Re: how to add barre indications to automatic fret diagrams?

[pls]

On 21.05.2015, at 21:06, Carl Sorensen <address@hidden> wrote:

> 
> 
> On 5/21/15 8:39 AM, "pls" <address@hidden> wrote:
>> 
>>> 
>>> I thought about this issue quite a bit when I was creating predefined
>>> fret
>>> diagrams.  There, we introduced the idea of a chord shape.  There is a
>>> function that shifts a chord shape by N frets (offset-fret).  At
>>> present,
>>> it adds N to the fret number for every dot.  I thought about setting the
>>> fret number to N for every open string, but elected not to do it
>>> because I
>>> wouldn't know what to do with the finger.  I guess it's possible to set
>>> it
>>> to 1.
>> 
>> I would argue that it would make a lot of sense to "set the fret number
>> to N for every open string² and to automatically add a barre indication
>> when transposing open chord shapes.  Otherwise these resulting diagrams
>> look really daunting and unplayable.
> 
> There is a difference between transposing and shape shifting.
> 
> Shape shifting is done on chord shapes, rather than music.  It would be
> trivial to set the fret to N and the finger to 1 when shifting a chord
> shape.  I think that probably makes sense to do.
> 
> Transposing doesn't work on chord shapes.  Transposing works on notes.
> The automatic fretboard creator looks at the notes and creates a
> fretboard.  At that point, it has no knowledge of a chord shape, so we
> can't do the shape shifting algorithm there.

Ah, ok, now I’m beginning to understand the problem.  The line between 
transposing and shape shifting is sometimes very thin, though.  (The notes of) 
Some chord structures like e.g. 1.3.5.8.10.15 (G shape) or 1.5.8.10.12.15 (E 
shape) cannot be transposed without also shifting and thus keeping their 
shapes.  Transposing the notes of other chord structures like 1.5.8.10 could 
mean using either the same shape (shape shifting) or switching to at least one 
(sometimes two) alternative shape(s) (A shape, D shape, E shape)

> 
> Do you represent an E chord as
> 
> <e, b,-3 e-4 gis-2 b e'>
> or
> <e,-0 b,-3 e-4 gis-2 b-0 e'-c> ?
> 
> If the latter, you will get a warning when you try to transpose the chord,
> because you're asking for open strings, and the transposed notes don't
> work on open strings.  It makes for an incorrect diagram, with the finger
> listed as 0 and a dot on the fret corresponding to the transposition.
> 
> \new FretBoards {
> <e,-0 b,-3 e-4 gis-2 b-0 e'-0>1
> \transpose e f <e,-0 b,-3 e-4 gis-2 b-0 e'-0>1
> }
> 
> 
> 
> If you use the former notation, you get an incomplete fretboard when you
> transpose the code,
> because you:
> 
> 1) Don't have the barre indicator
> 2) Don't have the finger listed for the barred notes
> 
> However, you don't get the warning, and you don't have the inconsistency
> of asking for an open string and showing a dot simultaneously.
> 
> \new FretBoards {
> <e, b,-3 e-4 gis-2 b  e'>1
> \transpose e f <e, b,-3 e-4 gis-2 b  e'>1
> 
>  }

Hm, I’d either use <e,-0 b,-3 e-4 gis-2 b-0 e’-0> or (even more likely) <e,-0 
b,-2 e-3 gis-1 b-0 e’-0>, the latter making it even more complicated! When 
transposing this open chord to a barred chord all fingers would have to be 
raised by 1.

> 
> It would be possible to employ some code like the following:
> 
> If (some notes have fingers given) and
>   (there is more than one dot on the lowest fret in the diagram)
> then
>   make a barre on the lowest fret and set the fingering of all the dots
> on the lowest fret to 1
> 
> Or alternatively 
> 
> If (some notes have fingers given) and
>   (a note has a finger of 0 and a fret >= 1)
> then
>   give that note a finger of 1
> 
> If (we have more than one note with the same finger)
> then
>   make a barre from the lowest note to the highest note on that finger
> 
> 
> 
> Do you think either of these algorithms would do what you want?

They both sound fine to me!  Are they mutually exclusive? I’d suggest another 
condition:

if we make a barre on the lowest fret and set the fingering of all the dots on 
the lowest fret to 1, the other fingers should be automatically raised by one.

Does that make sense? I will probably need some more time to think about it 
myself...

Thanks for your help and your detailed explanations!
patrick