IR issues (was: Property/ies to control the shape of ties/slurs)

[Urs Liska]

Am 23.11.2015 um 11:20 schrieb David Kastrup:

Urs Liska <address@hidden> writes:

Am 23.11.2015 um 10:39 schrieb David Kastrup:

Urs Liska <address@hidden> writes:

I don't seem to be able to find the right property to control the shape
of ties.

I would like to make the default appearance of ties less flat than what
you see in the first attachment. I *think* what I want is having a
steeper slope. But reading through the IR for tie and tie-interface I
didn't see anything.

Using
    \shape #'((0 . 0) (0 . .75) (0 . .75) (0 . 0)) Tie

results in the second attachment, which is what I'd like to achieve. But
I don't want to use \shape but set some properties so I can put it in a
stylesheet.

Any suggestions?

Uh, \shape ... Tie _is_ an override.  You don't get closer to "set some
properties" than that.

Maybe I wasn't clear: I want to alter the default shape of ties to have
a steeper slope. \shape is not an override but a \once \override and has
to be applied to individual ties. But I want to change the appearance in
a stylesheet.

\once is ignored in context definitions/modifications.

At any rate, you can also play with settings height-limit and ratio.

OK, I've now found out how height-limit and ratio play together. Actually ratio is the setting to deal with the behaviour of curves of different length.

Interestingly I have to override Slur.height-limit but Tie.details.height-limit

But looking for another property of Slurs and Ties leads me to another question:
Is this:
http://lilypond.org/doc/v2.19/Documentation/internals/slur
and
http://lilypond.org/doc/v2.19/Documentation/internals/slur_002dinterface

really the reference for how I can change the appearance of slurs and ties?

If that's true I think it's really awful. I know the IR is a *reference* and not a tutorial but I'm sure that *noone* will be able to look up the information for tweaks they need anything near efficiently. The majority of properties is described in a completely inaccessible manner.

"

same-slope-penalty

Demerit for slurs with attachment points that are horizontally aligned."

What the heck does that mean?

Or
"

absolute-closeness-measure

Factor to calculate demerit for variance between a note head and slur.

"

Huh?

And even a more "humane" item like
"

ratio (number)

Parameter for slur shape. The higher this number, the quicker the slur attains its height-limit.

"
Is actually ambiguous, to say the least. When I read this I expected that this controls the steepness at the edges of the slur. But effectively it controls *if* the slur reaches its "height-limit" at all: shorter slurs don't and longer do.


The point is: if the descriptions of the properties are that cryptic the user can only find out by trial-and-error. Which is significantly constrained through the fact that often there's *no* visible change when changing a value because that property only works in conjunction with another one or only in certain graphical situations.

Summing up: I find it practically impossible to use the NR efficiently for learning about the possibilities for tweaking LilyPond's layout. I have also re-read the respective sections of the Learning Manual and they are of no help. While they lead through the basic use of the IR they don't help anything with the issues outlined above.

*Is* there any material around that goes beyond the IR at all?
Or would we need in-depth tutorial-style explanations for at least the more important notation items?

So far I've always kept away from touching these internals and somehow assumed I was too dumb or - more probable - too lazy to follow the trail of information. But now I have the impression there is really something fundamental missing.
I would say: While we claim to provide automatic engraving most of the time things like tweaking properties of common objects such as slurs, or barlines, or beams etc. should really be accessible for the user and not hidden away behind truly cryptic docstrings.

Urs