source: code/forks/sandbox_light/src/external/ogremath/OgrePlane.cpp

/*
-----------------------------------------------------------------------------
This source file is part of OGRE
(Object-oriented Graphics Rendering Engine)
For the latest info, see http://www.ogre3d.org/

Copyright (c) 2000-2006 Torus Knot Software Ltd
Also see acknowledgements in Readme.html

This program is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License as published by the Free Software
Foundation; either version 2 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 Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with
this program; if not, write to the Free Software Foundation, Inc., 59 Temple
Place - Suite 330, Boston, MA 02111-1307, USA, or go to
http://www.gnu.org/copyleft/lesser.txt.

You may alternatively use this source under the terms of a specific version of
the OGRE Unrestricted License provided you have obtained such a license from
Torus Knot Software Ltd.
-----------------------------------------------------------------------------
*/
#include "OgrePlane.h"
#include "OgreMatrix3.h"

namespace Ogre {
        //-----------------------------------------------------------------------
        Plane::Plane ()
        {
                normal = Vector3::ZERO;
                d = 0.0;
        }
        //-----------------------------------------------------------------------
        Plane::Plane (const Plane& rhs)
        {
                normal = rhs.normal;
                d = rhs.d;
        }
        //-----------------------------------------------------------------------
        Plane::Plane (const Vector3& rkNormal, Real fConstant)
        {
                normal = rkNormal;
                d = -fConstant;
        }
        //---------------------------------------------------------------------
        Plane::Plane (Real a, Real b, Real c, Real _d)
                : normal(a, b, c), d(_d)
        {
        }
        //-----------------------------------------------------------------------
        Plane::Plane (const Vector3& rkNormal, const Vector3& rkPoint)
        {
                redefine(rkNormal, rkPoint);
        }
        //-----------------------------------------------------------------------
        Plane::Plane (const Vector3& rkPoint0, const Vector3& rkPoint1,
                const Vector3& rkPoint2)
        {
                redefine(rkPoint0, rkPoint1, rkPoint2);
        }
        //-----------------------------------------------------------------------
        Real Plane::getDistance (const Vector3& rkPoint) const
        {
                return normal.dotProduct(rkPoint) + d;
        }
        //-----------------------------------------------------------------------
        Plane::Side Plane::getSide (const Vector3& rkPoint) const
        {
                Real fDistance = getDistance(rkPoint);

                if ( fDistance < 0.0 )
                        return Plane::NEGATIVE_SIDE;

                if ( fDistance > 0.0 )
                        return Plane::POSITIVE_SIDE;

                return Plane::NO_SIDE;
        }


    //-----------------------------------------------------------------------
    Plane::Side Plane::getSide (const Vector3& centre, const Vector3& halfSize) const
    {
        // Calculate the distance between box centre and the plane
        Real dist = getDistance(centre);

        // Calculate the maximise allows absolute distance for
        // the distance between box centre and plane
        Real maxAbsDist = normal.absDotProduct(halfSize);

        if (dist < -maxAbsDist)
            return Plane::NEGATIVE_SIDE;

        if (dist > +maxAbsDist)
            return Plane::POSITIVE_SIDE;

        return Plane::BOTH_SIDE;
    }
        //-----------------------------------------------------------------------
        void Plane::redefine(const Vector3& rkPoint0, const Vector3& rkPoint1,
                const Vector3& rkPoint2)
        {
                Vector3 kEdge1 = rkPoint1 - rkPoint0;
                Vector3 kEdge2 = rkPoint2 - rkPoint0;
                normal = kEdge1.crossProduct(kEdge2);
                normal.normalise();
                d = -normal.dotProduct(rkPoint0);
        }
        //-----------------------------------------------------------------------
        void Plane::redefine(const Vector3& rkNormal, const Vector3& rkPoint)
        {
                normal = rkNormal;
                d = -rkNormal.dotProduct(rkPoint);
        }
        //-----------------------------------------------------------------------
        Vector3 Plane::projectVector(const Vector3& p) const
        {
                // We know plane normal is unit length, so use simple method
                Matrix3 xform;
                xform[0][0] = 1.0f - normal.x * normal.x;
                xform[0][1] = -normal.x * normal.y;
                xform[0][2] = -normal.x * normal.z;
                xform[1][0] = -normal.y * normal.x;
                xform[1][1] = 1.0f - normal.y * normal.y;
                xform[1][2] = -normal.y * normal.z;
                xform[2][0] = -normal.z * normal.x;
                xform[2][1] = -normal.z * normal.y;
                xform[2][2] = 1.0f - normal.z * normal.z;
                return xform * p;

        }
        //-----------------------------------------------------------------------
    Real Plane::normalise(void)
    {
        Real fLength = normal.length();

        // Will also work for zero-sized vectors, but will change nothing
        if (fLength > 1e-08f)
        {
            Real fInvLength = 1.0f / fLength;
            normal *= fInvLength;
            d *= fInvLength;
        }

        return fLength;
    }
        //-----------------------------------------------------------------------
        std::ostream& operator<< (std::ostream& o, const Plane& p)
        {
                o << "Plane(normal=" << p.normal << ", d=" << p.d << ")";
                return o;
        }
} // namespace Ogre