GteDistTriangle3Triangle3.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: 3.0.0 (2016/06/19)

#pragma once

#include <Mathematics/GteDistSegment3Triangle3.h>

namespace gte
{

template <typename Real>
class DCPQuery<Real, Triangle3<Real>, Triangle3<Real>>
{
public:
    struct Result
    {
        Real distance, sqrDistance;
        Real triangle0Parameter[3], triangle1Parameter[3];
        Vector3<Real> closestPoint[2];
    };

    Result operator()(Triangle3<Real> const& triangle0,
        Triangle3<Real> const& triangle1);
};


template <typename Real>
typename DCPQuery<Real, Triangle3<Real>, Triangle3<Real>>::Result
DCPQuery<Real, Triangle3<Real>, Triangle3<Real>>::operator()(
    Triangle3<Real> const& triangle0, Triangle3<Real> const& triangle1)
{
    Result result;

    DCPQuery<Real, Segment3<Real>, Triangle3<Real>> stQuery;
    typename DCPQuery<Real, Segment3<Real>, Triangle3<Real>>::Result
        stResult;
    result.sqrDistance = std::numeric_limits<Real>::max();

    // Compare edges of triangle0 to the interior of triangle1.
    for (int i0 = 2, i1 = 0; i1 < 3; i0 = i1++)
    {
        Vector3<Real> segCenter = ((Real)0.5)*(triangle0.v[i0] +
            triangle0.v[i1]);
        Vector3<Real> segDirection = triangle0.v[i1] - triangle0.v[i0];
        Real segExtent = ((Real)0.5)*Normalize(segDirection);
        Segment3<Real> edge(segCenter, segDirection, segExtent);

        stResult = stQuery(edge, triangle1);
        if (stResult.sqrDistance < result.sqrDistance)
        {
            result.distance = stResult.distance;
            result.sqrDistance = stResult.sqrDistance;
            Real ratio = stResult.segmentParameter / segExtent;  // in [-1,1]
            result.triangle0Parameter[i0] = ((Real)0.5)*((Real)1 - ratio);
            result.triangle0Parameter[i1] =
                (Real)1 - result.triangle0Parameter[i0];
            result.triangle0Parameter[3 - i0 - i1] = (Real)0;
            result.triangle1Parameter[0] = stResult.triangleParameter[0];
            result.triangle1Parameter[1] = stResult.triangleParameter[1];
            result.triangle1Parameter[2] = stResult.triangleParameter[2];
            result.closestPoint[0] = stResult.closestPoint[0];
            result.closestPoint[1] = stResult.closestPoint[1];
        }
    }

    // Compare edges of triangle1 to the interior of triangle0.
    for (int i0 = 2, i1 = 0; i1 < 3; i0 = i1++)
    {
        Vector3<Real> segCenter = ((Real)0.5)*(triangle1.v[i0] +
            triangle1.v[i1]);
        Vector3<Real> segDirection = triangle1.v[i1] - triangle1.v[i0];
        Real segExtent = ((Real)0.5)*Normalize(segDirection);
        Segment3<Real> edge(segCenter, segDirection, segExtent);

        stResult = stQuery(edge, triangle0);
        if (stResult.sqrDistance < result.sqrDistance)
        {
            result.distance = stResult.distance;
            result.sqrDistance = stResult.sqrDistance;
            Real ratio = stResult.segmentParameter / segExtent;  // in [-1,1]
            result.triangle0Parameter[0] = stResult.triangleParameter[0];
            result.triangle0Parameter[1] = stResult.triangleParameter[1];
            result.triangle0Parameter[2] = stResult.triangleParameter[2];
            result.triangle1Parameter[i0] = ((Real)0.5)*((Real)1 - ratio);
            result.triangle1Parameter[i1] =
                (Real)1 - result.triangle0Parameter[i0];
            result.triangle1Parameter[3 - i0 - i1] = (Real)0;
            result.closestPoint[0] = stResult.closestPoint[0];
            result.closestPoint[1] = stResult.closestPoint[1];
        }
    }
    return result;
}


}