Package com.google.common.geometry

Class S2ShapeIndexRegion

java.lang.Object

com.google.common.geometry.S2ShapeIndexRegion

All Implemented Interfaces:

S2Region

@GwtCompatible(serializable=false)
public class S2ShapeIndexRegion
extends Object
implements S2Region

This class wraps an S2ShapeIndex object with the additional methods needed to implement the S2Region API, in order to allow S2RegionCoverer to compute S2CellId coverings of arbitrary collections of geometry.

Example usage:

 S2CellUnion getCovering(S2ShapeIndex index) {
   S2RegionCoverer coverer = new S2RegionCoverer();
   coverer.setMaxCells(20);
   return coverer.getCovering(new S2ShapeIndexRegion(index));
 }
 

This class uses a number of temporary mutable objects to keep allocation down, and so is not thread-safe. To use it in parallel, each thread should construct its own instance (this is not expensive).

Field Summary

Fields

Modifier and Type	Field	Description
private final R2Rect	bound	Temporary bound for internal usage.
private final S2Shape.MutableEdge	edge	Temporary edge for internal usage.
private final S2Iterator<S2ShapeIndex.Cell>	it	The iterator.
private final S2ContainsPointQuery.S2VertexModel	model	The vertex model for contains(S2Point) tests.
private final R2Vector	p0	Temporary R2 point for internal usage.
private final R2Vector	p1	Temporary R2 point for internal usage.
private final S2CellUnion	union	Temporary cell union for internal usage.

Constructor Summary

Constructors

Constructor	Description
S2ShapeIndexRegion(S2ShapeIndex index)	Creates a new region with the given index, and a semi-open vertex model.
S2ShapeIndexRegion(S2ShapeIndex index, S2ContainsPointQuery.S2VertexModel model)	Creates a new region with the given index, and a given S2ContainsPointQuery.S2VertexModel.

Method Summary

Modifier and Type	Method	Description
private boolean	anyEdgeIntersects(S2ShapeIndex.S2ClippedShape clipped, S2Cell target)	Returns true if any edge of the indexed shape "clipped" intersects the cell "target".
boolean	contains(S2Cell target)	Returns true if 'target' is contained by any single shape.
boolean	contains(S2Point p)	Returns true if the given point is contained by any two-dimensional shape (i.e., polygon).
private static void	coverRange(S2CellId first, S2CellId last, List<S2CellId> cellIds)	Computes the smallest S2Cell that covers the S2Cell range (first, last) and adds this cell to "cellIds".
S2Cap	getCapBound()	Return a bounding spherical cap.
void	getCellUnionBound(List<S2CellId> cellIds)	Clears the given list of cells and adds the cell union of this index.
S2LatLngRect	getRectBound()	Return a bounding latitude-longitude rectangle.
boolean	mayIntersect(S2Cell target)	Returns true if any shape intersects "target".

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

model

private final S2ContainsPointQuery.S2VertexModel model

The vertex model for contains(S2Point) tests.

it

private final S2Iterator<S2ShapeIndex.Cell> it

The iterator.

union

private final S2CellUnion union

Temporary cell union for internal usage.

edge

private final S2Shape.MutableEdge edge

Temporary edge for internal usage.

bound

private final R2Rect bound

Temporary bound for internal usage.

p0

private final R2Vector p0

Temporary R2 point for internal usage.

p1

private final R2Vector p1

Temporary R2 point for internal usage.

Constructor Details

S2ShapeIndexRegion

public S2ShapeIndexRegion(S2ShapeIndex index)

Creates a new region with the given index, and a semi-open vertex model.

S2ShapeIndexRegion

public S2ShapeIndexRegion(S2ShapeIndex index,
 S2ContainsPointQuery.S2VertexModel model)

Creates a new region with the given index, and a given S2ContainsPointQuery.S2VertexModel.

Method Details

getCapBound

public S2Cap getCapBound()

Description copied from interface: S2Region

Return a bounding spherical cap.

Specified by:

getCapBound in interface S2Region

getRectBound

public S2LatLngRect getRectBound()

Description copied from interface: S2Region

Return a bounding latitude-longitude rectangle.

Specified by:

getRectBound in interface S2Region

getCellUnionBound

public void getCellUnionBound(List<S2CellId> cellIds)

Clears the given list of cells and adds the cell union of this index. An index of shapes in one face adds up to 4 cells, otherwise up to 6 may be added.

coverRange

private static void coverRange(S2CellId first,
 S2CellId last,
 List<S2CellId> cellIds)

Computes the smallest S2Cell that covers the S2Cell range (first, last) and adds this cell to "cellIds".

Throws:

IllegalArgumentException - "first" and "last" don't have a common ancestor.

contains

public boolean contains(S2Point p)

Returns true if the given point is contained by any two-dimensional shape (i.e., polygon). Zero and one-dimensional shapes are ignored by this method.

Specified by:

contains in interface S2Region

contains

public boolean contains(S2Cell target)

Returns true if 'target' is contained by any single shape. If the cell is covered by a union of different shapes then it may return false.

This implementation is conservative but not exact; if a shape just barely contains the given cell then it may return false. The maximum error is less than 10 * DBL_EPSILON radians (or about 15 nanometers).

Specified by:

contains in interface S2Region

mayIntersect

public boolean mayIntersect(S2Cell target)

Returns true if any shape intersects "target".

This implementation is conservative but not exact; if a shape is just barely disjoint from the given cell then it may return true. The maximum error is less than 10 * DBL_EPSILON radians (or about 15 nanometers).

Specified by:

mayIntersect in interface S2Region

anyEdgeIntersects

private boolean anyEdgeIntersects(S2ShapeIndex.S2ClippedShape clipped,
 S2Cell target)

Returns true if any edge of the indexed shape "clipped" intersects the cell "target". It may also return true if an edge is very close to "target"; the maximum error is less than 10 * DBL_EPSILON radians (about 15 nanometers).