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/**
* \file
* \brief Linear fragment function class
*//*
* Authors:
* Nathan Hurst <njh@mail.csse.monash.edu.au>
* Michael Sloan <mgsloan@gmail.com>
* Krzysztof Kosiński <tweenk.pl@gmail.com>
*
* Copyright (C) 2006-2015 authors
*
* This library is free software; you can redistribute it and/or
* modify it either under the terms of the GNU Lesser General Public
* License version 2.1 as published by the Free Software Foundation
* (the "LGPL") or, at your option, under the terms of the Mozilla
* Public License Version 1.1 (the "MPL"). If you do not alter this
* notice, a recipient may use your version of this file under either
* the MPL or the LGPL.
*
* You should have received a copy of the LGPL along with this library
* in the file COPYING-LGPL-2.1; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
* You should have received a copy of the MPL along with this library
* in the file COPYING-MPL-1.1
*
* The contents of this file are subject to the Mozilla Public License
* Version 1.1 (the "License"); you may not use this file except in
* compliance with the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
* OF ANY KIND, either express or implied. See the LGPL or the MPL for
* the specific language governing rights and limitations.
*/
#ifndef LIB2GEOM_SEEN_LINEAR_H
#define LIB2GEOM_SEEN_LINEAR_H
#include <2geom/interval.h>
#include <2geom/math-utils.h>
namespace Geom {
class SBasis;
/**
* @brief Function that interpolates linearly between two values.
* @ingroup Fragments
*/
class Linear
: boost::additive< Linear
, boost::arithmetic< Linear, Coord
, boost::equality_comparable< Linear
> > >
{
public:
Coord a[2];
Linear() {a[0]=0; a[1]=0;}
Linear(Coord aa, Coord b) {a[0] = aa; a[1] = b;}
Linear(Coord aa) {a[0] = aa; a[1] = aa;}
Coord operator[](unsigned i) const {
assert(i < 2);
return a[i];
}
Coord &operator[](unsigned i) {
assert(i < 2);
return a[i];
}
//IMPL: FragmentConcept
typedef Coord output_type;
bool isZero(Coord eps=EPSILON) const { return are_near(a[0], 0., eps) && are_near(a[1], 0., eps); }
bool isConstant(Coord eps=EPSILON) const { return are_near(a[0], a[1], eps); }
bool isFinite() const { return std::isfinite(a[0]) && std::isfinite(a[1]); }
Coord at0() const { return a[0]; }
Coord &at0() { return a[0]; }
Coord at1() const { return a[1]; }
Coord &at1() { return a[1]; }
Coord valueAt(Coord t) const { return lerp(t, a[0], a[1]); }
Coord operator()(Coord t) const { return valueAt(t); }
// not very useful, but required for FragmentConcept
std::vector<Coord> valueAndDerivatives(Coord t, unsigned n) {
std::vector<Coord> result(n+1, 0.0);
result[0] = valueAt(t);
if (n >= 1) {
result[1] = a[1] - a[0];
}
return result;
}
//defined in sbasis.h
inline SBasis toSBasis() const;
OptInterval bounds_exact() const { return Interval(a[0], a[1]); }
OptInterval bounds_fast() const { return bounds_exact(); }
OptInterval bounds_local(double u, double v) const { return Interval(valueAt(u), valueAt(v)); }
double tri() const {
return a[1] - a[0];
}
double hat() const {
return (a[1] + a[0])/2;
}
// addition of other Linears
Linear &operator+=(Linear const &other) {
a[0] += other.a[0];
a[1] += other.a[1];
return *this;
}
Linear &operator-=(Linear const &other) {
a[0] -= other.a[0];
a[1] -= other.a[1];
return *this;
}
//
Linear &operator+=(Coord x) {
a[0] += x; a[1] += x;
return *this;
}
Linear &operator-=(Coord x) {
a[0] -= x; a[1] -= x;
return *this;
}
Linear &operator*=(Coord x) {
a[0] *= x; a[1] *= x;
return *this;
}
Linear &operator/=(Coord x) {
a[0] /= x; a[1] /= x;
return *this;
}
Linear operator-() const {
Linear ret(-a[0], -a[1]);
return ret;
}
bool operator==(Linear const &other) const {
return a[0] == other.a[0] && a[1] == other.a[1];
}
};
inline Linear reverse(Linear const &a) { return Linear(a[1], a[0]); }
inline Linear portion(Linear const &a, Coord from, Coord to) {
Linear result(a.valueAt(from), a.valueAt(to));
return result;
}
} // end namespace Geom
#endif //LIB2GEOM_SEEN_LINEAR_H
/*
Local Variables:
mode:c++
c-file-style:"stroustrup"
c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
indent-tabs-mode:nil
fill-column:99
End:
*/
// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:fileencoding=utf-8:textwidth=99 :
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