Issue 3128: add Haydn-style turns to Feta

Issue 3128: add Haydn-style turns to Feta

This adds two variants of a turn with a vertical slash:
scripts.slashturn (SMuFL U+E569) and scripts.haydnturn (SMuFL U+E56F)

Also, scripts \slashturn and \haydnturn are added.

I’ll attach a PDF showing them being used to the sourceforge issue.

[lemzwerg, 2018-04-08 14:17:21]

Very nice!  LGTM.

https://codereview.appspot.com/340660043/diff/1/mf/feta-scripts.mf
File mf/feta-scripts.mf (right):

https://codereview.appspot.com/340660043/diff/1/mf/feta-scripts.mf#newcode757
mf/feta-scripts.mf:757: set_char_box (wd# / 2, wd# / 2, ht# / 2 * height_factor,
ht# / 2 * height_factor);
Please avoid lines longer than 78 characters.

https://codereview.appspot.com/340660043/diff/1/mf/feta-scripts.mf#newcode840
mf/feta-scripts.mf:840: set_char_box (wd# / 2, wd# / 2, ht# / 2 * height_factor,
ht# / 2 * height_factor);
Ditto.

https://codereview.appspot.com/340660043/diff/1/mf/feta-scripts.mf#newcode861
mf/feta-scripts.mf:861: .. z3l{dir(60)}
Please use a space after `dir' to be in sync with the remaining code.

[Malte Meyn, 2018-04-08 14:22:16]

improve code style

[Malte Meyn, 2018-04-08 16:31:53]

add the turns to script-chart.ly (only used by the German NR), add the turns to
NR and Changes

[Dan Eble, 2018-04-08 17:08:42]

Is there a performance difference between these two scripts?  I read quickly
through the thread referenced in the ticket, but I couldn't find the answer.

[simon.albrecht, 2018-04-08 17:43:36]

On 08.04.2018 19:08, nine.fierce.ballads@gmail.com wrote:
> Is there a performance difference between these two scripts?  I read
> quickly through the thread referenced in the ticket, but I couldn't find
> the answer. 

I’m not sure what exactly the difference in performing is, but that’s 
not for us to consider; it’s important for scholarly editing (of 
mid-to-late 18th century music, especially Haydn) to have this symbol 
available.

Best, Simon

[Malte Meyn, 2018-04-08 17:55:03]

On 2018/04/08 17:08:42, Dan Eble wrote:
> Is there a performance difference between these two scripts?  I read quickly
> through the thread referenced in the ticket, but I couldn't find the answer.

I don’t know; I’m not even sure whether \haydnturn should be played as \mordent
or as \turn. The 1972 Henle edition of the piano sonatas writes “The sign
[\haydnturn] usually signifies [d32 c b c4]. In an appropriate musical context,
however, it can be performed as a mordent [c16 b c4]”.

After looking through different editions of some piano sonatas on IMSLP I’ve got
the impression that nobody knows exactly. I’ve seen \trill and \prall in the
same place, \prall and \mordent, \mordent and \haydnturn, \mordent and \turn,
\prall and \reverseturn, \turn and \reverseturn, … But no \slashturn. I added
the latter because it’s a form seen in SMuFL and here:
http://lilypond.1069038.n5.nabble.com/Requesting-an-addition-tp139819p139974....

[Dan Eble, 2018-04-08 18:05:49]

On 2018/04/08 17:43:36, simon.albrecht wrote:
> I’m not sure what exactly the difference in performing is, but that’s 
> not for us to consider; it’s important for scholarly editing (of 
> mid-to-late 18th century music, especially Haydn) to have this symbol 
> available.

Having two symbols available does not necessarily require having unique commands
for them.  For example, LilyPond supports different styles of multi-measure
rests, but they're all represented with R.  I'm trying to understand whether
these scripts are semantically distinct or just stylistically distinct.

It sounds like you're saying we don't know if they are semantically distinct,
therefore we should implement commands as if they are.  I have no objection to
that; I just want to understand the intent and encourage an implementation that
suits it.

Regards,
Dan

[Malte Meyn, 2018-04-09 07:42:12]

On 2018/04/08 18:05:49, Dan Eble wrote:
> Having two symbols available does not necessarily require having unique
commands
> for them.  For example, LilyPond supports different styles of multi-measure
> rests, but they're all represented with R.  I'm trying to understand whether
> these scripts are semantically distinct or just stylistically distinct.

How would one make a single command that can use both styles? Maybe something
like

\override Script.haydnturn-style = #'turn % default #'wiggle

?

