mgcdistvec3box3.cpp

3D Game Engine Design Source Code非常棒

// Magic Software, Inc.
// http://www.magic-software.com
// Copyright (c) 2000, All Rights Reserved
//
// Source code from Magic Software is supplied under the terms of a license
// agreement and may not be copied or disclosed except in accordance with the
// terms of that agreement.  The various license agreements may be found at
// the Magic Software web site.  This file is subject to the license
//
// FREE SOURCE CODE
// http://www.magic-software.com/License/free.pdf

#include "MgcDistVec3Box3.h"

//----------------------------------------------------------------------------
MgcReal MgcSqrDistance (const MgcVector3& rkPoint, const MgcBox3& rkBox,
    MgcReal* pfBParam0, MgcReal* pfBParam1, MgcReal* pfBParam2)
{
#ifdef _DEBUG
    // The three parameters pointers are either all non-null or all null.
    if ( pfBParam0 )
    {
        assert( pfBParam1 && pfBParam2 );
    }
    else
    {
        assert( !pfBParam1 && !pfBParam2 );
    }
#endif

    // compute coordinates of point in box coordinate system
    MgcVector3 kDiff = rkPoint - rkBox.Center();
    MgcVector3 kClosest(kDiff.Dot(rkBox.Axis(0)),kDiff.Dot(rkBox.Axis(1)),
        kDiff.Dot(rkBox.Axis(2)));

    // project test point onto box
    MgcReal fSqrDistance = 0.0;
    MgcReal fDelta;

    if ( kClosest.x < -rkBox.Extent(0) )
    {
        fDelta = kClosest.x + rkBox.Extent(0);
        fSqrDistance += fDelta*fDelta;
        kClosest.x = -rkBox.Extent(0);
    }
    else if ( kClosest.x > rkBox.Extent(0) )
    {
        fDelta = kClosest.x - rkBox.Extent(0);
        fSqrDistance += fDelta*fDelta;
        kClosest.x = rkBox.Extent(0);
    }

    if ( kClosest.y < -rkBox.Extent(1) )
    {
        fDelta = kClosest.y + rkBox.Extent(1);
        fSqrDistance += fDelta*fDelta;
        kClosest.y = -rkBox.Extent(1);
    }
    else if ( kClosest.y > rkBox.Extent(1) )
    {
        fDelta = kClosest.y - rkBox.Extent(1);
        fSqrDistance += fDelta*fDelta;
        kClosest.y = rkBox.Extent(1);
    }

    if ( kClosest.z < -rkBox.Extent(2) )
    {
        fDelta = kClosest.z + rkBox.Extent(2);
        fSqrDistance += fDelta*fDelta;
        kClosest.z = -rkBox.Extent(2);
    }
    else if ( kClosest.z > rkBox.Extent(2) )
    {
        fDelta = kClosest.z - rkBox.Extent(2);
        fSqrDistance += fDelta*fDelta;
        kClosest.z = rkBox.Extent(2);
    }

    if ( pfBParam0 )
    {
        *pfBParam0 = kClosest.x;
        *pfBParam1 = kClosest.y;
        *pfBParam2 = kClosest.z;
    }

    return fSqrDistance;
}
//----------------------------------------------------------------------------
MgcReal MgcDistance (const MgcVector3& rkPoint, const MgcBox3& rkBox,
    MgcReal* pfBParam0, MgcReal* pfBParam1, MgcReal* pfBParam2)
{
    return MgcMath::Sqrt(MgcSqrDistance(rkPoint,rkBox,pfBParam0,pfBParam1,
        pfBParam2));
}
//----------------------------------------------------------------------------