Re: rests in polyphonic music - 'stems down, rests up'

[Keith E OHara]

On Tue, 02 Nov 2010 09:19:53 -0700, <address@hidden> wrote:
> Yes, thanks.  The problem is getting at the automatic behaviour which is 
> already available.
>
> I beleive its a bug, that \stemDown obstructs explicit coming later.
>    \override Rest #'direction = #UP

Anders,
  LilyPond does obey a simultaneous \stemDown and Rest'direction=#UP, when 
deciding how to arrange a column where there are only rests,
> but when there are both notes and rests, the rests act as if they had the Stem 
> direction.

If you are interested in the code, rest-collision.cc makes the placement 
decisions based on the various 'directions.  The distinction between columns of 
rests, and columns with both notes and rests, is clearly intentional.  It is 
less clear if the use of Stem 'direction to place rests, in the 
notes-plus-rests case, was intentional.

For Rachmaninoff's Prelude in C-sharp minor, the voices are separated so far in 
pitch, that distinct stem directions are not required.  You could let the stems 
take their natural direction, and since rest-collision.cc insists on asking 
your rests what is their Stem direction, and since un-pitched rests in a 
stemNeutral voice answer based on neutral-direction :

\new Staff <<
  \new Voice {\voiceOne \stemNeutral
  \override Stem #'neutral-direction = #UP
  r8 c'' d'' e'' r  b' r d''}
  \new Voice {\voiceTwo \stemNeutral
  c2 d4 r4}   >>