The GtkRadiant sources as originally released under the GPL license.

libs/math/plane.h

@@ -0,0 +1,153 @@
+/*
+Copyright (C) 2001-2006, William Joseph.
+All Rights Reserved.
+
+This file is part of GtkRadiant.
+
+GtkRadiant 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 2 of the License, or
+(at your option) any later version.
+
+GtkRadiant 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 GtkRadiant; if not, write to the Free Software
+Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+*/
+
+#if !defined(INCLUDED_MATH_PLANE_H)
+#define INCLUDED_MATH_PLANE_H
+
+/// \file
+/// \brief Plane data types and related operations.
+
+#include "math/matrix.h"
+
+/// \brief A plane equation stored in double-precision floating-point.
+class Plane3
+{
+public:
+  double a, b, c, d;
+
+  Plane3()
+  {
+  }
+  Plane3(double _a, double _b, double _c, double _d)
+    : a(_a), b(_b), c(_c), d(_d)
+  {
+  }
+  template<typename Element>
+  Plane3(const BasicVector3<Element>& normal, double dist)
+    : a(normal.x()), b(normal.y()), c(normal.z()), d(dist)
+  {
+  }
+
+  BasicVector3<double>& normal()
+  {
+    return reinterpret_cast<BasicVector3<double>&>(*this);
+  }
+  const BasicVector3<double>& normal() const
+  {
+    return reinterpret_cast<const BasicVector3<double>&>(*this);
+  }
+  double& dist()
+  {
+    return d;
+  }
+  const double& dist() const
+  {
+    return d;
+  }
+};
+
+inline Plane3 plane3_normalised(const Plane3& plane)
+{
+  double rmagnitude = 1.0 / sqrt(plane.a * plane.a + plane.b * plane.b + plane.c * plane.c);
+  return Plane3(
+    plane.a * rmagnitude,
+    plane.b * rmagnitude,
+    plane.c * rmagnitude,
+    plane.d * rmagnitude
+  );
+}
+
+inline Plane3 plane3_translated(const Plane3& plane, const Vector3& translation)
+{
+  Plane3 transformed;
+  transformed.a = plane.a;
+  transformed.b = plane.b;
+  transformed.c = plane.c;
+  transformed.d = -((-plane.d * transformed.a + translation.x()) * transformed.a + 
+              (-plane.d * transformed.b + translation.y()) * transformed.b + 
+              (-plane.d * transformed.c + translation.z()) * transformed.c);
+  return transformed;
+}
+
+inline Plane3 plane3_transformed(const Plane3& plane, const Matrix4& transform)
+{
+  Plane3 transformed;
+  transformed.a = transform[0] * plane.a + transform[4] * plane.b + transform[8] * plane.c;
+  transformed.b = transform[1] * plane.a + transform[5] * plane.b + transform[9] * plane.c;
+  transformed.c = transform[2] * plane.a + transform[6] * plane.b + transform[10] * plane.c;
+  transformed.d = -((-plane.d * transformed.a + transform[12]) * transformed.a + 
+              (-plane.d * transformed.b + transform[13]) * transformed.b + 
+              (-plane.d * transformed.c + transform[14]) * transformed.c);
+  return transformed;
+}
+
+inline Plane3 plane3_inverse_transformed(const Plane3& plane, const Matrix4& transform)
+{
+  return Plane3
+  (
+    transform[ 0] * plane.a + transform[ 1] * plane.b + transform[ 2] * plane.c + transform[ 3] * plane.d,
+    transform[ 4] * plane.a + transform[ 5] * plane.b + transform[ 6] * plane.c + transform[ 7] * plane.d,
+    transform[ 8] * plane.a + transform[ 9] * plane.b + transform[10] * plane.c + transform[11] * plane.d,
+    transform[12] * plane.a + transform[13] * plane.b + transform[14] * plane.c + transform[15] * plane.d
+  );
+}
+
+inline Plane3 plane3_flipped(const Plane3& plane)
+{
+  return Plane3(vector3_negated(plane.normal()), -plane.dist());
+}
+
+const double c_PLANE_NORMAL_EPSILON = 0.0001f;
+const double c_PLANE_DIST_EPSILON = 0.02;
+
+inline bool plane3_equal(const Plane3& self, const Plane3& other)
+{
+  return vector3_equal_epsilon(self.normal(), other.normal(), c_PLANE_NORMAL_EPSILON)
+	  && float_equal_epsilon(self.dist(), other.dist(), c_PLANE_DIST_EPSILON);
+}
+
+inline bool plane3_opposing(const Plane3& self, const Plane3& other)
+{
+  return plane3_equal(self, plane3_flipped(other));
+}
+
+inline bool plane3_valid(const Plane3& self)
+{
+  return float_equal_epsilon(vector3_dot(self.normal(), self.normal()), 1.0, 0.01);
+}
+
+template<typename Element>
+inline Plane3 plane3_for_points(const BasicVector3<Element>& p0, const BasicVector3<Element>& p1, const BasicVector3<Element>& p2)
+{
+	Plane3 self;
+  self.normal() = vector3_normalised(vector3_cross(vector3_subtracted(p1, p0), vector3_subtracted(p2, p0)));
+	self.dist() = vector3_dot(p0, self.normal());
+	return self;
+}
+
+template<typename Element>
+inline Plane3 plane3_for_points(const BasicVector3<Element> planepts[3])
+{
+	return plane3_for_points(planepts[2], planepts[1], planepts[0]);
+}
+
+
+#endif