Re: how to write a scheme function to override glissando properties

[Patrick Schmidt]

Am 19.12.2010 um 20:13 schrieb Marc Hohl:

> Am 16.12.2010 17:04, schrieb Patrick Schmidt:
> > [...]
> > Hi Marc,
> >
> > thanks for your solution but I'm still trying to find out what's  
> > wrong with the scheme function I posted. I discussed the need for  
> > this function with Carl and he gave me some advice: http:// 
> > www.mail-archive.com/address@hidden/msg32745.html.
> >
> > It might be impossible to find a general set of values for staves  
> > and tab staves. If I don't succeed I learned something about  
> > writing scheme functions, at least. Maybe you can spot the mistake  
> > in the function?
> Hm, I don't know what's wrong - I tried something like
>
> slide =
> #(define-music-function (parser location len thick beg end)  
> (number? number? ly:music? ly:music?)
>   #{
>      \once \override Glissando #'minimum-length = $len
>      \once \override Glissando #'thickness = $thick
>      \once \override Glissando #'springs-and-rods =  
> #ly:spanner::set-spacing-rods
>       $beg \glissando $end
>   #})
>
>
> myMusic = \relative c' {
>   \slide #10 #5 a4 b4\3
> }
>
> \score {
> <<
>  \new Staff {
>    \new Voice {
>      \clef "treble_8"
>      \myMusic
>    }
>  }
>  \new TabStaff {
>    \new TabVoice {
>      \myMusic
>    }
>  }
> >>
> }
>
> and that doesn't work either. I don't understand why ...
Needless to say, that I don't understand it either...

Apparently it's not even possible to override the length of a  
glissando in one context without changing the look of the other  
context. Look at this:

\version "2.13.44"

slides = {
  a2\glissando b2\3
}

\score {
  <<
    \new Staff { \clef "treble_8" \slides }
    \new TabStaff { \slides }
  >>
  \layout {
    \context {
      \Voice
      \override Glissando #'minimum-length = #10
      \override Glissando #'springs-and-rods =
                          #ly:spanner::set-spacing-rods
      \override Glissando #'thickness = #3
    }
    \context {
      \TabVoice
      \override Glissando #'minimum-length = #1
      \override Glissando #'springs-and-rods =
                          #ly:spanner::set-spacing-rods
      \override Glissando #'thickness = #10
    }
  }
}

The values for  minimum-length in different contexts influence each  
other. The highest value wins. This is reasonable but unfortunately  
the glissandi staves and tab staves don't have the same length in  
print even when they were given the same value for minimum-length...

> Sorry for being not very helpful.
No, no, I appreciate your input very much.

Thanks,

patrick
> Marc