Re: Tweak Slur direction "neutral"

[Ahanu Banerjee]

Thank you so much!

-Ahanu 

On Sun, Jan 29, 2023, 20:36 Jean Abou Samra <jean@abou-samra.fr> wrote:

On 30/01/2023 02:20, Ahanu Banerjee wrote:
> When I attempt to change the "direction" property of a slur, whether that is with \tweak or \override, I cannot set the direction to neutral (0). UP (1) and DOWN (-1) work fine, but when setting to 0, I get the following error: 
>
> "Assertion failed: d, file /home/lily/lilypond-2.24.0/release/binaries/mingw/lilypond/lilypond-2.24.0/flower/include/drul-array.hh, line 56
> Exited with return code 3."
>
> This is necessary for a function I am creating; Slur.direction has already been set to UP or DOWN earlier in the document, and I need to temporarily set it to neutral while also changing its color. (\once \slurNeutral is not practical here)
>
> Below is example code that generates the error: 
>
> \version "2.24"
> \language "english"
> { c' d' \tweak Slur.direction #0 ( e' ) c' }
>
> Any suggestions?


You can see with

\void \displayLilyMusic \slurNeutral


that \slurNeutral is not equivalent to \override Slur.direction = #0,
but \revert Slur.direction, which reverts Slur.direction to its default
value #ly:slur::calc-direction. So you want

\version "2.24.0"


\language "english"
{ c' d' \tweak Slur.direction #ly:slur::calc-direction ( e' ) c' }


Jean