walker.blue.path.lib.finder

Class GridAStar

java.lang.Object

walker.blue.path.lib.base.AbstractPathfinder<GridNode,java.util.List<java.util.List<GridNode>>>

walker.blue.path.lib.finder.GridAStar

All Implemented Interfaces:

Pathfinder<GridNode,java.util.List<java.util.List<GridNode>>>

Direct Known Subclasses:

ThetaStar

public class GridAStar
extends AbstractPathfinder<GridNode,java.util.List<java.util.List<GridNode>>>

This class can be used to find a path between two nodes in a given two-dimensional list of nodes.

Constructor Summary

Constructors

Constructor and Description
GridAStar()

Method Summary

Modifier and Type	Method and Description
protected void	computeBestPath(GridNode node, GridNode neighbor) Determines whether to set a neighbor's parent to the node or to the node's parent.
protected int	distanceBetweenNodes(GridNode a, GridNode b) Returns the approximate distance between two nodes in the search area.
java.util.List<GridNode>	findPath(java.util.List<java.util.List<GridNode>> searchArea, GridNode start, GridNode dest) Returns a List representing the path between two nodes in a two-dimensional search space.
protected int	getManhattanDistance(GridNode a, GridNode b) Returns the distance between two nodes using the Manhattan method of adding up the x distance and the y distance together.
void	printPath(java.util.List<java.util.List<GridNode>> searchArea, java.util.List<GridNode> path) Prints the search area along with the given path in an easy-to-view format.
void	printSearchArea(java.util.List<java.util.List<GridNode>> searchArea) Prints the given search area in an easy-to-view format.
protected java.util.List<GridNode>	reconstructPath(GridNode start, GridNode dest) Reconstructs the path by traversing from the destination node back through each parent node until the start node is reached.

Methods inherited from class java.lang.Object

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

Constructor Detail

GridAStar

public GridAStar()

Method Detail

findPath

public java.util.List<GridNode> findPath(java.util.List<java.util.List<GridNode>> searchArea,
                                         GridNode start,
                                         GridNode dest)

Returns a List representing the path between two nodes in a two-dimensional search space.

Specified by:

findPath in interface Pathfinder<GridNode,java.util.List<java.util.List<GridNode>>>

Specified by:

findPath in class AbstractPathfinder<GridNode,java.util.List<java.util.List<GridNode>>>

Parameters:

searchArea - a 2D list holding all of the GridNodes that describe the space

start - the start node for the path search and must inherit from Node

dest - the destination node for the path search and must inherit from Node

Returns:

the List of nodes in the path starting from the start node and ending with the dest node

computeBestPath

protected void computeBestPath(GridNode node,
                               GridNode neighbor)

Determines whether to set a neighbor's parent to the node or to the node's parent.

Parameters:

node - the current node being visited in the path search

neighbor - a neighbor of node

distanceBetweenNodes

protected int distanceBetweenNodes(GridNode a,
                                   GridNode b)

Returns the approximate distance between two nodes in the search area.

Parameters:

a - first node

b - second node

Returns:

an int representing the approximate distance between the two nodes

getManhattanDistance

protected int getManhattanDistance(GridNode a,
                                   GridNode b)

Returns the distance between two nodes using the Manhattan method of adding up the x distance and the y distance together.

Parameters:

a - first node

b - second node

Returns:

an int representing the Manhattan distance between the two nodes

reconstructPath

protected java.util.List<GridNode> reconstructPath(GridNode start,
                                                   GridNode dest)

Reconstructs the path by traversing from the destination node back through each parent node until the start node is reached.

Parameters:

start - the node used as the starting point for the path search

dest - the destination node that ends the path search

Returns:

Returns a List of GridNodes, which are the path with the start node at the head of the List and the dest node at the tail

printSearchArea

public void printSearchArea(java.util.List<java.util.List<GridNode>> searchArea)

Prints the given search area in an easy-to-view format.

Parameters:

searchArea - a 2D list holding all of the GridNodes that describe the space

printPath

public void printPath(java.util.List<java.util.List<GridNode>> searchArea,
                      java.util.List<GridNode> path)

Prints the search area along with the given path in an easy-to-view format.

Parameters:

searchArea - a 2D list holding all of the GridNodes that describe the space

path - the path that is printed over the search area