--- /dev/null
+///////////////////////////////////////////////////////////////////////////
+//
+// Copyright (c) 2002, Industrial Light & Magic, a division of Lucas
+// Digital Ltd. LLC
+//
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+// * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+// * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+// * Neither the name of Industrial Light & Magic nor the names of
+// its contributors may be used to endorse or promote products derived
+// from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+//
+///////////////////////////////////////////////////////////////////////////
+
+
+
+#ifndef INCLUDED_IMATHPLANE_H
+#define INCLUDED_IMATHPLANE_H
+
+//----------------------------------------------------------------------
+//
+// template class Plane3
+//
+// The Imath::Plane3<> class represents a half space, so the
+// normal may point either towards or away from origin. The
+// plane P can be represented by Imath::Plane3 as either p or -p
+// corresponding to the two half-spaces on either side of the
+// plane. Any function which computes a distance will return
+// either negative or positive values for the distance indicating
+// which half-space the point is in. Note that reflection, and
+// intersection functions will operate as expected.
+//
+//----------------------------------------------------------------------
+
+#include "ImathVec.h"
+#include "ImathLine.h"
+
+namespace Imath {
+
+
+template <class T>
+class Plane3
+{
+ public:
+
+ Vec3<T> normal;
+ T distance;
+
+ Plane3() {}
+ Plane3(const Vec3<T> &normal, T distance);
+ Plane3(const Vec3<T> &point, const Vec3<T> &normal);
+ Plane3(const Vec3<T> &point1,
+ const Vec3<T> &point2,
+ const Vec3<T> &point3);
+
+ //----------------------
+ // Various set methods
+ //----------------------
+
+ void set(const Vec3<T> &normal,
+ T distance);
+
+ void set(const Vec3<T> &point,
+ const Vec3<T> &normal);
+
+ void set(const Vec3<T> &point1,
+ const Vec3<T> &point2,
+ const Vec3<T> &point3 );
+
+ //----------------------
+ // Utilities
+ //----------------------
+
+ bool intersect(const Line3<T> &line,
+ Vec3<T> &intersection) const;
+
+ bool intersectT(const Line3<T> &line,
+ T ¶meter) const;
+
+ T distanceTo(const Vec3<T> &) const;
+
+ Vec3<T> reflectPoint(const Vec3<T> &) const;
+ Vec3<T> reflectVector(const Vec3<T> &) const;
+};
+
+
+//--------------------
+// Convenient typedefs
+//--------------------
+
+typedef Plane3<float> Plane3f;
+typedef Plane3<double> Plane3d;
+
+
+//---------------
+// Implementation
+//---------------
+
+template <class T>
+inline Plane3<T>::Plane3(const Vec3<T> &p0,
+ const Vec3<T> &p1,
+ const Vec3<T> &p2)
+{
+ set(p0,p1,p2);
+}
+
+template <class T>
+inline Plane3<T>::Plane3(const Vec3<T> &n, T d)
+{
+ set(n, d);
+}
+
+template <class T>
+inline Plane3<T>::Plane3(const Vec3<T> &p, const Vec3<T> &n)
+{
+ set(p, n);
+}
+
+template <class T>
+inline void Plane3<T>::set(const Vec3<T>& point1,
+ const Vec3<T>& point2,
+ const Vec3<T>& point3)
+{
+ normal = (point2 - point1) % (point3 - point1);
+ normal.normalize();
+ distance = normal ^ point1;
+}
+
+template <class T>
+inline void Plane3<T>::set(const Vec3<T>& point, const Vec3<T>& n)
+{
+ normal = n;
+ normal.normalize();
+ distance = normal ^ point;
+}
+
+template <class T>
+inline void Plane3<T>::set(const Vec3<T>& n, T d)
+{
+ normal = n;
+ normal.normalize();
+ distance = d;
+}
+
+template <class T>
+inline T Plane3<T>::distanceTo(const Vec3<T> &point) const
+{
+ return (point ^ normal) - distance;
+}
+
+template <class T>
+inline Vec3<T> Plane3<T>::reflectPoint(const Vec3<T> &point) const
+{
+ return normal * distanceTo(point) * -2.0 + point;
+}
+
+
+template <class T>
+inline Vec3<T> Plane3<T>::reflectVector(const Vec3<T> &v) const
+{
+ return normal * (normal ^ v) * 2.0 - v;
+}
+
+
+template <class T>
+inline bool Plane3<T>::intersect(const Line3<T>& line, Vec3<T>& point) const
+{
+ T d = normal ^ line.dir;
+ if ( d == 0.0 ) return false;
+ T t = - ((normal ^ line.pos) - distance) / d;
+ point = line(t);
+ return true;
+}
+
+template <class T>
+inline bool Plane3<T>::intersectT(const Line3<T>& line, T &t) const
+{
+ T d = normal ^ line.dir;
+ if ( d == 0.0 ) return false;
+ t = - ((normal ^ line.pos) - distance) / d;
+ return true;
+}
+
+template<class T>
+std::ostream &operator<< (std::ostream &o, const Plane3<T> &plane)
+{
+ return o << "(" << plane.normal << ", " << plane.distance
+ << ")";
+}
+
+template<class T>
+Plane3<T> operator* (const Plane3<T> &plane, const Matrix44<T> &M)
+{
+ // T
+ // -1
+ // Could also compute M but that would suck.
+ //
+
+ Vec3<T> dir1 = Vec3<T> (1, 0, 0) % plane.normal;
+ T dir1Len = dir1 ^ dir1;
+
+ Vec3<T> tmp = Vec3<T> (0, 1, 0) % plane.normal;
+ T tmpLen = tmp ^ tmp;
+
+ if (tmpLen > dir1Len)
+ {
+ dir1 = tmp;
+ dir1Len = tmpLen;
+ }
+
+ tmp = Vec3<T> (0, 0, 1) % plane.normal;
+ tmpLen = tmp ^ tmp;
+
+ if (tmpLen > dir1Len)
+ {
+ dir1 = tmp;
+ }
+
+ Vec3<T> dir2 = dir1 % plane.normal;
+ Vec3<T> point = plane.distance * plane.normal;
+
+ return Plane3<T> ( point * M,
+ (point + dir2) * M,
+ (point + dir1) * M );
+}
+
+template<class T>
+Plane3<T> operator- (const Plane3<T> &plane)
+{
+ return Plane3<T>(-plane.normal,-plane.distance);
+}
+
+
+} // namespace Imath
+
+#endif