Re: alternative notehead style breaks cross-staff stem

[Thomas Morley]

2016-11-13 15:45 GMT+01:00 Urs Liska <address@hidden>:
> Hi all,
>
> I'm trying to build something like similar to an automated harmonic
> display on two staves, and it seems that alternative note head styles
> break the cross staff stems:
>
> Is this known (at least not said in the NR)? Is there a way around this
> issue? Note that the example code isn't necessarily the ideal approach
> but a first attempt. What I eventually need is a way for a music
> function to produce such a "chord" distributed on two staves, connected
> by a cross-staff stem and either note head configurable in appearance.
>
> TIA for any hints or pointers
> Urs
>
>
> \version "2.19.51"
>
> \layout {
>   \context {
>     \PianoStaff
>     \consists #Span_stem_engraver
>   }
> }
>
> \score {
>   <<
>     \new PianoStaff <<
>       \new Staff = "one" {
>         s1
>       }
>
>       \new Staff = "two" {
>         \clef bass
>         <<
>           \crossStaff {
>             c,4 c, c, c,
>           }
>           \new Voice {
>             \stemUp
>             \change Staff = "one"
>             \override NoteHead.style = #'harmonic
>             e' g' bes' c''
>           }
>         >>
>
>       }
>     >>
>   >>
> }


Hi Urs,

cross-staff Stems are only printed if certain conditions are fullfilled.
One of them is the Stem's left edge are within a range 0.001
-> `close-enough?' in music-functions.scm

In a recent thread I developed `pushNC' to force the Stems doing so.
http://lists.gnu.org/archive/html/lilypond-user/2016-11/msg00230.html

Works here as well:


\version "2.19.49"

pushNC =
\override NoteColumn.X-offset =
  #(lambda (grob)
    (let* ((p-c (ly:grob-parent grob X))
           (p-c-elts (ly:grob-object p-c 'elements))
           (stems
             (if (ly:grob-array? p-c-elts)
                 (filter
                   (lambda (elt)(grob::has-interface elt 'stem-interface))
                   (ly:grob-array->list p-c-elts))
                 #f))
           (stems-x-exts
             (if stems
                 (map
                   (lambda (stem)
                     (ly:grob-extent
                       stem
                       (ly:grob-common-refpoint grob stem X)
                       X))
                   stems)
                 '()))
           (sane-ext
             (filter interval-sane? stems-x-exts))
           (cars (map car sane-ext)))
    (if (pair? cars)
        (abs (- (apply max cars)  (apply min cars)))
        0)))

\layout {
  \context {
    \PianoStaff
    \consists #Span_stem_engraver
  }
}

\score {
  <<
    \new PianoStaff <<
      \new Staff = "one" {
        s1
      }

      \new Staff = "two" {
        \clef bass
        <<
          \crossStaff {
            c,4 c, c, c,
          }
          \new Voice {
            \stemUp
            \change Staff = "one"
            \override NoteHead.style = #'harmonic
            %\once
            \pushNC
            e' g' bes' c''
          }
        >>
      }
    >>
  >>
}

HTH,
  Harm