy, floating — jazz and bossa nova',
tip: 'The major 7th creates a luminous, slightly unresolved quality. Do not over-play it — let it breathe.',
lh: [0],
rh: [0, 4, 7, 11],
},
{
name: 'Shell (1-3-7)',
desc: 'Root + 3rd + maj7 — lush and clean',
tip: 'Skip the 5th. The major 7th directly above the root defines the chord without clutter.',
lh: [0],
rh: [4, 11],
},
{
name: 'Spread Maj7',
desc: 'Maj7 in left hand — wide, orchestral texture',
tip: 'Place the 7th below the root (or an octave down). Creates a spacious, choir-like sound.',
lh: [0, 11],
rh: [12, 16, 19],
},
{
name: 'Add9 Variation',
desc: 'Add the 9th for extra colour',
tip: 'Maj9 territory. Remove the root in the right hand, add the 9th (D for Cmaj9). Very smooth.',
lh: [0],
rh: [4, 7, 11, 14],
},
],
min7: [
{
name: 'Full Min7',
desc: 'Smooth and mellow — soul and jazz workhorse',
tip: 'The minor 7th chord is the most versatile in jazz. Comp behind everything with this.',
lh: [0],
rh: [0, 3, 7, 10],
},
{
name: 'Shell (1-♭3-♭7)',
desc: 'Just the 3rd and 7th in right — spacious',
tip: 'Root in left, minor 3rd + minor 7th in right. Leaves maximum space for the soloist.',
lh: [0],
rh: [3, 10],
},
{
name: 'Rootless Min7',
desc: 'No root — upper structure only',
tip: '♭3rd in left, build up from there. Very advanced jazz voicing — trust the bass player.',
lh: [3],
rh: [10, 14, 15],
},
{
name: 'Spread Atmospheric',
desc: 'Wide voicing — ambient and cinematic',
tip: 'Minor 7ths voiced wide feel endless. Great for intro sections or building tension.',
lh: [0, 7],
rh: [10, 15, 19],
},
],
dim: [
{
name: 'Full Diminished',
desc: 'All three tones — tense and unstable',
tip: 'Always wants to resolve. Use as a passing chord between diatonic chords.',
lh: [0],
rh: [0, 3, 6],
},
{
name: 'Octave + Dim',
desc: 'Root octave in left — more weight',
tip: 'Dim triads are thin — doubling the root in left hand adds body.',
lh: [0, 12],
rh: [3, 6, 12],
},
],
dim7: [
{
name: 'Full Dim7',
desc: 'Symmetrical — repeats every 3 frets',
tip: 'Any note in a dim7 chord can be the root. It modulates effortlessly. Horror/drama gold.',
lh: [0],
rh: [0, 3, 6, 9],
},
{
name: 'Arpeggiated',
desc: 'Roll the notes — tension without crash',
tip: 'Roll from bottom to top quickly. Dim7 arpeggios feel like falling — use before a big resolve.',
lh: [0, 3],
rh: [6, 9, 12],
},
],
aug: [
{
name: 'Full Augmented',
desc: 'Dreamy, unresolved — whole-tone territory',
tip: 'Aug chords are symmetrical like dim7 — every inversion sounds the same. Very otherworldly.',
lh: [0],
rh: [0, 4, 8],
},
{
name: 'Spread Aug',
desc: 'Wide voicing — maximises the instability',
tip: 'Spread over two octaves. The raised 5th wants to resolve up — let the listener feel the pull.',
lh: [0, 8],
rh: [12, 16, 20],
},
],
sus4: [
{
name: 'Full Sus4',
desc: 'Suspended — neither major nor minor',
tip: 'Ambiguous and open. Resolve down to the major 3rd for instant satisfaction.',
lh: [0],
rh: [0, 5, 7],
},
{
name: 'Sus4 → Major',
desc: 'Play sus4 then resolve — creates motion',
tip: 'Hit sus4 on the beat, release to major on the off-beat. The oldest trick in the book.',
lh: [0],
rh: [5, 7, 12],
},
{
name: 'Root + 5th + Sus',
desc: 'Power chord with the fourth on top',
tip: 'Very rock and dramatic. The sus4 on top gives it an anthemic, U2-esque quality.',
lh: [0, 7],
rh: [7, 12, 17],
},
],
sus2: [
{
name: 'Full Sus2',
desc: 'Open, airy — the 2nd instead of 3rd',
tip: 'Sus2 chords feel free and unanchored. Great for intros and ambient sections.',
lh: [0],
rh: [0, 2, 7],
},
{
name: 'Spread Sus2',
desc: 'Wide and spacious — very ambient',
tip: 'The 2nd voiced wide feels like an open landscape. Sigur Rós territory.',
lh: [0, 7],
rh: [12, 14, 19],
},
],
half_dim: [
{
name: 'Full m7♭5',
desc: 'Half-diminished — minor 7th with flat 5',
tip: 'The ii chord in minor keys (e.g. Bø in C minor). Tense but smoother than full diminished.',
lh: [0],
rh: [0, 3, 6, 10],
},
{
name: 'Shell (1-♭3-♭7)',
desc: 'Skip the flat 5 — cleaner jazz comp',
tip: 'The ♭5 is optional in jazz. Root + minor 3rd + minor 7th is clean and functional.',
lh: [0],
rh: [3, 10],
},
],
maj6: [
{
name: 'Full Maj6',
desc: 'Major with added 6th — vintage jazz sound',
tip: 'Maj6 and min7 are inversions of each other. Interchangeable in many jazz contexts.',
lh: [0],
rh: [0, 4, 7, 9],
},
{
name: 'Shell (1-3-6)',
desc: 'Clean and retro — skip the 5th',
tip: 'The 6th adds sweetness without too much colour. Django Reinhardt loved this voicing.',
lh: [0],
rh: [4, 9],
},
],
min6: [
{
