Re: ties between voices

[Steve D]

LilyPond 2.11.13, Linux

This message pertains to ties between single and multiple voice sections
of notation of polyphonic instruments, using a technique suggested by
Joe Neeman of moving the Tie_engraver from the default Voice context to
the Staff context instead.

A Goal
------
Piano (and presumably other polyphonic instrument) notation
often includes sections where a single polyphonic voice splits into two
or more voices for the sake of convenience and clarity of notation.
These temporary changes in number of voices per staff, often as brief as
a mere fraction of a measure, are common and there are frequently ties
between these sections of one-, two-, or three- or more voice sections.

It would be very nice if there were an easy way to allow ties to extend
from one voice to another voice, from a single voice to multiple voices, or
from multiple voices to fewer voices or a single voice, without
resorting to code that is complex, verbose or which uses "tricks" to
accomplish the task.

A Proposed Solution
-------------------
One possible solution, proposed by Joe Neeman, is to cause the
Tie_engraver to act at the Staff level instead of the Voice level, by
removing it in the \layout section from the Voice context and inserting
the Tie_engraver into the Staff context.

This seems like a great solution, but because the Tie_engraver was
originally intended for a Voice context, some unexpected issues may
occur when trying to use the Tie_engraver at the Staff level instead of
the Voice level.

Issues So Far
-------------
In trying the technique of moving the Tie_engraver from the Voice level
to the Staff level while notating a piano piece with many instances of
single-to-multiple voices and vice versa, with many ties between the
sections of fewer and more numerous voices, I have encountered a few
issues so far.

    Issue 1:
As illustrated in Figure 1 (attached PNG), LilyPond's default placement
of the tie between the top notes of chords 2 and 3 of the illustration
is so short (to avoid the flat symbol on the 3rd chord) that it is
invisible, unless the chords (and measures that contain the chords) are
spaced farther apart horizontally (which I did with the \break command
at the end of the second measure), as illustrated in Figure 2.

    Issue 2:
I tried to manually add horizontal space between the second and third
chord with the following--

\once \override Score.SeparationItem #'padding = #2

--between the 2nd and 3rd chord. However, that had no effect. Does this
tweak still work, or has it been deprecated?

    Issue 3:
I tried to manually configure the ties between the second and third
chords using--

<ees g c>8~ \once \override Score.TieColumn #'tie-configuration =
#'( (4 . 1) #t ) <ees aes c>4

--However, as is illustrated in Figure 3 (attached PNG image), although
the top tie was correctly formatted, the lower tie, which is supposed to
be beween the lowest notes of the 3-note chords, was misplaced for some
reason by LilyPond. Notice that instead of "TieColumn" I had to use
"Score.TieColumn" because the Tie_engraver is now in the Staff rather
than Voice context, and a simple "TieColumn" had no effect whatsoever.
Also note that I had to raise the top tie to staff position 4 (3 was
insufficient to cause the tie to clear the top of the flat symbol on the
3rd chord).

*** *** *** *** *** *** ***

I would be _happy_to_sponsor_ whatever work these issues might require,
if Han-Wen and the developers consider the features worthy enough.  :-)

I'm sure more issues will come to light as I "stress-test" this idea of
moving the Tie_engraver from the Voice to the Staff context, but I think
it's a great idea and a great solution if the "kinks" can be worked out.
Notators of polyphonic instruments such as the piano will be very
grateful for this functionality.

Best wishes everyone,

Steve D
New Mexico, US
-- 
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figure-1.png
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figure-2.png
Description: PNG image

figure-3.png
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