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Diffstat (limited to '')
| -rw-r--r-- | src/2geom/curve.cpp | 187 |
1 files changed, 187 insertions, 0 deletions
diff --git a/src/2geom/curve.cpp b/src/2geom/curve.cpp new file mode 100644 index 0000000..8ad0178 --- /dev/null +++ b/src/2geom/curve.cpp @@ -0,0 +1,187 @@ +/* Abstract curve type - implementation of default methods + * + * Authors: + * MenTaLguY <mental@rydia.net> + * Marco Cecchetti <mrcekets at gmail.com> + * Krzysztof Kosiński <tweenk.pl@gmail.com> + * + * Copyright 2007-2009 Authors + * + * This library is free software; you can redistribute it and/or + * modify it either under the terms of the GNU Lesser General Public + * License version 2.1 as published by the Free Software Foundation + * (the "LGPL") or, at your option, under the terms of the Mozilla + * Public License Version 1.1 (the "MPL"). If you do not alter this + * notice, a recipient may use your version of this file under either + * the MPL or the LGPL. + * + * You should have received a copy of the LGPL along with this library + * in the file COPYING-LGPL-2.1; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + * You should have received a copy of the MPL along with this library + * in the file COPYING-MPL-1.1 + * + * The contents of this file are subject to the Mozilla Public License + * Version 1.1 (the "License"); you may not use this file except in + * compliance with the License. You may obtain a copy of the License at + * http://www.mozilla.org/MPL/ + * + * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY + * OF ANY KIND, either express or implied. See the LGPL or the MPL for + * the specific language governing rights and limitations. + */ + +#include <2geom/curve.h> +#include <2geom/exception.h> +#include <2geom/nearest-time.h> +#include <2geom/sbasis-geometric.h> +#include <2geom/sbasis-to-bezier.h> +#include <2geom/ord.h> +#include <2geom/path-sink.h> + +//#include <iostream> + +namespace Geom +{ + +Coord Curve::nearestTime(Point const& p, Coord a, Coord b) const +{ + return nearest_time(p, toSBasis(), a, b); +} + +std::vector<Coord> Curve::allNearestTimes(Point const& p, Coord from, Coord to) const +{ + return all_nearest_times(p, toSBasis(), from, to); +} + +Coord Curve::length(Coord tolerance) const +{ + return ::Geom::length(toSBasis(), tolerance); +} + +int Curve::winding(Point const &p) const +{ + try { + std::vector<Coord> ts = roots(p[Y], Y); + if(ts.empty()) return 0; + std::sort(ts.begin(), ts.end()); + + // skip endpoint roots when they are local maxima on the Y axis + // this follows the convention used in other winding routines, + // i.e. that the bottommost coordinate is not part of the shape + bool ignore_0 = unitTangentAt(0)[Y] <= 0; + bool ignore_1 = unitTangentAt(1)[Y] >= 0; + + int wind = 0; + for (std::size_t i = 0; i < ts.size(); ++i) { + Coord t = ts[i]; + //std::cout << t << std::endl; + if ((t == 0 && ignore_0) || (t == 1 && ignore_1)) continue; + if (valueAt(t, X) > p[X]) { // root is ray intersection + Point tangent = unitTangentAt(t); + if (tangent[Y] > 0) { + // at the point of intersection, curve goes in +Y direction, + // so it winds in the direction of positive angles + ++wind; + } else if (tangent[Y] < 0) { + --wind; + } + } + } + return wind; + } catch (InfiniteSolutions const &e) { + // this means we encountered a line segment exactly coincident with the point + // skip, since this will be taken care of by endpoint roots in other segments + return 0; + } +} + +std::vector<CurveIntersection> Curve::intersect(Curve const &/*other*/, Coord /*eps*/) const +{ + // TODO: approximate as Bezier + THROW_NOTIMPLEMENTED(); +} + +std::vector<CurveIntersection> Curve::intersectSelf(Coord eps) const +{ + std::vector<CurveIntersection> result; + // Monotonic segments cannot have self-intersections. + // Thus, we can split the curve at roots and intersect the portions. + std::vector<Coord> splits; + std::unique_ptr<Curve> deriv(derivative()); + splits = deriv->roots(0, X); + if (splits.empty()) { + return result; + } + deriv.reset(); + splits.push_back(1.); + + boost::ptr_vector<Curve> parts; + Coord previous = 0; + for (unsigned i = 0; i < splits.size(); ++i) { + if (splits[i] == 0.) continue; + parts.push_back(portion(previous, splits[i])); + previous = splits[i]; + } + + Coord prev_i = 0; + for (unsigned i = 0; i < parts.size()-1; ++i) { + Interval dom_i(prev_i, splits[i]); + prev_i = splits[i]; + + Coord prev_j = 0; + for (unsigned j = i+1; j < parts.size(); ++j) { + Interval dom_j(prev_j, splits[j]); + prev_j = splits[j]; + + std::vector<CurveIntersection> xs = parts[i].intersect(parts[j], eps); + for (unsigned k = 0; k < xs.size(); ++k) { + // to avoid duplicated intersections, skip values at exactly 1 + if (xs[k].first == 1. || xs[k].second == 1.) continue; + + Coord ti = dom_i.valueAt(xs[k].first); + Coord tj = dom_j.valueAt(xs[k].second); + + CurveIntersection real(ti, tj, xs[k].point()); + result.push_back(real); + } + } + } + return result; +} + +Point Curve::unitTangentAt(Coord t, unsigned n) const +{ + std::vector<Point> derivs = pointAndDerivatives(t, n); + for (unsigned deriv_n = 1; deriv_n < derivs.size(); deriv_n++) { + Coord length = derivs[deriv_n].length(); + if ( ! are_near(length, 0) ) { + // length of derivative is non-zero, so return unit vector + return derivs[deriv_n] / length; + } + } + return Point (0,0); +}; + +void Curve::feed(PathSink &sink, bool moveto_initial) const +{ + std::vector<Point> pts; + sbasis_to_bezier(pts, toSBasis(), 2); //TODO: use something better! + if (moveto_initial) { + sink.moveTo(initialPoint()); + } + sink.curveTo(pts[0], pts[1], pts[2]); +} + +} // namespace Geom + +/* + Local Variables: + mode:c++ + c-file-style:"stroustrup" + c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +)) + indent-tabs-mode:nil + fill-column:99 + End: +*/ +// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:fileencoding=utf-8:textwidth=99 : |