Bounding sphere — an approximation to the smallest sphere enclosing a set of 3D points. More...

#include <EBGeometry_BoundingVolumes.hpp>

Public Types
enum class	BuildAlgorithm { Ritter }
	Algorithm used to compute a bounding sphere for a set of 3D points. More...

using	Vec3 = Vec3T< T >
	Alias to cut down on typing.

Public Member Functions
	SphereT () noexcept=default
	Default constructor. Sets radius to -1 (invalid sentinel).

	SphereT (const Vec3T< T > &a_center, const T &a_radius) noexcept
	Construct a sphere with an explicit centre and radius.

	SphereT (const std::vector< SphereT< T > > &a_otherSpheres) noexcept
	Construct the smallest sphere enclosing all `a_otherSpheres`.

	SphereT (const SphereT &a_other) noexcept
	Copy constructor.

template<class P >
	SphereT (const std::vector< Vec3T< P > > &a_points, const BuildAlgorithm &a_alg=BuildAlgorithm::Ritter) noexcept
	Construct a bounding sphere enclosing a set of 3D points.

	~SphereT () noexcept
	Destructor.

SphereT &	operator= (const SphereT &a_other)=default
	Copy assignment operator.

	SphereT (SphereT &&a_other) noexcept=default
	Move constructor.

SphereT &	operator= (SphereT &&a_other) noexcept=default
	Move assignment operator.

template<class P >
void	define (const std::vector< Vec3T< P > > &a_points, const BuildAlgorithm &a_alg) noexcept
	Fit this sphere to a set of 3D points using the specified algorithm.

bool	intersects (const SphereT &a_other) const noexcept
	Test whether this bounding sphere intersects `a_other`.

T &	getRadius () noexcept
	Get a modifiable reference to the sphere radius.

const T &	getRadius () const noexcept
	Get the sphere radius.

Vec3 &	getCentroid () noexcept
	Get a modifiable reference to the sphere centroid.

const Vec3 &	getCentroid () const noexcept
	Get the sphere centroid.

T	getOverlappingVolume (const SphereT< T > &a_other) const noexcept
	Compute the overlapping volume between this sphere and `a_other`.

T	getDistance (const Vec3 &a_x0) const noexcept
	Compute the unsigned distance from `a_x0` to this sphere.

T	getDistance2 (const Vec3 &a_x0) const noexcept
	Compute the squared unsigned distance from `a_x0` to this sphere.

T	getVolume () const noexcept
	Compute the sphere volume (4/3 * pi * r^3).

T	getArea () const noexcept
	Compute the sphere surface area (4 * pi * r^2).

Protected Member Functions
template<class P >
void	buildRitter (const std::vector< Vec3T< P > > &a_points) noexcept
	Fit a bounding sphere to `a_points` using Ritter's algorithm.

Protected Attributes
T	m_radius = T(-1)
	Sphere radius. Initialised to -1 (invalid sentinel).

Vec3	m_center = Vec3::zeros()
	Sphere centre. Initialised to the origin.

Friends
std::ostream &	operator<< (std::ostream &os, const SphereT< T > &sphere)
	Output a bounding sphere to a stream in the form "(centroid, radius)".

Detailed Description

template<class T>
class EBGeometry::BoundingVolumes::SphereT< T >

Bounding sphere — an approximation to the smallest sphere enclosing a set of 3D points.

Template Parameters

T	Floating-point precision (e.g., float or double).

Member Enumeration Documentation

◆ BuildAlgorithm

template<class T >

enum class EBGeometry::BoundingVolumes::SphereT::BuildAlgorithm

strong

Algorithm used to compute a bounding sphere for a set of 3D points.

Enumerator
Ritter	Ritter's simple two-pass approximation. Fast but may overestimate the radius slightly.

Constructor & Destructor Documentation

◆ SphereT() [1/6]

template<class T >

EBGeometry::BoundingVolumes::SphereT< T >::SphereT ( )

defaultnoexcept

Default constructor. Sets radius to -1 (invalid sentinel).

