walker.blue.path.lib.finder

Class ThetaStar

java.lang.Object

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

walker.blue.path.lib.finder.GridAStar

walker.blue.path.lib.finder.ThetaStar

All Implemented Interfaces:

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

public class ThetaStar
extends GridAStar

This class expands upon GridAStar by providing a means for generating paths with fewer turns by incorporating a line of sight check during execution so that as long as the previous node's parent is within line of sight of the current node, the current node's parent is set to the previous node's parent. If there is no line of sight, then the current node's parent is set to the previous node, which introduces a turn in the path.

Constructor Summary

Constructors

Constructor and Description
ThetaStar()

Method Summary

Modifier and Type	Method and Description
protected void	computeBestPath(java.util.List<java.util.List<GridNode>> searchArea, 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.
java.util.List<java.util.List<java.lang.String>>	getVisibilityGraph(java.util.List<java.util.List<GridNode>> searchArea, GridNode node) Checks if every node in the search area is within line of sight with the given node.
void	printAllLOSNodeCombinations(java.util.List<java.util.List<GridNode>> searchArea) Calculates the line of sight for every node to every other node and prints out the results.

Methods inherited from class walker.blue.path.lib.finder.GridAStar

computeBestPath, getManhattanDistance, printPath, printSearchArea, reconstructPath

Methods inherited from class java.lang.Object

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

Constructor Detail

ThetaStar

public ThetaStar()

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>>>

Overrides:

findPath in class GridAStar

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(java.util.List<java.util.List<GridNode>> searchArea,
                               GridNode node,
                               GridNode neighbor)

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

Parameters:

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

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.

Overrides:

distanceBetweenNodes in class GridAStar

Parameters:

a - first node

b - second node

Returns:

an int representing the approximate distance between the two nodes

printAllLOSNodeCombinations

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

Calculates the line of sight for every node to every other node and prints out the results.

Parameters:

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

getVisibilityGraph

public java.util.List<java.util.List<java.lang.String>> getVisibilityGraph(java.util.List<java.util.List<GridNode>> searchArea,
                                                                           GridNode node)

Checks if every node in the search area is within line of sight with the given node.

Parameters:

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

node - the node used to

Returns:

A 2D list of strings where "S" represents the given node, "V" marks that the node is within line of sight of "S", "X" marks a boundary where sight does not pass, and " " marks nodes that are out of sight of "S"