\repeat unfold 8 {c8}
@end lilypond
-In traditional engraving, eighth notes can have special beaming rules.
-A measure consisting of only eighth notes can be beamed in one. This rule is
-controlled by the context property @code{beamWholeMeasure}:
+In a similar fashion, eighth notes in 3/4 time are beamed as a full
+measure by default. To beam eighth notes in 3/4 time on the beat,
+reset @code{beamExceptions}.
@lilypond[quote,verbatim,relative=2]
\time 3/4
-% By default we beam in one
-\repeat unfold 6 { a8 }
-% We can avoid beaming in one
-\set Timing.beamWholeMeasure = ##f
-\repeat unfold 6 { a8 }
+% by default we beam in (3) due to beamExceptions
+\repeat unfold 6 {a8} |
+% This will beam (1 1 1) due to beatLength
+\set Timing.beamExceptions = #'()
+\repeat unfold 6 {a8}
@end lilypond
-In some engraving from the Romantic and Classical periods,
-a half-measure of eighth notes can be beamed
-together even though this violates the general rule (see Gould, p. 153).
-This behavior is controlled by the context property @code{beamHalfMeasure}:
+In engraving from the Romantic and Classical periods,
+beams often begin midway through the measure in 3/4 time,
+but modern practice is to avoid the false impression of 6/8 time
+(see Gould, p. 153). Similar situations arise in 3/8 time.
+This behavior is controlled by the context property @code{beamHalfMeasure},
+which has effect only in time signatures with 3 in the numerator:
@lilypond[quote,verbatim,relative=2]
\time 3/4
-% By default we avoid half-measure beams
r4. a8 a a |
-% We can allow half-measure beams
-\set Timing.beamHalfMeasure = ##t
+\set Timing.beamHalfMeasure = ##f
r4. a8 a a |
@end lilypond
-\version "2.15.31"
+\version "2.15.40"
\header {
doctitle = "Special beaming rules for 3/4 time"
- texinfo = "
-Whole-measure and half-measure beaming in 3/4 time can be controlled.
-The first measure should be beamed in one. The second measure should
-be beamed in three. The third and fourth measures should be beamed
-at 3/8.
- "
+ texinfo = "Beaming in 3/4 time has special treatment. By default
+six eighth notes are beamed in one. Beams that would imply 6/8 time
+may be avoided with @code{beamHalfMeasure = ##f}. When the beaming
+is changed, beams should start at the beginning of the measure.
+"
}
\relative c' {
- \time 3/4
- c8^\markup "Beam in one" c c c c c
- \set Timing.beamWholeMeasure = ##f
- c8^\markup "Beam in three" c c c c c
- \set Timing.beamHalfMeasure = ##t
- r4.^\markup "Beam in Two" c8 c c
- c8 c c r4.
+ \time 3/4
+ \set Timing.beamHalfMeasure = ##f
+ r4.^\markup "Prevent beams that imply 6/8 time" c8 c c |
+ c8 c r c c r |
+ r8_"but these beams are okay" c c c c c | c c c r r4 \bar "||"
+
+ \set Timing.beamHalfMeasure = ##t
+ r4.^\markup "Or allow them" c8 c c c c r c c r
+ \break
+
+ \unset Timing.beamExceptions
+ r8^\markup "Beam to the beat" c c c c c
+ c c c r r4 \bar "||"
+
+ \set Timing.baseMoment = #(ly:make-moment 1 8)
+ \set Timing.beatStructure = #'(3 3)
+ r8^\markup "Override to beam groups of 3 eighth notes" c c c c c
+ r4. c8 c c c c c r4.
}
+++ /dev/null
-\version "2.14.0"
-
-\header {
-
- texidoc = "
-3/4 beaming has special rules, that are hardcoded in the autobeam
-routines. When the beaming is changed, beams should start at the
-beginning of the measure. In this case, the measure should be beamed
-in two.
-"
-}
-
-\relative c' {
- \time 3/4
- \set Timing.baseMoment = #(ly:make-moment 1 8)
- \set Timing.beatStructure = #'(3 3)
- \set Timing.beamExceptions = #'()
- c8 c c c c c
-}
\new Staff{
\relative c' {
- \overrideTimeSignatureSettings
+ \overrideTimeSignatureSettings
#'(4 . 4) % time signature fraction
#'(1 . 4) % base moment fraction
#'(1 1 1 1) % beatStructure
#'(3 . 4) % time signature fraction
#'(1 . 4) % base moment fraction
#'(1 1 1) % beatStructure
- #'((end . (((1 . 8) . (2 2 2))))) % set exceptions to beam by 1/4
+ #'() % beamExceptions
\time 4/4
c8^\markup {"Beam by 1/4"} c c c c c c c |
\time 3/4
"autoBeaming "
"baseMoment "
"beamExceptions "
+ "beamHalfMeasure "
"beatStructure "
"subdivideBeams ",
beatStructure = #'(1 1 1 1)
beamExceptions = #'((end . (((1 . 8) . (4 4))
((1 . 12) . (3 3 3 3)))))
- beamWholeMeasure = ##t
- beamHalfMeasure = ##f
+ beamHalfMeasure = ##t
autoBeaming = ##t
autoBeamCheck = #default-auto-beam-check
not_first (r"\2 \\default"), str)
return str
+@rule ((2, 15, 40), r"Remove beamWholeMeasure")
+def conv (str):
+ if re.search (r"\bbeamWholeMeasure\b", str):
+ stderr_write (NOT_SMART % "beamWholeMeasure")
+ stderr_write (_ ("beamExceptions controls whole-measure beaming.") + "\n")
+ return str
+
# Guidelines to write rules (please keep this at the end of this file)
#
# - keep at most one rule per version; if several conversions should be done,
;;;; along with LilyPond. If not, see <http://www.gnu.org/licenses/>.
