Desktop/sourceforge/geometria/src/kernel/line_join_algorithm.cpp

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/*
This file is part of geometria.

geometria 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.

geometria 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 geometria; if not, write to the Free Software 
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA

(c) Philipp Moritz, 2006
*/

#include "line_join_algorithm.hpp"

#include <cmath>

line_join_algorithm::line_join_algorithm(boost::shared_ptr<geo_point> p, boost::shared_ptr<geo_point> q)
: m_p(p), m_q(q)
{
        m_p->register_observer(this);
        m_q->register_observer(this);
}

line_join_algorithm::~line_join_algorithm()
{
        m_p->unregister_observer(this);
        m_q->unregister_observer(this);
}

line line_join_algorithm::calculate()
{
        point p = m_p->get_point();
        point q = m_q->get_point();
        //y = m*x + t
        //m = delta_y/delta_x
        //t = y - m*x
        double delta_x = p.get_x() - q.get_x();
        double delta_y = p.get_y() - q.get_y();

        double m = delta_y/delta_x;

        double t = p.get_y() - m*p.get_x();
        return line(m, t);
}

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