rthm-chain/add-voice [ Methods ]

[ Top ] [ rthm-chain ] [ Methods ]

DESCRIPTION

 The main rthm-chain algorithm generates only two voices.  Rather than
 generate further voices in the same fashion, use the already created
 rthm-seqs to create other voices.  The challenge here is that each rthm-seq
 has potentially its own time signature structure: there could be a 2/4 bar
 followed by 5/4 then 3/16; or any other combination of any meter.  So first
 of all, we analyse the time-signature structure of the existing rthm-seqs
 and save those with the same bar/meter structure together in the order in
 which they occurred.  When creating the extra voice then, we actually start
 ahead of the main voice, by choosing <offset> similar rthm-seqs in advance

ARGUMENTS

 - the rthm-chain instance
 - the parent voice i.e. a reference into the create rthm-seq-map (e.g. '(1
 perc1) 
 - the id of the new player (symbol)
 - (optional: offset default 1): which similar rthm-seq to start at (so
 generated voice will be ahead of main voice)

RETURN VALUE

 t

EXAMPLE

DATE

SYNOPSIS

(defmethod add-voice ((rc rthm-chain) parent new-player &optional (offset 1))

rthm-chain/hash-least-used [ Functions ]

[ Top ] [ rthm-chain ] [ Functions ]

DESCRIPTION

ARGUMENTS

OPTIONAL ARGUMENTS

RETURN VALUE

EXAMPLE

SYNOPSIS

(defun hash-least-used (hash &key (start 0) end ignore (auto-inc t))

rthm-chain/make-rthm-chain [ Functions ]

[ Top ] [ rthm-chain ] [ Functions ]

DESCRIPTION

 Create an instance of a rthm-chain object. The rthm-chain class enables the
 algorithmic generation of a rthm-seq-map (with just one section) and its
 associated rthm-seq-palette, which consists in turn of algorithmically
 generated rthm-seq objects.

 The rhythm-seq objects are made up of both faster material based on 1-beat
 groups and slower-moving counterpoint based on 2- or 3-beat groups.

 The rthm-chain class also allows for control of the degree of activity in
 the parts over time through user-specified envelopes.

 Rests are automatically inserted at regular but changing intervals.

 Specified 'sticking points' cause individual rhythms to be repeated a
 certain number of times. Sticking happens after rests and can also be
 controlled with an activity envelope. 

 NB: Because this method uses the procession method internally, each
     collection of 1-beat-rthms and slower-rthms defined must contain at
     least four items.

 NB: Since this method automatically inserts rests into the chains, the user
     may like to implement the various tie-over-rests post-generation
     editing methods. If this is done, the handle-ties method may also be
     recommended, as the tie-over-rests methods only affect printed output
     and not MIDI output.

ARGUMENTS

 - A number, symbol, or string that is to be the ID of the new rthm-chain
   object. 
 - An integer that is the number of beats to be generated prior to adding
   additional material created from sticking points and the automatic
   addition of rests.
 - A list with sublists of rhythms that are to be the 1-beat rhythms used to
   construct the faster-moving material of the rthm-seq-palette. Each
   sublist represents the repertoire of rhythms that will be used by the
   procession method. Each sublist must contain the same number of rthms but
   their number and the number of sublists is open. A transition will be
   made from one group of rhythms to the next over the whole output
   (i.e. not one unit to another within e.g. the 1-beat rhythms) according
   to a fibonacci-transition method.
 - A list with sublists of 2-beat and 3-beat full bars of rhythms used to
   construct the slower-moving counterpoint material of the
   rthm-seq-palette. This will be turned into a rthm-chain-slow object, and
   will therefore remain as lists of unparsed rhythms. Each sublist must
   contain the same number of rthms but their number and the number of
   sublists is open. A transition will be made from one group of rhythms to
   the next over the whole output (i.e. not one unit to another within
   e.g. the 1-beat rhythms) according to a fibonacci-transition method. 
   NB: The rhythm units of slower-rthms must be expressed in single beats;
   e.g., a 2/4 bar must consist of q+q rather than h. The consolidate-notes
   method can be called afterwards if desired.

