lily/bezier-bow.cc

   1 /*
   2   bezier.cc -- implement Bezier and Bezier_bow
   3
   4   source file of the GNU LilyPond music typesetter
   5
   6   (c) 1998--2000 Jan Nieuwenhuizen <janneke@gnu.org>
   7 */
   8
   9 #include <math.h>
  10 #include "bezier-bow.hh"
  11 #include "misc.hh"
  12 #include "bezier.hh"
  13 #include "dimensions.hh"
  14 #include "direction.hh"
  15 #include "debug.hh"
  16 #include "main.hh"
  17 #include "lily-guile.hh"
  18 #include "paper-def.hh"
  19
  20
  21 Bezier_bow::Bezier_bow (Array<Offset> encompass, Direction dir)
  22 {
  23   alpha_ = 0;
  24   dir_ = dir;
  25   encompass_ = encompass;
  26   to_canonical_form ();
  27 }
  28
  29 Bezier
  30 Bezier_bow::get_bezier () const
  31 {
  32   Bezier rv = curve_;
  33   if (dir_ == DOWN)
  34     {
  35       rv.flip (Y_AXIS);
  36     }
  37
  38   rv.rotate (alpha_);
  39   rv.translate (origin_);
  40
  41   return rv;
  42 }
  43
  44 void
  45 Bezier_bow::to_canonical_form ()
  46 {
  47   origin_ = encompass_[0];
  48   translate (&encompass_, -origin_);
  49
  50   Offset delta = encompass_.top () - encompass_[0];
  51   alpha_ = delta.arg ();
  52
  53   rotate (&encompass_, -alpha_);
  54   if (dir_ == DOWN)
  55     {
  56       flip (&encompass_, Y_AXIS);
  57     }
  58
  59   while (encompass_.size () > 1 && encompass_[1][X_AXIS] <= 0.0)
  60     {
  61       programming_error ("Degenerate bow: infinite steepness reqd");
  62       encompass_.del (1);
  63     }
  64
  65   Real l = encompass_.top ()[X_AXIS];
  66   while (encompass_.size () > 1 && encompass_.top (1)[X_AXIS] >= l)
  67     {
  68       programming_error ("Degenerate bow: infinite steepness reqd");
  69       encompass_.del (encompass_.size ()-2);
  70     }
  71 }
  72
  73 void
  74 Bezier_bow::set_default_bezier (Real h_inf, Real r_0)
  75 {
  76   curve_ = get_default_bezier (h_inf, r_0);
  77 }
  78
  79 /*
  80   See Documentation/programmer/fonts.doc
  81  */
  82 Bezier
  83 Bezier_bow::get_default_bezier (Real h_inf, Real r_0) const
  84 {
  85   Offset delta (encompass_.top ()[X_AXIS] - encompass_[0][X_AXIS], 0);
  86   Real b = delta.length ();
  87   Real height = get_default_height (h_inf, r_0, b);
  88   // urg: scmify this?
  89   Real indent = height;
  90
  91   Bezier curve;
  92   curve.control_[0] = Offset (0, 0);
  93   curve.control_[1] = Offset (indent, height);
  94   curve.control_[2] = Offset (b - indent, height);
  95   curve.control_[3] = Offset (b, 0);
  96   return curve;
  97 }
  98
  99 /*
 100   See Documentation/programmer/fonts.doc
 101  */
 102 Real
 103 Bezier_bow::get_default_height (Real h_inf, Real r_0, Real b) const
 104 {
 105 #if 0
 106   Real pi = M_PI;
 107
 108   Real alpha = 2.0 * h_inf / pi;
 109   Real beta = pi * r_0 / (2.0 * h_inf);
 110
 111   return alpha * atan (beta * b);
 112 #else
 113   SCM h = scm_eval (scm_listify (ly_symbol2scm ("slur-default-height"),
 114                                  gh_double2scm (h_inf),
 115                                  gh_double2scm (r_0),
 116                                  gh_double2scm (b),
 117                                  SCM_UNDEFINED));
 118   return gh_scm2double (h);
 119 #endif
 120 }
 121