Package com.google.common.geometry

Class S2ShapeIndex

java.lang.Object

com.google.common.geometry.S2ShapeIndex

All Implemented Interfaces:

Serializable

@GwtCompatible
public class S2ShapeIndex
extends Object
implements Serializable

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	S2ShapeIndex.Cell	This class contains the set of clipped shapes within a particular index cell, sorted in increasing order of shape id.
static class	S2ShapeIndex.CellRelation	The possible relationships between a "target" cell and the cells of the S2ShapeIndex.
static class	S2ShapeIndex.Options	Options that affect construction of the S2ShapeIndex.
static class	S2ShapeIndex.RangeIterator	RangeIterator is a wrapper over CellIterator that is specialized for merging shape indices.
static class	S2ShapeIndex.S2ClippedShape	S2ClippedShape represents the part of a shape that intersects an S2Cell.

Field Summary

Fields

Modifier and Type	Field	Description
static double	CELL_PADDING	The amount in UV coordinates by which cells are "padded" to compensate for numerical errors when clipping line segments to cell boundaries.
static int	CURRENT_ENCODING_VERSION	The current encoding version.
static double	DEFAULT_CELL_SIZE_TO_LONG_EDGE_RATIO	Default maximum cell size, relative to an edge's length, for which that edge is considered 'long'.
static int	DEFAULT_MAX_EDGES_PER_CELL	Default maximum number of edges per cell (not counting 'long' edges).
protected List<S2Shape>	shapes	Shapes currently in the index.

Constructor Summary

Constructors

Constructor	Description
S2ShapeIndex()	Creates an S2ShapeIndex that uses the default options, S2ShapeIndex.Options.
S2ShapeIndex(S2ShapeIndex.Options options)	Creates an S2ShapeIndex with the given options.

Method Summary

Modifier and Type	Method	Description
void	add(S2Shape shape)	Adds the given shape to this index.
List<S2Shape>	getShapes()	Returns an immutable list view of shapes in the index.
boolean	isFresh()	Returns true if there are no pending updates that need to be applied.
S2Iterator<S2ShapeIndex.Cell>	iterator()	Returns a new iterator over the cells of this index, positioned at the first cell in the index, after initializing any pending updates.
S2ShapeIndex.Options	options()	Returns the options used for this index.
void	remove(S2Shape shape)	Currently not implemented.
void	reset()	Clears the contents of the index and resets it to its original state.

Methods inherited from class java.lang.Object

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

Field Detail

CELL_PADDING

public static final double CELL_PADDING

The amount in UV coordinates by which cells are "padded" to compensate for numerical errors when clipping line segments to cell boundaries. The total error when clipping an edge comes from two sources:

1. Clipping the original spherical edge to a cube face (the "face edge"). The maximum error in this step is S2EdgeUtil.FACE_CLIP_ERROR_UV_COORD.
2. Clipping the face edge to the u- or v-coordinate of a cell boundary. The maximum error in this step is S2EdgeUtil.EDGE_CLIP_ERROR_UV_COORD.

Finally, since we encounter the same errors when clipping query edges, we double the total error so that we only need to pad edges during indexing and not at query time.

DEFAULT_MAX_EDGES_PER_CELL

public static final int DEFAULT_MAX_EDGES_PER_CELL

Default maximum number of edges per cell (not counting 'long' edges). Reasonable values range from 10 to 50. Small values makes queries faster, while large values make construction faster and use less memory.

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Constant Field Values

DEFAULT_CELL_SIZE_TO_LONG_EDGE_RATIO

public static final double DEFAULT_CELL_SIZE_TO_LONG_EDGE_RATIO

Default maximum cell size, relative to an edge's length, for which that edge is considered 'long'. Long edges are not counted towards S2ShapeIndex.Options.maxEdgesPerCell. The size and speed of the index are typically not very sensitive to this parameter. Reasonable values range from 0.1 to 10, with smaller values causing more aggressive subdivision of long edges grouped closely together.

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Constant Field Values

CURRENT_ENCODING_VERSION

public static final int CURRENT_ENCODING_VERSION

The current encoding version. When adding a new encoding, be aware that old binaries will not be able to decode it.

See Also:

Constant Field Values

shapes

protected List<S2Shape> shapes

Shapes currently in the index.

Constructor Detail

S2ShapeIndex

public S2ShapeIndex()

Creates an S2ShapeIndex that uses the default options, S2ShapeIndex.Options.

S2ShapeIndex

public S2ShapeIndex(S2ShapeIndex.Options options)

Creates an S2ShapeIndex with the given options.

Method Detail

options

public S2ShapeIndex.Options options()

Returns the options used for this index.

getShapes

public List<S2Shape> getShapes()

Returns an immutable list view of shapes in the index. When shapes are added or removed, the returned view is updated as well.

add

public void add(S2Shape shape)

Adds the given shape to this index. Invalidates all iterators and their associated data.

remove

public void remove(S2Shape shape)

Currently not implemented. Will eventually remove the given shape from the index, and invalidate all iterators and their associated data.

Parameters:

shape - the shape to remove

reset

public void reset()

Clears the contents of the index and resets it to its original state.

iterator

public S2Iterator<S2ShapeIndex.Cell> iterator()

Returns a new iterator over the cells of this index, positioned at the first cell in the index, after initializing any pending updates.

isFresh

public boolean isFresh()

Returns true if there are no pending updates that need to be applied. This can be useful to avoid building the index unnecessarily, or for choosing between two different algorithms depending on whether the index is available.