X-Git-Url: https://git.donarmstrong.com/?a=blobdiff_plain;f=lily%2Fbezier.cc;h=7d3ad6af14fff2d8d2a24267f6fc9e9b729dff6b;hb=0b544cfb7332615ef809b71b57ab656741311ae1;hp=ce84ce8da89c7623c68548539c49112c67b4c481;hpb=3f8a827aad721ed546b823e3f9f2605f61b90e20;p=lilypond.git

diff --git a/lily/bezier.cc b/lily/bezier.cc
index ce84ce8da8..7d3ad6af14 100644
--- a/lily/bezier.cc
+++ b/lily/bezier.cc
@@ -1,7 +1,7 @@
 /*
   This file is part of LilyPond, the GNU music typesetter.
 
-  Copyright (C) 1998--2011 Jan Nieuwenhuizen <janneke@gnu.org>
+  Copyright (C) 1998--2014 Jan Nieuwenhuizen <janneke@gnu.org>
 
   LilyPond is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -21,7 +21,8 @@
 #include "warn.hh"
 #include "libc-extension.hh"
 
-Real binomial_coefficient_3[] =
+Real binomial_coefficient_3[]
+=
 {
   1, 3, 3, 1
 };
@@ -139,6 +140,24 @@ Bezier::curve_point (Real t) const
   return o;
 }
 
+Real
+Bezier::slope_at_point (Real t) const
+{
+  Offset second_order[3];
+  Offset third_order[2];
+
+  for (vsize i = 0; i < 3; i++)
+    second_order[i] = ((control_[i + 1] - control_[i]) * t) + control_[i];
+
+  for (vsize i = 0; i < 2; i++)
+    third_order[i] = ((second_order[i + 1] - second_order[i]) * t) + second_order[i];
+
+  if (third_order[1][X_AXIS] - third_order[0][X_AXIS] == 0)
+    return infinity_f;
+
+  return (third_order[1][Y_AXIS] - third_order[0][Y_AXIS]) / (third_order[1][X_AXIS] - third_order[0][X_AXIS]);
+}
+
 /*
   Cache binom (3, j) t^j (1-t)^{3-j}
 */
@@ -213,49 +232,51 @@ Bezier::solve_point (Axis ax, Real coordinate) const
   return filter_solutions (sol);
 }
 
+/**
+   For the portion of the curve between L and R along axis AX,
+   return the bounding box limit in direction D along the cross axis to AX.
+   If there is no portion between L and R, return 0.0 and report error.
+*/
 Real
 Bezier::minmax (Axis ax, Real l, Real r, Direction d) const
 {
-  return minmax (ax, l, r, d, 0, 0);
-}
+  Axis bx = other_axis (ax);
+
+  // The curve could hit its bounding box limit along BX at:
+  //  points where the curve is parallel to AX,
+  Offset vec (0.0, 0.0);
+  vec[ax] = 1.0;
+  vector<Real> sols (solve_derivative (vec));
+  //  or endpoints of the curve,
+  sols.push_back (0.999);
+  sols.push_back (0.001);
+  // (using points just inside the ends, so that an endpoint is evaulated
+  //  if it falls within rounding error of L or R and the curve lies inside)
 
-Real
-Bezier::minmax (Axis axis, Real l, Real r, Direction d, vsize left_index, vsize right_index) const
-{
-  Axis other = other_axis (axis);
-  Interval lr (l, r);
-  Drul_array<vector<Real> > sol;
-  Direction dir = LEFT;
-  do
+  Interval iv;
+  for (vsize i = sols.size (); i--;)
     {
-      Polynomial p (polynomial (axis));
-      p.coefs_[0] -= lr[dir];
-
-      sol[dir] = filter_solutions (p.solve ());
+      Offset p (curve_point (sols[i]));
+      if (p[ax] >= l && p[ax] <= r)
+        iv.add_point (p[bx]);
     }
-  while (flip (&dir) != LEFT);
 
-  if (!sol[LEFT].size () || !sol[RIGHT].size ())
+  //  or intersections of the curve with the bounding lines at L and R.
+  Interval lr (l, r);
+  for (LEFT_and_RIGHT (dir))
     {
-      programming_error ("no solution found for Bezier intersection");
-      return 0.0;
+      vector<Real> v = get_other_coordinates (ax, lr[dir]);
+      for (vsize i = v.size (); i--;)
+        iv.add_point (v[i]);
     }
 
-  Polynomial p (polynomial (other));
-
-  Drul_array<vsize> indices(left_index, right_index);
-  do
+  if (iv.is_empty ())
     {
-      vector_sort (sol[dir], less<Real> ());
-      if (!Interval (0, sol[LEFT].size () - 1).contains (indices[dir]))
-        {
-          programming_error ("requested bezier solution outside range of solutions.  defaulting to lowest solution.");
-          indices[dir] = 0;
-        }
+      programming_error ("Bezier curve does not cross region of concern");
+      return 0.0;
     }
-  while (flip (&dir) != LEFT);
 
-  return p.minmax (sol[LEFT][indices[LEFT]], sol[RIGHT][indices[RIGHT]], d != LEFT);
+  return iv.at (d);
 }
 
 /**