Frustum_gcc.cpp

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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.

===========================================================================
*/
#include "../precompiled.h"

void BoxToPoints( const idVec3 &center, const idVec3 &extents, const idMat3 &axis, idVec3 points[8] );

/*
============
idFrustum::ProjectionBounds
============
*/
bool idFrustum::ProjectionBounds( const idBox &box, idBounds &projectionBounds ) const {
        int i, p1, p2, pointCull[8], culled, outside;
        float scale1, scale2;
        idFrustum localFrustum;
        idVec3 points[8], localOrigin;
        idMat3 localAxis, localScaled;
        idBounds bounds( -box.GetExtents(), box.GetExtents() );

        // if the frustum origin is inside the bounds
        if ( bounds.ContainsPoint( ( origin - box.GetCenter() ) * box.GetAxis().Transpose() ) ) {
                // bounds that cover the whole frustum
                float boxMin, boxMax, base;

                base = origin * axis[0];
                box.AxisProjection( axis[0], boxMin, boxMax );

                projectionBounds[0].x = boxMin - base;
                projectionBounds[1].x = boxMax - base;
                projectionBounds[0].y = projectionBounds[0].z = -1.0f;
                projectionBounds[1].y = projectionBounds[1].z = 1.0f;

                return true;
        }

        projectionBounds.Clear();

        // transform the bounds into the space of this frustum
        localOrigin = ( box.GetCenter() - origin ) * axis.Transpose();
        localAxis = box.GetAxis() * axis.Transpose();
        BoxToPoints( localOrigin, box.GetExtents(), localAxis, points );

        // test outer four edges of the bounds
        culled = -1;
        outside = 0;
        for ( i = 0; i < 4; i++ ) {
                p1 = i;
                p2 = 4 + i;
                AddLocalLineToProjectionBoundsSetCull( points[p1], points[p2], pointCull[p1], pointCull[p2], projectionBounds );
                culled &= pointCull[p1] & pointCull[p2];
                outside |= pointCull[p1] | pointCull[p2];
        }

        // if the bounds are completely outside this frustum
        if ( culled ) {
                return false;
        }

        // if the bounds are completely inside this frustum
        if ( !outside ) {
                return true;
        }

        // test the remaining edges of the bounds
        for ( i = 0; i < 4; i++ ) {
                p1 = i;
                p2 = (i+1)&3;
                AddLocalLineToProjectionBoundsUseCull( points[p1], points[p2], pointCull[p1], pointCull[p2], projectionBounds );
        }

        for ( i = 0; i < 4; i++ ) {
                p1 = 4 + i;
                p2 = 4 + ((i+1)&3);
                AddLocalLineToProjectionBoundsUseCull( points[p1], points[p2], pointCull[p1], pointCull[p2], projectionBounds );
        }

        // if the bounds extend beyond two or more boundaries of this frustum
        if ( outside != 1 && outside != 2 && outside != 4 && outside != 8 ) {

                localOrigin = ( origin - box.GetCenter() ) * box.GetAxis().Transpose();
                localScaled = axis * box.GetAxis().Transpose();
                localScaled[0] *= dFar;
                localScaled[1] *= dLeft;
                localScaled[2] *= dUp;

                // test the outer edges of this frustum for intersection with the bounds
                if ( (outside & 2) && (outside & 8) ) {
                        BoundsRayIntersection( bounds, localOrigin, localScaled[0] - localScaled[1] - localScaled[2], scale1, scale2 );
                        if ( scale1 <= scale2 && scale1 >= 0.0f ) {
                                projectionBounds.AddPoint( idVec3( scale1 * dFar, -1.0f, -1.0f ) );
                                projectionBounds.AddPoint( idVec3( scale2 * dFar, -1.0f, -1.0f ) );
                        }
                }
                if ( (outside & 2) && (outside & 4) ) {
                        BoundsRayIntersection( bounds, localOrigin, localScaled[0] - localScaled[1] + localScaled[2], scale1, scale2 );
                        if ( scale1 <= scale2 && scale1 >= 0.0f  ) {
                                projectionBounds.AddPoint( idVec3( scale1 * dFar, -1.0f, 1.0f ) );
                                projectionBounds.AddPoint( idVec3( scale2 * dFar, -1.0f, 1.0f ) );
                        }
                }
                if ( (outside & 1) && (outside & 8) ) {
                        BoundsRayIntersection( bounds, localOrigin, localScaled[0] + localScaled[1] - localScaled[2], scale1, scale2 );
                        if ( scale1 <= scale2 && scale1 >= 0.0f  ) {
                                projectionBounds.AddPoint( idVec3( scale1 * dFar, 1.0f, -1.0f ) );
                                projectionBounds.AddPoint( idVec3( scale2 * dFar, 1.0f, -1.0f ) );
                        }
                }
                if ( (outside & 1) && (outside & 2) ) {
                        BoundsRayIntersection( bounds, localOrigin, localScaled[0] + localScaled[1] + localScaled[2], scale1, scale2 );
                        if ( scale1 <= scale2 && scale1 >= 0.0f  ) {
                                projectionBounds.AddPoint( idVec3( scale1 * dFar, 1.0f, 1.0f ) );
                                projectionBounds.AddPoint( idVec3( scale2 * dFar, 1.0f, 1.0f ) );
                        }
                }
        }

        return true;
}