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

[mike]

On Oct 25, 2011, at 5:32 AM, Keith OHara wrote:

> There are lots of broken beams in Scriabin's first prelude
> <http://imslp.org/wiki/24_Preludes,_Op.11_(Scriabin,_Aleksandr)>
> The original publisher makes no attempt at consistent slopes.
> Peters Edition prints nearly-equal slopes across the line-breaks, but
> lets the beam height 
> 
> There is a Lilypond version at 
> <http://www.mutopiaproject.org/cgibin/piece-info.cgi?id=1779>
> Applying consistent-broken-slope = #t (beware the error in this thread 
> subject line) produces output with distractingly strange stem lengths.
> 
> The patch at <http://codereview.appspot.com/5293060>
> seems to help.  The odd stem lengths, required to match the vertical
> position of the beam across the line-break, are still distracting.
> 
> Consistent slopes seem to help readability somewhat.
> 

Hey Keith,

Thanks for the suggestion!
I've uploaded a new patch set that brings my work closer to the Peters.

A few thoughts:

1) For hardcore contemporary music, I actually like the aesthetic of completely 
consistent slopes.  I'll code a property for that once I've gotten comments on 
the newest version of this patch.

2) I get the sense from the Peters that the rule seems to be "the OKness of 
slope modifications is directly proportional to the absolute value of the 
slope."  That is, for flat slopes breaking across lines, a change in slope 
seems very bad, whereas for slopes that are @ 20ish degrees, a change in slope 
seems OK.  Although I don't know anything about human psychology/cognition, my 
gut tells me that this corresponds to the way we perceive slopes: if something 
goes from flat to not flat it sticks out, but if something goes from not flat 
to more note flat it sticks out less.

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.

Cheers,
MS