X-Git-Url: https://git.donarmstrong.com/?a=blobdiff_plain;f=lily%2Fbezier.cc;h=eacd4fe6a44e95f224d6a9f4894455198167710a;hb=97a0169312a260933246ab224e4f8b0969871dd5;hp=1808821029595f95bd707a31d9aff26ef087984f;hpb=f9214bac21e9926dc3248416f58190c98c4167a9;p=lilypond.git diff --git a/lily/bezier.cc b/lily/bezier.cc index 1808821029..eacd4fe6a4 100644 --- a/lily/bezier.cc +++ b/lily/bezier.cc @@ -1,16 +1,29 @@ /* - bezier.cc -- implement Bezier and Bezier_bow + This file is part of LilyPond, the GNU music typesetter. - source file of the GNU LilyPond music typesetter + Copyright (C) 1998--2015 Jan Nieuwenhuizen - (c) 1998--2007 Jan Nieuwenhuizen + LilyPond is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation, either version 3 of the License, or + (at your option) any later version. + + LilyPond is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with LilyPond. If not, see . */ #include "bezier.hh" #include "warn.hh" #include "libc-extension.hh" -Real binomial_coefficient_3[] = { +Real binomial_coefficient_3[] += +{ 1, 3, 3, 1 }; @@ -25,9 +38,9 @@ scale (vector *array, Real x, Real y) } void -rotate (vector *array, Real phi) +rotate (vector *array, Real deg) { - Offset rot (complex_exp (Offset (0, phi))); + Offset rot (offset_directed (deg)); for (vsize i = 0; i < array->size (); i++) (*array)[i] = complex_multiply (rot, (*array)[i]); } @@ -51,7 +64,7 @@ translate (vector *array, Offset o) Real Bezier::get_other_coordinate (Axis a, Real x) const { - Axis other = Axis ((a +1) % NO_AXES); + Axis other = Axis ((a + 1) % NO_AXES); vector ts = solve_point (a, x); if (ts.size () == 0) @@ -69,6 +82,17 @@ Bezier::get_other_coordinate (Axis a, Real x) const return curve_coordinate (ts[0], other); } +vector +Bezier::get_other_coordinates (Axis a, Real x) const +{ + Axis other = other_axis (a); + vector ts = solve_point (a, x); + vector sols; + for (vsize i = 0; i < ts.size (); i++) + sols.push_back (curve_coordinate (ts[i], other)); + return sols; +} + Real Bezier::curve_coordinate (Real t, Axis a) const { @@ -82,7 +106,7 @@ Bezier::curve_coordinate (Real t, Axis a) const for (int j = 0; j < 4; j++) { r += control_[j][a] * binomial_coefficient_3[j] - * tj * one_min_tj[3 - j]; + * tj * one_min_tj[3 - j]; tj *= t; } @@ -103,7 +127,7 @@ Bezier::curve_point (Real t) const for (int j = 0; j < 4; j++) { o += control_[j] * binomial_coefficient_3[j] - * tj * one_min_tj[3 - j]; + * tj * one_min_tj[3 - j]; tj *= t; } @@ -116,18 +140,35 @@ Bezier::curve_point (Real t) const return o; } +// The return value is normalized unless zero or indefinite. +Offset +Bezier::dir_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]; + + return (third_order[1] - third_order[0]).direction (); +} + /* - Cache binom(3,j) t^j (1-t)^{3-j} + Cache binom (3, j) t^j (1-t)^{3-j} */ -struct Polynomial_cache { +struct Polynomial_cache +{ Polynomial terms_[4]; Polynomial_cache () { for (int j = 0; j <= 3; j++) terms_[j] - = binomial_coefficient_3[j] - * Polynomial::power (j, Polynomial (0, 1)) - * Polynomial::power (3 - j, Polynomial (1, -1)); + = binomial_coefficient_3[j] + * Polynomial::power (j, Polynomial (0, 1)) + * Polynomial::power (3 - j, Polynomial (1, -1)); } }; @@ -189,13 +230,60 @@ 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 +{ + 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 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) + + Interval iv; + for (vsize i = sols.size (); i--;) + { + Offset p (curve_point (sols[i])); + if (p[ax] >= l && p[ax] <= r) + iv.add_point (p[bx]); + } + + // or intersections of the curve with the bounding lines at L and R. + Interval lr (l, r); + for (LEFT_and_RIGHT (dir)) + { + vector v = get_other_coordinates (ax, lr[dir]); + for (vsize i = v.size (); i--;) + iv.add_point (v[i]); + } + + if (iv.is_empty ()) + { + programming_error ("Bezier curve does not cross region of concern"); + return 0.0; + } + + return iv.at (d); +} + /** Compute the bounding box dimensions in direction of A. */ Interval Bezier::extent (Axis a) const { - int o = (a + 1)%NO_AXES; + int o = (a + 1) % NO_AXES; Offset d; d[Axis (o)] = 1.0; Interval iv; @@ -217,10 +305,9 @@ Bezier::control_point_extent (Axis a) const for (int i = CONTROL_COUNT; i--;) ext.add_point (control_[i][a]); - return ext; + return ext; } - /** Flip around axis A */ @@ -235,9 +322,9 @@ Bezier::scale (Real x, Real y) } void -Bezier::rotate (Real phi) +Bezier::rotate (Real deg) { - Offset rot (complex_exp (Offset (0, phi))); + Offset rot (offset_directed (deg)); for (int i = 0; i < CONTROL_COUNT; i++) control_[i] = complex_multiply (rot, control_[i]); } @@ -254,7 +341,7 @@ Bezier::assert_sanity () const { for (int i = 0; i < CONTROL_COUNT; i++) assert (!isnan (control_[i].length ()) - && !isinf (control_[i].length ())); + && !isinf (control_[i].length ())); } void @@ -265,3 +352,51 @@ Bezier::reverse () b2.control_[CONTROL_COUNT - i - 1] = control_[i]; *this = b2; } + +/* + Subdivide a bezier at T into LEFT_PART and RIGHT_PART + using deCasteljau's algorithm. +*/ +void +Bezier::subdivide (Real t, Bezier *left_part, Bezier *right_part) const +{ + Offset p[CONTROL_COUNT][CONTROL_COUNT]; + + for (int i = 0; i < CONTROL_COUNT; i++) + p[i][CONTROL_COUNT - 1 ] = control_[i]; + for (int j = CONTROL_COUNT - 2; j >= 0; j--) + for (int i = 0; i < CONTROL_COUNT - 1; i++) + p[i][j] = p[i][j + 1] + t * (p[i + 1][j + 1] - p[i][j + 1]); + for (int i = 0; i < CONTROL_COUNT; i++) + { + left_part->control_[i] = p[0][CONTROL_COUNT - 1 - i]; + right_part->control_[i] = p[i][i]; + } +} + +/* + Extract a portion of a bezier from T_MIN to T_MAX +*/ + +Bezier +Bezier::extract (Real t_min, Real t_max) const +{ + if ((t_min < 0) || (t_max) > 1) + programming_error + ("bezier extract arguments outside of limits: curve may have bad shape"); + if (t_min >= t_max) + programming_error + ("lower bezier extract value not less than upper value: curve may have bad shape"); + Bezier bez1, bez2, bez3, bez4; + if (t_min == 0.0) + bez2 = *this; + else + subdivide (t_min, &bez1, &bez2); + if (t_max == 1.0) + return bez2; + else + { + bez2.subdivide ((t_max - t_min) / (1 - t_min), &bez3, &bez4); + return bez3; + } +}