Re: * Fix arpeggio overshoot for chords which reach centre line.

[n . puttock]

On 2008/10/01 00:56:41, hanwenn wrote:
> http://codereview.appspot.com/6453/diff/1/3
> File lily/arpeggio.cc (right):
>
> http://codereview.appspot.com/6453/diff/1/3#newcode108
> Line 108: y += rint (squiggle.extent (Y_AXIS).length ()))
> while the original is obviously wrong for the .ly you show, the fix
looks fishy
> to me as you would be accumulating roundoff errors. The loop should be

> while (mol.extent(Y_AXIS) <  heads[RIGHT])
>  { add_at_edge }
>
>
> perhaps to prevent the problem, there could be something like
>
> while (mol.extent(Y_AXIS) + 1.0 <  heads[RIGHT])
>  { add_at_edge }
>
> (where 1.0 is intelligently chosen.)

That's similar to how I approached it originally, without changing the
loop,

for (Real y = heads[LEFT]; y + EPS < heads[RIGHT];

where EPS = 1e-3.

I decided to use rint () instead since I can't see a situation where it
wouldn't work (obviously apart from the case where somebody changes
Arpeggio #'font-size); isn't the extent of the squiggle glyph
deliberately set to be one staff-space, so it fits between two staff
lines exactly?

The while loop looks more elegant though, of course.

This is possibly a stupid question, but why are the directions for the
drul_array heads[] horizontal?

http://codereview.appspot.com/6453