#include <Circle.h>

Inheritance diagram for lsst::sphgeom::Circle:

Public Member Functions
	Circle ()
	This constructor creates an empty circle.

	Circle (UnitVector3d const &c)

	Circle (UnitVector3d const &c, Angle a)

	Circle (UnitVector3d const &c, double cl2)

bool	operator== (Circle const &c) const

bool	operator!= (Circle const &c) const

bool	isEmpty () const override

bool	isFull () const

UnitVector3d const &	getCenter () const

double	getSquaredChordLength () const

Angle	getOpeningAngle () const

bool	contains (Circle const &x) const

Circle &	dilateBy (Angle r)

Circle	dilatedBy (Angle r) const

Circle &	erodeBy (Angle r)

Circle	erodedBy (Angle r) const

double	getArea () const
	`getArea` returns the area of this circle in steradians.

Circle &	complement ()

Circle	complemented () const
	`complemented` returns the closure of the complement of this circle.

Relationship	relate (UnitVector3d const &v) const

std::unique_ptr< Region >	clone () const override

Box	getBoundingBox () const override

Box3d	getBoundingBox3d () const override

Circle	getBoundingCircle () const override

bool	contains (UnitVector3d const &v) const override

Relationship	relate (Region const &r) const override

Relationship	relate (Box const &) const override

Relationship	relate (Circle const &) const override

Relationship	relate (ConvexPolygon const &) const override

Relationship	relate (Ellipse const &) const override

TriState	overlaps (Region const &other) const override

TriState	overlaps (Box const &) const override

TriState	overlaps (Circle const &) const override

TriState	overlaps (ConvexPolygon const &) const override

TriState	overlaps (Ellipse const &) const override

std::vector< std::uint8_t >	encode () const override


bool	isDisjointFrom (UnitVector3d const &x) const

bool	isDisjointFrom (Circle const &x) const


bool	intersects (UnitVector3d const &x) const

bool	intersects (Circle const &x) const


bool	isWithin (UnitVector3d const &) const

bool	isWithin (Circle const &x) const


Circle &	clipTo (UnitVector3d const &x)

Circle &	clipTo (Circle const &x)


Circle	clippedTo (UnitVector3d const &x) const

Circle	clippedTo (Circle const &x) const


Circle &	expandTo (UnitVector3d const &x)

Circle &	expandTo (Circle const &x)


Circle	expandedTo (UnitVector3d const &x) const

Circle	expandedTo (Circle const &x) const

Public Member Functions inherited from lsst.sphgeom._continue_class.Region
Region	from_ivoa_pos (cls, str pos)

str	to_ivoa_pos (self)

Static Public Member Functions
static Circle	empty ()

static Circle	full ()

static double	squaredChordLengthFor (Angle openingAngle)

static Angle	openingAngleFor (double squaredChordLength)


static std::unique_ptr< Circle >	decode (std::vector< std::uint8_t > const &s)

static std::unique_ptr< Circle >	decode (std::uint8_t const *buffer, size_t n)

Static Public Attributes
static constexpr std::uint8_t	TYPE_CODE = 'c'

Detailed Description

Circle is a circular region on the unit sphere that contains its boundary. Internally, the circle is represented by its center vector and the squared length of the chords between its center and points on its boundary. This yields a fast point-in-circle test but, unlike a representation that uses the center vector and cosine of the circle opening angle, remains accurate for circles with very small opening angles.

Constructor & Destructor Documentation

◆ Circle() [1/3]

lsst::sphgeom::Circle::Circle ( UnitVector3d const & c )

inlineexplicit

This constructor creates the circle with center c and squared chord length / opening angle of zero. Because of rounding error, (v - c).squaredNorm() == 0.0 does not imply that v == c. Therefore calling contains(v) on the resulting circle may return true for unit vectors v != c.

◆ Circle() [2/3]

lsst::sphgeom::Circle::Circle	(	UnitVector3d const &	c,
		Angle	a )

inline

This constructor creates a circle with center c and opening angle a. If a is negative or NaN, the circle will be empty, and if a is greater than or equal to PI, the circle will be full.

◆ Circle() [3/3]

lsst::sphgeom::Circle::Circle	(	UnitVector3d const &	c,
		double	cl2 )

inline

This constructor creates a circle with center c and squared chord length cl2. If cl2 is negative or NaN, the circle will be empty, and if cl2 is greater than or equal to 4, the circle will be full.

