a_circle.h

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/*
Copyright 2009-12 Pierre SMARS (smars@yuntech.edu.tw)
This program is free software: 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 2 of the License, or
(at your option) any later version.
 
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.
 
You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef _A_CIRCLE_H_
#define _A_CIRCLE_H_
 
#include <iostream>
#include "a_point.h"
 
const double pi = 3.14159265358979;
 
class a_circle: public a_geom_base
{
public:
        a_circle() = default; 
 
        virtual const std::string classname() { return "a_segment";}
        static const std::string help();
 
        void centre(const a_point c) {c_=c;}
        a_point centre() const {return c_;}
        
        void normal(const a_point n) {n_=n; n_.normalise();}
        a_point normal() const {return n_;}
 
        void radius(double r) {r_=r;}
        double radius() const {return r_;}
 
        void p3(const a_point p1, const a_point p2, const a_point p3);
        void p2(const a_point p1, const a_point p2); //use r_ and n_, order of points matters!
 
        bool operator==(const a_circle& p);
        a_circle& operator=(const a_circle& v);
 
        inline double length() const { return 2*pi*r_;}
        inline double area() const { return pi*r_*r_;}
 
        //: input/output
        virtual void read(std::istream &i);
        virtual void write(std::ostream &o) const;
 
        class null_circle_error  {};
   
protected:
        a_point c_; // centre
        a_point n_ = a_point(1.,0.,0.); // normal to the circle plane
        double  r_ = 0.; // radius
};
 
#endif