Re: \override Beam #'consistent-slope = ##t should be default

[David Kastrup]

address@hidden writes:

> 3) Aside from what I mention in (2), are there any other criteria
> that, in your opinion, seem to govern slope breaking?  Could these
> criteria vary from work to work, edition to edition, style to style?
> Does Elaine Gould have anything to say on the subject?  I can change
> the name of consistent-broken-slope to slope-style (with styles like
> hardcore-contemporary, 'peters-fin-de-siecle, 'break-without-unifying,
> etc.).  But it'd be good to do this now before I have to start dealing
> with convert-ly rules (uggghhhhh :).
>
> I know beam-quanting.cc pretty well now, so any changes to the scorer
> wouldn't take me a long time.  What is most important is that we
> brainstorm this thing correctly so that we can get as much right as
> possible with this patch.

Well, I still maintain that maintaining stem length consistency is
overrated.  However, just optimizing on the constraints

a) beam slope is identical before and after break
b) stem lengths are scored independently before and after break

is not quite sufficient: If we have something like [c c b, \break c' c'
b] then we would get a consistently falling slope which is
counterintuitive.  The overall slope orientation needs to be chosen
according to the overall melody line.  But we need not keep it at full
tilt, since otherwise we are quite close to the original "maintain stem
length".

A first approach would be
a) calculate slope and stem lengths as though we have total consistency.
b) do the break
c) allow the stem lengths before and after the break to relax
   independently from the respective other group.
d) allow the slopes before and after the break to relax in lockstep, but
   in a manner that is stiffer when horizontal.  Like scoring on
   differences in the cotangent of the beam angle while maintaining its
   sign.

The important thing is keeping the character, since we might have a
repeated phrase with just one beam in one repetition being broken.
There must be a certain optical qualitative similarity, balanced against
ugliness of the individual broken pieces.

-- 
David Kastrup