Any geometric method called on a default-constructed sphere will fire an EBGEOMETRY_EXPECT assertion. Call define() or use the explicit constructor before use.

◆ SphereT() [2/6]

template<class T >

EBGeometry::BoundingVolumes::SphereT< T >::SphereT	(	const Vec3T< T > &	a_center,
		const T &	a_radius
	)

inlinenoexcept

Construct a sphere with an explicit centre and radius.

Parameters

[in]	a_center	Sphere centre.
[in]	a_radius	Sphere radius.

◆ SphereT() [3/6]

template<class T >

EBGeometry::BoundingVolumes::SphereT< T >::SphereT ( const std::vector< SphereT< T > > & a_otherSpheres )

inlinenoexcept

Construct the smallest sphere enclosing all a_otherSpheres.

Parameters

[in] a_otherSpheres Spheres to enclose.

◆ SphereT() [4/6]

template<class T >

EBGeometry::BoundingVolumes::SphereT< T >::SphereT ( const SphereT< T > & a_other )

inlinenoexcept

Copy constructor.

Parameters

[in] a_other Sphere to copy.

◆ SphereT() [5/6]

template<class T >

template<class P >

EBGeometry::BoundingVolumes::SphereT< T >::SphereT	(	const std::vector< Vec3T< P > > &	a_points,
		const BuildAlgorithm &	a_alg = `BuildAlgorithm::Ritter`
	)

inlinenoexcept

Construct a bounding sphere enclosing a set of 3D points.

Mixed floating-point precision is allowed: P may differ from T.

Template Parameters

P	Floating-point precision of the input points.

Parameters

[in]	a_points	Set of 3D points.
[in]	a_alg	Algorithm to use (default: Ritter).

◆ SphereT() [6/6]

template<class T >

EBGeometry::BoundingVolumes::SphereT< T >::SphereT ( SphereT< T > && a_other )

defaultnoexcept

Move constructor.

Parameters

[in] a_other Sphere to move from.

Member Function Documentation

◆ buildRitter()

template<class T >

template<class P >

void EBGeometry::BoundingVolumes::SphereT< T >::buildRitter ( const std::vector< Vec3T< P > > & a_points )

inlineprotectednoexcept

Fit a bounding sphere to a_points using Ritter's algorithm.

Template Parameters

P	Floating-point precision of the input points.

Parameters

[in] a_points Set of 3D points to enclose.

◆ define()

template<class T >

template<class P >

void EBGeometry::BoundingVolumes::SphereT< T >::define	(	const std::vector< Vec3T< P > > &	a_points,
		const BuildAlgorithm &	a_alg
	)

inlinenoexcept

Fit this sphere to a set of 3D points using the specified algorithm.

Mixed floating-point precision is allowed: P may differ from T.

Template Parameters

P	Floating-point precision of the input points.

Parameters

[in]	a_points	Set of 3D points.
[in]	a_alg	Algorithm to use.

◆ getArea()

template<class T >

T EBGeometry::BoundingVolumes::SphereT< T >::getArea ( ) const

inlinenoexcept

Compute the sphere surface area (4 * pi * r^2).

Returns: Sphere surface area.

◆ getCentroid() [1/2]

template<class T >

const Vec3 & EBGeometry::BoundingVolumes::SphereT< T >::getCentroid ( ) const

inlinenoexcept

Get the sphere centroid.

Returns: Const reference to the sphere centroid.

◆ getCentroid() [2/2]

template<class T >

Vec3 & EBGeometry::BoundingVolumes::SphereT< T >::getCentroid ( )

inlinenoexcept

Get a modifiable reference to the sphere centroid.

Returns: Reference to the sphere centroid.

◆ getDistance()

template<class T >

T EBGeometry::BoundingVolumes::SphereT< T >::getDistance ( const Vec3 & a_x0 ) const

inlinenoexcept

Compute the unsigned distance from a_x0 to this sphere.

Parameters

[in] a_x0 3D query point.

Returns: Distance from a_x0 to the sphere surface; zero if a_x0 is inside.

