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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* ... some mathematical functions
*
* Authors:
* Johan Engelen <goejendaagh@zonnet.nl>
*
* Copyright (C) 2007 Johan Engelen
*
* Released under GNU GPL v2+, read the file 'COPYING' for more information.
*/
#ifndef SEEN_INKSCAPE_UTIL_MATHFNS_H
#define SEEN_INKSCAPE_UTIL_MATHFNS_H
#include <2geom/point.h>
namespace Inkscape {
namespace Util {
/**
* Returns area in triangle given by points; may be negative.
*/
inline double
triangle_area (Geom::Point p1, Geom::Point p2, Geom::Point p3)
{
using Geom::X;
using Geom::Y;
return (p1[X]*p2[Y] + p1[Y]*p3[X] + p2[X]*p3[Y] - p2[Y]*p3[X] - p1[Y]*p2[X] - p1[X]*p3[Y]);
}
/**
* \return x rounded to the nearest multiple of c1 plus c0.
*
* \note
* If c1==0 (and c0 is finite), then returns +/-inf. This makes grid spacing of zero
* mean "ignore the grid in this dimension".
*/
inline double round_to_nearest_multiple_plus(double x, double const c1, double const c0)
{
return floor((x - c0) / c1 + .5) * c1 + c0;
}
/**
* \return x rounded to the lower multiple of c1 plus c0.
*
* \note
* If c1==0 (and c0 is finite), then returns +/-inf. This makes grid spacing of zero
* mean "ignore the grid in this dimension".
*/
inline double round_to_lower_multiple_plus(double x, double const c1, double const c0 = 0)
{
return floor((x - c0) / c1) * c1 + c0;
}
/**
* \return x rounded to the upper multiple of c1 plus c0.
*
* \note
* If c1==0 (and c0 is finite), then returns +/-inf. This makes grid spacing of zero
* mean "ignore the grid in this dimension".
*/
inline double round_to_upper_multiple_plus(double x, double const c1, double const c0 = 0)
{
return ceil((x - c0) / c1) * c1 + c0;
}
}
}
#endif
/*
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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