Re: Cross-staff beaming

[Hilary Snaden]

Phil Holmes wrote:
> "Hilary Snaden" <address@hidden> wrote in message 
> news:address@hidden
> > Manual beamings of cross-staff note groups are mangled, but
> > inconsistently. The beaming in this extract works for the first 6 bars,
> > then fails on beats 1 and 3 on the following bars. (Beamings on beats 2
> > and 4 are as they were.) Versions 2.12.2, 2.13.61 and 2.13.62 behave in
> > the same way.
>
> Could you prepare a tiny example that demonstrates this, please? (See 
> http://lilypond.org/website/bug-reports.html)

The original example showed that the beam-mangling didn't start (in the 
real-world case) for several bars and that the mangling occurred only on 
the 1st and 3rd beats of the original 4/4. (Bugs within bugs?)

Another oddity: if the ais16 on the second 4 is replaced with a rest, 
the semiquaver group *before* it renders correctly.

> I'm also curious to know whether this occurs with "normal" manual 
> beaming - i.e. [ ]

It does. (That was one of the first things I tried!)

\version "2.13.62"

csu = \change Staff = "upper"
csl = \change Staff = "lower"

manualBeam =
#(define-music-function (parser location beg-end)
  (pair?)
  #{
  \once \override Beam #'positions = #$beg-end
  #})

\pointAndClickOff

\score {
  \new PianoStaff {
    <<
      \new Staff = "upper" \relative ais {
        \clef treble \key a \major \time 2/4
        \stemUp
        r16 \csl \manualBeam #'(1 . 1.5) ais^( g \csu e'
        \csl \manualBeam #'(1.5 . 2) ais, \csu g'=' e g)
      }
      \new Staff = "lower" \relative cis {
        \clef bass \key a \major \time 2/4
        \stemDown cis4 r
      }
    >>
  }
}

Log warnings:

21:41: warning: weird stem size, check for narrow beams
        r16 \csl \manualBeam #'(1 . 1.5)
                                         ais^( g \csu e'
21:47: warning: weird stem size, check for narrow beams
        r16 \csl \manualBeam #'(1 . 1.5) ais^(
                                               g \csu e'
21:54: warning: weird stem size, check for narrow beams
        r16 \csl \manualBeam #'(1 . 1.5) ais^( g \csu
                                                      e'

--
Hilary Snaden

beambug3.pdf
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