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/****************************************************************************
* Core Library Version 1.7, August 2004
* Copyright (c) 1995-2004 Exact Computation Project
* All rights reserved.
*
* This file is part of CORE (http://cs.nyu.edu/exact/core/).
* 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.
*
* Licensees holding a valid commercial license may use this file in
* accordance with the commercial license agreement provided with the
* software.
*
* This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
* WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*
*
* $URL$
* $Id$
***************************************************************************/
/*****************************************************************
* File: circle2d.h
* Synopsis:
* Basic 2-dimensional geometry
* Author: Shubin Zhao (shubinz@cs.nyu.edu), 2001.
*
*****************************************************************
* CORE Library Version 1.4 (July 2001)
* Chee Yap <yap@cs.nyu.edu>
* Chen Li <chenli@cs.nyu.edu>
* Zilin Du <zilin@cs.nyu.edu>
*
* Copyright (c) 1995, 1996, 1998, 1999, 2000, 2001 Exact Computation Project
*
* WWW URL: http://cs.nyu.edu/exact/
* Email: exact@cs.nyu.edu
*
* $Id$
*****************************************************************/
#ifndef _CIRCLE2D_H
#define _CIRCLE2D_H
#include <CGAL/CORE/geom2d/point2d.h>
#include <CGAL/CORE/geom2d/line2d.h>
class Circle2d : public GeomObj {
/* An instance C of the data type circle is an oriented circle
in the plane passing through three points p1, p2, p3. The
orientation of C is equal to the orientation of the three defining
points. i.e. orientation(p1, p2, p3).
If \Labs{\{p1, p2, p3\}} = 1, C is the empty circle with center p1.
If p1, p2 and p3 are collinear, C is a straight line passing through
p1, p2 and p3 in this order and the center of C is undefined.
*/
private:
Point2d p1; // the 3 points defining the circle
Point2d p2;
Point2d p3;
int orient; //orientation(p1, p2, p3)
Point2d* cp; //pointer to center
double * rp; //pointer to radius
public:
Circle2d( const Point2d& p1, const Point2d& p2, const Point2d& p3);
//initialized to the oriented circle through points p1, p2, p3
Circle2d(const Point2d& a, const Point2d& b0);
//initialized to the counter-clockwise oriented circle with center a
//passing through b0
Circle2d(const Point2d& p);
//initialized to the trivial circle with center p
Circle2d();
//initialized to the trivial circle with center (0,0)
Circle2d(const Point2d& c, double r);
//initialized to the circle with center c and radius r with positive
//(i.e. counter-clockwise) orientation
Circle2d(const Circle2d& c);
//copy constructor
virtual ~Circle2d();
Circle2d& operator=(const Circle2d& C);
//operations
Point2d center();
//return the center of the circle
double radius();
//returns the radius.
//precond: the orientation of the circle is not 0
Point2d point1() const { return p1; }
Point2d point2() const { return p2; }
Point2d point3() const { return p3; }
// Point2d point_on_circle(float alpha);
//returns a point p on the circle with angle of alpha
bool is_degerate() const { return orient == 0; }
//returns true if the defining points are collinear
bool is_trivial() const {return p1 == p2; }
//returns true if radius is zero
int orientation() const { return orient; }
int side_of(const Point2d& p) const;
// returns -1, +1 or 0 if p lies right of, left of or on the circle
// respectively
bool inside(const Point2d& p);
//returns true if p lies inside of the circle
bool outside(const Point2d& p);
bool contains(const Point2d& p) const ;
//returns true if p lies on the circle, false otherwise
double distance(const Point2d& p);
//returns the distance between p and the circle: distance to center - radius
double distance(const Line2d& l);
//returns the distance between l and the circle
//distance from center to l minus radius
double distance(Circle2d& D);
//returns the distance between this circle and circle D
//distance between two centers minus two radius
bool operator==(const Circle2d& D) const ;
bool operator!=(const Circle2d& D) const
{ return !operator==(D); }
friend std::ostream& operator<<(std::ostream& out, Circle2d& c);
friend std::istream& operator>>(std::istream& in, Circle2d c); //?? Circle2d &
}; // class Circle2d
#endif
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