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// SPDX-License-Identifier: GPL-2.0-or-later
/** \file
* LPE "Circle through 3 points" implementation
*/
/*
* Authors:
* Maximilian Albert
*
* Copyright (C) Johan Engelen 2007 <j.b.c.engelen@utwente.nl>
* Copyright (C) Maximilian Albert 2008 <maximilian.albert@gmail.com>
*
* Released under GNU GPL v2+, read the file 'COPYING' for more information.
*/
#include "live_effects/lpe-circle_3pts.h"
// You might need to include other 2geom files. You can add them here:
#include <2geom/circle.h>
#include <2geom/path-sink.h>
// TODO due to internal breakage in glibmm headers, this must be last:
#include <glibmm/i18n.h>
namespace Inkscape {
namespace LivePathEffect {
LPECircle3Pts::LPECircle3Pts(LivePathEffectObject *lpeobject) :
Effect(lpeobject)
{
}
LPECircle3Pts::~LPECircle3Pts() = default;
static void _circle3(Geom::Point const &A, Geom::Point const &B, Geom::Point const &C, Geom::PathVector &path_out) {
using namespace Geom;
Point D = (A + B)/2;
Point E = (B + C)/2;
Point v = (B - A).ccw();
Point w = (C - B).ccw();
double det = -v[0] * w[1] + v[1] * w[0];
Point M;
if (!v.isZero()) {
Point F = E - D;
double lambda = det == 0 ? 0 : (-w[1] * F[0] + w[0] * F[1]) / det;
M = D + v * lambda;
} else {
M = E;
}
double radius = L2(M - A);
Geom::Circle c(M, radius);
path_out = Geom::Path(c);
}
Geom::PathVector
LPECircle3Pts::doEffect_path (Geom::PathVector const & path_in)
{
Geom::PathVector path_out = Geom::PathVector();
// we assume that the path has >= 3 nodes
Geom::Point A = path_in[0].initialPoint();
Geom::Point B = path_in[0].pointAt(1);
Geom::Point C = path_in[0].pointAt(2);
_circle3(A, B, C, path_out);
return path_out;
}
/* ######################## */
} //namespace LivePathEffect
} /* namespace Inkscape */
/*
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 :
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