Re: Stem tremolo and staff switch don't work together

[Aaron Hill]

On 2020-10-05 9:50 am, Rutger Hofman wrote:
> Good evening bug list,
>
> when a beam of notes with stem tremolo switches staff, the result is
> decidedly buggy. See source and png. Adding \stemUp|Down doesn't make
> things better. Without stem tremolo or without staff switch, things
> are fine.

You can see the issue perhaps a little better with some manual tweaking 
and a comparison without tremolo:

%%%%
\version "2.20.0"

music = \relative c'' {
  f,16-\tweak positions #'(5 . 5) [
  e d c \change Staff = down b a g f]
  \change Staff = up
  f'16-\tweak positions #'(5 . 5) [
  e d c g'' f e d]

  f,16:32-\tweak positions #'(5 . 5) [
  e: d: c: \change Staff = down b: a: g: f:]
  \change Staff = up
  f'16:32-\tweak positions #'(5 . 5) [
  e: d: c: g'': f: e: d:]
}

\score {
  \new PianoStaff <<
    \new Staff = up { \music }
    \new Staff = down { \clef bass s1*2 }
  >>
}
%%%%

When the StemTremolo is present, Stem lengths are not calculated 
properly for cross-staff notes.  The broken lower notes have the same 
lengths as notes in equivalent positioning within the upper Staff.  It 
would seem the Beam positions need to be adjusted when crossing the 
Staff to account for the separation of the staves.  Otherwise, the lower 
notes *think* the Beam is much closer than it is.


-- Aaron Hill

cross-staff-stem-tremolo-bug.cropped.png
Description: PNG image