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| author | Johan B. C. Engelen <jbc.engelen@swissonline.ch> | 2008-07-03 20:06:40 +0000 |
|---|---|---|
| committer | johanengelen <johanengelen@users.sourceforge.net> | 2008-07-03 20:06:40 +0000 |
| commit | e07de7ce18ff4cc440dc8947d61825122afea062 (patch) | |
| tree | 9ffdd823777582d6b5b8d3de135a03da42041402 /src/2geom/ellipse.cpp | |
| parent | Patch so Inkscape will compile on Solaris 10 from LP https://bugs.launchpad.n... (diff) | |
| download | inkscape-e07de7ce18ff4cc440dc8947d61825122afea062.tar.gz inkscape-e07de7ce18ff4cc440dc8947d61825122afea062.zip | |
update 2geom (svn rev1433)
(bzr r6134)
Diffstat (limited to 'src/2geom/ellipse.cpp')
| -rw-r--r-- | src/2geom/ellipse.cpp | 206 |
1 files changed, 206 insertions, 0 deletions
diff --git a/src/2geom/ellipse.cpp b/src/2geom/ellipse.cpp new file mode 100644 index 000000000..c9c5b9ec4 --- /dev/null +++ b/src/2geom/ellipse.cpp @@ -0,0 +1,206 @@ +/*
+ * Ellipse Curve
+ *
+ * Authors:
+ * Marco Cecchetti <mrcekets at gmail.com>
+ *
+ * Copyright 2008 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.
+ */
+
+
+#include <2geom/ellipse.h>
+#include <2geom/svg-elliptical-arc.h>
+#include <2geom/numeric/fitting-tool.h>
+#include <2geom/numeric/fitting-model.h>
+
+
+namespace Geom
+{
+
+void Ellipse::set(double A, double B, double C, double D, double E, double F)
+{
+ double den = 4*A*C - B*B;
+ if ( den == 0 )
+ {
+ THROW_LOGICALERROR("den == 0, while computing ellipse centre");
+ }
+ m_centre[X] = (B*E - 2*C*D) / den;
+ m_centre[Y] = (B*D - 2*A*E) / den;
+
+ // evaluate the a coefficient of the ellipse equation in normal form
+ // E(x,y) = a*(x-cx)^2 + b*(x-cx)*(y-cy) + c*(y-cy)^2 = 1
+ // where b = a*B , c = a*C, (cx,cy) == centre
+ double num = A * sqr(m_centre[X])
+ + B * m_centre[X] * m_centre[Y]
+ + C * sqr(m_centre[Y])
+ - A * F;
+
+
+ //evaluate ellipse rotation angle
+ double rot = std::atan2( -B, -(A - C) )/2;
+// std::cerr << "rot = " << rot << std::endl;
+ bool swap_axes = false;
+ if ( are_near(rot, 0) ) rot = 0;
+ if ( are_near(rot, M_PI/2) || rot < 0 )
+ {
+ swap_axes = true;
+ }
+
+ // evaluate the length of the ellipse rays
+ double cosrot = std::cos(rot);
+ double sinrot = std::sin(rot);
+ double cos2 = cosrot * cosrot;
+ double sin2 = sinrot * sinrot;
+ double cossin = cosrot * sinrot;
+
+ den = A * cos2 + B * cossin + C * sin2;
+ if ( den == 0 )
+ {
+ THROW_LOGICALERROR("den == 0, while computing 'rx' coefficient");
+ }
+ double rx2 = num/den;
+ if ( rx2 < 0 )
+ {
+ THROW_LOGICALERROR("rx2 < 0, while computing 'rx' coefficient");
+ }
+ double rx = std::sqrt(rx2);
+
+ den = C * cos2 - B * cossin + A * sin2;
+ if ( den == 0 )
+ {
+ THROW_LOGICALERROR("den == 0, while computing 'ry' coefficient");
+ }
+ double ry2 = num/den;
+ if ( ry2 < 0 )
+ {
+ THROW_LOGICALERROR("ry2 < 0, while computing 'rx' coefficient");
+ }
+ double ry = std::sqrt(ry2);
+
+ // the solution is not unique so we choose always the ellipse
+ // with a rotation angle between 0 and PI/2
+ if ( swap_axes ) std::swap(rx, ry);
+ if ( are_near(rot, M_PI/2)
+ || are_near(rot, -M_PI/2)
+ || are_near(rx, ry) )
+ {
+ rot = 0;
+ }
+ else if ( rot < 0 )
+ {
+ rot += M_PI/2;
+ }
+
+ m_ray[X] = rx;
+ m_ray[Y] = ry;
+ m_angle = rot;
+}
+
+
+void Ellipse::set(std::vector<Point> const& points)
+{
+ size_t sz = points.size();
+ if (sz < 5)
+ {
+ THROW_RANGEERROR("fitting error: too few points passed");
+ }
+ NL::LFMEllipse model;
+ NL::least_squeares_fitter<NL::LFMEllipse> fitter(model, sz);
+
+ for (size_t i = 0; i < sz; ++i)
+ {
+ fitter.append(points[i]);
+ }
+ fitter.update();
+
+ NL::Vector z(sz, 0.0);
+ model.instance(*this, fitter.result(z));
+}
+
+
+SVGEllipticalArc
+Ellipse::arc(Point const& initial, Point const& inner, Point const& final,
+ bool _svg_compliant)
+{
+ Point sp_cp = initial - center();
+ Point ep_cp = final - center();
+ Point ip_cp = inner - center();
+
+ double angle1 = angle_between(sp_cp, ep_cp);
+ double angle2 = angle_between(sp_cp, ip_cp);
+ double angle3 = angle_between(ip_cp, ep_cp);
+
+ bool large_arc_flag = true;
+ bool sweep_flag = true;
+
+ if ( angle1 > 0 )
+ {
+ if ( angle2 > 0 && angle3 > 0 )
+ {
+ large_arc_flag = false;
+ sweep_flag = true;
+ }
+ else
+ {
+ large_arc_flag = true;
+ sweep_flag = false;
+ }
+ }
+ else
+ {
+ if ( angle2 < 0 && angle3 < 0 )
+ {
+ large_arc_flag = false;
+ sweep_flag = false;
+ }
+ else
+ {
+ large_arc_flag = true;
+ sweep_flag = true;
+ }
+ }
+
+ SVGEllipticalArc ea( initial, ray(X), ray(Y), rot_angle(),
+ large_arc_flag, sweep_flag, final, _svg_compliant);
+ return ea;
+}
+
+
+} // end namespace Geom
+
+
+/*
+ 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:encoding=utf-8:textwidth=99 :
+
+
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