/**
 *  \file angle.h
 *  \brief Various trigoniometric helper functions
 *
 *  Authors:
 *   Johan Engelen <goejendaagh@zonnet.nl>
 *
 * Copyright (C) 2007 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.
 *
 */
 
#ifndef LIB2GEOM_SEEN_ANGLE_H
#define LIB2GEOM_SEEN_ANGLE_H

namespace Geom {

#ifndef M_PI
# define M_PI 3.14159265358979323846
#endif

inline double deg_to_rad(double deg) { return deg*M_PI/180.0;}

inline double rad_to_deg(double rad) { return rad*180.0/M_PI;}

/*
 *  start_angle and angle must belong to [0, 2PI[
 *  and angle must belong to the cirsular arc defined by
 *  start_angle, end_angle and with rotation direction cw
 */
inline
double map_circular_arc_on_unit_interval( double angle, double start_angle, double end_angle, bool cw = true )
{
    double d = end_angle - start_angle;
    double t = angle - start_angle;
    if ( !cw ) 
    {
    	d = -d;
    	t = -t;
    }
    if ( d < 0 ) d += 2*M_PI;	
    if ( t < 0 ) t += 2*M_PI;
    return t / d;
}

inline
Coord map_unit_interval_on_circular_arc(Coord t, double start_angle, double end_angle, bool cw = true)
{
	double sweep_angle = end_angle - start_angle;
	if ( !cw ) sweep_angle = -sweep_angle;
	if ( sweep_angle < 0 ) sweep_angle += 2*M_PI;
	
    if ( cw )
    {
        Coord angle = start_angle + sweep_angle * t;
        if ( !(angle < 2*M_PI) )
            angle -= 2*M_PI;
        return angle;
    }
    else
    {
        Coord angle = start_angle - sweep_angle * t;
        if ( angle < 0 ) angle += 2*M_PI;
        return angle;
    }
}


}

#endif


/*
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  End:
*/
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