Hello Ponders! Recently I’ve created a small function to invert chords to match Fretboard Diagrams, which I’d like to share with you all.
Cheers, Valentin
#(define (normalize pitch)
(if (>= (ly:pitch-alteration pitch) 1)
(normalize (ly:pitch-transpose pitch (ly:make-pitch 0 1 -1)))
(if (<= (ly:pitch-alteration pitch) -1)
(normalize (ly:pitch-transpose pitch (ly:make-pitch 0 -1 1/2)))
pitch)))
#(define (semitones->pitch st chord)
(if (null? chord)
(normalize (ly:make-pitch 0 0 (/ st 2)))
(if (eqv? 0
(modulo (-
st
(ly:pitch-semitones (car chord)))
12))
(let* ((ref-pitch (ly:make-pitch 0
(ly:pitch-notename (car chord))
(ly:pitch-alteration (car chord))))
(ref-st (ly:pitch-semitones ref-pitch))
(st-diff (- st ref-st)))
(ly:make-pitch (/ st-diff 12)
(ly:pitch-notename (car chord))
(ly:pitch-alteration (car chord))))
(semitones->pitch st (cdr chord)))))
#(define (defn-to-frets defn)
(if (null? defn)
defn
(let ((string (cadar defn))
(fret (cond ((eqv? (caar defn) 'open) 0)
((eqv? (caar defn) 'place-fret) (caddar defn))
(else #f))))
(if fret
(cons (cons string fret) (defn-to-frets (cdr defn)))
(defn-to-frets (cdr defn))))))
translateToChords =
#(define-music-function (fretboard-table tuning music) (hash-table? list? ly:music?)
(define (iter music)
(let ((elts (ly:music-property music 'elements))
(elt (ly:music-property music 'element)))
(if (music-is-of-type? music 'event-chord)
(let* ((pitches (event-chord-pitches music))
(hash-key (cons tuning pitches))
(defn (hash-ref fretboard-table hash-key #f))
(dparts (if defn (defn-to-frets defn)))
(notes (event-chord-notes music))
(dur (if (not (null? notes)) (ly:music-property (car notes) 'duration))))
(if defn
(let* ((notes (map
(lambda (def)
(let* ((sno (car def))
(rpi (list-ref tuning (1- sno)))
(fret-no (cdr def))
(root-st (ly:pitch-semitones rpi))
(pitch (semitones->pitch (+ root-st fret-no)
pitches)))
(if (< fret-no 0)
#f
(make-music 'NoteEvent
'pitch pitch
'duration dur
'articulations
(list (make-music
'StringNumberEvent
'string-number
sno
'tweaks
'((stencil . #f))))))))
dparts)))
(ly:music-set-property! music 'elements
(filter (lambda (x) x) notes)))))
(begin
(if (not (null? elt))
(iter elt))
(for-each iter elts)))))
(iter music)
music)
\include "predefined-ukulele-fretboards.ly"
chordmusic = \relative {
\chordmode {
g4 c a:m f
}
}
<<
\new ChordNames {
\chordmusic
}
\new FretBoards \with {
stringTunings = #ukulele-tuning
} {
\chordmusic
}
\new Staff {
\translateToChords #default-fret-table #ukulele-tuning \chordmusic
}
\new TabStaff \with {
stringTunings = #ukulele-tuning
} {
\translateToChords #default-fret-table #ukulele-tuning \chordmusic
}
>>
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