Re: Controlling hairpin length - revisited!

[Thomas Morley]

Hi David:

2016-10-11 15:51 GMT+02:00 David Sumbler <address@hidden>:
> The reasons for the long gap were (a) moving house in February and,
> more importantly (b) feeling very discouraged by the apparent
> unpredictability of hairpin lengths in Lilypond, despite all Harm's
> valiant efforts.

sorry for not being more helpful :(


2016-10-14 10:44 GMT+02:00 David Sumbler <address@hidden>:
> On Thu, 2016-10-13 at 23:54 +0200, Simon Albrecht wrote:
>> On 13.10.2016 14:41, David Sumbler wrote:
>> >
>> > On Wed, 2016-10-12 at 14:10 -0400, Kieren MacMillan wrote:
>> > >
>> > > Hi David,
>> > >
>> > > >
>> > > > But I realise that often what I need in order to get
>> > > > satisfactory
>> > > > hairpins is more space between the note heads, and simply
>> > > > moving
>> > > > the
>> > > > ends of the hairpin does not reposition the relevant notes.
>> > > Have you tried adjusting the minimum-length?
>> > >
>> > > %%%  SNIPPET BEGINS
>> > > \version "2.18.2"
>> > > \language "english"
>> > >
>> > > after =
>> > > #(define-music-function (parser location t e m)
>> > >       (ly:duration? ly:music? ly:music?)
>> > >       #{
>> > >           \context Bottom <<
>> > >               #m
>> > >               { \skip $t <> -\tweak extra-spacing-width #empty-
>> > > interval $e }
>> > >           >>
>> > >       #})
>> > >
>> > > testing = \relative e'' {
>> > >    \override Hairpin.minimum-length = #5
>> > >    e8 cs ds d \after 4 \> \after 4 \mf cs2\< ~ cs4 d8(\p cs)
>> > > }
>> > >
>> > > \score { \testing }
>> > > %%%  SNIPPET ENDS
>> > >
>> > > Hope that helps!
>> > > Kieren.
>> > Thanks, that's brilliant.  With this and Hairpin.shorten-pair I
>> > should
>> > be able to solve most or all of the problems I often find with
>> > hairpins.
>> >
>> > I have read all the material in the list archive relating to this
>> > function.
>> Which function? \after?
>
> Yes
>
>> after =
>> %% create a music function with three arguments and assign it to the
>> variable `after`
>> #(define-music-function (parser location t e m)
>>     ;; give the types of the three arguments as predicate procedures
>>     (ly:duration? ly:music? ly:music?)
>>     ;; have the expression in #{#} evaluated by the LilyPond parser
>>     #{
>>       %% Bottom is a kind of alias usually referring to Voice.
>>       %% In this case, it’s there to prevent creating new Voices,
>>       %% so the simultaneous music <<>> remains in one Voice.
>>       \context Bottom <<
>>         %% first expression in the simultaneous music: the last
>> argument
>> passed to the function
>>         #m
>>
>>         %% second expression:
>>         %% \skip $t creates a skip of the duration given as first
>> argument of the function
>>         %% <> is an empty chord with no duration
>>         %% the tweak prevents the spacing to be distorted by the
>> inserted item $e
>>         %% empty-interval is defined in scm/lily-library.scm as
>> #'(+inf.0 . -inf.0),
>>         %% i.e. actually an infinitely small interval. Maybe #'(0 .
>> 0)
>> would work just as well,
>>         %% but it might also cause errors or unwanted behaviour.
>>         { \skip $t <> -\tweak extra-spacing-width #empty-interval $e
>> }
>>       >>
>>     #})
>>
>> HTH, Simon
>
> Thank you - that is very helpful, and most of it is clear to me now.
>
> If I could bother you a bit further...
>
> We have
> #(define-music-function (parser location t e m)
>
> In my file, I have at one point
> \after 4 \> cs2\< ~ cs4
>
> Clearly the value of t is 4 (a crotchet or quarter-note length);
> e is \> (a hairpin);
> m is cs2; or probably cs2\< (since the crescendo hairpin has to be
> placed before the other dynamics).  I'm not quite sure what is
> considered a single item of music.  What is the value of m here?
>
> Looking at the function code, it seems that the music items are
> processed in reverse order (which is what one would expect), i.e. item
> m is processed, then the additional item e, which is placed later.  So
> far, so good.
>
> What I actually have at one point in the file is
> \after 4 \mf \after 4 \> cs2\< ~ cs4
>
> At the first call of the function, t has the value 4, but I'm a bit
> unclear about how the rest is parsed.  What are the values of e and m
> in this case?
>
> I imagine that the music items are processed in reverse order here too,
> i.e. cs2, then the diminuendo hairpin, then the mf mark.  By
> experimenting I find that it doesn't make any practical difference
> whether I put the mf first and the hairpin second or vice versa.  But
> it would be nice to know just what is going on here.
>
> David

I always let things display to understand things better. In this case
you could do:

\version "2.19.48"

\language "english"

#(define counter 0)

after =
#(define-music-function (parser location t e m)
     (ly:duration? ly:music? ly:music?)

(set! counter (1+ counter))
(display "\n%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\n")
(format #t  "the function ran ~a. time" counter)
(display "\n%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\n")
;; scheme
;(display "\n------------------------------------------\n")
;(display "scheme -----------------------------------")
;(display "\n------------------------------------------\n")
;(display "scheme-t----------:\n")(display-scheme-music t)
;(display "scheme-e----------:\n")(display-scheme-music e)
;(display "scheme-m----------:\n")(display-scheme-music m)
;; lily
(display "\n------------------------------------------")
(display "\nlily -------------------------------------")
(display "\n------------------------------------------\n")
(display "\nlily-t----------: ")(display-lily-music  t)
(display "\nlily-e----------: ")(display-lily-music  e)
(display "\nlily-m----------: ")(display-lily-music  m)
(display "\n%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\n")

     #{
         \context Bottom <<
             #m
             { \skip $t <> -\tweak extra-spacing-width #empty-interval $e }
         >>
     #})


{ \after 4 \mf \after 4 \> cs2\< ~ cs4 }

Which will return in terminal:

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
the function ran 1. time
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

------------------------------------------
lily -------------------------------------
------------------------------------------

lily-t----------: %{ expecting a music expression: #<Duration 4 > %}

lily-e----------: \>

lily-m----------: cs2\< ~

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
the function ran 2. time
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

------------------------------------------
lily -------------------------------------
------------------------------------------

lily-t----------: %{ expecting a music expression: #<Duration 4 > %}

lily-e----------: \mf

lily-m----------: \context Bottom << cs2\< ~ { \skip 4 < >-\tweak
extra-spacing-width #(cons +inf.0 -inf.0)

 \> } >>

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Interpreting music...
atest-40.ly:1603:16: warning: unterminated decrescendo
{ \after 4 \mf
               \after 4 \> cs2\< ~ cs4 }


The output in scheme-syntax is commented because being too verbose,
you may try it as well, though. The counter is an addition to make it
even more clear when what is done.


Hope that helps a bit,
  Harm

P.S.
Please always post compilable examples, with version and language (if
not default). Would be nice to eliminate unrelated errors/warnings as
well.