[Lilypond-auto] Issue 2663 in lilypond: add a command to tell LilyPond where on the staff to change the direction of stem or beams

[lilypond]

Status: Accepted
Owner: ----
Labels: Type-Enhancement
New issue 2663 by elu...@gmail.com: add a command to tell LilyPond where on  
the staff to change the direction of stem or beams
http://code.google.com/p/lilypond/issues/detail?id=2663

sometimes it would be nice to choose a different neutral-position for stems  
(and beams) to point down or up.

David has already shown an approach:

StemSplit =
#(define-music-function (parser location p) (ly:pitch?)
   #{ \override Stem #'direction =
      #(lambda (grob) (if (ly:pitch<? (ly:event-property (event-cause grob)
                                      'pitch) p) UP DOWN))
   #})

\new Voice {
  \relative c' { \StemSplit e'' c d e f g a b c d e f g a b c }
}

but as Janek observes this can break with beams:

\relative f' {
  \time 2/4
  \StemSplit d''
  f8 a g b
  a c b d
  c e d f
}


see the full discussion on  
http://old.nabble.com/rest-position-in-a-polyphonic-staff-ts34161013.html