◆ getDistance2()

template<class T >

T EBGeometry::BoundingVolumes::SphereT< T >::getDistance2 ( const Vec3 & a_x0 ) const

inlinenoexcept

Compute the squared unsigned distance from a_x0 to this sphere.

Mirrors AABBT::getDistance2(), giving both bounding volumes a uniform squared-distance query (e.g. for a BVH's sqrt-free pruning). Unlike the box, a sphere's surface distance is inherently radial, so this cannot avoid the square root the way AABBT::getDistance2() does – it is simply getDistance() squared.

Parameters

[in] a_x0 3D query point.

Returns: Squared distance from a_x0 to the sphere surface; zero if a_x0 is inside.

◆ getOverlappingVolume()

template<class T >

T EBGeometry::BoundingVolumes::SphereT< T >::getOverlappingVolume ( const SphereT< T > & a_other ) const

inlinenoexcept

Compute the overlapping volume between this sphere and a_other.

Parameters

[in] a_other Other bounding sphere.

Returns: Overlap volume; zero if the spheres do not intersect.

◆ getRadius() [1/2]

template<class T >

const T & EBGeometry::BoundingVolumes::SphereT< T >::getRadius ( ) const

inlinenoexcept

Get the sphere radius.

Returns: Const reference to the sphere radius.

◆ getRadius() [2/2]

template<class T >

T & EBGeometry::BoundingVolumes::SphereT< T >::getRadius ( )

inlinenoexcept

Get a modifiable reference to the sphere radius.

Returns: Reference to the sphere radius.

◆ getVolume()

template<class T >

T EBGeometry::BoundingVolumes::SphereT< T >::getVolume ( ) const

inlinenoexcept

Compute the sphere volume (4/3 * pi * r^3).

Returns: Sphere volume.

◆ intersects()

template<class T >

bool EBGeometry::BoundingVolumes::SphereT< T >::intersects ( const SphereT< T > & a_other ) const

inlinenoexcept

Test whether this bounding sphere intersects a_other.

Parameters

[in] a_other Other bounding sphere.

Returns: True if the two spheres overlap, false otherwise.

◆ operator=() [1/2]

template<class T >

SphereT & EBGeometry::BoundingVolumes::SphereT< T >::operator= ( const SphereT< T > & a_other )

default

Copy assignment operator.

Parameters

[in] a_other Sphere to copy.

Returns: Reference to (*this).

◆ operator=() [2/2]

template<class T >

SphereT & EBGeometry::BoundingVolumes::SphereT< T >::operator= ( SphereT< T > && a_other )

defaultnoexcept

Move assignment operator.

Parameters

[in] a_other Sphere to move from.

Returns: Reference to (*this).

Friends And Related Symbol Documentation

◆ operator<<

template<class T >

std::ostream & operator<<	(	std::ostream &	os,
		const SphereT< T > &	sphere
	)

friend

Output a bounding sphere to a stream in the form "(centroid, radius)".

Parameters

[in,out]	os	Output stream.
[in]	sphere	Bounding sphere to print.

Returns: Reference to os to allow chaining.

The documentation for this class was generated from the following file:

Source/EBGeometry_BoundingVolumes.hpp

Public Types

Public Member Functions

Protected Member Functions

Protected Attributes

Friends

Detailed Description

Member Enumeration Documentation

◆ BuildAlgorithm

Constructor & Destructor Documentation

◆ SphereT() [1/6]

◆ SphereT() [2/6]

◆ SphereT() [3/6]

◆ SphereT() [4/6]

◆ SphereT() [5/6]

◆ SphereT() [6/6]

Member Function Documentation

◆ buildRitter()

◆ define()

◆ getArea()

◆ getCentroid() [1/2]

◆ getCentroid() [2/2]

◆ getDistance()

◆ getDistance2()

◆ getOverlappingVolume()

◆ getRadius() [1/2]

◆ getRadius() [2/2]

◆ getVolume()

◆ intersects()

◆ operator=() [1/2]

◆ operator=() [2/2]

Friends And Related Symbol Documentation

◆ operator<<