Re: question about ottava spanner

[Thomas Morley]

Am Sa., 30. Nov. 2019 um 02:19 Uhr schrieb Jinsong Zhao
<address@hidden>:
>
> On 2019/11/30 2:23, Thomas Morley wrote:
> >
> > \ottava works for Staff. You told LilyPond to write your entered
> > Staff-input one octave below. Thus the OttavaBracket _needs_ to span
> > the upper Voice (although you tweaked it's direction down)
> >
> > Though, I somehow doubt that's what you intended ...
> >
> > Cheers,
> >    Harm
> >
>
> Thanks a lot. However, I don't understand your reply very well. The
> snippet I want to input is something like the attached figure.
>
> BTW, where can I find the reference for every command used in Lilypond?
>
> Thanks again.
>
> Best,
> Jinsong

Iiuc, then you want only the bass in the left hand indicated to be
played one octave below, the other chords in the left hand should be
played as written.
I.e. \ottava should target only one Voice of two.
This is impossible per design, because it _always_ works at Staff-level.
Though, there are workarounds. See NR for one:
http://lilypond.org/doc/v2.19/Documentation/notation/displaying-pitches#ottava-brackets

To prevent multiple subsequent OttavaBrackets from joining use setting
`ottavation´
The description is a bit misleading:
"ottavation (markup)
  If set, the text for an ottava spanner. Changing this creates a new
text spanner."
Read it like: As soon as you use it, a new spanner is created, even if
the used markup is _not_ changed, but the same as before.

You may want to use shorten-pair as well.

Leading to:

\version "2.19.83"

{
  \clef bass
  \time 3/4
  <<
  \new Voice {
      \voiceOne
      \set Voice.middleCPosition = #6
      s4
      <b, e g b>2
      s4
      <b, f>2
      \unset Voice.middleCPosition
      }
  \new Voice {
      \voiceTwo
      \once \override Staff.OttavaBracket.shorten-pair = #'(-0.8 . 1.5)
      \ottava #-1
      \set Staff.ottavation = #"8"
      <b,,, b,,>2
      \set Staff.ottavation = #"8"
      q4
      \once \override Staff.OttavaBracket.shorten-pair = #'(-0.8 . 1.5)
      \set Staff.ottavation = #"8"
      q2
      \set Staff.ottavation = #"8"
      q4
      \ottava #0
  }
  >>
}

HTH,
  Harm