GteDistSegment3AlignedBox3.h

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// David Eberly, Geometric Tools, Redmond WA 98052
// Copyright (c) 1998-2017
// Distributed under the Boost Software License, Version 1.0.
// http://www.boost.org/LICENSE_1_0.txt
// http://www.geometrictools.com/License/Boost/LICENSE_1_0.txt
// File Version: 3.0.1 (2016/11/17)

#pragma once

#include <Mathematics/GteDistLine3AlignedBox3.h>
#include <Mathematics/GteSegment.h>

namespace gte
{

template <typename Real>
class DCPQuery<Real, Segment3<Real>, AlignedBox3<Real>>
{
public:
    struct Result
    {
        Real distance, sqrDistance;
        Real segmentParameter;
        Vector3<Real> closestPoint[2];
    };

    Result operator()(Segment3<Real> const& segment,
        AlignedBox3<Real> const& box);
};


template <typename Real>
typename DCPQuery<Real, Segment3<Real>, AlignedBox3<Real>>::Result
DCPQuery<Real, Segment3<Real>, AlignedBox3<Real>> ::operator()(
    Segment3<Real> const& segment, AlignedBox3<Real> const& box)
{
    Result result;

    Vector3<Real> segCenter, segDirection;
    Real segExtent;
    segment.GetCenteredForm(segCenter, segDirection, segExtent);

    Line3<Real> line(segCenter, segDirection);
    DCPQuery<Real, Line3<Real>, AlignedBox3<Real>> lbQuery;
    auto lbResult = lbQuery(line, box);

    if (lbResult.lineParameter >= -segExtent)
    {
        if (lbResult.lineParameter <= segExtent)
        {
            result.sqrDistance = lbResult.sqrDistance;
            result.distance = lbResult.distance;
            result.segmentParameter = lbResult.lineParameter;
            result.closestPoint[0] = lbResult.closestPoint[0];
            result.closestPoint[1] = lbResult.closestPoint[1];
        }
        else
        {
            DCPQuery<Real, Vector3<Real>, AlignedBox3<Real>> pbQuery;
            Vector3<Real> point = segCenter + segExtent*segDirection;
            auto pbResult = pbQuery(point, box);
            result.sqrDistance = pbResult.sqrDistance;
            result.distance = pbResult.distance;
            result.segmentParameter = segExtent;
            result.closestPoint[0] = point;
            result.closestPoint[1] = pbResult.boxClosest;
        }
    }
    else
    {
        DCPQuery<Real, Vector3<Real>, AlignedBox3<Real>> pbQuery;
        Vector3<Real> point = segCenter - segExtent*segDirection;
        auto pbResult = pbQuery(point, box);
        result.sqrDistance = pbResult.sqrDistance;
        result.distance = pbResult.distance;
        result.segmentParameter = -segExtent;
        result.closestPoint[0] = point;
        result.closestPoint[1] = pbResult.boxClosest;
    }
    return result;
}


}