Box.h

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/*
===========================================================================

Doom 3 GPL Source Code
Copyright (C) 1999-2011 id Software LLC, a ZeniMax Media company. 

This file is part of the Doom 3 GPL Source Code (?Doom 3 Source Code?).  

Doom 3 Source Code 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 3 of the License, or
(at your option) any later version.

Doom 3 Source Code 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 Doom 3 Source Code.  If not, see <http://www.gnu.org/licenses/>.

In addition, the Doom 3 Source Code is also subject to certain additional terms. You should have received a copy of these additional terms immediately following the terms and conditions of the GNU General Public License which accompanied the Doom 3 Source Code.  If not, please request a copy in writing from id Software at the address below.

If you have questions concerning this license or the applicable additional terms, you may contact in writing id Software LLC, c/o ZeniMax Media Inc., Suite 120, Rockville, Maryland 20850 USA.

===========================================================================
*/

#ifndef __BV_BOX_H__
#define __BV_BOX_H__

/*
===============================================================================

        Oriented Bounding Box

===============================================================================
*/

class idBox {
public:
                                        idBox( void );
                                        explicit idBox( const idVec3 &center, const idVec3 &extents, const idMat3 &axis );
                                        explicit idBox( const idVec3 &point );
                                        explicit idBox( const idBounds &bounds );
                                        explicit idBox( const idBounds &bounds, const idVec3 &origin, const idMat3 &axis );

        idBox                   operator+( const idVec3 &t ) const;                             // returns translated box
        idBox &                 operator+=( const idVec3 &t );                                  // translate the box
        idBox                   operator*( const idMat3 &r ) const;                             // returns rotated box
        idBox &                 operator*=( const idMat3 &r );                                  // rotate the box
        idBox                   operator+( const idBox &a ) const;
        idBox &                 operator+=( const idBox &a );
        idBox                   operator-( const idBox &a ) const;
        idBox &                 operator-=( const idBox &a );

        bool                    Compare( const idBox &a ) const;                                                // exact compare, no epsilon
        bool                    Compare( const idBox &a, const float epsilon ) const;   // compare with epsilon
        bool                    operator==(     const idBox &a ) const;                                         // exact compare, no epsilon
        bool                    operator!=(     const idBox &a ) const;                                         // exact compare, no epsilon

        void                    Clear( void );                                                                  // inside out box
        void                    Zero( void );                                                                   // single point at origin

        const idVec3 &  GetCenter( void ) const;                                                // returns center of the box
        const idVec3 &  GetExtents( void ) const;                                               // returns extents of the box
        const idMat3 &  GetAxis( void ) const;                                                  // returns the axis of the box
        float                   GetVolume( void ) const;                                                // returns the volume of the box
        bool                    IsCleared( void ) const;                                                // returns true if box are inside out

        bool                    AddPoint( const idVec3 &v );                                    // add the point, returns true if the box expanded
        bool                    AddBox( const idBox &a );                                               // add the box, returns true if the box expanded
        idBox                   Expand( const float d ) const;                                  // return box expanded in all directions with the given value
        idBox &                 ExpandSelf( const float d );                                    // expand box in all directions with the given value
        idBox                   Translate( const idVec3 &translation ) const;   // return translated box
        idBox &                 TranslateSelf( const idVec3 &translation );             // translate this box
        idBox                   Rotate( const idMat3 &rotation ) const;                 // return rotated box
        idBox &                 RotateSelf( const idMat3 &rotation );                   // rotate this box

        float                   PlaneDistance( const idPlane &plane ) const;
        int                             PlaneSide( const idPlane &plane, const float epsilon = ON_EPSILON ) const;

        bool                    ContainsPoint( const idVec3 &p ) const;                 // includes touching
        bool                    IntersectsBox( const idBox &a ) const;                  // includes touching
        bool                    LineIntersection( const idVec3 &start, const idVec3 &end ) const;
                                        // intersection points are (start + dir * scale1) and (start + dir * scale2)
        bool                    RayIntersection( const idVec3 &start, const idVec3 &dir, float &scale1, float &scale2 ) const;

                                        // tight box for a collection of points
        void                    FromPoints( const idVec3 *points, const int numPoints );
                                        // most tight box for a translation
        void                    FromPointTranslation( const idVec3 &point, const idVec3 &translation );
        void                    FromBoxTranslation( const idBox &box, const idVec3 &translation );
                                        // most tight box for a rotation
        void                    FromPointRotation( const idVec3 &point, const idRotation &rotation );
        void                    FromBoxRotation( const idBox &box, const idRotation &rotation );

        void                    ToPoints( idVec3 points[8] ) const;
        idSphere                ToSphere( void ) const;

                                        // calculates the projection of this box onto the given axis
        void                    AxisProjection( const idVec3 &dir, float &min, float &max ) const;
        void                    AxisProjection( const idMat3 &ax, idBounds &bounds ) const;

                                        // calculates the silhouette of the box
        int                             GetProjectionSilhouetteVerts( const idVec3 &projectionOrigin, idVec3 silVerts[6] ) const;
        int                             GetParallelProjectionSilhouetteVerts( const idVec3 &projectionDir, idVec3 silVerts[6] ) const;

private:
        idVec3                  center;
        idVec3                  extents;
        idMat3                  axis;
};

extern idBox    box_zero;

ID_INLINE idBox::idBox( void ) {
}

ID_INLINE idBox::idBox( const idVec3 &center, const idVec3 &extents, const idMat3 &axis ) {
        this->center = center;
        this->extents = extents;
        this->axis = axis;
}