OPTIONAL ARGUMENTS

 keyword arguments:
 - :beat. An integer that indicates the rhythmic unit of the primary beat
   basis of the rhythms specified. Default = 4.
 - :1-beat-fibonacci. T or NIL to indicate whether the sequence of 1-beat
   rhythms is to be generated using the fibonacci-transitions method or the
   processions method. T = use fibonacci-transitions method. Default = NIL.
 - :slow-fibonacci. T or NIL to indicate whether the sequence of the slow
   rhythms will be generated using the fibonacci-transitions method or the
   processions method. This affects the order in which each 2- or 3-beat
   unit is used when necessary, not the order in which each 2- or 3-beat
   unit is selected; the latter is decided by the next element in the DATA
   slot of the rthm-chain-slow object, which simply cycles through 
   '(2 3 2 2 3 2 2 3 3 3). T = use fibonacci-transisitions method.
   Default = NIL.
 - :players. A list of player IDs. When used in conjunction with a
   slippery-chicken object (which is the standard usage), these must be IDs
   as they are defined in that object's ENSEMBLE slot. 
   Default = '(player1 player2).
 - :section-id. An integer that will be used as the ID of the rthm-seq-map
   created. NB: rthm-chain only creates rthm-seq-maps with one section,
   making it possible to create several different ones for different
   sections in the given piece, and requiring that these be manually
   assigned IDs. Default = 1. 
 - :rests. The rhythmic duration unit(s) of the rests that will be used when
   the method uses the rest-insertion algorithm to automatically insert
   rests into the resulting objects. The specified rests are used in a
   sequence determined by a recurring-event object. Default = '(e q q. w).
 - :do-rests. T or NIL to indicate whether to apply the automatic
   rest-insertion algorithm. T = use. Default = T.
 - :rest-cycle. A list of 2-item lists that indicate the pattern by which
   rests of specific rhythmic durations will be selected from the RESTS slot
   for automatic insertion. The first number of each pair is a 0-based
   position referring to the list of rests in the RESTS slot, and the second
   number is the number of times the rest at that particular position should
   be inserted. (This number does not mean that the selected rest will be
   inserted that many times at once, but rather that each consecutive time
   the rest algorithm selects one rest to be inserted, it will insert that
   specific rest, for the specified number of consecutive times.) For
   example, (0 3) indicates that for the next three times that the rest
   algorithm selects one rest to insert, it will select the rest located at
   position 0 in the list of rests in the RESTS slot (e by default).
   Default ='((0 3) (1 1) (0 2) (2 1) (1 1) (3 1)).
 - :do-rests-curve. A list of break-point pairs with y values of either 0 or
   1 indicating whether the do-rests algorithm is active or disabled. This
   values are interpolated between each pair, with all values 0.5 and higher
   being round up to 1 and all below 0.5 rounded to 0. Default = NIL.
 - :rest-re. A list of 2-item lists that indicate the pattern by which rests
   will be automatically inserted. The first number of each pair determines
   how many events occur before inserting a rest, and the second number of
   each pair determines how many times that period will be repeated. For
   example, (2 3) indicates that a rest will be inserted every two events,
   three times in a row. The list passed here will be treated as data for a
   recurring-event object that will be repeatedly cycled through.  
   Default = '((2 3) (3 2) (2 2) (5 1) (3 3) (8 1)).
 - :activity-curve. A list of break-point pairs with y values from 1 to 10
   indicating the amount of activity there should be over the course of the
   piece. A value of 1 indicates that only 1 in 10 beats will have notes
   in/on them, and a value of 10 indicates that all beats will have
   notes. This process uses the patterns given in
   activity-levels::init-instance below, where 1 means 'play' and 0 means
   'rest'. There are three examples of each level, so that if the curve
   remains on one level of activity for some time it won't always return the
   same pattern; these will be rotated instead. If the activity curve
   indicates a rest for one of the slower-rhythms groups, the whole 2-3 beat
   group is omitted.
 - :harmonic-rthm-curve. A list of break-point pairs that indicates how many
   slower-rthms will be combined into one rthm-seq (each rthm-seq has a
   single harmony). The default is 2 bars (slower-rthms) per rthm-seq,
   i.e. '(0 2 100 2).
 - :do-sticking. T or NIL to indicate whether the method should apply the
   sticking algorithm. T = apply. Default = T.
 - :do-sticking-curve. A list of break-point pairs that can be used,
   alternatively, to control whether the sticking algorithm is being applied
   or not at any given point over the course of the piece. The y values for
   this curve should be between 0 and 1, and the decimal fractions achieved
   from interpolation will be rounded. The 1 values resulting from this
   curve will only be actively applied to if do-sticking is set to T.
 - :sticking-curve. A list of break-point pairs that acts as an activity
   envelope to control the sticking, which always occurs after rests. As
   with the activity curve, this curve can take y values up to 10, but also
   allows 0. A y value of 0 or 1 here refers to either a specific number of
   repeats (1) or none (0). The number of repeats may be determined, for
   example, by use of the procession method, such as 
   (procession 34 '(2 3 5 8 13) :peak 1 :expt 3). Every sticking point is
   accompanied by a slower group, which is simply chosen in sequence and
   repeated for the duration of the sticking period.
 - :sticking-repeats. A list of integers to indicate the number of
   repetitions applied in sticking segments. When the values of this list
   have been exhausted, the method cycles to the beginning and continues
   drawing from the head of the list again. NB: This list is made into a
   circular-sclist object when the given rthm-chain object is initialized
   unless a circular-sclist object is explicitly provided.
 - :sticking-rthm. A list of rhythmic units that will serve as the rhythms
   employed by the sticking algorithm. These are generated at initialization
   if not specified here. NB: This list is used to create a list using the
   procession algorithm at initialization, so it is best to apply something
   similar to the default if not accepting the default (if the user would
   like to specify a different list). If a circular-sclist object is
   provided here, it will be used instead of the default procession.
 - :split-data. NIL or a two-item list of integers that are the minimum and
   maximum beat duration of bars generated. If NIL, the bars will not be
   split. Default = '(2 5)

