1 /**
2 * \file angle.h
3 * \brief Various trigoniometric helper functions
4 *
5 * Authors:
6 * Johan Engelen <goejendaagh@zonnet.nl>
7 *
8 * Copyright (C) 2007 authors
9 *
10 * This library is free software; you can redistribute it and/or
11 * modify it either under the terms of the GNU Lesser General Public
12 * License version 2.1 as published by the Free Software Foundation
13 * (the "LGPL") or, at your option, under the terms of the Mozilla
14 * Public License Version 1.1 (the "MPL"). If you do not alter this
15 * notice, a recipient may use your version of this file under either
16 * the MPL or the LGPL.
17 *
18 * You should have received a copy of the LGPL along with this library
19 * in the file COPYING-LGPL-2.1; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
21 * You should have received a copy of the MPL along with this library
22 * in the file COPYING-MPL-1.1
23 *
24 * The contents of this file are subject to the Mozilla Public License
25 * Version 1.1 (the "License"); you may not use this file except in
26 * compliance with the License. You may obtain a copy of the License at
27 * http://www.mozilla.org/MPL/
28 *
29 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
30 * OF ANY KIND, either express or implied. See the LGPL or the MPL for
31 * the specific language governing rights and limitations.
32 *
33 */
35 #ifndef LIB2GEOM_SEEN_ANGLE_H
36 #define LIB2GEOM_SEEN_ANGLE_H
38 namespace Geom {
40 #ifndef M_PI
41 # define M_PI 3.14159265358979323846
42 #endif
44 inline double deg_to_rad(double deg) { return deg*M_PI/180.0;}
46 inline double rad_to_deg(double rad) { return rad*180.0/M_PI;}
48 /*
49 * start_angle and angle must belong to [0, 2PI[
50 * and angle must belong to the cirsular arc defined by
51 * start_angle, end_angle and with rotation direction cw
52 */
53 inline
54 double map_circular_arc_on_unit_interval( double angle, double start_angle, double end_angle, bool cw = true )
55 {
56 double d = end_angle - start_angle;
57 double t = angle - start_angle;
58 if ( !cw )
59 {
60 d = -d;
61 t = -t;
62 }
63 if ( d < 0 ) d += 2*M_PI;
64 if ( t < 0 ) t += 2*M_PI;
65 return t / d;
66 }
68 inline
69 Coord map_unit_interval_on_circular_arc(Coord t, double start_angle, double end_angle, bool cw = true)
70 {
71 double sweep_angle = end_angle - start_angle;
72 if ( !cw ) sweep_angle = -sweep_angle;
73 if ( sweep_angle < 0 ) sweep_angle += 2*M_PI;
75 if ( cw )
76 {
77 Coord angle = start_angle + sweep_angle * t;
78 if ( !(angle < 2*M_PI) )
79 angle -= 2*M_PI;
80 return angle;
81 }
82 else
83 {
84 Coord angle = start_angle - sweep_angle * t;
85 if ( angle < 0 ) angle += 2*M_PI;
86 return angle;
87 }
88 }
91 }
93 #endif
96 /*
97 Local Variables:
98 mode:c++
99 c-file-style:"stroustrup"
100 c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
101 indent-tabs-mode:nil
102 fill-column:99
103 End:
104 */
105 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :