Re: Ties and retrograde

[David Kastrup]

address@hidden writes:

> The \retrograde function doesn't seem to handle ties at all, as seen in
> this example, which engraves only one tie:
>
> music = { c'4~ c'8 g'8 }
>
> \new Staff {
>   \music
>   \retrograde \music
> }
>
> The notation manual mentions that "manual" ties are not handled, and
> suggests that "some" ties can be generated automatically instead, by
> entering longer notes and using automatic note splitting to break them at
> bar lines.  But that doesn't work for me, because I have a note made up of
> a quarter and a sixteenth tied together across the middle of a bar, not
> across a bar line.  Does someone perhaps have a snippet that will do
> retrograde with correct handling of this kind of tie?

See
Tracker issue: 4956 (https://sourceforge.net/p/testlilyissues/issues/4956/)
Rietveld issue: 302470043 (https://codereview.appspot.com/302470043)
Issue description:
  Change \retrograde to deal with ties and repeat chords/notes
  Consists of commits:  Remove warning about ties in \retrograde
  Change retrograde-music function to deal with ties   Let \retrograde
  expand repeat chords/notes  Since those lose their point of
  reference, expanding them prior to retrograding keeps the results
  sane.

You will likely want to pull the definition of retrograde-music from
scm/modal-transforms.scm .

It would be appreciated if you took the opportunity to create a nice
regtest also exercising chord ties.

\retrograde still leaves a lot to be desired, of course.  Overrides
should likely _not_ be reversed with the music they apply to, grace
notes are a whole fat problem, things like time signatures are of course
at the wrong side of what they apply to, dynamic spanners would need to
get inverted, repeat ties and laissez-vibrer ties should likely be
exchanged, volta repeats with alternatives become awful and so on and so
on.

-- 
David Kastrup