lsst.sphgeom 22.0.1-8-gfb2c8f9+1b4e7dc7c0
Public Member Functions | Static Public Member Functions | Static Public Attributes | List of all members
lsst::sphgeom::ConvexPolygon Class Reference

#include <ConvexPolygon.h>

Inheritance diagram for lsst::sphgeom::ConvexPolygon:
lsst::sphgeom::Region

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< Regionclone () const override
 clone returns a deep copy of this region. More...
 
Box getBoundingBox () const override
 getBoundingBox returns a bounding-box for this region. More...
 
Box3d getBoundingBox3d () const override
 getBoundingBox3d returns a 3-dimensional bounding-box for this region. More...
 
Circle getBoundingCircle () const override
 getBoundingCircle returns a bounding-circle for this region. More...
 
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
 
std::vector< uint8_t > encode () const override
 
virtual bool contains (UnitVector3d const &) const=0
 contains tests whether the given unit vector is inside this region. More...
 
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< ConvexPolygondecode (std::vector< uint8_t > const &s)
 
static std::unique_ptr< ConvexPolygondecode (uint8_t const *buffer, size_t n)
 
- Static Public Member Functions inherited from lsst::sphgeom::Region
static std::unique_ptr< Regiondecode (std::vector< uint8_t > const &s)
 
static std::unique_ptr< Regiondecode (uint8_t const *buffer, size_t n)
 

Static Public Attributes

static constexpr uint8_t TYPE_CODE = 'p'
 

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() [1/4]

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() [2/4]

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() [3/4]

virtual bool lsst::sphgeom::Region::contains ( UnitVector3d const &  ) const
virtual

contains tests whether the given unit vector is inside this region.

Implements lsst::sphgeom::Region.

◆ contains() [4/4]

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< uint8_t > const &  s)
inlinestatic

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

◆ encode()

std::vector< 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.

◆ 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.

◆ 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.


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