Re: Chapter "Collision resolution"

[David Kastrup]

"Trevor Daniels" <address@hidden> writes:

> David Kastrup wrote Wednesday, January 12, 2011 4:23 PM
>
>
>> "Trevor Daniels" <address@hidden> writes:
>>
>>> LilyPond currently has a documented restriction that
>>> merging cannot take place if there are three or more
>>> notes in the same note column.  Here there are three,
>>> so the third note has to be moved out to permit the
>>> first two notes to merge.  See the Real music example
>>> in the Learning Manual where this is explained.
>>
>> Is there an insurmountable technical reason for this restriction? It
>> seems rather arbitrary.
>
> Well, I guess it's just because it's more difficult
> to handle than arbitrary, but I don't know.  I'll
> have to hand further discussion over to those more
> familiar with the internals than I am.

I've decided that this is not a restriction, but a bug.  Here is the
reason: when merge-differently-headed is set and three or more notes are
in the note column, heads _are_ getting merged but get assigned the
wrong notehead.

If it were merely a _restriction_, Lilypond would refrain from
attempting to merge the noteheads in this situation at all instead of
merging them with a bad result.

So this bug needs to be resolved either

a) completely by letting Lilypond pick the right notehead in this case
b) by turning it into a restriction, namely not letting Lilypond attempt
   merging heads at all when there are too many of them

I am taking a look at the code to figure out what happens and what one
might want to do about this.

-- 
David Kastrup