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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/FIQuery.h>
#include <Mathematics/TIQuery.h>
#include <Mathematics/DistPoint3Plane3.h>
#include <Mathematics/Hypersphere.h>
#include <Mathematics/Circle3.h>
namespace gte
{
template <typename Real>
class TIQuery<Real, Plane3<Real>, Sphere3<Real>>
{
public:
struct Result
{
bool intersect;
};
Result operator()(Plane3<Real> const& plane, Sphere3<Real> const& sphere)
{
Result result;
DCPQuery<Real, Vector3<Real>, Plane3<Real>> ppQuery;
auto ppResult = ppQuery(sphere.center, plane);
result.intersect = (ppResult.distance <= sphere.radius);
return result;
}
};
template <typename Real>
class FIQuery<Real, Plane3<Real>, Sphere3<Real>>
{
public:
struct Result
{
bool intersect;
// If 'intersect' is true, the intersection is either a point or a
// circle. When 'isCircle' is true, 'circle' is valid. When
// 'isCircle' is false, 'point' is valid.
bool isCircle;
Circle3<Real> circle;
Vector3<Real> point;
};
Result operator()(Plane3<Real> const& plane, Sphere3<Real> const& sphere)
{
Result result;
DCPQuery<Real, Vector3<Real>, Plane3<Real>> ppQuery;
auto ppResult = ppQuery(sphere.center, plane);
if (ppResult.distance < sphere.radius)
{
result.intersect = true;
result.isCircle = true;
result.circle.center = sphere.center - ppResult.signedDistance * plane.normal;
result.circle.normal = plane.normal;
// The sum and diff are both positive numbers.
Real sum = sphere.radius + ppResult.distance;
Real dif = sphere.radius - ppResult.distance;
// arg = sqr(sphere.radius) - sqr(ppResult.distance)
Real arg = sum * dif;
result.circle.radius = std::sqrt(arg);
return result;
}
else if (ppResult.distance == sphere.radius)
{
result.intersect = true;
result.isCircle = false;
result.point = sphere.center - ppResult.signedDistance * plane.normal;
return result;
}
else
{
result.intersect = false;
return result;
}
}
};
}