RE: Transposable Fret Diagrams for Guitar

[Rick Hansen (aka RickH)]

Carl D. Sorensen wrote:
> 
> Rick H wrote: 
> 
> 
> A user-maintained table of chord shapes wouldn't be transposable.  It's
> using the Lilypond chord naming structure that makes the transposing
> work, IMO.  This functionality wouldn't work for you, because you're an
> excellent guitar player.  It would work for my purposes -- creating
> introductory guitar books of campfire songs to help novices have fun
> with the guitar.
> 
> Thanks for your feedback,
> 
> Carl
> 
> 
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> 
> 

By a table lookup were you thinking of something like this?


I think as long as the table knew what the root note is and what the slash
note is (if present) then it could also transpose, (because thats the only
two note letters it would ever encounter in a chord name).  So to depict a
common chord in the key of C like: Bm7b5 (the chord built on the 7th degree
of the C major scale ) the table entry could separate the root name from the
chord name in two dimensions:

B,m7b5

For slash chords you can use a three dimension table entry so for Bm7b5/F:

B,m7b5,F

The fourth dimension could be a simple enumerator (to break duplicate name
ties):

B,m7b5,F,1

The fifth dimension would be the desired fretboard markup:

B,m7b5,F,1,<my notes go here>

So if you have to store 10 different forms of a Bm7b5 chord you have
numerous ways to avoid duplicates names in the hash table and can support a
robust library of names.

B,m7b5,F,1,<my notes go here>
B,m7b5,F,2,<my notes go here>
B,m7b5,G,1,<my notes go here>
B,m7b5,,1,<my notes go here>
B,m7b5,,2,<my notes go here>

etc...

The transpose algorithm would always know to transpose dimensions 1 and 3 of
the table entry as these are named notes.  Typically you would probably only
maintain all the names with C roots then use traspose to do the lookup, this
way you only need to maintain 1/12 of the number of chord names in the
library table.  The "my notes go here" above would be interpreted by the
current FretBoards and depicted as frets.

Rick






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