release: 1.3.90

[lilypond.git] / scm / basic-properties.scm

diff --git a/scm/basic-properties.scm b/scm/basic-properties.scm
index 469cc1e3fea762aa7a3c828f15bc9f389731fd58..3dadb920c01d054832691d0f6eef98c325962dbc 100644 (file)
--- a/scm/basic-properties.scm
+++ b/scm/basic-properties.scm
@@ -11,13 +11,11 @@
 
 (define mark-visibility end-of-line-invisible)
 
-; ugh: should calculate from beam-thickness.
-; result in staff-space
 
-;beam_thickness = 0.52 * (\staffspace - \stafflinethickness);
-;interbeam = (2.0 * \staffspace + \stafflinethickness - \beam_thickness) / 2.0;
-;interbeam4 = (3.0 * \staffspace - \beam_thickness) / 3.0;
 
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;                  BEAMS
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 (define (default-beam-space-function multiplicity)
   (if (<= multiplicity 3) 0.816 0.844)
@@ -34,19 +32,138 @@
    ))
 
 
+; This is a mess : global namespace pollution. We should wait
+;  till guile has proper toplevel environment support.
+
+
+;; Beams should be prevented to conflict with the stafflines, 
+;; especially at small slopes
+;;    ----------------------------------------------------------
+;;                                                   ########
+;;                                        ########
+;;                             ########
+;;    --------------########------------------------------------
+;;       ########
+;;
+;;       hang       straddle   sit        inter      hang
+
+;; inter seems to be a modern quirk, we don't use that
+
+  
+;; Note: quanting period is take as quants.top () - quants[0], 
+;; which should be 1 (== 1 interline)
+(define (mean a b) (* 0.5 (+ a  b)))
+(define (default-beam-dy-quants beam stafflinethick)
+  (let ((thick (ly-get-elt-property beam 'thickness))
+       )
+    
+    (list 0 (mean thick stafflinethick) (+ thick stafflinethick) 1)
+    ))
+
+;; two popular veritcal beam quantings
+;; see params.ly: #'beam-vertical-quants
+
+; (todo: merge these 2 funcs ? )
+
+(define (default-beam-y-quants beam multiplicity dy staff-line)
+  (let* ((beam-straddle 0)
+        (thick (ly-get-elt-property beam 'thickness))
+        (beam-sit (/ (+ thick staff-line) 2))
+        (beam-hang (- 1 (/ (- thick staff-line) 2)))
+        (quants (list beam-hang))
+        )
+    
+    (if (or (<= multiplicity 1) (>= (abs dy) (/ staff-line 2)))
+       (set! quants (cons beam-sit quants)))
+    (if (or (<= multiplicity 2) (>= (abs dy) (/ staff-line 2)))
+       (set! quants (cons beam-straddle quants)))
+    ;; period: 1 (interline)
+    (append quants (list (+ 1 (car quants))))))
+
+(define (beam-traditional-y-quants beam multiplicity dy staff-line)
+  (let* ((beam-straddle 0)
+       (thick (ly-get-elt-property beam 'thickness))
+       (beam-sit (/ (+ thick staff-line) 2))
+       (beam-hang (- 1 (/ (- thick staff-line) 2)))
+       (quants '())
+       )
+    (if (>= dy (/ staff-line -2))
+       (set! quants (cons beam-hang quants)))
+    (if (and (<= multiplicity 1) (<= dy (/ staff-line 2)))
+       (set! quants (cons beam-sit quants)))
+    (if (or (<= multiplicity 2) (>= (abs dy) (/ staff-line 2)))
+       (set! quants (cons beam-straddle quants)))
+    ;; period: 1 (interline)
+    (append quants (list (+ 1 (car quants))))))
+
+
+;; There are several ways to calculate the direction of a beam
+;;
+;; * majority: number count of up or down notes
+;; * mean    : mean centre distance of all notes
+;; * median  : mean centre distance weighted per note
+
+(define (dir-compare up down)
+  (sign (- up down)))
+
+;; arguments are in the form (up . down)
+(define (beam-dir-majority count total)
+  (dir-compare (car count) (cdr count)))
+
+(define (beam-dir-mean count total)
+  (dir-compare (car total) (cdr total)))
+
+(define (beam-dir-median count total)
+  (if (and (> (car count) 0)
+          (> (cdr count) 0))
+      (dir-compare (/ (car total) (car count)) (/ (cdr total) (cdr count)))
+      (dir-compare (car count) (cdr count))))
+           
+
+
+;; [Ross] states that the majority of the notes dictates the
+;; direction (and not the mean of "center distance")
+;;
+;; But is that because it really looks better, or because he wants
+;; to provide some real simple hands-on rules?
+;;     
+;; We have our doubts, so we simply provide all sensible alternatives.
+
+
+
+
+
+;; array index multiplicity, last if index>size
+;; beamed stems
+
+
+;; TODO
+;;  - take #forced stems into account (now done in C++)?
+;;  - take y-position of chord or beam into account
+
+;;;;;;;;;;;;;;;;;;;;;;;
+
+
+;
+; todo: clean this up a bit: the list is getting rather long.
+; 
 (define basic-beam-properties
   `(
     (interfaces . (beam-interface))
     (molecule-callback . ,Beam::brew_molecule)
-    (beam-thickness . 0.42) ; staff-space, should use stafflinethick?
+    (thickness . 0.42) ; in staff-space, should use stafflinethick?
     (before-line-breaking-callback . ,Beam::before_line_breaking)
     (after-line-breaking-callback . ,Beam::after_line_breaking)
     (default-neutral-direction . 1)
+    (dir-function . ,beam-dir-majority)
+    (height-quants .  ,default-beam-dy-quants)
+    (vertical-position-quant-function . ,default-beam-y-quants)
+    (beamed-stem-shorten . (0.5))
     (outer-stem-length-limit . 0.2)
     (slope-limit . 0.2)
-    (beam-flag-width-function . ,default-beam-flag-width-function)
-    (beam-space-function . ,default-beam-space-function)
+    (flag-width-function . ,default-beam-flag-width-function)
+    (space-function . ,default-beam-space-function)
     (damping . 1)
-    (name . "beam")            
+    (name . "beam")
     )
   )