XPath Class Reference

Extended Path. More...

Detailed Description

Extended Path.

This is the same as a standard path but it is possible to customize when the target should be considered reached. Can be used to for example signal a path as complete when it is within a specific distance from the target.

Note

More customizations does make it slower to calculate than an ABPath but not by very much.

A* Pro Feature:

This is an A* Pathfinding Project Pro feature only. This function/class/variable might not exist in the Free version of the A* Pathfinding Project or the functionality might be limited
The Pro version can be bought here

See Also

Pathfinding.PathEndingCondition

Public Member Functions
	XPath ()
override void	CalculateStep (long targetTick)
	Calculates the path until completed or until the time has passed targetTick.
override void	Reset ()
	Reset all values to their default values.
Public Member Functions inherited from ABPath
override void	Cleanup ()
	Always called after the path has been calculated.
override string	DebugString (PathLog logMode)
	Returns a debug string for this path.
override uint	GetConnectionSpecialCost (GraphNode a, GraphNode b, uint currentCost)
	May be called by graph nodes to get a special cost for some connections.
Vector3	GetMovementVector (Vector3 point)
	Returns in which direction to move from a point on the path.
override void	Initialize ()
	Initializes the path.
override void	Prepare ()
	Prepares the path.
void	ResetCosts (Path p)
	Resets End Node Costs.
	ABPath ()
	Default constructor.
Public Member Functions inherited from Path
void	AdvanceState (PathState s)
	Threadsafe increment of the state.
uint	CalculateHScore (GraphNode node)
	Estimated cost from the specified node to the target.
bool	CanTraverse (GraphNode node)
	Returns if the node can be traversed.
void	Claim (System.Object o)
	Claim this path (pooling).
void	Error ()
	Aborts the path because of an error.
Int3	GetHTarget ()
PathState	GetState ()
	Returns the state of the path in the pathfinding pipeline.
uint	GetTagPenalty (int tag)
	Returns penalty for the given tag.
float	GetTotalLength ()
	Total Length of the path.
uint	GetTraversalCost (GraphNode node)
bool	IsDone ()
	Returns if this path is done calculating.
virtual void	OnEnterPool ()
	Called when the path enters the pool.
void	Release (System.Object o, bool silent=false)
	Releases a path claim (pooling).
void	ReleaseSilent (System.Object o)
	Releases the path silently (pooling).
virtual void	ReturnPath ()
	Calls callback to return the calculated path.
IEnumerator	WaitForPath ()
	Waits until this path has been calculated and returned.

Static Public Member Functions
static new XPath	Construct (Vector3 start, Vector3 end, OnPathDelegate callback=null)
Static Public Member Functions inherited from ABPath
static ABPath	Construct (Vector3 start, Vector3 end, OnPathDelegate callback=null)
	Construct a path with a start and end point.

Public Attributes
PathEndingCondition	endingCondition
	Ending Condition for the path.
Public Attributes inherited from ABPath
bool	calculatePartial
	Calculate partial path if the target node cannot be reached.
GraphNode	endHint
	Hints can be set to enable faster Get Nearest Node queries.
GraphNode	endNode
	End node of the path.
Vector3	endPoint
	End point of the path.
Vector3	originalEndPoint
	End Point exactly as in the path request.
Vector3	originalStartPoint
	Start Point exactly as in the path request.
bool	recalcStartEndCosts = true
	Defines if start and end nodes will have their connection costs recalculated for this path.
GraphNode	startHint
	Hints can be set to enable faster Get Nearest Node queries.
Int3	startIntPoint
	Start point in integer coordinates.
GraphNode	startNode
	Start node of the path.
Vector3	startPoint
	Start point of the path.
Public Attributes inherited from Path
OnPathDelegate	callback
	Callback to call when the path is complete.
float	duration
	The duration of this path in ms.
int	enabledTags = -1
	Which graph tags are traversable.
Heuristic	heuristic
	Determines which heuristic to use.
float	heuristicScale = 1F
	Scale of the heuristic values.
OnPathDelegate	immediateCallback
	Immediate callback to call when the path is complete.
NNConstraint	nnConstraint = PathNNConstraint.Default
	Constraint for how to search for nodes.
List< GraphNode >	path
	Holds the path as a Node array.
int	searchedNodes
	Number of nodes this path has searched.
int	searchIterations
	The number of frames/iterations this path has executed.
List< Vector3 >	vectorPath
	Holds the (perhaps post processed) path as a Vector3 list.