RETURN VALUE

 A rthm-chain object.

EXAMPLE

;; An example using a number of the keyword arguments.
(make-rthm-chain
 'test-rch 14
 '((((e) e) ; 4 in total
    (- s (s) (s) s -)
    ({ 3 (te) - te te - })
    ((e.) s))
   (({ 3 (te) te (te) }) ; what we transition to
    ({ 3 - te (te) te - })
    ({ 3 (te) - te te - })
    ({ 3 (te) (te) te })))
 '((((q q) ; the 2/4 bars: 5 total
     ((q) q)
     ((q) q)
     ((q) (s) e.)
     (- e e - (e) e))
    (({ 3 te+te te+te te+te }) ; what we transition to
     (q - s e. -)
     (q (s) e.)
     (q (s) - s e -)
     ({ 3 te+te te+te - te te - })))
   ((((e.) s (e) e (s) e.) ; the 3/4 bars: 4 total
     (- e e - (e) e (q))
     (- e. s - - +e e - (q))
     (q (e.) s (q)))
    (({ 3 (te) (te) te+te te+te } (q)) ; what we transition to
     (- e. s - (q) (s) - s e -)
     ({ 3 te+te te } (q) q)
     ({ 3 - te te te - } (e) e { 3 (te) (te) te }))))
 :players '(fl cl)
 :slow-fibonacci t
 :activity-curve '(0 1 100 10)
 :harmonic-rthm-curve '(0 1 100 3)
 :do-sticking t
 :do-sticking-curve '(0 1 25 0 50 1 75 0 100 1)
 :sticking-curve '(0 0 100 10)
 :sticking-repeats '(3 5 7 11 2 7 5 3 13)
 :sticking-rthms '(e s. 32 e.)
 :split-data '(4 7))

