lsst::sphgeom::ConvexPolygon Class Reference

#include <ConvexPolygon.h>

Inheritance diagram for lsst::sphgeom::ConvexPolygon:

Public Member Functions
	ConvexPolygon (std::vector< UnitVector3d > const &points)
	ConvexPolygon (UnitVector3d const &v0, UnitVector3d const &v1, UnitVector3d const &v2)
	ConvexPolygon (UnitVector3d const &v0, UnitVector3d const &v1, UnitVector3d const &v2, UnitVector3d const &v3)
bool	operator== (ConvexPolygon const &p) const
	Two convex polygons are equal iff they contain the same points.
bool	operator!= (ConvexPolygon const &p) const
std::vector< UnitVector3d > const &	getVertices () const
UnitVector3d	getCentroid () const
std::unique_ptr< Region >	clone () const override
	clone returns a deep copy of this region.
bool	isEmpty () const override
	isEmpty returns true when a region does not contain any points.
Box	getBoundingBox () const override
	getBoundingBox returns a bounding-box for this region.
Box3d	getBoundingBox3d () const override
	getBoundingBox3d returns a 3-dimensional bounding-box for this region.
Circle	getBoundingCircle () const override
	getBoundingCircle returns a bounding-circle for this region.
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	contains (double x, double y, double z) const
bool	contains (double lon, double lat) const
bool	contains (UnitVector3d const &v) const override
bool	contains (Region const &r) const
bool	isDisjointFrom (Region const &r) const
bool	intersects (Region const &r) const
bool	isWithin (Region const &r) const
Public Member Functions inherited from lsst::sphgeom::Region
bool	contains (double x, double y, double z) const
bool	contains (double lon, double lat) const

Static Public Member Functions
static ConvexPolygon	convexHull (std::vector< UnitVector3d > const &points)
static std::unique_ptr< ConvexPolygon >	decode (std::vector< std::uint8_t > const &s)
static std::unique_ptr< ConvexPolygon >	decode (std::uint8_t const *buffer, size_t n)
Static Public Member Functions inherited from lsst::sphgeom::Region
static std::vector< std::unique_ptr< Region > >	getRegions (Region const &region)
	getRegions returns a vector of Region.
static std::unique_ptr< Region >	decode (std::vector< std::uint8_t > const &s)
static std::unique_ptr< Region >	decode (std::uint8_t const *buffer, size_t n)
static std::unique_ptr< Region >	decodeBase64 (std::string const &s)
static std::unique_ptr< Region >	decodeBase64 (std::string_view const &s)
static TriState	decodeOverlapsBase64 (std::string const &s)
static TriState	decodeOverlapsBase64 (std::string_view const &s)

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

Additional Inherited Members
Static Protected Member Functions inherited from lsst::sphgeom::Region
static TriState	_relationship_to_overlaps (Relationship r)

Detailed Description

ConvexPolygon is a closed convex polygon on the unit sphere. Its edges are great circles (geodesics), and the shorter of the two great circle segments between any two points on the polygon boundary is contained in the polygon.

The vertices of a convex polygon are distinct and have counter-clockwise orientation when viewed from outside the unit sphere. No three consecutive vertices are coplanar and edges do not intersect except at vertices.

Furthermore, if a convex polygon contains a point p of S², then we require that it be disjoint from point -p. This guarantees the existence of a unique shortest great circle segment between any 2 points contained in the polygon, but means e.g. that hemispheres and lunes cannot be represented by convex polygons.

Currently, the only way to construct a convex polygon is to compute the convex hull of a point set.

Constructor & Destructor Documentation

ConvexPolygon() [1/3]

lsst::sphgeom::ConvexPolygon::ConvexPolygon ( std::vector< UnitVector3d > const & points )

explicit

This constructor creates a convex polygon that is the convex hull of the given set of points.

ConvexPolygon() [2/3]

lsst::sphgeom::ConvexPolygon::ConvexPolygon ( UnitVector3d const & v0, UnitVector3d const & v1, UnitVector3d const & v2 )

inline

This constructor creates a triangle with the given vertices.

It is assumed that orientation(v0, v1, v2) = 1. Use with caution - for performance reasons, this is not verified!

ConvexPolygon() [3/3]

lsst::sphgeom::ConvexPolygon::ConvexPolygon ( UnitVector3d const & v0, UnitVector3d const & v1, UnitVector3d const & v2, UnitVector3d const & v3 )

inline

This constructor creates a quadrilateral with the given vertices.

It is assumed that orientation(v0, v1, v2), orientation(v1, v2, v3), orientation(v2, v3, v0), and orientation (v3, v0, v1) are all 1. Use with caution - for performance reasons, this is not verified!

Member Function Documentation

clone()

std::unique_ptr< Region > lsst::sphgeom::ConvexPolygon::clone ( ) const

inlineoverridevirtual

clone returns a deep copy of this region.