Protected Member Functions
override void	CompletePathIfStartIsValidTarget ()
	The start node need to be special cased and checked here if it is a valid target.
override bool	EndPointGridGraphSpecialCase (GraphNode endNode)
	Applies a special case for grid nodes.
Protected Member Functions inherited from ABPath
void	UpdateStartEnd (Vector3 start, Vector3 end)
	Sets the start and end points.
void	Setup (Vector3 start, Vector3 end, OnPathDelegate callbackDelegate)
Protected Member Functions inherited from Path
void	DebugStringPrefix (PathLog logMode, System.Text.StringBuilder text)
	Writes text shared for all overrides of DebugString to the string builder.
void	DebugStringSuffix (PathLog logMode, System.Text.StringBuilder text)
	Writes text shared for all overrides of DebugString to the string builder.
bool	HasExceededTime (int searchedNodes, long targetTime)
virtual void	Trace (PathNode from)
	Traces the calculated path from the end node to the start.

Private Member Functions
void	ChangeEndNode (GraphNode target)
	Changes the endNode to target and resets some temporary flags on the previous node.

Additional Inherited Members
Protected Attributes inherited from ABPath
int[]	endNodeCosts
	Saved original costs for the end node.
PathNode	partialBestTarget
	Current best target for the partial path.
Package Functions inherited from Path
void	ForceLogError (string msg)
	Logs an error and calls Error().
void	Log (string msg)
	Appends a message to the errorLog.
void	LogError (string msg)
	Appends msg to errorLog and logs msg to the console.
void	PrepareBase (PathHandler pathHandler)
	Prepares low level path variables for calculation.
Package Attributes inherited from Path
Path	next
	Internal linked list implementation.
bool	pooled
	True if the path is currently pooled.
Properties inherited from ABPath
virtual bool	hasEndPoint [get]
	Determines if a search for an end node should be done.

Constructor & Destructor Documentation

XPath

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Member Function Documentation

override void CalculateStep ( long  targetTick )

virtual

Calculates the path until completed or until the time has passed targetTick.

Usually a check is only done every 500 nodes if the time has passed targetTick. Time/Ticks are got from System.DateTime.UtcNow.Ticks.

Basic outline of what the function does for the standard path (Pathfinding.ABPath).

while the end has not been found and no error has ocurred
check if we have reached the end
if so, exit and return the path

open the current node, i.e loop through its neighbours, mark them as visited and put them on a heap

check if there are still nodes left to process (or have we searched the whole graph)
if there are none, flag error and exit

pop the next node of the heap and set it as current

check if the function has exceeded the time limit
if so, return and wait for the function to get called again

Reimplemented from ABPath.

void ChangeEndNode ( GraphNode  target )

private

Changes the endNode to target and resets some temporary flags on the previous node.

Also sets endPoint to the position of target.

override void CompletePathIfStartIsValidTarget ( )

protectedvirtual

The start node need to be special cased and checked here if it is a valid target.

Reimplemented from ABPath.

static new XPath Construct ( Vector3  start, Vector3  end, OnPathDelegate  callback = null  )

static

override bool EndPointGridGraphSpecialCase ( GraphNode  closestWalkableEndNode )

protectedvirtual

Applies a special case for grid nodes.

Assume the closest walkable node is a grid node. We will now apply a special case only for grid graphs. In tile based games, an obstacle often occupies a whole node. When a path is requested to the position of an obstacle (single unwalkable node) the closest walkable node will be one of the 8 nodes surrounding that unwalkable node but that node is not neccessarily the one that is most optimal to walk to so in this special case we mark all nodes around the unwalkable node as targets and when we search and find any one of them we simply exit and set that first node we found to be the 'real' end node because that will be the optimal node (this does not apply in general unless the heuristic is set to None, but for a single unwalkable node it does). This also applies if the nearest node cannot be traversed for some other reason like restricted tags.

Returns

True if the workaround was applied. If this happens the endPoint, endNode, hTarget and hTargetNode fields will be modified.

Image below shows paths when this special case is applied. The path goes from the white sphere to the blue orange box.

Image below shows paths when this special case has been disabled

Reimplemented from ABPath.

override void Reset ( )

virtual

Reset all values to their default values.

All inheriting path types must implement this function, resetting ALL their variables to enable recycling of paths. Call this base function in inheriting types with base.Reset ();

Reimplemented from ABPath.

Member Data Documentation

PathEndingCondition endingCondition

Ending Condition for the path.

The ending condition determines when the path has been completed. Can be used to for example signal a path as complete when it is within a specific distance from the target.

If ending conditions are used that are not centered around the endpoint of the path you should also switch the heuristic to None to make sure that optimal paths are still found. This has quite a large performance impact so you might want to try to run it with the default heuristic and see if the path is optimal in enough cases.

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The documentation for this class was generated from the following file:

• /Users/arong/Unity/a-pathfinding-project/Assets/AstarPathfindingProject/Pathfinders/XPath.cs