1 /*
2 *
3 * Authors:
4 * MenTaLguY <mental@rydia.net>
5 * Marco Cecchetti <mrcekets at gmail.com>
6 *
7 * Copyright 2007-2008 authors
8 *
9 * This library is free software; you can redistribute it and/or
10 * modify it either under the terms of the GNU Lesser General Public
11 * License version 2.1 as published by the Free Software Foundation
12 * (the "LGPL") or, at your option, under the terms of the Mozilla
13 * Public License Version 1.1 (the "MPL"). If you do not alter this
14 * notice, a recipient may use your version of this file under either
15 * the MPL or the LGPL.
16 *
17 * You should have received a copy of the LGPL along with this library
18 * in the file COPYING-LGPL-2.1; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20 * You should have received a copy of the MPL along with this library
21 * in the file COPYING-MPL-1.1
22 *
23 * The contents of this file are subject to the Mozilla Public License
24 * Version 1.1 (the "License"); you may not use this file except in
25 * compliance with the License. You may obtain a copy of the License at
26 * http://www.mozilla.org/MPL/
27 *
28 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
29 * OF ANY KIND, either express or implied. See the LGPL or the MPL for
30 * the specific language governing rights and limitations.
31 */
34 #include <2geom/curve.h>
35 #include <2geom/ord.h>
38 namespace Geom
39 {
41 int CurveHelpers::root_winding(Curve const &c, Point p) {
42 std::vector<double> ts = c.roots(p[Y], Y);
44 if(ts.empty()) return 0;
46 double const fudge = 0.01; //fudge factor used on first and last
48 std::sort(ts.begin(), ts.end());
50 // winding determined by crossings at roots
51 int wind=0;
52 // previous time
53 double pt = ts.front() - fudge;
54 for ( std::vector<double>::iterator ti = ts.begin()
55 ; ti != ts.end()
56 ; ++ti )
57 {
58 double t = *ti;
59 if ( t <= 0. || t >= 1. ) continue; //skip endpoint roots
60 if ( c.valueAt(t, X) > p[X] ) { // root is ray intersection
61 // Get t of next:
62 std::vector<double>::iterator next = ti;
63 next++;
64 double nt;
65 if(next == ts.end()) nt = t + fudge; else nt = *next;
67 // Check before in time and after in time for positions
68 // Currently we're using the average times between next and previous segs
69 Cmp after_to_ray = cmp(c.valueAt((t + nt) / 2, Y), p[Y]);
70 Cmp before_to_ray = cmp(c.valueAt((t + pt) / 2, Y), p[Y]);
71 // if y is included, these will have opposite values, giving order.
72 Cmp dt = cmp(after_to_ray, before_to_ray);
73 if(dt != EQUAL_TO) //Should always be true, but yah never know..
74 wind += dt;
75 pt = t;
76 }
77 }
79 return wind;
80 }
83 } // end namespace Geom
85 /*
86 Local Variables:
87 mode:c++
88 c-file-style:"stroustrup"
89 c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
90 indent-tabs-mode:nil
91 fill-column:99
92 End:
93 */
94 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :