Re: Adding parallel thirds to the notes of a melody

[Mark Knoop]

At 07:15 on 03 Apr 2019, Gianmaria Lari wrote:
> The following "test" function adds parallel thirds to the notes of a
> melody:
>
> \version "2.21.0"
> scale = {c d e f g a b}
> test  =
> #(define-music-function (music) (ly:music?)
>    #{
>      \partCombine $music \modalTranspose c e \scale $music
>    #})
>
> \test {\voiceOne a b c'}
>
> I don't have lilypond programming experience and I would like to know:
>
> - if there are hidden mistakes
> - if it is better to write the function in a different way
> - how I could avoid to write \voiceOne in \test {\voiceOne a b c'}
> - how I can encapsulate scale, inside the "test" function

Funnily enough, I wrote something to do this last week, adapted from 
http://lsr.di.unimi.it/LSR/Item?id=445

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\version "2.19.82"
%% adapted from http://lsr.di.unimi.it/LSR/Item?id=445

#(define (third-up m)
   (let* ((new-note (ly:music-deep-copy m))
          (new-pitch (ly:pitch-transpose
                      (ly:music-property m 'pitch)
                      (ly:make-pitch 0 2 0))))
     (set! (ly:music-property new-note 'pitch) new-pitch)
     new-note))

#(define (addthird-chord elements)
   (cond ((null? elements) elements)
         ((eq? (ly:music-property (car elements) 'name) 'NoteEvent)
          (cons (car elements)
                (cons (third-up (car elements))
                      (addthird-chord (cdr elements)))))
         (else (cons (car elements) (addthird-chord (cdr elements))))))

#(define (addthird music)
   (if (eq? (ly:music-property music 'name) 'EventChord)
       (ly:music-set-property! music 'elements (addthird-chord
                                                (ly:music-property music 
'elements))))
   music)

makeThirds =
#(define-music-function
   (mus)
   (ly:music?)
   (music-map (lambda (x)
                (addthird x)) (event-chord-wrap! mus)))

\makeThirds {
  \clef bass
  dis8( e dis)~ dis8.( cis16 b8 ais gis dis) cis( dis <dis gis>)
  c d e fis gis aes bes c'
  \clef treble
  bes des' ees' f' g' a' b' c'' d'' e'' fis''
  <f c'>
}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

--
Mark Knoop