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/*
* affine.cc -- ePiX::affine class
*
* This file is part of ePiX, a C++ library for creating high-quality
* figures in LaTeX
*
* Version 1.1.21
* Last Change: September 23, 2007
*
*
* Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007
* Andrew D. Hwang <rot 13 nujnat at zngupf dot ubylpebff dot rqh>
* Department of Mathematics and Computer Science
* College of the Holy Cross
* Worcester, MA, 01610-2395, USA
*
*
* ePiX 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.
*
* ePiX 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 ePiX; if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <cmath>
#include "errors.h"
#include "constants.h"
#include "pairs.h"
#include "triples.h"
#include "functions.h"
#include "affine.h"
namespace ePiX {
// rotate/reflect about (0,0)
static pair __epix_rotate(double Cs, double Sn, const pair& arg)
{
double x(arg.x1()), y(arg.x2());
return pair(Cs*x - Sn*y, Sn*x + Cs*y);
}
static pair __epix_reflect(double Cs, double Sn, const pair& arg)
{
double x(arg.x1()), y(arg.x2());
return pair(Cs*x + Sn*y, Sn*x - Cs*y);
}
// identity
affine::affine()
: m_00(0,0), m_10(1,0), m_01(0,1) { }
// images of (1,0), (0,1), (0,0)
affine::affine(const pair& pr1, const pair& pr2, const pair& loc)
: m_00(loc), m_10(pr1), m_01(pr2) { }
affine::affine(const P& pr1, const P& pr2, const P& loc)
: m_00(loc.x1(), loc.x2()),
m_10(pr1.x1(), pr1.x2()),
m_01(pr2.x1(), pr2.x2()) { }
affine& affine::shift(const pair& arg)
{
m_00 += arg;
m_10 += arg;
m_01 += arg;
return *this;
}
affine& affine::shift(const P& arg)
{
return shift(pair(arg.x1(), arg.x2()));
}
affine& affine::rotate(double theta, const pair& ctr)
{
const double Cs(Cos(theta));
const double Sn(Sin(theta));
// shift
m_00 -= ctr;
m_10 -= ctr;
m_01 -= ctr;
// rotate about origin and shift back
m_00 = __epix_rotate(Cs, Sn, m_00) + ctr;
m_10 = __epix_rotate(Cs, Sn, m_10) + ctr;
m_01 = __epix_rotate(Cs, Sn, m_01) + ctr;
return *this;
}
affine& affine::rotate(double theta, const P& ctr)
{
return rotate(theta, pair(ctr.x1(), ctr.x2()));
}
affine& affine::reflect(double theta, const pair& ctr)
{
const double Cs(Cos(2*theta));
const double Sn(Sin(2*theta));
// shift
m_00 -= ctr;
m_10 -= ctr;
m_01 -= ctr;
// reflect about origin and shift back
m_00 = __epix_reflect(Cs, Sn, m_00) + ctr;
m_10 = __epix_reflect(Cs, Sn, m_10) + ctr;
m_01 = __epix_reflect(Cs, Sn, m_01) + ctr;
return *this;
}
affine& affine::reflect(double theta, const P& ctr)
{
return reflect(theta, pair(ctr.x1(), ctr.x2()));
}
affine& affine::h_scale(double sc, const pair& ctr)
{
m_00 -= ctr;
m_10 -= ctr;
m_01 -= ctr;
const pair scale(sc, 1);
m_00 = (m_00 & scale) + ctr;
m_10 = (m_10 & scale) + ctr;
m_01 = (m_01 & scale) + ctr;
return *this;
}
affine& affine::h_scale(double sc, const P& ctr)
{
return h_scale(sc, pair(ctr.x1(), ctr.x2()));
}
affine& affine::v_scale(double sc, const pair& ctr)
{
// shift
m_00 -= ctr;
m_10 -= ctr;
m_01 -= ctr;
const pair scale(1, sc);
m_00 = (m_00 & scale) + ctr;
m_10 = (m_10 & scale) + ctr;
m_01 = (m_01 & scale) + ctr;
return *this;
}
affine& affine::v_scale(double sc, const P& ctr)
{
return v_scale(sc, pair(ctr.x1(), ctr.x2()));
}
affine& affine::scale(double sc, const pair& ctr)
{
// shift
m_00 -= ctr;
m_10 -= ctr;
m_01 -= ctr;
const pair scale(sc, sc);
m_00 = (m_00 & scale) + ctr;
m_10 = (m_10 & scale) + ctr;
m_01 = (m_01 & scale) + ctr;
return *this;
}
affine& affine::scale(double sc, const P& ctr)
{
return scale(sc, pair(ctr.x1(), ctr.x2()));
}
affine& affine::h_shear(double sc, const pair& ctr)
{
// shift
m_00 -= ctr;
m_10 -= ctr;
m_01 -= ctr;
m_00 += pair(sc*m_00.x2(), 0) + ctr;
m_10 += pair(sc*m_10.x2(), 0) + ctr;
m_01 += pair(sc*m_01.x2(), 0) + ctr;
return *this;
}
affine& affine::h_shear(double sc, const P& ctr)
{
return h_shear(sc, pair(ctr.x1(), ctr.x2()));
}
affine& affine::v_shear(double sc, const pair& ctr)
{
// shift
m_00 -= ctr;
m_10 -= ctr;
m_01 -= ctr;
m_00 += pair(0, sc*m_00.x1()) + ctr;
m_10 += pair(0, sc*m_10.x1()) + ctr;
m_01 += pair(0, sc*m_01.x1()) + ctr;
return *this;
}
affine& affine::v_shear(double sc, const P& ctr)
{
return v_shear(sc, pair(ctr.x1(), ctr.x2()));
}
affine& affine::postcomp(const affine& af)
{
m_00 = af(m_00);
m_10 = af(m_10);
m_01 = af(m_01);
return *this;
}
affine& affine::invert()
{
m_10 -= m_00;
m_01 -= m_00;
const double denom(m_10.x1()*m_01.x2() - m_10.x2()*m_01.x1());
if (fabs(denom) < EPIX_EPSILON)
{
// restore
m_10 += m_00;
m_01 += m_00;
epix_warning("affine not invertible, no action");
return *this;
}
// else compute inverse entries
const double a11( m_01.x2()/denom);
const double a12(-m_01.x1()/denom);
const double a21(-m_10.x2()/denom);
const double a22( m_10.x1()/denom);
pair tmp_00(-a11*m_00.x1() + a12*m_00.x2(),
a21*m_00.x1() - a22*m_00.x2());
m_00 = tmp_00;
m_10 = m_00 + pair(a11, a21);
m_01 = m_00 + pair(a12, a22);
return *this;
}
// evaluation
pair affine::operator() (const pair& arg) const
{
return m_00 + arg.x1()*(m_10 - m_00) + arg.x2()*(m_01 - m_00);
}
pair affine::operator() (const P& arg) const
{
return m_00 + arg.x1()*(m_10 - m_00) + arg.x2()*(m_01 - m_00);
}
// pre-composition
affine affine::operator() (const affine& af) const
{
return affine(this->operator()(af.m_10),
this->operator()(af.m_01),
this->operator()(af.m_00));
}
bool affine::reverses_orientation() const
{
const pair col1(m_10 - m_00);
const pair col2(m_01 - m_00);
return (col1.x1()*col2.x2() - col1.x2()*col2.x1() < -EPIX_EPSILON);
}
} // end of namespace
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