name: 'Full Min6',
desc: 'Minor with major 6th — exotic and dark',
tip: 'The major 6th over a minor triad is a flamenco and tango staple. Very striking colour.',
lh: [0],
rh: [0, 3, 7, 9],
},
{
name: 'Shell (1-♭3-6)',
desc: 'Tense and colourful — the ♭3+6 tension',
tip: 'The minor 3rd + major 6th interval is the characteristic clash of min6. Lean into it.',
lh: [0],
rh: [3, 9],
},
],
add9: [
{
name: 'Full Add9',
desc: 'Major chord + 9th — no 7th, stays bright',
tip: 'The 9th adds colour without the jazz sophistication of maj9. Feels modern and open.',
lh: [0],
rh: [0, 4, 7, 14],
},
{
name: 'No Root Add9',
desc: 'Skip root in right — 3rd + 9th float',
tip: 'Root in left, right hand plays 3rd + 5th + 9th. Airy and modern — Radiohead / Coldplay territory.',
lh: [0],
rh: [4, 7, 14],
},
{
name: 'Sus2-style',
desc: 'Add9 voiced as sus2 clusters',
tip: 'Place the 9th close to the root (2nd instead of 9th). Creates a shimmering cluster effect.',
lh: [0, 7],
rh: [2, 4, 7],
},
],
}
// Fallback for chord types not in the map
const GENERIC_PIANO = [
{
name: 'Full Chord',
desc: 'Root in left, chord tones in right',
tip: 'Play the chord tones in right hand while anchoring the root in the left.',
lh: [0],
rh: [0], // will be replaced by computed intervals
},
]
// ─── Compute functions ────────────────────────────────────────────────────────
// Parse a chord name like "C#m7" → { rootPc: 1, type: 'min7' }
// Mirrors the logic in theory.js parseChord
function parseChord(name) {
if (!name) return null
const NOTES = ['C','C#','D','D#','E','F','F#','G','G#','A','A#','B']
const NOTES_FLAT = ['C','Db','D','Eb','E','F','Gb','G','Ab','A','Bb','B']
const suffixMap = {
'': 'maj', 'm': 'min', 'min': 'min', 'maj': 'maj',
'7': 'dom7', 'maj7': 'maj7', 'm7': 'min7', 'min7': 'min7',
'dim': 'dim', 'dim7': 'dim7', 'm7b5': 'half_dim', 'ø': 'half_dim', 'ø7': 'half_dim',
'aug': 'aug', '+': 'aug',
'sus4': 'sus4', 'sus2': 'sus2',
'6': 'maj6', 'm6': 'min6', 'min6': 'min6',
'add9': 'add9',
}
let rest = name
let root = ''
if (rest.length > 1 && (rest[1] === '#' || rest[1] === 'b')) {
root = rest.slice(0, 2); rest = rest.slice(2)
} else {
root = rest.slice(0, 1); rest = rest.slice(1)
}
let rootPc = NOTES.indexOf(root)
if (rootPc === -1) rootPc = NOTES_FLAT.indexOf(root)
if (rootPc === -1) return null
const type = suffixMap[rest] ?? 'maj'
return { rootPc, type }
}
/**
* Returns an array of voicing objects for a given chord name.
* Each voicing: { label, frets[6], fingers[6], barre?, baseFret }
* frets values: number (fret) or 'x' (muted) or 0 (open)
*/
export function getGuitarVoicings(chordName) {
const parsed = parseChord(chordName)
if (!parsed) return []
const { rootPc, type } = parsed
const shapes = GUITAR_SHAPES[type] ?? GUITAR_SHAPES.maj
const result = []
for (const shape of shapes) {
if (shape.type === 'open') {
if (shape.onlyRoot !== undefined && shape.onlyRoot !== rootPc) continue
result.push({
label: shape.label,
frets: shape.frets,
fingers: shape.fingers,
barre: null,
baseFret: 1,
})
continue
}
// barre shape: compute rootFret on rootStr
const strIdx = shape.rootStr - 1 // 0=s6 … 5=s1
const openPc = OPEN[strIdx]
let rootFret = (rootPc - openPc + 12) % 12
// Compute absolute frets
const frets = shape.offsets.map((off, i) => {
if (off === 'x') return 'x'
return rootFret + off
})
// Skip impossible positions
if (frets.some(f => typeof f === 'number' && f < 0)) continue
const maxFret = Math.max(...frets.filter(f => f !== 'x'))
if (maxFret > 15) continue
// baseFret: start diagram so the chord fits in 5 frets
const minFret = Math.min(...frets.filter(f => f !== 'x' && f > 0))
const baseFret = rootFret === 0 ? 1 : Math.max(1, minFret)
// Compute barre position if applicable
let barre = null
if (shape.barre) {
barre = {
fret: rootFret + shape.barre.fo,
fromStr: shape.barre.fromStr,
toStr: shape.barre.toStr,
}
}
// For open-string E/A chords (rootFret=0), no barre needed
if (rootFret === 0) barre = null
result.push({
label: shape.label + (rootFret === 0 ? ' (Open)' : rootFret > 5 ? ` — Fret ${rootFret}` : ''),
frets,
fingers: shape.fingers,
barre,
baseFret,
})
}
return result
}
/**
* Returns piano techniques for a chord name.
* Each technique has: { name, desc, tip, lh (intervals), rh (intervals) }
*/
export function getPianoTechniques(chordName) {
const parsed = parseChord(chordName)
if (!parsed) return []
const { type } = parsed
return PIANO_TECHNIQUES[type] ?? GENERIC_PIANO
}
export { parseChord }
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