ID_INLINE idBox::idBox( const idVec3 &point ) {
        this->center = point;
        this->extents.Zero();
        this->axis.Identity();
}

ID_INLINE idBox::idBox( const idBounds &bounds ) {
        this->center = ( bounds[0] + bounds[1] ) * 0.5f;
        this->extents = bounds[1] - this->center;
        this->axis.Identity();
}

ID_INLINE idBox::idBox( const idBounds &bounds, const idVec3 &origin, const idMat3 &axis ) {
        this->center = ( bounds[0] + bounds[1] ) * 0.5f;
        this->extents = bounds[1] - this->center;
        this->center = origin + this->center * axis;
        this->axis = axis;
}

ID_INLINE idBox idBox::operator+( const idVec3 &t ) const {
        return idBox( center + t, extents, axis );
}

ID_INLINE idBox &idBox::operator+=( const idVec3 &t ) {
        center += t;
        return *this;
}

ID_INLINE idBox idBox::operator*( const idMat3 &r ) const {
        return idBox( center * r, extents, axis * r );
}

ID_INLINE idBox &idBox::operator*=( const idMat3 &r ) {
        center *= r;
        axis *= r;
        return *this;
}

ID_INLINE idBox idBox::operator+( const idBox &a ) const {
        idBox newBox;
        newBox = *this;
        newBox.AddBox( a );
        return newBox;
}

ID_INLINE idBox &idBox::operator+=( const idBox &a ) {
        idBox::AddBox( a );
        return *this;
}

ID_INLINE idBox idBox::operator-( const idBox &a ) const {
        return idBox( center, extents - a.extents, axis );
}

ID_INLINE idBox &idBox::operator-=( const idBox &a ) {
        extents -= a.extents;
        return *this;
}

ID_INLINE bool idBox::Compare( const idBox &a ) const {
        return ( center.Compare( a.center ) && extents.Compare( a.extents ) && axis.Compare( a.axis ) );
}

ID_INLINE bool idBox::Compare( const idBox &a, const float epsilon ) const {
        return ( center.Compare( a.center, epsilon ) && extents.Compare( a.extents, epsilon ) && axis.Compare( a.axis, epsilon ) );
}

ID_INLINE bool idBox::operator==( const idBox &a ) const {
        return Compare( a );
}

ID_INLINE bool idBox::operator!=( const idBox &a ) const {
        return !Compare( a );
}

ID_INLINE void idBox::Clear( void ) {
        center.Zero();
        extents[0] = extents[1] = extents[2] = -idMath::INFINITY;
        axis.Identity();
}

ID_INLINE void idBox::Zero( void ) {
        center.Zero();
        extents.Zero();
        axis.Identity();
}

ID_INLINE const idVec3 &idBox::GetCenter( void ) const {
        return center;
}

ID_INLINE const idVec3 &idBox::GetExtents( void ) const {
        return extents;
}

ID_INLINE const idMat3 &idBox::GetAxis( void ) const {
        return axis;
}

ID_INLINE float idBox::GetVolume( void ) const {
        return ( extents * 2.0f ).LengthSqr();
}

ID_INLINE bool idBox::IsCleared( void ) const {
        return extents[0] < 0.0f;
}

ID_INLINE idBox idBox::Expand( const float d ) const {
        return idBox( center, extents + idVec3( d, d, d ), axis );
}

ID_INLINE idBox &idBox::ExpandSelf( const float d ) {
        extents[0] += d;
        extents[1] += d;
        extents[2] += d;
        return *this;
}

ID_INLINE idBox idBox::Translate( const idVec3 &translation ) const {
        return idBox( center + translation, extents, axis );
}

ID_INLINE idBox &idBox::TranslateSelf( const idVec3 &translation ) {
        center += translation;
        return *this;
}

ID_INLINE idBox idBox::Rotate( const idMat3 &rotation ) const {
        return idBox( center * rotation, extents, axis * rotation );
}

ID_INLINE idBox &idBox::RotateSelf( const idMat3 &rotation ) {
        center *= rotation;
        axis *= rotation;
        return *this;
}

ID_INLINE bool idBox::ContainsPoint( const idVec3 &p ) const {
        idVec3 lp = p - center;
        if ( idMath::Fabs( lp * axis[0] ) > extents[0] ||
                        idMath::Fabs( lp * axis[1] ) > extents[1] ||
                                idMath::Fabs( lp * axis[2] ) > extents[2] ) {
                return false;
        }
        return true;
}

ID_INLINE idSphere idBox::ToSphere( void ) const {
        return idSphere( center, extents.Length() );
}

ID_INLINE void idBox::AxisProjection( const idVec3 &dir, float &min, float &max ) const {
        float d1 = dir * center;
        float d2 = idMath::Fabs( extents[0] * ( dir * axis[0] ) ) +
                                idMath::Fabs( extents[1] * ( dir * axis[1] ) ) +
                                idMath::Fabs( extents[2] * ( dir * axis[2] ) );
        min = d1 - d2;
        max = d1 + d2;
}

ID_INLINE void idBox::AxisProjection( const idMat3 &ax, idBounds &bounds ) const {
        for ( int i = 0; i < 3; i++ ) {
                float d1 = ax[i] * center;
                float d2 = idMath::Fabs( extents[0] * ( ax[i] * axis[0] ) ) +
                                        idMath::Fabs( extents[1] * ( ax[i] * axis[1] ) ) +
                                        idMath::Fabs( extents[2] * ( ax[i] * axis[2] ) );
                bounds[0][i] = d1 - d2;
                bounds[1][i] = d1 + d2;
        }
}

#endif /* !__BV_BOX_H__ */