Re: Customizing tremolo

[Thomas Morley]

Am So., 21. Aug. 2022 um 13:10 Uhr schrieb Thomas Morley
<thomasmorley65@gmail.com>:
>
> Hi,
>
> this arose in the german forum about typesetting tremolos for
> https://imslp.org/wiki/String_Quartet_(Carre%C3%B1o%2C_Teresa).
> https://lilypondforum.de/index.php/topic,1091.msg5888.html
> An excerpt of Vl 2 is attached.
> In measure 8 there are tremolos with one connecting beam and one
> floating beam lasting a quarter note.
>
> How to do so?
>
> Obviously we establish a certain default, but I'm not able to override
> the default with Beam.gap-count in every case.
> Although even non-tremolo Beams react:
>
> \relative c'' {
>   %\override Beam.gap = 0
>   \override Beam.gap-count = #1
>
>   \repeat tremolo 16 { a64 f }
>   \repeat tremolo 8 { a64 f }
>   \repeat tremolo 4 { a64 f }
>   r8
>   \repeat tremolo 8 { a32 f }
>   \repeat tremolo 4 { a32 f }
>   \repeat tremolo 2 { a32 f }
>   r8
>   \repeat tremolo 4 { a16 f }
>   \repeat tremolo 2 { a16 f }
>   \repeat tremolo 1 { a16 f }
>   r8
>   \repeat unfold 16 b16
> }
>
> Am I missing something?
>
> Thanks,
>   Harm

To answer my own question, below works although not obvious and I
found no documentation or snippet for it:

{
  \key b \minor
  \repeat tremolo 4 { e'16 g' }

  \override Beam.before-line-breaking =
    #(lambda (grob) (ly:grob-set-property! grob 'gap-count 1))
  \repeat tremolo 2 { e'16 g' }
  \repeat tremolo 2 { e'16 fis' }
  \revert Beam.before-line-breaking
  \repeat tremolo 4 { d'16 fis' }
  \repeat tremolo 4 { cis'16 fis' }
}

Maybe it's worth to at least extend the doc tagged lsr snippet
"Engraving tremolos with floating beams"
https://lsr.di.unimi.it/LSR/Item?id=553

Cheers,
  Harm