Re: Problems with parallel voices when using David's accordion push spanner

[Mojca Miklavec]

Hi,

I just wanted to repeat my question (as I'm unable to get rid of some
pretty annoying side effects when typesetting musing for accordion).

I would greatly appreciate any hints for solving the problem.

Thank you,
    Mojca

On 24 February 2017 at 13:47, Mojca Miklavec wrote:
> Hi,
>
> A while ago David Nalesnik wrote some wonderful macros to help me
> write a thick line that denote accordion pushing [1]. The macros work
> wonderfully in 99% of cases, but there are some strange examples where
> this fails.
>
> The example below produces output you can see in the attached PNG. If
> I remove "AccordionPushPull", then the scores typeset fine, but I do
> need those events.
>
> I tried several other strategies. All I need is a small chunk of code
> with different properties (tails pointing in different direction,
> perhaps the size or colour of the scores slightly changed to denote
> optional part for the player, ...). But whatever I try that works in
> normal conditions, fails here.
>
> I'm attaching a "minimal" working example that includes David's code
> (which I left untouched).
>
> melody = \fixed c' {
>   \time 3/4
>   \partial 2
>   \startPush d' e' | \stopPush
>   << { f'4 e' d' | f'4 d'2 | } \\ { <f a>2.~ | <f a>2. | } >>
> }
>
> basses = \fixed c {
>   \clef bass
>   \partial 2
>   f,4 <f a c'> | d,4 <d f a> <d f a> | a,4 <d f a> <d f a> |
> }
>
> \score {
>   \new PianoStaff <<
>     \new Voice = "melody" { \melody }
>     \new AccordionPushPull \with {
>       \override VerticalAxisGroup.nonstaff-nonstaff-spacing.padding = 1
>     } {
>       \melody
>     }
>     \new Staff = "staff" <<
>       \new Voice = "bass" { \basses }
>     >>
>   >>
> }
>
> If I change the above line of melody to
>
>   <<
>     {
>       \voiceOne f'4 e' d' | f'4 d'2 |
>     }
>     \new Voice {
>       \voiceTwo <f a>2.~ | <f a>2. |
>     }
>   >>
>
> then I get the attached screenshot (lily-accordion-with-new-voices.png)
> which is "equally" bad, only in a different way.)
>
> The example was taken from
>      http://lilypond.org/doc/v2.18/Documentation/notation/multiple-voices
>
> The first example with "\\" as voice separator has the additional
> problem that I cannot add lyrics to it (which is not acceptable), but
> this one repeats the second voice which is highly undesirable.
>
> I would be grateful for a bit of help to fix this.
>
> Thank you very much,
>     Mojca
> (please CC me)
>
>
> [1] http://lists.gnu.org/archive/html/lilypond-user/2016-07/msg00392.html
>
> PS: Other examples of the push/pull macros not really obeying me (but
> those are all cases with much lower priority and there's no need to do
> anything about those now unless it's related to the problem at hand):
>
> - When push/pull spanner starts at "\repeat volta 2 {}", it's not
> properly aligned
>
> - Sometimes I need:
>     melodyA = {\startPush ... \stopPush}
>     melodyB = {\startPush ... \stopPush}
>     melody = {\melodyA \melodyB}
> but I need to delete the last \stopPush in A and the first \startPush
> in B, else the line is disconnected (placed at different heights).
> This is also a problem with \repeat volta 2 {} \alternative { {} {} }
> where push events need to cross alternatives even if they are not
> logically connected, but I need to make sure that it looks visually
> accepting.
>
> - The code sometimes says
>     warning: I think there's a dangling accordion push spanner :-(
> but it doesn't tell me the line to help me debug the problem.

lily-accordion-with-parallel-voices.png
Description: PNG image

test-lily-multiple-voices.ly
Description: Binary data

lily-accordion-with-new-voices.png
Description: PNG image