Package com.google.common.geometry

Class S2Loop.LoopCrosser

java.lang.Object

com.google.common.geometry.S2Loop.LoopCrosser

Enclosing class:

S2Loop

private static final class S2Loop.LoopCrosser
extends java.lang.Object

LoopCrosser is a helper class for determining whether two loops cross. It is instantiated twice for each pair of loops to be tested, once for the pair (A, B) and once for the pair (B, A), in order to be able to process edges in either loop nesting order.

Field Summary

Fields

Modifier and Type	Field	Description
private S2Loop	a
private int	aCrossingTarget
private int	aj
private S2Loop	b
private java.util.List<S2ShapeIndex.Cell>	bCells
private int	bCrossingTarget
private int	bjPrev
private S2EdgeQuery	bQuery
private S2EdgeUtil.EdgeCrosser	crosser
private S2Loop.LoopRelation	relation
private boolean	swapped

Constructor Summary

Constructors

Constructor	Description
LoopCrosser(S2Loop a, S2Loop b, S2Loop.LoopRelation relation, boolean swapped)	If swapped is true, the loops A and B have been swapped.

Method Summary

Modifier and Type	Method	Description
int	aCrossingTarget()	Returns the crossing targets for the loop relation, taking into account whether the loops have been swapped.
int	bCrossingTarget()
private boolean	cellCrossesAnySubcell(S2ShapeIndex.S2ClippedShape aClipped, S2CellId bId)	Given an index cell of A, returns true if there are any edge or wedge crossings with any index cell of B contained within bId.
boolean	cellCrossesCell(S2ShapeIndex.S2ClippedShape aClipped, S2ShapeIndex.S2ClippedShape bClipped)	Given two index cells, returns true if there are any edge crossings or wedge crossings within those cells.
private boolean	edgeCrossesCell(S2ShapeIndex.S2ClippedShape bClipped)	Checks the current edge of loop A for crossings with all edges of the given index cell of loop B.
private boolean	hasCrossing(S2ShapeIndex.RangeIterator ai, S2ShapeIndex.RangeIterator bi)	Given two iterators positioned such that ai.id().contains(bi.id()), returns true if there is an edge crossing or a wedge crossing anywhere within ai.id().
boolean	hasCrossingRelation(S2ShapeIndex.RangeIterator ai, S2ShapeIndex.RangeIterator bi)	Given two iterators positioned such that ai.id().contains(bi.id()), returns true if there is a crossing relationship anywhere within ai.id().
private void	startEdge(int aj)	Prepares to check the given edge of loop A for crossings.

Methods inherited from class java.lang.Object

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

Field Detail

a

private final S2Loop a

b

private final S2Loop b

relation

private final S2Loop.LoopRelation relation

swapped

private final boolean swapped

aCrossingTarget

private final int aCrossingTarget

bCrossingTarget

private final int bCrossingTarget

crosser

private S2EdgeUtil.EdgeCrosser crosser

aj

private int aj

bjPrev

private int bjPrev

bQuery

private final S2EdgeQuery bQuery

bCells

private final java.util.List<S2ShapeIndex.Cell> bCells

Constructor Detail

LoopCrosser

public LoopCrosser(S2Loop a,
                   S2Loop b,
                   S2Loop.LoopRelation relation,
                   boolean swapped)

If swapped is true, the loops A and B have been swapped. This affects how arguments are passed to the given loop relation, since for example A.contains(B) is not the same as B.contains(A).

Method Detail

aCrossingTarget

public int aCrossingTarget()

Returns the crossing targets for the loop relation, taking into account whether the loops have been swapped.

bCrossingTarget

public int bCrossingTarget()

hasCrossingRelation

public boolean hasCrossingRelation(S2ShapeIndex.RangeIterator ai,
                                   S2ShapeIndex.RangeIterator bi)

Given two iterators positioned such that ai.id().contains(bi.id()), returns true if there is a crossing relationship anywhere within ai.id(). Specifically, this method returns true if there is an edge crossing, a wedge crossing, or a point P that matches both "crossing targets". Advances both iterators past ai.id().

cellCrossesCell

public boolean cellCrossesCell(S2ShapeIndex.S2ClippedShape aClipped,
                               S2ShapeIndex.S2ClippedShape bClipped)

Given two index cells, returns true if there are any edge crossings or wedge crossings within those cells.

hasCrossing

private boolean hasCrossing(S2ShapeIndex.RangeIterator ai,
                            S2ShapeIndex.RangeIterator bi)

Given two iterators positioned such that ai.id().contains(bi.id()), returns true if there is an edge crossing or a wedge crossing anywhere within ai.id(). Advances bi (only) past ai.id().

cellCrossesAnySubcell

private boolean cellCrossesAnySubcell(S2ShapeIndex.S2ClippedShape aClipped,
                                      S2CellId bId)

Given an index cell of A, returns true if there are any edge or wedge crossings with any index cell of B contained within bId.

startEdge

private void startEdge(int aj)

Prepares to check the given edge of loop A for crossings.

edgeCrossesCell

private boolean edgeCrossesCell(S2ShapeIndex.S2ClippedShape bClipped)

Checks the current edge of loop A for crossings with all edges of the given index cell of loop B.