a_circle.cxx

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/*
Copyright 2000-12 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/>.
*/
#include "a_circle.h"
#include <vector>
#include <algorithm>
#include <math.h>
#include <sstream>
 
//---------------------------------------------------------------------------
const std::string a_circle::help()
{
        std::ostringstream o;
        o << "*********" << std::endl;
        o << "a_circle:" << std::endl;
        o << "*********" << std::endl;
        o << "This is a 'circle' class" << std::endl;
        o << std::endl;
        o << "Create a circle:" << std::endl;
        o << " a_point a" << std::endl;
        o << std::endl;
        o << "Commands:" << std::endl;
        o << "centre: get or set centre." << std::endl;
        o << "normal: get or set normal." << std::endl;
        o << "radius: get or set radius." << std::endl;
        o << "p3 _p1 _p2 _p3: set circle passing by 3 points." << std::endl;
        o << "p2 _p1 _p2: move a circle to make it pass by 2 points; keeps radius and normal of original circle." << std::endl;
        o << "length: returns length." << std::endl;
        o << "area: returns area." << std::endl;
        o << "print: prints parameters." << std::endl;
        o << a_geom_base::help();
        return o.str();
}
//---------------------------------------------------------------------------
bool a_circle::operator==(const a_circle& s)
{
        return ((c_ == s.centre())&&(n_ == s.normal())&&(r_ == s.radius()));
}
//---------------------------------------------------------------------------
a_circle & a_circle::operator=(const a_circle& s)
{
        c_ = s.centre();
        n_ = s.normal();
        r_ = s.radius();
        return *this;
}
//---------------------------------------------------------------------------
void a_circle::p3(const a_point p1, const a_point p2, const a_point p3)
{
        a_point d1 = p2-p1;
        a_point d2 = p3-p1;
        a_point dir = cross(d1,d2);
        if (dir.norm()==0) return;
        this->normal(dir);
        a_point ce = circle_centre(p1,p2,p3);
        this->centre(ce);
        this->radius(((p1-ce).norm()+(p2-ce).norm()+(p3-ce).norm())/3.);
}
//---------------------------------------------------------------------------
void a_circle::p2(const a_point p1, const a_point p2)
{
        a_point d = p2-p1;
        double b = d.norm()/2.;
        if (b>r_)
                return;
        double n = sqrt(r_*r_-b*b);
        a_point m = (p1+p2)/2.;
        a_point t = cross(d,n_).normalise();
        this->centre(m+n*t);
}
//***************************************************************************
//---------------------------------------------------------------------------
void a_circle::read(std::istream &in)
{
        in >> c_;
        in >> n_;
        in >> r_;
}
//---------------------------------------------------------------------------
void a_circle::write(std::ostream &o) const
{
        o << this->centre() << " ";
        o << this->normal() << " ";
        o << this->radius() << " ";
}