Re: Exclude staves from keep-alive-together

[Jean Abou Samra]

Le 20/11/2021 à 11:54, David Stephen Grant a écrit :
> Hi all,
>
> Can individual staves in eg. a StaffGroup with \consists 
> "Keep_alive_together_engraver" be excluded from keep-alive-together?
>
> I'm aware of VerticalAxisGroup.remove-layer which possibly does what I 
> need it to, but this morning I can't wrap my head around it in the 
> attached example.
>
> - Empty staves for player 1, 2a and 3a should only be removed when the 
> whole group is empty (system 3).
> But:
> - 2b should also be removed on the second system
> - 3b should also be removed on both the first and second system.
>
> Thanks!


The rules are somewhat complex. I believe what
you want here is

\layout {
  \context {
    \Staff
    \override VerticalAxisGroup.remove-layer = 0
  }
}

to set a default of 0, and

  \override VerticalAxisGroup.remove-layer = 1

in staves 2b and 3b. Full example:

\version "2.23.4"

\paper {
  indent = 1 \in
  short-indent = 1 \in
}

\layout {
  \context {
    \Staff
    \RemoveAllEmptyStaves
  }
}

music = \repeat unfold 4 { c'1 }
rests = \repeat unfold 4 { R1 }

\layout {
  \context {
    \Staff
    \override VerticalAxisGroup.remove-layer = 0
  }
}

\score {
  <<
    \new Staff \with {
          instrumentName = "0"
          shortInstrumentName = "0"
        } {
          \music \break
          \music \break
          \music
        }
    \new StaffGroup \with {
      \consists "Keep_alive_together_engraver"
    } {
      <<
        \new Staff \with {
          instrumentName = "1"
          shortInstrumentName = "1"
        } {
          \rests
          \rests
        }

        \new StaffGroup \with {
          systemStartDelimiter = #'SystemStartBrace
        } {
          <<
            \new Staff \with {
              instrumentName = "2a"
              shortInstrumentName = "2a"
            }
            {
              \music
              \music
            }
            \new Staff \with {
              instrumentName = "2b"
              shortInstrumentName = "2b"
              \override VerticalAxisGroup.remove-layer = 1
            }
            {
              \music
              \rests
            }
          >>
        }

        \new StaffGroup \with {
          systemStartDelimiter = #'SystemStartBrace
        } {
          <<
            \new Staff \with {
              instrumentName = "3a"
              shortInstrumentName = "3a"
            }
            {
              \rests
              \rests
            }
            \new Staff \with {
              instrumentName = "3b"
              shortInstrumentName = "3b"
              \override VerticalAxisGroup.remove-layer = 1
            }
            {
              \rests
              \rests
            }
          >>
        }
      >>
    }
  >>
}

Best,
Jean