org.kynosarges.tektosyne

Class QuadTree.Node<V>

java.lang.Object

org.kynosarges.tektosyne.QuadTree.Node<V>

Type Parameters:

V - the type of all values in the QuadTree

Enclosing class:

QuadTree<V>

public static final class QuadTree.Node<V>
extends java.lang.Object

Provides a generic tree node within a QuadTree. Represents a collection of PointD keys and V values within a QuadTree. This collection and all references to related QuadTree.Node instances within the QuadTree are exposed as read-only properties.

QuadTree.Node was inspired by the QuadTreeNode class by Michael J. Laszlo, Computational Geometry and Computer Graphics in C++, Prentice Hall 1996, p.236ff.

Field Summary

Fields

Modifier and Type	Field and Description
RectD	bounds The RectD bounds of all PointD keys in the QuadTree.Node.
PointD	center The center of the bounds of the QuadTree.Node.
QuadTree.Node<V>	parent The parent of the QuadTree.Node in the QuadTree.
int	signature The unique signature of the QuadTree.Node.

Method Summary

Modifier and Type	Method and Description
java.util.Map<PointD,V>	entries() Gets all keys and values stored in the QuadTree.Node.
int	gridX() Gets the x-coordinate of the QuadTree.Node in the tree structure.
int	gridY() Gets the y-coordinate of the QuadTree.Node in the tree structure.
boolean	hasCapacity() Indicates whether the QuadTree.Node has any remaining entries() capacity.
boolean	isLeaf() Indicates whether the QuadTree.Node is a leaf node.
int	level() Gets the level of the QuadTree.Node in the QuadTree.
QuadTree.Node<V>	maxXmaxY() Gets the child QuadTree.Node for the bounds quadrant containing its greater x- and greater y-coordinates.
QuadTree.Node<V>	maxXminY() Gets the child QuadTree.Node for the bounds quadrant containing its greater x- and smaller y-coordinates.
QuadTree.Node<V>	minXmaxY() Gets the child QuadTree.Node for the bounds quadrant containing its smaller x- and greater y-coordinates.
QuadTree.Node<V>	minXminY() Gets the child QuadTree.Node for the bounds quadrant containing its smaller x- and smaller y-coordinates.
QuadTree<V>	owner() Gets the QuadTree that contains the QuadTree.Node.

Methods inherited from class java.lang.Object

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

Field Detail

bounds

public final RectD bounds

The RectD bounds of all PointD keys in the QuadTree.Node. Indicates the subrange of the containing QuadTree that is covered by the QuadTree.Node and its children. Always has a positive RectD.width() and RectD.height(). The two dimensions are not necessarily equal.

Any PointD keys stored in the associated entries() lie within bounds. The extreme RectD.max coordinates are considered part of the neighboring QuadTree.Node on that side, if any.

center

public final PointD center

The center of the bounds of the QuadTree.Node. Divides the associated bounds into four equal-sized quadrants, corresponding to the minXminY(), minXmaxY(), maxXminY(), and maxXmaxY() child nodes. center is precomputed to speed up the traversal of the tree structure.

parent

public final QuadTree.Node<V> parent

The parent of the QuadTree.Node in the QuadTree. Never null except for the permanent QuadTree.rootNode of the containing QuadTree.

signature

public final int signature

The unique signature of the QuadTree.Node. Holds an Integer value containing a bitwise combination of level(), gridX(), and gridY(). This value uniquely identifies the position of each QuadTree.Node in the containing QuadTree, and also serves as its key within the QuadTree.nodes() hashtable.

Method Detail

entries

public java.util.Map<PointD,V> entries()

Gets all keys and values stored in the QuadTree.Node. Usually contains up to QuadTree.capacity elements when not null. If level() equals QuadTree.MAX_LEVEL, the number of elements is unbounded. Use the containing QuadTree to add, change, or remove elements.

If entries() is valid, the four child links minXminY(), minXmaxY(), maxXminY(), and maxXmaxY() are all null. Conversely, at least one link is valid if entries() is null.

Returns:

an unmodifiable Map of PointD keys and V values, or null if isLeaf() is false

gridX

public int gridX()

Gets the x-coordinate of the QuadTree.Node in the tree structure. Returns the middle 14 bits of signature.

Returns:

the x-coordinate of the QuadTree.Node within the grid of its level(), ranging from zero to 2^level()

gridY

public int gridY()

Gets the y-coordinate of the QuadTree.Node in the tree structure. Returns the highest 14 bits of signature.

Returns:

the y-coordinate of the QuadTree.Node within the grid of its level(), ranging from zero to 2^level()

hasCapacity

public boolean hasCapacity()

Indicates whether the QuadTree.Node has any remaining entries() capacity. Does not check whether level() equals QuadTree.MAX_LEVEL, in which case the number of entries() may exceed QuadTree.capacity.

Returns:

true if isLeaf() is true and the number of entries() is less than QuadTree.capacity, else false

isLeaf

public boolean isLeaf()

Indicates whether the QuadTree.Node is a leaf node. Returns true exactly if entries() is not null.

Returns:

true if the QuadTree.Node is a leaf node, false if it is an internal node

level

public int level()

Gets the level of the QuadTree.Node in the QuadTree. Returns the lowest four bits of signature.

Returns:

the level of the QuadTree.Node in the QuadTree, ranging from zero to QuadTree.MAX_LEVEL

maxXmaxY

public QuadTree.Node<V> maxXmaxY()

Gets the child QuadTree.Node for the bounds quadrant containing its greater x- and greater y-coordinates.

Returns:

the child QuadTree.Node for the bounds quadrant containing its greater x- and greater y-coordinates, or null if none

maxXminY

public QuadTree.Node<V> maxXminY()

Gets the child QuadTree.Node for the bounds quadrant containing its greater x- and smaller y-coordinates.

Returns:

the child QuadTree.Node for the bounds quadrant containing its greater x- and smaller y-coordinates, or null if none

minXmaxY

public QuadTree.Node<V> minXmaxY()

Gets the child QuadTree.Node for the bounds quadrant containing its smaller x- and greater y-coordinates.

Returns:

the child QuadTree.Node for the bounds quadrant containing its smaller x- and greater y-coordinates, or null if none

minXminY

public QuadTree.Node<V> minXminY()

Gets the child QuadTree.Node for the bounds quadrant containing its smaller x- and smaller y-coordinates.

Returns:

the child QuadTree.Node for the bounds quadrant containing its smaller x- and smaller y-coordinates, or null if none

owner

public QuadTree<V> owner()

Gets the QuadTree that contains the QuadTree.Node. Returns null if the QuadTree.Node has been removed from its QuadTree. Otherwise, returns the same valid object throughout the lifetime of the QuadTree.Node.

Returns:

the QuadTree that contains the QuadTree.Node