=>
RTHM-CHAIN: 1-beat-rthms: (((E E) (S S S S) (TE TE TE) (E. S))
                           ((TE TE TE) (TE TE TE) (TE TE TE) (TE TE TE)))
            slower-rthms: ((((Q Q) ((Q) Q) ((Q) Q) ((Q) (S) E.)
                             (- E E - (E) E))
                            (({ 3 TE+TE TE+TE TE+TE }) (Q - S E. -)
                             (Q (S) E.) (Q (S) - S E -)
                             ({ 3 TE+TE TE+TE - TE TE - })))
                           ((((E.) S (E) E (S) E.) (- E E - (E) E (Q))
                             (- E. S - - +E E - (Q)) (Q (E.) S (Q)))
                            (({ 3 (TE) (TE) TE+TE TE+TE } (Q))
                             (- E. S - (Q) (S) - S E -)
                             ({ 3 TE+TE TE } (Q) Q)
                             ({ 3 - TE TE TE - } (E) E { 3 (TE) (TE) TE
                              }))))
            1-beat-fibonacci: NIL
            num-beats: 14
            slow-fibonacci: NIL
            num-1-beat-rthms: 4
            num-1-beat-groups: 2
            sticking-curve: (0.0 0 13 10)
            harmonic-rthm-curve: (0.0 1 13 3)
            beat: 4
            do-sticking: T
            do-rests: T
            do-sticking-curve: (0.0 1 3.25 0 6.5 1 9.75 0 13 1)
            do-rests-curve: NIL
            sticking-al: (not printed for brevity's sake)
            sticking-rthms: (E S. E S. 32 E 32 E E E. S. 32 S. E. S. 32 S.
                             32 E. E)
            sticking-repeats: (3 5 3 5 7 3 7 3 3 11 5 7 5 11 5 7 5 7 11 3
                               7 3 3 11 5 7 5 11 3 7 3 7 11 5 7 5 5 11 3
                               11 3 2 11 2 11 2 7 2 7 2 2 5 5 3 5)
            activity-curve: (0.0 1 13 10)
            main-al: (not printed for brevity's sake)
            slower-al: (not printed for brevity's sake)
            num-slower-bars: 11
            rcs: (not printed for brevity's sake)
            rests: (E Q Q. W)
            rest-re: (not printed for brevity's sake)
            rest-cycle: ((0 3) (1 1) (0 2) (2 1) (1 1) (3 1))
            num-rthm-seqs: 11
            section-id: 1
            split-data: (4 7)
RTHM-SEQ-MAP: num-players: 2 
              players: (CL FL)
SC-MAP: palette id: RTHM-CHAIN-RSP
[...]

SYNOPSIS

(defun make-rthm-chain (id num-beats 1-beat-rthms slower-rthms &key
                        (1-beat-fibonacci nil)
                        (slow-fibonacci nil)
                        (players '(player1 player2))
                        (section-id 1)
                        (rests '(e q q. w))
                        (do-rests t)
                        (do-rests-curve nil)
                        (rest-re '((2 3) (3 2) (2 2) (5 1) (3 3) (8 1)))
                        (rest-cycle '((0 3) (1 1) (0 2) (2 1) (1 1) (3 1)))
                        (activity-curve '(0 10 100 10))
                        (sticking-curve '(0 2 100 2))
                        (harmonic-rthm-curve '(0 2 100 2))
                        (do-sticking t)
                        (do-sticking-curve nil)
                        (sticking-repeats '(3 5 3 5 8 13 21))
                        (sticking-rthms '(e e e. q e s))
                        (split-data '(2 5)))

rthm-chain/procession [ Functions ]

[ Top ] [ rthm-chain ] [ Functions ]

DATE

 26-Jan-2010

DESCRIPTION

 Generate a list of a specified length consisting of items extrapolated from
 a specified starting list. All elements of the resulting list will be
 members of the original list. 

 The method generates the new list by starting with the first 3 elements of
 the initial list and successively adding consecutive elements from the
 initial list until all elements have been added.

ARGUMENTS

 - An integer that is the number of items in the list to be generated.
 - A list of at least 4 starting items or an integer >=4. If an integer is
   given rather than a list, the method will process a list of consecutive
   numbers from 1 to the specified integer.

