X-Git-Url: https://git.donarmstrong.com/?a=blobdiff_plain;f=lily%2Fbezier.cc;h=0a0f4cfc6ff3f18962548c44bf391e9ba99762ad;hb=689ca8e732f71bcfc117211e4a980f22b13bc1ed;hp=09bcd54a1a80b755a18231623f0ec81c170a0fab;hpb=4ecdbd7d70ca7441be4dddd15ac01cc255bc2a35;p=lilypond.git diff --git a/lily/bezier.cc b/lily/bezier.cc index 09bcd54a1a..0a0f4cfc6f 100644 --- a/lily/bezier.cc +++ b/lily/bezier.cc @@ -1,41 +1,35 @@ /* - 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--2011 Jan Nieuwenhuizen - (c) 1998--2005 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. -#include -using namespace std; + 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 }; -Real -binomial_coefficient (Real over, int under) -{ - Real x = 1.0; - - while (under) - { - x *= over / Real (under); - - over -= 1.0; - under--; - } - return x; -} - void -scale (Array *array, Real x, Real y) +scale (vector *array, Real x, Real y) { - for (int i = 0; i < array->size (); i++) + for (vsize i = 0; i < array->size (); i++) { (*array)[i][X_AXIS] = x * (*array)[i][X_AXIS]; (*array)[i][Y_AXIS] = y * (*array)[i][Y_AXIS]; @@ -43,17 +37,17 @@ scale (Array *array, Real x, Real y) } void -rotate (Array *array, Real phi) +rotate (vector *array, Real phi) { Offset rot (complex_exp (Offset (0, phi))); - for (int i = 0; i < array->size (); i++) + for (vsize i = 0; i < array->size (); i++) (*array)[i] = complex_multiply (rot, (*array)[i]); } void -translate (Array *array, Offset o) +translate (vector *array, Offset o) { - for (int i = 0; i < array->size (); i++) + for (vsize i = 0; i < array->size (); i++) (*array)[i] += o; } @@ -69,8 +63,8 @@ translate (Array *array, Offset o) Real Bezier::get_other_coordinate (Axis a, Real x) const { - Axis other = Axis ((a +1)%NO_AXES); - Array ts = solve_point (a, x); + Axis other = Axis ((a + 1) % NO_AXES); + vector ts = solve_point (a, x); if (ts.size () == 0) { @@ -87,6 +81,17 @@ 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 { @@ -100,7 +105,7 @@ 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; } @@ -121,7 +126,7 @@ 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; } @@ -135,33 +140,31 @@ Bezier::curve_point (Real t) const } /* - Cache binom(3,j) t^j (1-t)^{3-j} + Cache binom (3, j) t^j (1-t)^{3-j} */ -static struct Polynomial bezier_term_cache[4]; -static bool done_cache_init; - -void -init_polynomial_cache () +struct Polynomial_cache { - for (int j = 0; j <= 3; j++) - bezier_term_cache[j] - = binomial_coefficient_3[j] - * Polynomial::power (j, Polynomial (0, 1)) - * Polynomial::power (3 - j, Polynomial (1, -1)); - done_cache_init = true; -} + 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)); + } +}; + +static Polynomial_cache poly_cache; Polynomial Bezier::polynomial (Axis a) const { - if (!done_cache_init) - init_polynomial_cache (); - Polynomial p (0.0); Polynomial q; for (int j = 0; j <= 3; j++) { - q = bezier_term_cache[j]; + q = poly_cache.terms_[j]; q *= control_[j][a]; p += q; } @@ -172,19 +175,19 @@ Bezier::polynomial (Axis a) const /** Remove all numbers outside [0, 1] from SOL */ -Array -filter_solutions (Array sol) +vector +filter_solutions (vector sol) { - for (int i = sol.size (); i--;) + for (vsize i = sol.size (); i--;) if (sol[i] < 0 || sol[i] > 1) - sol.del (i); + sol.erase (sol.begin () + i); return sol; } /** find t such that derivative is proportional to DERIV */ -Array +vector Bezier::solve_derivative (Offset deriv) const { Polynomial xp = polynomial (X_AXIS); @@ -200,30 +203,85 @@ Bezier::solve_derivative (Offset deriv) const /* Find t such that curve_point (t)[AX] == COORDINATE */ -Array +vector Bezier::solve_point (Axis ax, Real coordinate) const { Polynomial p (polynomial (ax)); p.coefs_[0] -= coordinate; - Array sol (p.solve ()); + vector sol (p.solve ()); return filter_solutions (sol); } +/** + Assuming AX is X_AXIS, and D is UP, finds the + maximum value of curve_coordinate(t, Y_AXIS) subject to + l <= curve_coordinate(t, X_AXIS) <= r. +*/ +Real +Bezier::minmax (Axis ax, Real l, Real r, Direction d) const +{ + Axis other = other_axis (ax); + Interval lr (l, r); + vector solutions; + + // Possible solutions are: + // t = 0 or 1, or... + solutions.push_back (0); + solutions.push_back (1); + + // t is a critical point for the other-axis polynomial, or... + Polynomial p_prime (polynomial (other)); + p_prime.differentiate (); + vector criticals = p_prime.solve (); + solutions.insert (solutions.end (), criticals.begin (), criticals.end ()); + + // t solves curve_coordinate(t, X_AXIS) = l or r. + Direction dir = LEFT; + do + { + Polynomial p (polynomial (ax)); + p.coefs_[0] -= lr[dir]; + + vector sol = p.solve (); + solutions.insert (solutions.end (), sol.begin (), sol.end ()); + } + while (flip (&dir) != LEFT); + + Polynomial p (polynomial (ax)); + Polynomial other_p (polynomial (other)); + vector values; + for (vsize i = solutions.size (); i--;) + { + Real t = solutions[i]; + if (t >= 0 && t <= 1 && p.eval (t) >= l && p.eval (t) <= r) + values.push_back (other_p.eval (t)); + } + + if (values.empty ()) + { + programming_error ("no solution found for Bezier intersection"); + return 0.0; + } + + vector_sort (values, less ()); + return (d == DOWN) ? values[0] : values.back (); +} + /** 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; - Array sols (solve_derivative (d)); - sols.push (1.0); - sols.push (0.0); - for (int i = sols.size (); i--;) + vector sols (solve_derivative (d)); + sols.push_back (1.0); + sols.push_back (0.0); + for (vsize i = sols.size (); i--;) { Offset o (curve_point (sols[i])); iv.unite (Interval (o[a], o[a])); @@ -231,6 +289,16 @@ Bezier::extent (Axis a) const return iv; } +Interval +Bezier::control_point_extent (Axis a) const +{ + Interval ext; + for (int i = CONTROL_COUNT; i--;) + ext.add_point (control_[i][a]); + + return ext; +} + /** Flip around axis A */ @@ -264,7 +332,7 @@ 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 @@ -275,3 +343,51 @@ 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; + } +}