Re: Dynamics context doesn't work with polyphony(?)

[Aaron Hill]

On 2020-09-11 1:56 am, Martín Rincón Botero wrote:
> Hello,
>
> sorry to bother again. I've been further exploring the Dynamics 
> context. I
> just noticed that when there's a polyphonic passage, not only dynamics
> don't align anymore, but also \remove engravers fails to do its job. Is
> this a bug or is there any other engraver I should remove from the 
> Dynamics
> context so that notes and text are not duplicated in polyphonic 
> passages?

The issue seems to be with the << \\ >> construct implicitly referencing 
named Voice contexts.  Events within the Dynamics context are 
unintentionally leaking into the existing contexts and doubling the 
notes.  Consider:

%%%%
\version "2.20.0"

musicI = << b'2\f \\ { g'4 4 } >>
<< \new Voice \musicI \new Dynamics \musicI >>

musicII = << \context Voice = "1" { \voiceOne b'2\f }
             \context Voice = "2" { \voiceTwo g'4 4 } >>
<< \new Voice \musicII \new Dynamics \musicII >>
%%%%

While I may be overlooking some details, the above expressions are 
logically equivalent.  That makes the << \\ >> construct tricky when 
being reused for Dynamics.

Stripping out the VoiceSeparator *might* work:

%%%%
removeVoiceSeparator =
#(define-music-function (music) (ly:music?)
  (define (not-music-separator? m) (not (music-separator? m)))
  (music-filter not-music-separator? music))

<< \new Voice \musicI
   \new Dynamics \removeVoiceSeparator \musicI >>
%%%%

Whether this brings about new issues, I could not say.


-- Aaron Hill