Re: filter out pitches higher/ or lower than a certain pitch

[Aaron Hill]

On 2020-09-24 5:23 am, Stefan Thomas wrote:
> Dear community,
> I would like to achieve , in a certain example, that all pitches will 
> get
> automatically an accent sign.
> Like this:
> Music = { \time 6/8 g 8  r a g c'-> r g d'-> r g e'-> r  }
> MusikwithAccents  = { \time 6/8 g 8  r a g c->' r g d'-> r d e'-> r }
> Can this be done with  lilypond?
> Has someone an idea, how this can be implemented?

Here is one approach of conditionally attaching articulations to notes 
based on their pitch:

%%%%
\version "2.20.0"

addArticulation =
#(define-scheme-function
  (direction articulation)
  ((number? #f) string?)
  (lambda (m)
    (if (music-is-of-type? m 'note-event)
      (ly:music-set-property! m 'articulations
        (cons
          (let ((a (make-music 'ArticulationEvent
                               'articulation-type articulation)))
            (if (number? direction)
              (ly:music-set-property! a 'direction direction))
            a)
          (ly:music-property m 'articulations))))
    m))

whenPitchAbove =
#(define-scheme-function
  (pitch proc)
  (ly:pitch? procedure?)
  (lambda (m)
    (let ((p (ly:music-property m 'pitch)))
      (if (and (ly:pitch? p) (ly:pitch<? pitch p))
        (proc m)
        m))))

whenPitchBelow =
#(define-scheme-function
  (pitch proc)
  (ly:pitch? procedure?)
  (lambda (m)
    (let ((p (ly:music-property m 'pitch)))
      (if (and (ly:pitch? p) (ly:pitch<? p pitch))
        (proc m)
        m))))

whenPitchWithin =
#(define-scheme-function
  (lower upper proc)
  (ly:pitch? ly:pitch? procedure?)
  (lambda (m)
    (let ((p (ly:music-property m 'pitch)))
      (if (and (ly:pitch? p)
               (not (ly:pitch<? p lower))
               (not (ly:pitch<? upper p)))
        (proc m)
        m))))

\musicMap \whenPitchBelow b' \addArticulation #DOWN "tenuto"
\musicMap \whenPitchWithin b' d'' \addArticulation "staccato"
\musicMap \whenPitchAbove c'' \addArticulation "accent"
\fixed c'' { \time 6/8 b,4 a, g,8 c d f e <a, c e>4. }
%%%%


-- Aaron Hill

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