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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/Cylinder3.h>
#include <Mathematics/Vector3.h>
// The queries consider the cylinder to be a solid.
namespace gte
{
template <typename Real>
class DCPQuery<Real, Vector3<Real>, Cylinder3<Real>>
{
public:
struct Result
{
Real distance;
Vector3<Real> cylinderClosest;
};
Result operator()(Vector3<Real> const& point, Cylinder3<Real> const& cylinder)
{
Result result;
// Convert the point to the cylinder coordinate system. In this
// system, the point believes (0,0,0) is the cylinder axis origin
// and (0,0,1) is the cylinder axis direction.
Vector3<Real> basis[3];
basis[0] = cylinder.axis.direction;
ComputeOrthogonalComplement(1, basis);
Vector3<Real> delta = point - cylinder.axis.origin;
Vector3<Real> P
{
Dot(basis[1], delta),
Dot(basis[2], delta),
Dot(basis[0], delta)
};
if (cylinder.height == std::numeric_limits<Real>::max())
{
DoQueryInfiniteCylinder(P, cylinder.radius, result);
}
else
{
DoQueryFiniteCylinder(P, cylinder.radius, cylinder.height, result);
}
// Convert the closest point from the cylinder coordinate system
// to the original coordinate system.
result.cylinderClosest = cylinder.axis.origin +
result.cylinderClosest[0] * basis[1] +
result.cylinderClosest[1] * basis[2] +
result.cylinderClosest[2] * basis[0];
return result;
}
private:
void DoQueryInfiniteCylinder(Vector3<Real> const& P, Real radius,
Result& result)
{
Real sqrRadius = radius * radius;
Real sqrDistance = P[0] * P[0] + P[1] * P[1];
if (sqrDistance >= sqrRadius)
{
// The point is outside the cylinder or on the cylinder wall.
Real distance = std::sqrt(sqrDistance);
result.distance = distance - radius;
Real temp = radius / distance;
result.cylinderClosest[0] = P[0] * temp;
result.cylinderClosest[1] = P[1] * temp;
result.cylinderClosest[2] = P[2];
}
else
{
// The point is inside the cylinder.
result.distance = (Real)0;
result.cylinderClosest = P;
}
}
void DoQueryFiniteCylinder(Vector3<Real> const& P, Real radius,
Real height, Result& result)
{
DoQueryInfiniteCylinder(P, radius, result);
// Clamp the infinite cylinder's closest point to the finite
// cylinder.
if (result.cylinderClosest[2] > height)
{
result.cylinderClosest[2] = height;
result.distance = Length(result.cylinderClosest - P);
}
else if (result.cylinderClosest[2] < -height)
{
result.cylinderClosest[2] = -height;
result.distance = Length(result.cylinderClosest - P);
}
}
};
}