[ggt-devel] changes tu Frustum.h -> added documentation and made code simpler.

[Benjamin S. <bes...@go...>]

/************************************************************** ggt-head beg
 *
 * GGT: Generic Graphics Toolkit
 *
 * Original Authors:
 *   Benjamin Schulz
 *
 * -----------------------------------------------------------------
 * File:          Frustum.h
 * Date modified: 2004/12/14 03:35:01
 * Version:       1.0
 * -----------------------------------------------------------------
 *
 *********************************************************** ggt-head end */
/*************************************************************** ggt-cpr beg
*
* GGT: The Generic Graphics Toolkit
* Copyright (C) 2001,2002 Allen Bierbaum
*
* This library 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 2.1 of the License, or (at your option) any later version.
*
* This library 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 library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
 ************************************************************ ggt-cpr end */

#ifndef _GMTL_FRUSTUM_H_
#define _GMTL_FRUSTUM_H_

#include <gmtl/Plane.h>

namespace gmtl
{
    /**
     * This class defines a View Frustum Volume as a set of 6 planes
     *
     * @ingroup Types
     */
    template <class DATA_TYPE>
    class Frustum
    {
        public:
            typedef DATA_TYPE DataType;
            typedef Frustum<DATA_TYPE> FrustumType;

        public:
            enum PlaneNames
            {
                PLANE_LEFT = 0,
                PLANE_RIGHT = 1,
                PLANE_BOTTOM = 2,
                PLANE_TOP = 3,
                PLANE_NEAR = 4,
                PLANE_FAR = 5
            };

            /**
            * Constructs a new frustum with all planes in default state
            */
            Frustum()
            {

            }

            /**
            * Constructs a new frustum with the given projection matrix.
            *
            * @param projMatrix   the projection matrix of you camera or
light or what ever
            */
            Frustum(const gmtl::Matrix44f & projMatrix)
            {
                this->extractPlanes(projMatrix);
            }

            /**
            * Constructs a new frustum with given projection and modelview
matricies.
            * the matricies are multiplied in this order : M = projMatrix *
modelviewMatrix.
            * the planes are than extracted from M.
            *
            * @param modelviewMatrix    the modelview matrix of you camera
or light or what ever
            * @param projMatrix            the projection matrix of you
camera or light or what ever
            */
            Frustum(const gmtl::Matrix44f & modelviewMatrix, const
gmtl::Matrix44f & projMatrix)
            {
                this->extractPlanes(modelviewMatrix, projMatrix);
            }

            /**
            * extracts the planes from the given projection matrix.
            *
            * @param projMatrix   the projection matrix of you camera or
light or what ever
            */
            void extractPlanes(const gmtl::Matrix44f & modelviewMatrix,
const gmtl::Matrix44f & projMatrix)
            {
                this->extractPlanes(projMatrix * modelviewMatrix);
            }

            /**
            * extracts the planes from the given projection and modelview
matricies.
            * the matricies are multiplied in this order : M = projMatrix *
modelviewMatrix.
            * the planes are than extracted from M.
            *
            * @param modelviewMatrix    the modelview matrix of you camera
or light or what ever
            * @param projMatrix            the projection matrix of you
camera or light or what ever
            */
            void extractPlanes(const gmtl::Matrix44f & projMatrix)
            {
                const gmtl::Matrix44f & m = projMatrix;

                //left
                this->m_planes[PLANE_LEFT].setNormal( gmtl::Vec3f( m[3][0] +
m[0][0], m[3][1] + m[0][1], m[3][2] + m[0][2] ) );
                this->m_planes[PLANE_LEFT].setOffset(m[3][3] + m[0][3]);
                //right
                this->m_planes[PLANE_RIGHT].setNormal( gmtl::Vec3f( m[3][0]
- m[0][0], m[3][1] - m[0][1], m[3][2] - m[0][2] ) );
                this->m_planes[PLANE_RIGHT].setOffset(m[3][3] - m[0][3]);
                //bottom
                this->m_planes[PLANE_BOTTOM].setNormal( gmtl::Vec3f( m[3][0]
+ m[1][0], m[3][1] + m[1][1], m[3][2] + m[1][2] ) );
                this->m_planes[PLANE_BOTTOM].setOffset(m[3][3] + m[1][3]);
                //top
                this->m_planes[PLANE_TOP].setNormal( gmtl::Vec3f( m[3][0] -
m[1][0], m[3][1] - m[1][1], m[3][2] - m[1][2] ) );
                this->m_planes[PLANE_TOP].setOffset(m[3][3] - m[1][3]);
                //near
                this->m_planes[PLANE_NEAR].setNormal( gmtl::Vec3f( m[3][0] +
m[2][0], m[3][1] + m[2][1], m[3][2] + m[2][2] ) );
                this->m_planes[PLANE_NEAR].setOffset(m[2][3] + m[3][3]);
                //far
                this->m_planes[PLANE_FAR].setNormal( gmtl::Vec3f( m[3][0] -
m[2][0], m[3][1] - m[2][1], m[3][2] - m[2][2] ) );
                this->m_planes[PLANE_FAR].setOffset(m[3][3] - m[2][3]);
            }

            gmtl::Plane<DATA_TYPE> m_planes[6];
    };

    typedef Frustum<float> Frustumf;
    typedef Frustum<double> Frustumd;
};

#endif /* _GMTL_FRUSTUM_H_ */