Re: Fix issue 4355 -- broken beam subdivision (issue 226700043 by address@hidden)

[Urs Liska]

Am 25.04.2015 um 13:33 schrieb address@hidden:
> Reviewers: lemzwerg, uliska,
>
> Message:
> Ok, so let me see if I understand what you are saying.

Unfortunately I'm not 100% sure if I understand your questions 
correctly, so I'm not sure if my answers will make perfect sense to you ...

> When we choose to subdivide beams with a given baseMoment, there should
> be a subdivision at baseMoment and at every even interval larger than
> that.
>
> So if we have a baseMoment of 1/32, we should subdivide at 1/32, 1/16,
> and 1/8.

That depends on how you mean that.
Subdivisions should be present at each 32nd note hear, as 1/32, 2/32 .. 
n/32. But they should have different numbers of beams. But you can also 
see that as "layered" subdivisions.

I think that could be a viable approach:
- start with the larges value (1/8) and determine all possible 
subdivision points
  (having 1 beam)
- go on to 16th notes and determine all possible subdivision points
  (having 2 beams) and apply them to all where 1/8 didn't already match
- go on until you reach baseMoment.

In that context I'd like to raise the question if baseMoment really is 
the appropriate property for configuring beamSubdivision or if it 
shouldn't have a dedicated property. Changing baseMoment might have 
side-effects on other aspects of the engraving that may or may not be 
intended.

Urs

> If we have a baseMoment of 1/16, we should subdivide at 1/16 and 1/8.
>
> If we have a baseMoment of 1/8, we should subdivide at 1/8.
>
> And presumably if we have a baseMoment of 1/128, we should subdivide at
> 1/128, 1/64, 1/32, 1/16, and 1/8.
>
> Is this correct?
>
>
> Description:
> Fix issue 4355 -- broken beam subdivision
>
> When beams are subdivided, the number of beams joining the subdivisions
> should match the length of the subdivision.  Previously, the
> subdivisions
> were joined by a single beam.
>
> Please review this at https://codereview.appspot.com/226700043/
>
> Affected files (+25, -2 lines):
>   A input/regression/beam-subdivision.ly
>   M lily/beaming-pattern.cc
>
>
> Index: input/regression/beam-subdivision.ly
> diff --git a/input/regression/beam-subdivision.ly 
> b/input/regression/beam-subdivision.ly
> new file mode 100644
> index 
> 0000000000000000000000000000000000000000..812e3ae62e5d7e8b72411ede7535eadac0dafd8f
> --- /dev/null
> +++ b/input/regression/beam-subdivision.ly
> @@ -0,0 +1,21 @@
> +\header {
> +
> +  texidoc = "Beam subdivisions should match the durations of the 
> subdivided
> +groups, as established by baseMoment.  The first beamed group should 
> be joined
> +by a single beam.  The second should be joined by a double beam."
> +  }
> +
> +\version "2.19.19"
> +
> +\layout {
> +  ragged-right = ##t
> +}
> +
> +{
> +  \set subdivideBeams = ##t
> +  \set baseMoment = #(ly:make-moment 1 8)
> +  c''32[ c'' c'' c'' c'' c'' c'' c'']
> +  \set baseMoment = #(ly:make-moment 1 16)
> +  c''32[ c'' c'' c'' c'' c'' c'' c'']
> +}
> +
> Index: lily/beaming-pattern.cc
> diff --git a/lily/beaming-pattern.cc b/lily/beaming-pattern.cc
> index 
> 5ffbcfb9d9047ef558213bcc3293b117c9443c37..5f9be8a901e1df02fc3bfcc144a7a9e428054d59 
> 100644
> --- a/lily/beaming-pattern.cc
> +++ b/lily/beaming-pattern.cc
> @@ -156,6 +156,7 @@ Beaming_pattern::beamify (Beaming_options const 
> &options)
>          flag_directions[i] = LEFT;
>      }
>
> +  Duration base_dur = Duration(options.base_moment_.main_part_, false);
>    // Set the count on each side of the stem
>    // We need to run this code twice to make both the
>    // left and the right counts work properly
> @@ -166,8 +167,9 @@ Beaming_pattern::beamify (Beaming_options const 
> &options)
>          if (non_flag_dir)
>            {
>              int importance = infos_[i + 1].rhythmic_importance_;
> -            int count = (importance < 0 && options.subdivide_beams_)
> -                        ? 1 : min (min (infos_[i].count (non_flag_dir),
> +            int count = (importance < 0 && options.subdivide_beams_)
> +                        ? base_dur.duration_log () - 2 // durlog 3 
> has 1 beams
> +                        : min (min (infos_[i].count (non_flag_dir),
>                                          infos_[i + 
> non_flag_dir].count (-non_flag_dir)),
>                                     infos_[i - non_flag_dir].count 
> (non_flag_dir));
>
>
>
>
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