OPTIONAL ARGUMENTS

 keyword arguments:
 - :peak. A decimal number >0.0 and <=1.0. This number indicates the target
   location in the new list at which the last element is to finally occur,
   whereby e.g. 0.7 = ~70% of the way through the resulting list. This is an
   approximate value only. The last element may occur earlier or later
   depending on the values of the other arguments. In particular, initial
   lists with a low number of items are likely to result in new lists in
   which the final element occurs quite early on, perhaps even nowhere near
   the specified peak value. Default = 0.7.
 - :expt. A (decimal) number that indicates the "curve" that determines the
   intervals at which each successive element of the initial list is
   introduced to the new list. A higher number indicates a steeper
   exponential curve. Default = 1.3.
 - :orders. The patterns by which the elements are added. The method
   cyclically applies these orders, the numbers 1, 2, and 3 representing the
   three least used elements at each pass. These orders must therefore
   contain all of the numbers 1, 2, and 3, and those numbers only. 
   Default = '((1 2 1 2 3) (1 2 1 1 3) (1 2 1 3)).

RETURN VALUE

 Returns two values, the first being the new list, with a secondary value
 that is a list of 2-item lists that show the distribution of each element
 in the new list.

EXAMPLE

(procession 300 30 :peak 0.1)

=>
(1 2 1 2 3 4 5 4 4 6 7 8 7 9 10 11 10 11 12 13 14 13 13 15 16 17 16 18 19 20 19
   20 21 22 23 22 22 24 25 26 25 27 28 29 28 29 30 3 5 3 3 6 8 9 8 12 14 15 14
   15 17 18 21 18 18 23 24 26 24 27 1 2 1 2 30 5 6 5 5 7 9 10 9 11 12 16 12 16
   17 19 20 19 19 21 23 25 23 26 27 28 27 28 29 4 6 4 4 30 7 8 7 10 11 13 11 13
   14 15 17 15 15 20 21 22 21 24 25 26 25 26 29 1 2 1 1 30 3 6 3 8 9 10 9 10 12
   14 16 14 14 17 18 20 18 22 23 24 23 24 27 28 29 28 28 30 2 5 2 6 7 8 7 8 11
   12 13 12 12 16 17 19 17 20 21 22 21 22 25 26 27 26 26 29 3 4 3 30 5 6 5 6 9
   10 11 10 10 13 15 16 15 18 19 20 19 20 23 24 25 24 24 27 1 29 1 30 2 4 2 4 7
   8 9 8 8 11 13 14 13 16 17 18 17 18 21 22 23 22 22 25 27 28 27 29 3 5 3 5 30
   6 7 6 6 9 11 12 11 14 15 16 15 16 19 20 21 20 20 23 25 26 25 28 1 29 1 29 30
   2 4 2 2 7 9 10 9 12 13 14 13 14 17 18), ((2 12) (20 11) (14 11) (13 11) 
   (9 11) (6 11) (1 11) (29 10) (25 10) (22 10) (18 10) (17 10) (16 10) (15 10)
   (12 10) (11 10) (10 10) (8 10) (7 10) (5 10) (4 10) (3 10) (30 9) (28 9) 
   (27 9) (26 9) (24 9) (23 9) (21 9) (19 9))

(procession 300 30 :peak 0.9)

