Re: slur corehack

[David Wright]

On Thu 26 May 2016 at 00:31:59 (-0700), Flaming Hakama by Elaine wrote:
> > > I would say that, on the contrary, \tweak and \override are not
> > documented.
> > > At least, not well enough to be useful for use with slurs.
> > >
> > > In the case of slurs, searching for "lilypond slurs tweak", the
> > > documentation that comes up describes how to tweak slurs relative to
> > text,
> > > not how to tweak the actual curves themselves.
> > >
> > http://lilypond.org/doc/v2.19/Documentation/learning/outside_002dstaff-objects
> >
> > I typed that string into google and the top hit was
> >
> > http://lilypond.org/doc/v2.19/Documentation/notation/modifying-shapes
> >
> > which is the page you've quoted from in this thread.
> >
> 
> Yes, and if you paid attention, or read that page carefully,
> then you would see that these techniques are not presented on that page
> (nor any of the other pages you cited.).

On that page it says: "In other words, the \shape function can act as
either a \once\override command or a \tweak command depending on
whether the item argument is a grob name, like “Slur”, or a music
expression, like “(”."

I guess "tweak" is spelled "shape" here.

> What was your point?

It got snipped: "The inefficiency or inconsistency of search engines
is hardly a criticism that can be aimed at LP or its docs."

For some reason, your search took you to a different page from mine,
and this page was reportedly unsatisfactory.

I snipped your "The override page doesn't even mention slurs" because
Simon covers that with "transfer of learning". I don't think it would
be possible to cover all the individual functions of \override.
Possibly what's not covered well enough (I still reserve judgment
as it might be my own failing) is how to express individual \set and
\overrides as \layout { \context { ... overrides to be applied
throughout a score. (Helped, but not helped, by simplifications of
the syntax: I like the simplifications, but it can make the search
strings for hunting down examples trickier.)

> > > Rather, I am suggesting that the approach of changing all slurs' default
> > > values should be described in addition to (and probably ahead of) the
> > > approach of changing a single curve's control points.
> >
> > I don't understand why you'd describe how to change every foo before
> > you'd described the effect of making changes to one instance.
> >
> 
> The shape of curves affects the overall look of the page.  You would want
> to affect them globally to achieve a "house style".

Yes, once you understand how to affect individual aspects, then you
can design a house style. An apprentice music engraver would learn to
perfect using each punch before getting to design the overall style.

> Or, simply choose a starting point that fixes most of the issues with the
> curves, before proceeding to the tedious work of one-at-a-time techniques.

My experience of learning is to start with specific examples and then
generalise them, so I remain unconvinced (from a learning angle).

> Plus, while you can achieve similar results using the different
> techniques,these different approaches are not comparable:  one is
> manipulating differences in control points from the default algorithm, the
> other is affecting the values used in the underlying algorithm itself.

AIUI from this thread, the former involves scheme and the latter can
be done in LP. If I am wrong, then presumably examples of the former,
coded in LP, will appear in the thread. That would please me, as I'm
not a scheme coder.

> > And is it sensible to try to teach:
> > [...]
> > before teaching:
> > [...]
> > ?
> 
> No one is suggesting that.
> 
> Are you trolling?

Well, it was your first example, and it troubled me. Changes that get
embedded into the underlying code can be difficult to cope with at the
level of LP source. (An OT example would be the changes in horizontal
spacing of notes that has changed significantly between LP versions.)

I was troubled because, like others possibly, I wasn't sure of your
distinguishing setting defaults within, say, ily files and setting
them in scm files (a closed book to most LP users, I suspect).

> > > For now, here are some proof-of concept intermediate versions from the
> > > piece that spurred me to try this approach.
> >
> ...
> 
> > > My final version is not ideal to compare since the line breaking is
> > vastly
> > > different.
> >
> 
> 
> > Comparing appearances is pointless unless you either put extra \breaks
> > into (1) and (2), probably easier, or manually set fewer in (3),
> > probably harder. Oh, and keep the notes the same.
> >
> 
> So, it seems you either have problems with reading comprehension, or
> attitude.

Your thesis is that LP's slurs are too shallow, and you've provided
an example. Unfortunately, I feel like someone being asked to make an
artistic judgment on the curvature of the Mona Lisa's smile, given an
image having the wrong aspect ratio.

Trying to be objective rather than subjective: increasing the
curvature of a specific slur makes the maximum angle reached wrt the
horizontal greater. Stretching the music by having fewer bars per
line decreases the maximum angle.

That's the main problem with my making an A-B comparison between the
examples you gave (apart from having to have two screens to keep track
of corresponding bars). I thought my suggestions were apposite for
making a pair (or triple) of A-B-comparable PDFs.

I can see you have avoided one collision in bar 31 (67 is the same,
though (3) lacks it altogether). I wondered whether there might be
any mileage in using the penalty mechanism to make avoidances like
this happen. Way over my head, though. A technical disadvantage of
using bendy slurs is their potential interference with lyrics and,
consequently, an increase in vertical spacing (always a battle when
moving from A4 to Letter).

I don't see where my attitude comes into it. You've made yours clear
in your first and last sentences (and the implication of trolling).

> > Cheers,
> > David.
> >
> 
> Seems more like a snarl, but I'll try to take you at your word.

Cheers,
David.