text: /*
  -----------------------------------------------------------------------------
  This source file is part of OGRE
      (Object-oriented Graphics Rendering Engine)
  For the latest info, see http://www.ogre3d.org/
  
  Copyright (c) 2000-2016 Torus Knot Software Ltd
  
  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:
  
  The above copyright notice and this permission notice shall be included in
  all copies or substantial portions of the Software.
  
  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  THE SOFTWARE.
  -----------------------------------------------------------------------------
  */
  // This file is based on material originally from:
  // Geometric Tools, LLC
  // Copyright (c) 1998-2010
  // Distributed under the Boost Software License, Version 1.0.
  // http://www.boost.org/LICENSE_1_0.txt
  // http://www.geometrictools.com/License/Boost/LICENSE_1_0.txt
  
  
  #ifndef __Plane_H__
  #define __Plane_H__
  
  #include "OgrePrerequisites.h"
  
  #include "OgreVector3.h"
  
  namespace Ogre {
  
      /** \addtogroup Core
      *  @{
      */
      /** \addtogroup Math
      *  @{
      */
      /** Defines a plane in 3D space.
          @remarks
              A plane is defined in 3D space by the equation
              Ax + By + Cz + D = 0
          @par
              This equates to a vector (the normal of the plane, whose x, y
              and z components equate to the coefficients A, B and C
              respectively), and a constant (D) which is the distance along
              the normal you have to go to move the plane back to the origin.
       */
      class _OgreExport Plane
      {
      public:
          Vector3 normal;
          Real d;
  
      public:
          /** Default constructor - sets everything to 0.
          */
          Plane ();
          Plane (const Plane& rhs);
          /** Construct a plane through a normal, and a distance to move the plane along the normal.*/
          Plane (const Vector3& rkNormal, Real fConstant);
          /** Construct a plane using the 4 constants directly **/
          Plane (Real a, Real b, Real c, Real d);
          Plane (const Vector3& rkNormal, const Vector3& rkPoint);
          Plane (const Vector3& rkPoint0, const Vector3& rkPoint1,
              const Vector3& rkPoint2);
  
          /** The "positive side" of the plane is the half space to which the
              plane normal points. The "negative side" is the other half
              space. The flag "no side" indicates the plane itself.
          */
          enum Side
          {
              NO_SIDE,
              POSITIVE_SIDE,
              NEGATIVE_SIDE,
              BOTH_SIDE
          };
  
          Side getSide (const Vector3& rkPoint) const;
  
          /**
          Returns the side where the alignedBox is. The flag BOTH_SIDE indicates an intersecting box.
          One corner ON the plane is sufficient to consider the box and the plane intersecting.
          */
          Side getSide (const AxisAlignedBox& rkBox) const;
  
          /** Returns which side of the plane that the given box lies on.
              The box is defined as centre/half-size pairs for effectively.
          @param centre The centre of the box.
          @param halfSize The half-size of the box.
          @return
              POSITIVE_SIDE if the box complete lies on the "positive side" of the plane,
              NEGATIVE_SIDE if the box complete lies on the "negative side" of the plane,
              and BOTH_SIDE if the box intersects the plane.
          */
          Side getSide (const Vector3& centre, const Vector3& halfSize) const;
  
          /** This is a pseudodistance. The sign of the return value is
              positive if the point is on the positive side of the plane,
              negative if the point is on the negative side, and zero if the
              point is on the plane.
              @par
              The absolute value of the return value is the true distance only
              when the plane normal is a unit length vector.
          */
          Real getDistance (const Vector3& rkPoint) const;
  
          /** Redefine this plane based on 3 points. */
          void redefine(const Vector3& rkPoint0, const Vector3& rkPoint1,
              const Vector3& rkPoint2);
  
          /** Redefine this plane based on a normal and a point. */
          void redefine(const Vector3& rkNormal, const Vector3& rkPoint);
  
          /** Project a vector onto the plane. 
          @remarks This gives you the element of the input vector that is perpendicular 
              to the normal of the plane. You can get the element which is parallel
              to the normal of the plane by subtracting the result of this method
              from the original vector, since parallel + perpendicular = original.
          @param v The input vector
          */
          Vector3 projectVector(const Vector3& v) const;
  
          /** Normalises the plane.
              @remarks
                  This method normalises the plane's normal and the length scale of d
                  is as well.
              @note
                  This function will not crash for zero-sized vectors, but there
                  will be no changes made to their components.
              @return The previous length of the plane's normal.
          */
          Real normalise(void);
  
          /// Get flipped plane, with same location but reverted orientation
          Plane operator - () const
          {
              return Plane(-(normal.x), -(normal.y), -(normal.z), -d); // not equal to Plane(-normal, -d)
          }
  
          /// Comparison operator
          bool operator==(const Plane& rhs) const
          {
              return (rhs.d == d && rhs.normal == normal);
          }
          bool operator!=(const Plane& rhs) const
          {
              return (rhs.d != d || rhs.normal != normal);
          }
  
          _OgreExport friend std::ostream& operator<< (std::ostream& o, const Plane& p);
      };
  
      typedef vector<Plane>::type PlaneList;
      /** @} */
      /** @} */
  
  } // namespace Ogre
  
  #endif
  