> It sounds like you're saying we don't know if they are semantically distinct,
> therefore we should implement commands as if they are.  I have no objection to
> that; I just want to understand the intent and encourage an implementation
that
> suits it.

We don’t exactly know if \slashturn and \turn are semantically distinct either …
As stated in my last post above it looks like many of these
prall/mordent/turn/XXXturn symbols can replace each other in different editions.

[Lukas-Fabian Moser, 2018-04-10 09:47:31]

This is gorgeous! Thanks very much!

Is the \haydnturn supposed to be symmetrical w.r.t. the stem? To me it looks as
if it weighs slightly more on the left, but maybe I'm wrong? (And I'm also not
sure if this would be a problem if I were right.)

(The Henle score that prompted me to ask in the first place - Haydn Symphony Nr.
13 in Haydn, Werke, Reihe I, Band 3, ed. Braun/Gerlach - has a less curly
version of the \haydnturn, but I like your design better.)

As for the \slashturn: I think the lenght of the stem is okay. But I started to
wonder if the \slashturn should really be as "thick" at its waist as the usual
\turn. Maybe there is a slight disbalance between the two parts (turn vs.
slash).

Best
Lukas

[Malte Meyn, 2018-04-10 17:20:17]

On 2018/04/10 09:47:31, Lukas-Fabian Moser wrote:
> This is gorgeous! Thanks very much!
> 
> Is the \haydnturn supposed to be symmetrical w.r.t. the stem? To me it looks
as
> if it weighs slightly more on the left, but maybe I'm wrong? (And I'm also not
> sure if this would be a problem if I were right.)

The symbol is 100% symmetrical as I tested with the following code:

\markup \fill-line {
  \fontsize #20 \overlay {
    \rotate #180 \with-color #red \musicglyph "scripts.haydnturn"
    \musicglyph "scripts.haydnturn"
  }
}

But maybe it’s not well-balanced nethertheless? 

> (The Henle score that prompted me to ask in the first place - Haydn Symphony
Nr.
> 13 in Haydn, Werke, Reihe I, Band 3, ed. Braun/Gerlach - has a less curly
> version of the \haydnturn, but I like your design better.)

Yes, I don’t like the Henle (1972) version as well. I copied the fact that it’s
less bold than the turn and mordent but I made it a little but more curly and
centered the stem vertically (Henle makes the upper half of the stem longer than
the lower).

> As for the \slashturn: I think the lenght of the stem is okay. But I started
to
> wonder if the \slashturn should really be as "thick" at its waist as the usual
> \turn. Maybe there is a slight disbalance between the two parts (turn vs.
> slash).

You’re right. \turn and \reverseturn are 10% thicker at the very center than at
the “outer” thick parts. Making the \slashturn 4% thinner instead looks good to
me.

Maybe that’s also the reason for imbalance in the \haydnturn. Same thickness
instead of 10% thicker might look better.

I’ll make a patch set for slimmer center parts and attach the resulting PDF to
the sourceforge issue.

[Malte Meyn, 2018-04-10 17:21:43]

make slashturn 4% thinner at the center (instead of 10% thicker), haydnturn 0%
thicker (instead of 10% thicker)

[Malte Meyn, 2018-04-10 17:29:48]

On 2018/04/10 17:21:43, Malte Meyn wrote:
> make slashturn 4% thinner at the center (instead of 10% thicker)

IMHO that’s an improvement.

> haydnturn 0%
> thicker (instead of 10% thicker)

I’m not sure whether this is, the glyph shouldn’t be too slim to match the
overall style of the Feta font.

[Lukas-Fabian Moser, 2018-04-10 21:53:23]

> On 2018/04/10 17:21:43, Malte Meyn wrote:
> > make slashturn 4% thinner at the center (instead of 10% thicker)
> 
> IMHO that’s an improvement.

Yes, I agree.

> > haydnturn 0%
> > thicker (instead of 10% thicker)
> 
> I’m not sure whether this is, the glyph shouldn’t be too slim to match the
> overall style of the Feta font.

You're probably right.
I am a little confused as to my eye-sight - even after I checked that the glyph
is completely symmetric, I "feel" that the \haydnturn's right part is "steeper".
At one point I thought it might be an optical illusion triggered by the note
head below, but that's not the case (as can be seen by deleting that note head).
So it's probably best to forget my remark after all. Anyway, this was not
influenced by your change of thickness, so you might just as well follow your
judgement about what look of the symbol matches the Feta 'flavour'.