=>
(1 2 1 2 3 1 3 1 1 4 2 3 2 4 3 4 3 4 5 2 4 2 2 5 1 3 1 5 3 4 3 4 5 1 5 1 1 6 2
   5 2 6 4 5 4 5 6 3 6 3 3 7 5 6 5 7 2 6 2 6 7 6 7 6 6 8 4 7 4 8 7 8 7 8 9 7 8
   7 7 9 8 9 8 10 8 9 8 9 10 8 9 8 8 10 9 10 9 11 9 10 9 10 11 10 11 10 10 12
   10 11 10 12 11 12 11 12 13 11 12 11 11 13 12 13 12 14 12 13 12 13 14 13 14
   13 13 15 13 14 13 15 11 14 11 14 15 14 15 14 14 16 15 16 15 17 15 16 15 16
   17 16 17 16 16 18 16 17 16 18 17 18 17 18 19 17 18 17 17 19 18 19 18 20 18
   19 18 19 20 19 20 19 19 21 15 20 15 21 20 21 20 21 22 20 21 20 20 22 21 22
   21 23 21 22 21 22 23 22 23 22 22 24 23 24 23 25 23 24 23 24 25 24 25 24 24
   26 23 25 23 26 25 26 25 26 27 26 27 26 26 28 25 27 25 28 27 28 27 28 29 27
   28 27 27 29 28 29 28 30 24 29 24 29 30 26 29 26 26 30 28 29 28 30 19 29 19
   29 30 22 25 22 22 30 12 27 12 30 14 16 14 16 30 17), ((8 12) (22 11)
   (16 11) (14 11) (12 11) (11 11) (10 11) (4 11) (3 11) (2 11) (26 10) 
   (19 10) (17 10) (15 10) (13 10) (9 10) (7 10) (6 10) (5 10) (1 10)
   (29 9) (28 9) (27 9) (25 9) (24 9) (23 9) (21 9) (20 9) (18 9) (30 8))

SYNOPSIS

(defun procession (num-results items 
                   &key 
                   ;; what proportion of the way through should we aim to reach
                   ;; the max number of items?  NB This is approximate only:
                   ;; you may find the first occurrence of the highest element
                   ;; earlier or later depending on the values of the other
                   ;; arguments.  In particular, with a low number of items the
                   ;; highest element will be hit very early on, perhaps
                   ;; nowhere near the peak argument.
                   (peak 0.7)
                   ;; for an exponential curve going from 3 to num <items>
                   (expt 1.3)
                   ;; these are the orders we'll use at the beginning
                   ;; (cyclically). They will then be used when we've gone
                   ;; beyond 3 items by always using the 3 least used items.
                   ;; NB This must contain the numbers 1, 2, and 3 only but
                   ;; there can be 1 or any number of sublists. 
                   (orders '((1 2 1 2 3) (1 2 1 1 3) (1 2 1 3))))

rthm-chain/reset [ Methods ]

[ Top ] [ rthm-chain ] [ Methods ]

DESCRIPTION

ARGUMENTS

OPTIONAL ARGUMENTS

RETURN VALUE

EXAMPLE

SYNOPSIS

(defmethod reset ((rc rthm-chain) &optional where)

rthm-chain/rthm-chain-gen [ Methods ]

[ Top ] [ rthm-chain ] [ Methods ]

DESCRIPTION

 Generate a chain of rhythms, also internally making use of the procession
 function. 
 The basic algorithm for 2 parts is: we're given an arbitrary number of
 1-beat rthms (e.g. s s (e)) and 2-3 beat slower-moving counterpoints.  We
 generate a sequence of these using the procession function.  Then we apply
 the activity curve, and after that the insertion of 8th rests.  Then come
 the 'sticking points': these come after the rests and the activity curves
 applied to these count inserted rests not seqs or beats.
 
 NB: Rests are put into the rthm-seq mid-sequence so sticking points won't
     come straight after the rests, rather, at the end of the seq.
 
 The activity curves that turn notes into rests will be queried every beat
 so if we change an activity level we don't wait until the end of the
 previous level's ten beats.
 
 NB: This method is not generally called by the user (though it can be of
     course), rather it's called by the init function.

ARGUMENTS

 - A rthm-chain object.

OPTIONAL ARGUMENTS

 keyword arguments:
 - (key :rests ) whether to generate the rests default: t
 - (key :stick)  whether to generate the sticking point s
 - (key :num-beats ) how many beats to use for the
    algorithm. NB we'll generate considerably more if we have sticking and
    rests; this number really just refers to the number of standard 1-beat
    rhythms we'll generate.  If nil, then we use the num-beats slot of the
    rc instance. default: nil
 - (key :use-fibonacci ) whether to use a fibonacci transition to
    move through the 1-beat rhythms (so they'll be repeated) or the
    procession algorithm (where they'll be alternated). default t
 - (key :section-id ) for the sake of the map, what section we'll
    put the references into.  The rthm-seqs themselves will be parcelled up
    into an object with this id too, so we can avoid id conflicts if we
    combine 2+ sections generatd by separate rthm-chain objects. default 1
 - (key :split ): whether to split up longer generated bars
   (e.g. 7/4) into smaller bars.  If this is a two-element list it
    represents the min/max number of beats in a bar (where a 6/8 bar is two
    compound beats) default '(2 5)
 - (key :wrap ): when we create the 1-beat rythms' and slow
    rhythms' order, we can choose to start at any point in the list default nil

