X-Git-Url: https://git.donarmstrong.com/?a=blobdiff_plain;f=lily%2Fbezier-bow.cc;h=e049bd734c244f78c8411324296514e8de219cc1;hb=97a0169312a260933246ab224e4f8b0969871dd5;hp=8a92e9ddf4cfedd11f116faf96f2ef01869a07a8;hpb=736088f09a0b77acc84f6e1a54cddb8bad3d94c1;p=lilypond.git diff --git a/lily/bezier-bow.cc b/lily/bezier-bow.cc index 8a92e9ddf4..e049bd734c 100644 --- a/lily/bezier-bow.cc +++ b/lily/bezier-bow.cc @@ -1,113 +1,128 @@ /* - 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--2000 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 -#include "bezier-bow.hh" #include "misc.hh" #include "bezier.hh" -#include "dimensions.hh" -#include "direction.hh" -#include "debug.hh" -#include "main.hh" -#include "lily-guile.hh" -#include "paper-def.hh" - -Bezier_bow::Bezier_bow (Array encompass, Direction dir) +static Real +F0_1 (Real x) { - alpha_ = 0; - dir_ = dir; - encompass_ = encompass; - to_canonical_form (); + return 2 / M_PI * atan (M_PI * x / 2); } -Bezier -Bezier_bow::get_bezier () const +Real +slur_height (Real width, Real h_inf, Real r_0) { - Bezier rv = curve_; - if (dir_ == DOWN) - { - rv.flip (Y_AXIS); - } - - rv.rotate (alpha_); - rv.translate (origin_); - - return rv; + return F0_1 (width * r_0 / h_inf) * h_inf; } -void -Bezier_bow::to_canonical_form () -{ - origin_ = encompass_[0]; - translate (&encompass_, -origin_); - - Offset delta = encompass_.top () - encompass_[0]; - alpha_ = delta.arg (); - - rotate (&encompass_, -alpha_); - if (dir_ == DOWN) - { - flip (&encompass_, Y_AXIS); - } - - while (encompass_.size () > 1 && encompass_[1][X_AXIS] <= 0.0) - { - programming_error ("Degenerate bow: infinite steepness reqd"); - encompass_.del (1); - } - - Real l = encompass_.top ()[X_AXIS]; - while (encompass_.size () > 1 && encompass_.top (1)[X_AXIS] >= l) - { - programming_error ("Degenerate bow: infinite steepness reqd"); - encompass_.del (encompass_.size ()-2); - } -} +/* + ^ x x + | + height + | + v x x + + + + For small w, the height should be proportional to w, for w -> + infinity, the height should rise to a limit asymptotically. + + Hence we take F (x) such that + F (0) = 0 , F' (0) = 1, and F (infty) = 1 + + and use + + h = h_infinity * F (x * r_0 / h_infinity) + + + Examples: + + * F (x) = 2/pi * atan (pi x/2) + + * F (x) = 1/alpha * x^alpha / (1 + x^alpha) + + * (etc.) + + [with the 2nd recipe you can determine how quickly the conversion from + `small' slurs to `big' slurs occurs.] + + Although this might seem cand_idates to SCM-ify, it is not all clear + which parameters (ie. h_inf, r_0, F (.)) should be candidates for + this. At present h_inf and r_0 come from layout settings, but we did + no experiments for determining the best combinations of F, h_inf and + r_0. + + + The indent is proportional to the height of the slur for small + slurs. For large slurs, this gives a certain hookiness at the end, + so we increase the indent. + + indent = G (w) + + w -> 0, G (w) -> .33 w + + + (due to derivative constraints, we cannot have indent > len/3) + + w -> inf, G (w) -> 2*h_inf + + i.e. + + + G (0) = 0 , G'(0) 1/3, G (infty) = 2h_inf + + solve from + + G (w) = r + p/(w+q) + + yields + + G (w) = 2 h_inf - max_fraction * q^2/ (w + q) + + with q = 2 h_inf +*/ void -Bezier_bow::set_default_bezier (Real h_inf, Real r_0) +get_slur_indent_height (Real *indent, Real *height, + Real width, Real h_inf, Real r_0) { - curve_ = get_default_bezier (h_inf, r_0); + Real max_fraction = 1.0 / 3.1; + *height = slur_height (width, h_inf, r_0); + + Real q = 2 * h_inf / max_fraction; + *indent = 2 * h_inf - sqr (q) * max_fraction / (width + q); } -/* - See Documentation/programmer/fonts.doc - */ Bezier -Bezier_bow::get_default_bezier (Real h_inf, Real r_0) const +slur_shape (Real width, Real h_inf, Real r_0) { - Offset delta (encompass_.top ()[X_AXIS] - encompass_[0][X_AXIS], 0); - Real b = delta.length (); - Real height = get_default_height (h_inf, r_0, b); - // urg: scmify this? - Real indent = height; + Real indent; + Real height; + + get_slur_indent_height (&indent, &height, + width, h_inf, r_0); Bezier curve; curve.control_[0] = Offset (0, 0); curve.control_[1] = Offset (indent, height); - curve.control_[2] = Offset (b - indent, height); - curve.control_[3] = Offset (b, 0); + curve.control_[2] = Offset (width - indent, height); + curve.control_[3] = Offset (width, 0); return curve; } - -/* - See Documentation/programmer/fonts.doc - */ -Real -Bezier_bow::get_default_height (Real h_inf, Real r_0, Real b) const -{ - - SCM h = scm_eval (scm_listify (ly_symbol2scm ("slur-default-height"), - gh_double2scm (h_inf), - gh_double2scm (r_0), - gh_double2scm (b), - SCM_UNDEFINED)); - return gh_scm2double (h); -} -