RandomPath Class Reference

Finds a path in a random direction from the start node. More...

Detailed Description

Finds a path in a random direction from the start node.

Terminates and returns when G >= length (passed to the constructor) + RandomPath.spread or when there are no more nodes left to search.

// Call a RandomPath call like this, assumes that a Seeker is attached to the GameObject

// The path will be returned when the path is over a specified length (or more accurately when the traversal cost is greater than a specified value).
// A score of 1000 is approximately equal to the cost of moving one world unit.
int theGScoreToStopAt = 50000;

// Create a path object
RandomPath path = RandomPath.Construct(transform.position, theGScoreToStopAt);
// Determines the variation in path length that is allowed
path.spread = 5000;

// Get the Seeker component which must be attached to this GameObject
Seeker seeker = GetComponent<Seeker>();

// Start the path and return the result to MyCompleteFunction (which is a function you have to define, the name can of course be changed)
seeker.StartPath(path, MyCompleteFunction);

A* Pro Feature:

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Public Member Functions
	RandomPath ()
	RandomPath (Vector3 start, int length, OnPathDelegate callback=null)
override void	CalculateStep (long targetTick)
	Calculates the path until completed or until the time has passed targetTick.
override void	Initialize ()
	Initializes the path.
override void	Prepare ()
	Prepares the path.
override void	Reset ()
	Reset all values to their default values.
override void	ReturnPath ()
	Calls callback to return the calculated path.
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.
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).
IEnumerator	WaitForPath ()
	Waits until this path has been calculated and returned.

Static Public Member Functions
static RandomPath	Construct (Vector3 start, int length, 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
Vector3	aim
	An aim can be used to guide the pathfinder to not take totally random paths.
float	aimStrength
	If an aim is set, the higher this value is, the more it will try to reach aim.
int	searchLength
	G score to stop searching at.
int	spread = 5000
	All G scores between searchLength and searchLength+spread are valid end points, a random one of them is chosen as the final point.
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
RandomPath	Setup (Vector3 start, int length, OnPathDelegate callback)
Protected Member Functions inherited from ABPath
virtual void	CompletePathIfStartIsValidTarget ()
	Checks if the start node is the target and complete the path if that is the case.
virtual bool	EndPointGridGraphSpecialCase (GraphNode closestWalkableEndNode)
	Applies a special case for grid nodes.
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.

Properties
override bool	FloodingPath [get]
override bool	hasEndPoint [get]
Properties inherited from ABPath
virtual bool	hasEndPoint [get]
	Determines if a search for an end node should be done.
Properties inherited from Path
System.DateTime	callTime [get, set]
	When the call was made to start the pathfinding for this path.
PathCompleteState	CompleteState [get, set]
	Current state of the path.
bool	error [get]
	If the path failed, this is true.
string	errorLog [get]
	Log messages with info about eventual errors.
virtual bool	FloodingPath [get]
	True for paths that want to search all nodes and not jump over nodes as optimizations.
PathHandler	pathHandler [get, set]
	Data for the thread calculating this path.
ushort	pathID [get, set]
	ID of this path.
bool	recycled [get, set]
	True if the path is currently recycled (i.e in the path pool).
int[]	tagPenalties [get, set]
	Penalties for each tag.

Private Attributes
PathNode	chosenNodeR
	Currently chosen end node.
int	maxGScore
	The G score of maxGScoreNodeR.
PathNode	maxGScoreNodeR
	The node with the highest G score which is still lower than searchLength.
int	nodesEvaluatedRep
readonly System.Random	rnd = new System.Random()
	Random number generator.

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.

Constructor & Destructor Documentation

RandomPath

(

)

RandomPath	(	Vector3	start,
		int	length,
		OnPathDelegate	callback = null
	)

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.

static RandomPath Construct ( Vector3  start, int  length, OnPathDelegate  callback = null  )

static

override void Initialize ( )

virtual

Initializes the path.

Sets up the open list and adds the first node to it

Reimplemented from ABPath.

override void Prepare ( )

virtual

Prepares the path.

Searches for start and end nodes and does some simple checking if a path is at all possible

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.

override void ReturnPath ( )

virtual

Calls callback to return the calculated path.

See Also

callback

Reimplemented from Path.

RandomPath Setup ( Vector3  start, int  length, OnPathDelegate  callback  )

protected

Member Data Documentation

Vector3 aim

An aim can be used to guide the pathfinder to not take totally random paths.

For example you might want your AI to continue in generally the same direction as before, then you can specify aim to be transform.postion + transform.forward*10 which will make it more often take paths nearer that point

See Also

aimStrength

float aimStrength

If an aim is set, the higher this value is, the more it will try to reach aim.

PathNode chosenNodeR

private

Currently chosen end node.

int maxGScore

private

The G score of maxGScoreNodeR.

PathNode maxGScoreNodeR

private

The node with the highest G score which is still lower than searchLength.

Used as a backup if a node with a G score higher than searchLength could not be found

int nodesEvaluatedRep

private

readonly System.Random rnd = new System.Random()

private

Random number generator.

int searchLength

G score to stop searching at.

The G score is rougly the distance to get from the start node to a node multiplied by 1000 (per default, see Pathfinding.Int3.Precision), plus any penalties

int spread = 5000

All G scores between searchLength and searchLength+spread are valid end points, a random one of them is chosen as the final point.

On grid graphs a low spread usually works (but keep it higher than nodeSize*1000 since that it the default cost of moving between two nodes), on NavMesh graphs I would recommend a higher spread so it can evaluate more nodes

Property Documentation

override bool FloodingPath

get

override bool hasEndPoint

getprotected

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

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