Implements lsst::sphgeom::Region.

contains() [1/3]

bool lsst::sphgeom::Region::contains	(	double	lon,
		double	lat ) const

contains tests whether the unit vector defined by the given longitude and latitude coordinates (in radians) is inside this region.

contains() [2/3]

bool lsst::sphgeom::Region::contains	(	double	x,
		double	y,
		double	z ) const

contains tests whether the unit vector defined by the given (not necessarily normalized) coordinates is inside this region.

contains() [3/3]

bool lsst::sphgeom::ConvexPolygon::contains ( UnitVector3d const & v ) const

overridevirtual

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

Implements lsst::sphgeom::Region.

convexHull()

static ConvexPolygon lsst::sphgeom::ConvexPolygon::convexHull ( std::vector< UnitVector3d > const & points )

inlinestatic

convexHull returns the convex hull of the given set of points if it exists and throws an exception otherwise. Though points are supplied in a vector, they really are conceptually a set - the ConvexPolygon returned is invariant under permutation of the input array.

decode()

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

inlinestatic

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

encode()

std::vector< std::uint8_t > lsst::sphgeom::ConvexPolygon::encode ( ) const

overridevirtual

encode serializes this region into an opaque byte string. Byte strings emitted by encode can be deserialized with decode.

Implements lsst::sphgeom::Region.

getBoundingBox()

Box lsst::sphgeom::ConvexPolygon::getBoundingBox ( ) const

overridevirtual

getBoundingBox returns a bounding-box for this region.

Implements lsst::sphgeom::Region.

getBoundingBox3d()

Box3d lsst::sphgeom::ConvexPolygon::getBoundingBox3d ( ) const

overridevirtual

getBoundingBox3d returns a 3-dimensional bounding-box for this region.

Implements lsst::sphgeom::Region.

getBoundingCircle()

Circle lsst::sphgeom::ConvexPolygon::getBoundingCircle ( ) const

overridevirtual

getBoundingCircle returns a bounding-circle for this region.

Implements lsst::sphgeom::Region.

getCentroid()

UnitVector3d lsst::sphgeom::ConvexPolygon::getCentroid

(

)

const

The centroid of a polygon is its center of mass projected onto S², assuming a uniform mass distribution over the polygon surface.

intersects()

bool lsst::sphgeom::ConvexPolygon::intersects

(

Region const &

r

)

const

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

isDisjointFrom()

bool lsst::sphgeom::ConvexPolygon::isDisjointFrom

(

Region const &

r

)

const

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

isEmpty()

bool lsst::sphgeom::ConvexPolygon::isEmpty ( ) const

overridevirtual

isEmpty returns true when a region does not contain any points.

Implements lsst::sphgeom::Region.

isWithin()

bool lsst::sphgeom::ConvexPolygon::isWithin

(

Region const &

r

)

const

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

overlaps() [1/5]

TriState lsst::sphgeom::ConvexPolygon::overlaps ( Box const & b ) const

overridevirtual

Implements lsst::sphgeom::Region.

overlaps() [2/5]

TriState lsst::sphgeom::ConvexPolygon::overlaps ( Circle const & c ) const

overridevirtual

Implements lsst::sphgeom::Region.

overlaps() [3/5]

TriState lsst::sphgeom::ConvexPolygon::overlaps ( ConvexPolygon const & p ) const

overridevirtual

Implements lsst::sphgeom::Region.

overlaps() [4/5]

TriState lsst::sphgeom::ConvexPolygon::overlaps ( Ellipse const & e ) const

overridevirtual

Implements lsst::sphgeom::Region.

overlaps() [5/5]

TriState lsst::sphgeom::ConvexPolygon::overlaps ( Region const & other ) const

inlineoverridevirtual

overlaps tests whether two regions overlap. This method returns a TriState object, when the value is true it means that regions definitely overlap, false means they are definitely disjont, and unknown state means that they may or may not overlap.

Implements lsst::sphgeom::Region.

relate() [1/5]

Relationship lsst::sphgeom::ConvexPolygon::relate ( Box const & b ) const

overridevirtual

Implements lsst::sphgeom::Region.

relate() [2/5]

Relationship lsst::sphgeom::ConvexPolygon::relate ( Circle const & c ) const

overridevirtual

Implements lsst::sphgeom::Region.

relate() [3/5]

Relationship lsst::sphgeom::ConvexPolygon::relate ( ConvexPolygon const & p ) const

overridevirtual

Implements lsst::sphgeom::Region.

relate() [4/5]

Relationship lsst::sphgeom::ConvexPolygon::relate ( Ellipse const & e ) const

overridevirtual

Implements lsst::sphgeom::Region.

relate() [5/5]

Relationship lsst::sphgeom::ConvexPolygon::relate ( Region const & ) const

inlineoverridevirtual

relate computes the spatial relationships between this region A and another region B. The return value S is a bitset with the following properties:

• Bit S & DISJOINT is set only if A and B do not have any points in common.
• Bit S & CONTAINS is set only if A contains all points in B.
• Bit S & WITHIN is set only if B contains all points in A.

Said another way: if the CONTAINS, WITHIN or DISJOINT bit is set, then the corresponding spatial relationship between the two regions holds conclusively. If it is not set, the relationship may or may not hold.

These semantics allow for conservative relationship computations. In particular, a Region may choose to implement relate by replacing itself and/or the argument with a simplified bounding region.

Implements lsst::sphgeom::Region.

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

• include/lsst/sphgeom/ConvexPolygon.h
• src/ConvexPolygon.cc