From 5f5603d361555208897b9e1578c331c35f154094 Mon Sep 17 00:00:00 2001
From: Kilian Weishaupt <kilian.weishaupt@iws.uni-stuttgart.de>
Date: Thu, 29 Jul 2021 10:30:21 +0200
Subject: [PATCH] [geometry] Add function to calculate circumsphere of
trinangle
---
dumux/geometry/circumsphere.hh | 64 ++++++++++++++++++++++++++++++++++
1 file changed, 64 insertions(+)
create mode 100644 dumux/geometry/circumsphere.hh
diff --git a/dumux/geometry/circumsphere.hh b/dumux/geometry/circumsphere.hh
new file mode 100644
index 0000000000..e7bd64d7d0
--- /dev/null
+++ b/dumux/geometry/circumsphere.hh
@@ -0,0 +1,64 @@
+/*****************************************************************************
+ * See the file COPYING for full copying permissions. *
+ * *
+ * This program 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 3 of the License, or *
+ * (at your option) any later version. *
+ * *
+ * This program 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 this program. If not, see <http://www.gnu.org/licenses/>. *
+ *****************************************************************************/
+/*!
+ * \file
+ * \ingroup Geometry
+ * \brief A function to compute the circumsphere of a given geometry
+ * \note The circumscribed sphere (or circumsphere) is a sphere touching all vertices of the geometry
+ * Therefore it does not necessarily exist for all geometries.
+ */
+#ifndef DUMUX_GEOMETRY_CIRCUMSPHERE_HH
+#define DUMUX_GEOMETRY_CIRCUMSPHERE_HH
+
+#include <type_traits>
+#include <dumux/common/math.hh>
+#include <dumux/geometry/sphere.hh>
+
+namespace Dumux {
+
+/*!
+ * \ingroup Geometry
+ * \brief Computes the circumsphere of a triangle
+ * \note See https://www.ics.uci.edu/~eppstein/junkyard/circumcenter.html
+ */
+template<class Point>
+static inline Sphere<typename Point::value_type, Point::dimension>
+circumSphereOfTriangle(const Point& a, const Point& b, const Point& c)
+{
+ const auto ac = c - a;
+ const auto ab = b - a;
+ const auto n = crossProduct(ab, ac);
+ const auto distCenterToA = (crossProduct(n, ab)*ac.two_norm2() + crossProduct(ac, n)*ab.two_norm2()) / (2.0*n.two_norm2());
+
+ return { a + distCenterToA, distCenterToA.two_norm() };
+}
+
+/*!
+ * \ingroup Geometry
+ * \brief Computes the circumsphere of a triangle
+ */
+template<class Geometry, typename std::enable_if_t<Geometry::mydimension == 2, int> = 0>
+static inline Sphere<typename Geometry::ctype, Geometry::coorddimension>
+circumSphereOfTriangle(const Geometry& triangle)
+{
+ assert(triangle.corners() == 3 && "Geometry is not a triangle.");
+ return circumSphereOfTriangle(triangle.corner(0), triangle.corner(1), triangle.corner(2));
+}
+
+} // end namespace Dumux
+
+#endif
--
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