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// David Eberly, Geometric Tools, Redmond WA 98052
// Copyright (c) 1998-2021
// Distributed under the Boost Software License, Version 1.0.
// https://www.boost.org/LICENSE_1_0.txt
// https://www.geometrictools.com/License/Boost/LICENSE_1_0.txt
// Version: 4.0.2019.08.13
#pragma once
#include <Mathematics/DCPQuery.h>
#include <Mathematics/Line.h>
namespace gte
{
template <int N, typename Real>
class DCPQuery<Real, Line<N, Real>, Line<N, Real>>
{
public:
struct Result
{
Real distance, sqrDistance;
Real parameter[2];
Vector<N, Real> closestPoint[2];
};
Result operator()(Line<N, Real> const& line0, Line<N, Real> const& line1)
{
Result result;
Vector<N, Real> diff = line0.origin - line1.origin;
Real a01 = -Dot(line0.direction, line1.direction);
Real b0 = Dot(diff, line0.direction);
Real s0, s1;
if (std::fabs(a01) < (Real)1)
{
// Lines are not parallel.
Real det = (Real)1 - a01 * a01;
Real b1 = -Dot(diff, line1.direction);
s0 = (a01 * b1 - b0) / det;
s1 = (a01 * b0 - b1) / det;
}
else
{
// Lines are parallel, select any pair of closest points.
s0 = -b0;
s1 = (Real)0;
}
result.parameter[0] = s0;
result.parameter[1] = s1;
result.closestPoint[0] = line0.origin + s0 * line0.direction;
result.closestPoint[1] = line1.origin + s1 * line1.direction;
diff = result.closestPoint[0] - result.closestPoint[1];
result.sqrDistance = Dot(diff, diff);
result.distance = std::sqrt(result.sqrDistance);
return result;
}
};
// Template aliases for convenience.
template <int N, typename Real>
using DCPLineLine = DCPQuery<Real, Line<N, Real>, Line<N, Real>>;
template <typename Real>
using DCPLine2Line2 = DCPLineLine<2, Real>;
template <typename Real>
using DCPLine3Line3 = DCPLineLine<3, Real>;
}