GteDistAlignedBoxAlignedBox.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: 3.5.0 (2016/11/26)

#pragma once

#include <Mathematics/GteDCPQuery.h>
#include <Mathematics/GteAlignedBox.h>
#include <Mathematics/GteIntrIntervals.h>
#include <Mathematics/GteFunctions.h>

namespace gte
{

template <int N, typename Real>
class DCPQuery<Real, AlignedBox<N, Real>, AlignedBox<N, Real>>
{
public:
    struct Result
    {
        Real distance, sqrDistance;

        // To compute a single closest point on each box, use
        // Vector<N, Real> closest0 = (closestPoints[0].min + closestPoints[0].max)/2;
        // Vector<N, Real> closest1 = (closestPoints[1].min + closestPoints[1].max)/2;
        AlignedBox<N, Real> closestPoints[2];
    };

    Result operator()(AlignedBox<N, Real> const& box0, AlignedBox<N, Real> const& box1);
};


template <int N, typename Real>
typename DCPQuery<Real, AlignedBox<N, Real>, AlignedBox<N, Real>>::Result
DCPQuery<Real, AlignedBox<N, Real>, AlignedBox<N, Real>>::operator()(
    AlignedBox<N, Real> const& box0, AlignedBox<N, Real> const& box1)
{
    Result result;
    result.sqrDistance = (Real)0;
    for (int i = 0; i < N; ++i)
    {
        if (box0.min[i] >= box1.max[i])
        {
            Real delta = box0.min[i] - box1.min[i];
            result.sqrDistance += delta * delta;
            result.closestPoints[0].min[i] = box0.min[i];
            result.closestPoints[0].max[i] = box0.min[i];
            result.closestPoints[1].min[i] = box1.max[i];
            result.closestPoints[1].max[i] = box1.max[i];
        }
        else if (box1.min[i] >= box0.max[i])
        {
            Real delta = box1.min[i] - box0.max[i];
            result.sqrDistance += delta * delta;
            result.closestPoints[0].min[i] = box0.max[i];
            result.closestPoints[0].max[i] = box0.max[i];
            result.closestPoints[1].min[i] = box1.min[i];
            result.closestPoints[1].max[i] = box1.min[i];
        }
        else
        {
            std::array<Real, 2> intr0 = { box0.min[i], box0.max[i] };
            std::array<Real, 2> intr1 = { box1.min[i], box1.max[i] };
            FIQuery<Real, std::array<Real, 2>, std::array<Real, 2>> query;
            auto iiResult = query(intr0, intr1);
            for (int j = 0; j < 2; ++j)
            {
                result.closestPoints[j].min[i] = iiResult.overlap[0];
                result.closestPoints[j].max[i] = iiResult.overlap[1];
            }
        }
    }
    result.distance = Function<Real>::Sqrt(result.sqrDistance);
    return result;
}

}