Re: Polyphony confuses \change

[David Kastrup]

Jean Abou Samra <address@hidden> writes:

>    Hi again,
>
>    In this example, LilyPond complains and \change has no effect. However,
>    if you move the \change between the second and the third measure (i.e.
>    one line lower), then all is fine. So, it seems that \change does not
>    work right after the end of simultaneous voices.

Wrong.  \change does not work to change a Staff from Staff to Staff, and
at the point of your first \change command, you do not yet have a Voice
(the temporary voices started in << \\ >> have just ended).

So the solution is to actually start a voice.

>    \version "2.21.0"
>
>    <<
>      \new Staff = "up" {

try    \new Staff = "up" \new Voice {

and you'll actually _have_ a Voice that can change to the other Staff.

>        << { c'' } \\ { c' } >>
>        \change Staff = "down"
>        c'4
>        c'4
>      }
>      \new Staff = "down" {
>        s4*3
>      }
>    >>
>
>    The log contains:
>
>    warning: Change_iterator::process (): Staff = `up':
>    -:8:5: warning: cannot change `Staff' to `down': not changing to same
>    context type: Staff
>    \change Staff = "down"
>
>    A workaround is to add a \grace s8  in all voices, between the end of
>    simultaneous voices and the \change invocation.
>
>    Regards,
>
>    Jean Abou Samra
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> address@hidden
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-- 
David Kastrup