CesiumGeospatial::S2CellID Class Reference

A 64-bit unsigned integer that uniquely identifies a cell in the S2 cell decomposition. More...

#include <CesiumGeospatial/S2CellID.h>

Public Member Functions
	S2CellID (uint64_t id)
	Constructs a new S2 cell ID. More...
bool	isValid () const
	Determines if this cell ID is valid. More...
uint64_t	getID () const
	Gets the ID of the cell. More...
std::string	toToken () const
	Converts the cell ID to a hexadecimal token.
int32_t	getLevel () const
	Gets the level of the cell from the cell ID. More...
uint8_t	getFace () const
	Gets the face id (0...5) for this S2 cell.
Cartographic	getCenter () const
	Gets the longitude/latitude position at the center of this cell. More...
std::array< Cartographic, 4 >	getVertices () const
	Gets the vertices at the corners of the cell. More...
S2CellID	getParent () const
	Gets the parent cell of this cell. More...
S2CellID	getChild (size_t index) const
	Gets a child cell of this cell. More...
GlobeRectangle	computeBoundingRectangle () const
	Computes the globe rectangle that bounds this cell. More...

Static Public Member Functions
static S2CellID	fromToken (const std::string_view &token)
static S2CellID	fromFaceLevelPosition (uint8_t face, uint32_t level, uint64_t position)
	Creates a cell given its face (range 0..5), level, and Hilbert curve cell index within that face and level. More...
static S2CellID	fromQuadtreeTileID (uint8_t face, const CesiumGeometry::QuadtreeTileID &quadtreeTileID)
	Create an S2 id from a face and a quadtree tile id. More...

Detailed Description

A 64-bit unsigned integer that uniquely identifies a cell in the S2 cell decomposition.

It has the following format:

id = [face][face_pos]

face: a 3-bit number (range 0..5) encoding the cube face.

face_pos: a 61-bit number encoding the position of the center of this cell along the Hilbert curve over this face (see the Wiki pages for details).

Sequentially increasing cell ids follow a continuous space-filling curve over the entire sphere. They have the following properties:

• The id of a cell at level k consists of a 3-bit face number followed by k bit pairs that recursively select one of the four children of each cell. The next bit is always 1, and all other bits are 0. Therefore, the level of a cell is determined by the position of its lowest-numbered bit that is turned on (for a cell at level k, this position is 2 * (kMaxLevel - k).)
• The id of a parent cell is at the midpoint of the range of ids spanned by its children (or by its descendants at any level).

This class is adapted from S2CellId in https://github.com/google/s2geometry.

Definition at line 47 of file S2CellID.h.

Constructor & Destructor Documentation

S2CellID()

CesiumGeospatial::S2CellID::S2CellID

(

uint64_t

id

)

Constructs a new S2 cell ID.

The cell ID value is not validated. Use isValid to check the validity after constructions.

Parameters

id	The 64-bit cell ID value.

Member Function Documentation

computeBoundingRectangle()

GlobeRectangle CesiumGeospatial::S2CellID::computeBoundingRectangle

(

)

const

Computes the globe rectangle that bounds this cell.

Returns

The globe rectangle.

fromFaceLevelPosition()

static S2CellID CesiumGeospatial::S2CellID::fromFaceLevelPosition ( uint8_t  face, uint32_t  level, uint64_t  position  )

static

Creates a cell given its face (range 0..5), level, and Hilbert curve cell index within that face and level.

Parameters

face	The face index.
level	The level within the face.
position	The Hilbert-order index of the cell within the face and level.

Returns

The cell.

fromQuadtreeTileID()

static S2CellID CesiumGeospatial::S2CellID::fromQuadtreeTileID ( uint8_t  face, const CesiumGeometry::QuadtreeTileID &  quadtreeTileID  )

static

Create an S2 id from a face and a quadtree tile id.

Parameters

face	The S2 face (0...5) that this tile is on.
quadtreeTileID	The quadtree tile id for this tile, within the given face.

fromToken()

static S2CellID CesiumGeospatial::S2CellID::fromToken ( const std::string_view &  token )

static

Creates a new S2Cell from a token. A token is a hexadecimal representation of the 64-bit S2CellID.

Parameters

token

The token for the S2 Cell.

Returns

A new S2CellID.

getCenter()

Cartographic CesiumGeospatial::S2CellID::getCenter

(

)

const

Gets the longitude/latitude position at the center of this cell.

The height is always 0.0.

Returns

The center.

getChild()

S2CellID CesiumGeospatial::S2CellID::getChild

(

size_t

index

)

const

Gets a child cell of this cell.

If the index is less than 0 or greater than 3, or if this is a leaf cell, the behavior is unspecified.

Parameters

index

The index in the range 0 to 3.

Returns

The child cell.

getID()

uint64_t CesiumGeospatial::S2CellID::getID ( ) const

inline

Gets the ID of the cell.

Returns

The ID.

Definition at line 104 of file S2CellID.h.

getLevel()

int32_t CesiumGeospatial::S2CellID::getLevel

(

)

const

Gets the level of the cell from the cell ID.

Returns

The cell ID, where 0 is the root.

getParent()

S2CellID CesiumGeospatial::S2CellID::getParent

(

)

const

Gets the parent cell of this cell.

If this is a root cell, the behavior is unspecified.

getVertices()

std::array<Cartographic, 4> CesiumGeospatial::S2CellID::getVertices

(

)

const

Gets the vertices at the corners of the cell.

The height values are always 0.0.

Note that all positions inside the S2 Cell are not guaranteed to fall inside the rectangle formed by these vertices.

Returns

Four vertices specifying the corners of this cell.

isValid()

bool CesiumGeospatial::S2CellID::isValid

(

)

const

Determines if this cell ID is valid.

Returns

true if the the cell ID refers to a valid cell; otherwise, false.

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

• /home/runner/work/cesium-native/cesium-native/CesiumGeospatial/include/CesiumGeospatial/S2CellID.h