Re: Broken beams' slopes

[Mike Solomon]

On Aug 24, 2011, at 5:42 PM, David Kastrup wrote:

Mike Solomon <address@hidden> writes:

Hey all,

I'll be leaving on vacation in a week-ish, and as my summer-of-lily

comes to a close, I can likely do one more medium-scale thing before I

have to start correcting parallel fifths.

I'd like to work on broken beam slopes such that a beam can break

across lines and pick up where it left off at the same slope and

y-offset

The problem I see with this approach is that one does not, in general,

want the same slope and y-offset because it does not make sense to view

the broken beam as a single visual entity.

All the pdfs associated with my response are up at http://www.apollinemike.com/response_to_david

See chords2.pdf versus chords.pdf.  In chords.pdf, I use an override to make all beams flat.  In chords2.pdf, I remove this override and let lily run her course.  I think that, in chords2.pdf, the disparity in slopes across line breaks makes for really ugly typsetting.  I would much rather have long stems and continuity than more even stems and divergent slopes.

Creating a single visual

entity often means compromises like having over-long or -short stems in

between.  When "in between" moves right adjacent to the break, you don't

want the stems there to be overlong and overshort just to make y

positions match those of the next line.  The next line is far away.

In the case of beams, I actually think people often want this.  Check out measure 6 of broken.pdf.  I would gladly take a long stem before the line break (the same length, for example, as that of the D natural in the previous beam) such that the slope and Y-offset are continuous.  I think that it is important to make a scorer that can work on a per-line or all-line basis (like the one I'm proposing) so that people can decide between the two with a property (Beam #'preserve-slop-across-line-breaks).

So you will generally want to preserve the beam slope roughly, and

preferably the beam orientation.

I think that in the included PDFs, even roughly wouldn't work (I haven't tried though) - as a performer, especially at fast tempos, the consistency of slope would actually help me anticipate what is coming after the line break so that my hands can move in the right direction.

That means that if the unbroken beam

would have a _knee_ at the break, you would, when splitting it, tend to

prefer _unkneed_ beams with similar slope, even though that would mean a

significant jump in y-offset.

Agreed.

But that makes the visual connection

easier to make than a jump in beaming direction.

Agreed.

So thea esthetic decisions need to work under different constraints than

in the unbroken case.

Agreed.

We have the same "almost, but not quite as if unbroken" situation with

slurs and ties.  And it does not just occur with line breaks, but also

in connection with repeats and da capo.

True, but I think these grobs are different because they hover over or under early columns like clefs and key signatures, whereas beams start after these columns.  This allows beam continuity to be a lot better, as it does not have to compete with the presence of a giant clef at the beginning of the barline that would cause its y-offset to be very high or low.

Do we have a sound general strategy for tackling this sort of controlled

discontinuity?  Maybe it would be worth thinking about.

Not really, although I'm way for this (my vector graphics spanner does this sorta thing).

I think implementing this type of continuity for beams may be a good test case from which a general strategy (if appropriate) can be extrapolated and applied elsewhere.

Cheers,
MS