Member Function Documentation

◆ clippedTo()

Circle lsst::sphgeom::Circle::clippedTo ( UnitVector3d const & x ) const

inline

clippedTo returns the minimal bounding circle for the intersection of this circle and x.

◆ clipTo()

Circle & lsst::sphgeom::Circle::clipTo ( UnitVector3d const & x )

clipTo sets this circle to the minimal bounding circle for the intersection of this circle and x.

◆ complement()

Circle & lsst::sphgeom::Circle::complement ( )

complement sets this circle to the closure of its complement. Note that both the empty circle as well as all circles containing a single point are mapped to a full circle, so that taking the complement of a circle twice is not guaranteed to reproduce the original circle, even in the absence of rounding error.

◆ contains()

bool lsst::sphgeom::Circle::contains ( Circle const & x ) const

contains returns true if the intersection of this circle and x is equal to x.

◆ decode()

static std::unique_ptr< Circle > lsst::sphgeom::Circle::decode ( std::vector< std::uint8_t > const & s )

inlinestatic

decode deserializes a Circle from a byte string produced by encode.

◆ dilateBy()

Circle & lsst::sphgeom::Circle::dilateBy ( Angle r )

If r is positive, dilateBy increases the opening angle of this circle to include all points within angle r of its boundary. If r is negative, it decreases the opening angle to exclude those points instead.

If this circle is empty or full, or r is zero or NaN, there is no effect.

◆ expandedTo()

Circle lsst::sphgeom::Circle::expandedTo ( UnitVector3d const & x ) const

inline

expandedTo returns the minimal bounding circle for the union of this circle and x.

◆ expandTo()

Circle & lsst::sphgeom::Circle::expandTo ( UnitVector3d const & x )

expandTo minimally expands this circle to contain x.

◆ getCenter()

UnitVector3d const & lsst::sphgeom::Circle::getCenter ( ) const

inline

getCenter returns the center of this circle as a unit vector. It is arbitrary for empty and full circles.

◆ getOpeningAngle()

Angle lsst::sphgeom::Circle::getOpeningAngle ( ) const

inline

getOpeningAngle returns the opening angle of this circle - that is, the angle between its center vector and points on its boundary. It is negative or NaN for empty circles, and at least PI for full circles.

◆ getSquaredChordLength()

double lsst::sphgeom::Circle::getSquaredChordLength ( ) const

inline

getSquaredChordLength returns the squared length of chords between the circle center and points on the circle boundary. It is negative or NaN for empty circles, and at least 4 for full circles.

◆ intersects()

bool lsst::sphgeom::Circle::intersects ( UnitVector3d const & x ) const

inline

intersects returns true if the intersection of this circle and x is non-empty.

◆ isDisjointFrom()

bool lsst::sphgeom::Circle::isDisjointFrom ( UnitVector3d const & x ) const

inline

isDisjointFrom returns true if the intersection of this circle and x is empty.

◆ isWithin()

bool lsst::sphgeom::Circle::isWithin ( UnitVector3d const & ) const

inline

isWithin returns true if the intersection of this circle and x is this circle.

◆ openingAngleFor()

Angle lsst::sphgeom::Circle::openingAngleFor ( double squaredChordLength )

static

openingAngleFor computes and returns the angular separation between points in S² that are separated by the given squared chord length. The squared chord length l² and angle θ are related by l² = 4 sin²(θ/2).

◆ squaredChordLengthFor()

double lsst::sphgeom::Circle::squaredChordLengthFor ( Angle openingAngle )

static

squaredChordLengthFor computes and returns the squared chord length between points in S² that are separated by the given angle. The squared chord length l² and angle θ are related by l² = 4 sin²(θ/2).

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

include/lsst/sphgeom/Circle.h
src/Circle.cc

Public Member Functions

Static Public Member Functions

Static Public Attributes

Detailed Description

Constructor & Destructor Documentation

◆ Circle() [1/3]

◆ Circle() [2/3]

◆ Circle() [3/3]

Member Function Documentation

◆ clippedTo()

◆ clipTo()

◆ complement()

◆ contains()

◆ decode()

◆ dilateBy()

◆ expandedTo()

◆ expandTo()

◆ getCenter()

◆ getOpeningAngle()

◆ getSquaredChordLength()

◆ intersects()

◆ isDisjointFrom()

◆ isWithin()

◆ openingAngleFor()

◆ squaredChordLengthFor()