;; Determine whether an auto beam should be extended to the right
-;; of the current stem. In general, we start anywhere except on
-;; the last note of a beat. We end according to the follwing rules,
-;; in order of decreasing priority:
+;; of the current stem. We start anywhere, except mid-measure in
+;; 3/4 time. We end according to the follwing rules, in order of
+;; decreasing priority:
;;
;; 1. end <type>
;; 2. end <greater type>
(define (beat-end? moment beat-structure)
(pair? (member moment beat-structure))) ;; member returns a list if found, not #t
- (define (use-special-3-4-rules? fraction base-moment exceptions)
- "Should we use special 3/4 time signature beaming rules?"
- (and (equal? fraction '(3 . 4))
- (equal? base-moment (ly:make-moment 1 4))
- (null? (assoc-get '(1 . 8) exceptions '()))))
-
;; Start of actual auto-beam test routine
;;
;;
'())
beaming<?))
(function (if (= dir START) 'begin 'end))
- (beam-whole-measure (get 'beamWholeMeasure #t))
- (beam-half-measure (get 'beamHalfMeasure #f))
+ (beam-half-measure (get 'beamHalfMeasure #t))
(type (moment->fraction test-beam))
(non-grace (ly:make-moment
(ly:moment-main-numerator measure-pos)
exception-grouping 0 grouping-moment)))
(if (= dir START)
- ;; Start rules -- start anywhere unless 3/4 with default rules
- ;; #t if beam is to start
- (or (not (use-special-3-4-rules?
- time-signature-fraction
- base-moment
- exceptions)) ;; start anywhere if not default 3/4
- (= (ly:moment-main-numerator pos) 0) ;; start at beginning of measure
- (and beam-half-measure
- (equal? type '(1 . 8))
- (equal? pos (ly:make-moment 3 8))) ;; start at mid-measure if 1/8 note beam
- (beat-end? pos beat-endings) ;; start if at start of beat
- (and (not (equal? test-beam base-moment)) ;; is beat split?
- (not (beat-end? (ly:moment-add pos test-beam)
- beat-endings)))) ;; will this note end the beat
- ;; End rules -- #t if beam is to end
+ ;; Start rules -- #t if beam is allowed to start
+ (or beam-half-measure ;; Start anywhere, but option for mid-measure
+ (not (equal? (ly:moment-add pos pos) measure-length))
+ (not (= 3 (car time-signature-fraction))) ;; in triple meter
+ (not (= (cdr type) ;; when the beamed note is 1/6 of a measure
+ (* 2 (cdr time-signature-fraction)))))
+ ;; End rules -- #t if beam is required to end
(or (= (ly:moment-main-numerator pos) 0) ;; end at measure beginning
- (if (use-special-3-4-rules?
- time-signature-fraction
- base-moment
- exceptions)
- ;; special rule for default 3/4 beaming
- (if (and (equal? type '(1 . 8))
- (or beam-whole-measure
- (and beam-half-measure
- (not (equal? pos (ly:make-moment 3 8))))))
- #f
- (beat-end? pos beat-endings))
- ;; rules for all other cases -- check for applicable exception
- (if (null? exception-grouping)
- (beat-end? pos beat-endings) ;; no exception, so check beat ending
- (member pos exception-moments)))))))) ;; check exception rule
+ (if (null? exception-grouping)
+ (beat-end? pos beat-endings) ;; no exception, so check beat ending
+ (member pos exception-moments))))))) ;; check exception rule
@code{\\autochange}.")
(beamExceptions ,list? "An alist of exceptions to autobeam rules
that normally end on beats.")
- (beamHalfMeasure ,boolean? "Allow a half measure of eighth notes to
-be beamed together in 3/4 time?")
- (beamWholeMeasure ,boolean? "Allow a whole measure of eighth notes
-to be beamed together in 3/4 time?")
+ (beamHalfMeasure ,boolean? "Whether to allow a beam to begin
+halfway through the measure in triple time, which could look like 6/8.")
(beatStructure ,list? "List of @code{baseMoment}s that are combined
to make beats.")
((beamExceptions . ((end . (((1 . 32) . (8 8 8 8 8 8))))))))
;; in 3 4 time:
- ;; use defaults -- no entries necessary
+ ;; use defaults, but combine all beats into a unit if possible
;;
- ;; Whole measure beaming is controlled by context property
- ;; beamWholeMeasure
- ;; Half measure beaming is controlled by context property
- ;; beamHalfMeasure
-
+ ;; set all beams to end on beats, but 1 8 to beam entire measure
+ ;; in order to avoid beaming every beam type for the entire measure, we set
+ ;; triplets back to every beat.
((3 . 4) .
- ((beamExceptions . ())))
+ ((beamExceptions . ((end . (((1 . 8) . (6)) ;1/8 note whole measure
+ ((1 . 12) . (3 3 3)))))))) ;Anything shorter by beat
;; in 3 8 time:
;; beam entire measure together
projects / lilypond.git / commitdiff