RETURN VALUE

 the number of rthm-seqs we've generated

SYNOPSIS

(defmethod rthm-chain-gen ((rc rthm-chain)
                           &key
                           (use-fibonacci t) 
                           (rests t)
                           (stick t)
                           (section-id 1)
                           num-beats
                           wrap)

rthm-chain/split [ Methods ]

[ Top ] [ rthm-chain ] [ Methods ]

DESCRIPTION

ARGUMENTS

OPTIONAL ARGUMENTS

RETURN VALUE

EXAMPLE

SYNOPSIS

(defmethod split ((rc rthm-chain) &key
                  (min-beats 2) (max-beats 5) warn (clone t))

rthm-seq-map/rthm-chain [ Classes ]

[ Top ] [ rthm-seq-map ] [ Classes ]

NAME

 rthm-chain

 File:             rthm-chain.lsp

 Class Hierarchy:  named-object -> linked-named-object -> sclist -> 
                   circular-sclist -> assoc-list -> recursive-assoc-list ->
                   sc-map -> rthm-seq-map -> rthm-chain
 
 Version:          1.0.0-beta2

 Project:          slippery chicken (algorithmic composition)

 Purpose:          Algorithmic generation of rthm-seqs that include
                   slower-moving counterpoint and a means to control
                   activity development through curves.  Here we generate a
                   rthm-seq-map and its associated palette algorithmically.

                   Say we have 9 irregular 1 beat duration patterns; these
                   would enter in the sequence defined by (procession x 9)
                   where x would be the number of patterns to generate. 
 
                   Rests are inserted at regular but changing intervals e.g
 
                   3x every 2 beats (6)
                   2x every 3 beats (6)
                   3x every 5 beats (15)
                   2x every 8 beats (16)
 
                   e, q, and q. rests are used by default, in a sequence
                   determined by a recurring-event instance.
 
                   In order to make music that 'progresses' we have curves
                   with y values from 1-10 indicating how much activity
                   there should be: 1 would mean only 1 in 10 beats would
                   have notes in/on them, 10 would indicate that all do.  We
                   use the patterns given in activity-levels::init-instance
                   below, where 1 means 'play', 0 means 'rest'.  There are
                   three examples of each level so that if we stick on one
                   level of activity for some time we won't always get the
                   same pattern: these will instead be cycled through.
 
                   A slower moving (bass) line is also added that is made up
                   of 2 or 3 beat groups---if the activity curve indicates a
                   rest, then the whole 2-3 beat group is omitted.
 
                   There are also 'sticking points' where a rhythm will be
                   repeated a certain number of times (either s,e,e., or q
                   by default).  Sticking happens after rests.  This can be
                   controlled with an activity envelope too, also indicating
                   one of the 10 patterns above (but also including 0).  A 0
                   or 1 unit here would refer to a certain number of repeats
                   (1) or none (0).  How many repeats could be determined by
                   something like: (procession 34 '(2 3 5 8 13) :peak 1
                   :expt 3) There's always a slower group to accompany the
                   sticking points: simply the next in the sequence,
                   repeated for as long as we stick
 
                   The harmonic-rthm curve specifies how many slower-rthms
                   will be combined into a rthm-seq (each rthm-seq has a
                   single harmony).  The default is 2 bars (slower-rthms)
                   per rthm-seq.
 

 Author:           Michael Edwards: m@michael-edwards.org

 Creation date:    4th February 2010

 $$ Last modified: 15:11:21 Mon May 21 2012 BST

 SVN ID: $Id: rthm-chain.lsp 1982 2012-05-24 15:35:54Z medward2 $