Reviewers: ,
Message:
following up on modal transformation
Description:
exact inversion
Please review this at http://codereview.appspot.com/4173065/
Affected files:
M Documentation/notation/pitches.itely
M input/regression/modal-transforms.ly
M ly/music-functions-init.ly
M scm/modal-transforms.scm
Index: Documentation/notation/pitches.itely
diff --git a/Documentation/notation/pitches.itely
b/Documentation/notation/pitches.itely
index
78a222794d195e9ceae5c812971e5f6b2357a824..63c0ccce39465edcb1896eaa7e2940782e6fc002
100644
--- a/Documentation/notation/pitches.itely
+++ b/Documentation/notation/pitches.itely
@@ -594,6 +594,7 @@ This section discusses how to modify pitches.
@menu
* Octave checks::
* Transpose::
+* Inversion::
* Modal transformations::
@end menu
@@ -813,6 +814,23 @@ The relative conversion will not affect
@code{\transpose},
To use relative mode within transposed music, an additional
@code{\relative} must be placed inside @code{\transpose}.
+@node Inversion
+@unnumberedsubsubsec Inversion
+
+@cindex inversion
+
+A music expression can be inverted with @code{\inversion}.
+The syntax is
+
+@example
+\inversion @var{frompitch} @var{topitch} @var{musicexpr}
+@end example
+
+@noindent
+This means that @code{@var{musicexpr}} is inverted interval by
+interval, and transposition is chosen so that @code{@var{frompitch}}
+is mapped to @code{@var{topitch}}.
+
@node Modal transformations
@unnumberedsubsubsec Modal transformations
Index: input/regression/modal-transforms.ly
diff --git a/input/regression/modal-transforms.ly
b/input/regression/modal-transforms.ly
index
907060151073b9e77e147a19b120bfae8350b3ae..7487f2b8bfe34d6cf1752fa8e244f6b50439f704
100644
--- a/input/regression/modal-transforms.ly
+++ b/input/regression/modal-transforms.ly
@@ -22,12 +22,14 @@ motif = {
\modalTranspose c' f' \cOctatonicScale \motif
\retrograde \motif
\modalInversion aes' b' \cOctatonicScale \motif
+ \inversion aes' b' \motif
}
{
s1-"Octatonic motif" |
s1-"motif transposed from c to f" |
s1-"motif in retrograde" |
s1-"motif inverted around aes to b" |
+ s1-"motif inverted exactly"
}
>>
}
Index: ly/music-functions-init.ly
diff --git a/ly/music-functions-init.ly b/ly/music-functions-init.ly
index
34261c114b2d7f3e9606fa50c2d4f95bb0e7d869..ac62bffa9ae67575da8bbce6e60ec12fd8d18595
100644
--- a/ly/music-functions-init.ly
+++ b/ly/music-functions-init.ly
@@ -480,6 +480,13 @@ using @var{scale}.")
(change-pitches music transposer)
music))
+inversion =
+#(define-music-function
+ (parser location around to music) (ly:music? ly:music? ly:music?)
+ (_i "Invert @var{music} about @var{around} and
+transpose from @var{around} to @var{to}.")
+ (music-invert around to music))
+
musicMap =
#(define-music-function (parser location proc mus) (procedure? ly:music?)
(_i "Apply @var{proc} to @var{mus} and all of the music it contains.")
Index: scm/modal-transforms.scm
diff --git a/scm/modal-transforms.scm b/scm/modal-transforms.scm
index
cdaa015ccc08099c251c51304ece2c77a66c61d9..151fb8c3be06edcea7e213291989398428d43fea
100644
--- a/scm/modal-transforms.scm
+++ b/scm/modal-transforms.scm
@@ -220,3 +220,20 @@ Typically used to construct a scale for input to
transposer-factory
(map retrograde-music reversed)
music))
+
+(define-public (pitch-invert around to music)
+ "If @var{music} is a single pitch, inverts it about @var{around}
+and transposes from @var{around} to @var{to}."
+ (let ((p (ly:music-property music 'pitch)))
+ (if (ly:pitch? p)
+ (ly:music-set-property!
+ music 'pitch
+ (ly:pitch-transpose to (ly:pitch-diff around p))))
+ music))
+
+(define-public (music-invert around-pitch to-pitch music)
+ "Applies pitch-invert to all pitches in @var{music}."
+ (let ((around (car (extract-pitch-sequence around-pitch)))
+ (to (car (extract-pitch-sequence to-pitch))))
+ (music-map (lambda (x) (pitch-invert around to x)) music)))
+
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