Re: Instructing fretboard-diagram-verbose to space frets proportionally rather than equadistantly

[Aaron Hill]

On 2020-04-08 1:50 pm, Jake Whitton wrote:
> I'm trying to use lilypond to create some guitar neck diagrams for
> memorizing intervals and scale patterns.  I can use
> fretboard-diagram-verbose to place it in landscape orientation, extend 
> it
> to as many frets as I need, etc.  I now have some charts which are very
> nice, but I notice that the fretboard engraver renders each fret as the
> same size, and I'm trying to figure out if it would be possible to 
> instruct
> lilypond to render the leftmost frets to be wider than the rightmost 
> frets
> (as it actually appears visually on a guitar neck).
>
> I don't see any attributes in fret-diagram-details that would enable 
> that
> functionality.  I see in the internals reference that I can customize 
> the
> stencil, which is fret-board::calc-stencil by default.  Would writing a
> custom stencil be the best way to accomplish this?  If so, is there any
> guidance as to how one actually writes a custom stencil.  I can see 
> that
> the notation reference manual has a section on modifying stencils, but 
> the
> example given only substitutes one stencil in place of another.  Is 
> there
> any documentation on how to actually go about writing a stencil from
> scratch?

In this case, you would be modifying and/or replacing the markup command 
make-fret-diagram, which can be found in fret-diagrams.scm.  
Unfortunately, fret-distance is referenced in a number of places, and a 
fair bit of refactoring would be needed as there are current assumptions 
that all frets are equidistant.  But it should be possible to introduce 
a fret-distance-factor property to expand or contract fret spacing the 
further along the diagram you go.


-- Aaron Hill