FloodPath Class Reference

Floods the area completely for easy computation of any path to a single point. More...

Detailed Description

Floods the area completely for easy computation of any path to a single point.

This path is a bit special, because it does not do anything useful by itself. What it does is that it calculates paths to all nodes it can reach, it floods the graph. This data will remain stored in the path. Then you can call a FloodPathTracer path, that path will trace the path from it's starting point all the way to where this path started flooding and thus generating a path extremely quickly.
It is very useful in for example TD (Tower Defence) games where all your AIs will walk to the same point, but from different places, and you do not update the graph or change the target point very often, what changes is their positions and new AIs spawn all the time (which makes it hard to use the MultiTargetPath).

With this path type, it can all be handled easily.

• At start, you simply start ONE FloodPath and save the reference (it will be needed later).
• Then when a unit is spawned or needs its path recalculated, start a FloodPathTracer path from it's position. It will then find the shortest path to the point specified when you called the FloodPath extremely quickly.
• If you update the graph (for example place a tower in a TD game) or need to change the target point, you simply call a new FloodPath (and store it's reference).

Version

From 3.2 and up, path traversal data is now stored in the path class. So you can now use other path types in parallel with this one.

Here follows some example code of the above list of steps:

public static FloodPath fpath;

public void Start () {
fpath = FloodPath.Construct (someTargetPosition, null);
AstarPath.StartPath (fpath);
}

When searching for a new path to someTargetPosition from let's say transform.position, you do

FloodPathTracer fpathTrace = FloodPathTracer.Construct (transform.position,fpath,null);
seeker.StartPath (fpathTrace,OnPathComplete);

Where OnPathComplete is your callback function.
Another thing to note is that if you are using NNConstraints on the FloodPathTracer, they must always inherit from Pathfinding.PathIDConstraint.
The easiest is to just modify the instance of PathIDConstraint which is created as the default one.

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

Public Member Functions
	FloodPath ()
	Default constructor.
GraphNode	GetParent (GraphNode node)
bool	HasPathTo (GraphNode node)
Public Member Functions inherited from Path
void	BlockUntilCalculated ()
	Blocks until this path has been calculated and returned.
void	Claim (System.Object o)
	Claim this path (pooling).
void	Error ()
	Aborts the path because of an error.
PathState	GetState ()
	Returns the state of the path in the pathfinding pipeline.
float	GetTotalLength ()
	Total Length of the path.
bool	IsDone ()
	Returns if this path is done calculating.
void	Release (System.Object o, bool silent=false)
	Releases a path claim (pooling).
IEnumerator	WaitForPath ()
	Waits until this path has been calculated and returned.
Public Member Functions inherited from IPathInternals
void	AdvanceState (PathState s)
void	CalculateStep (long targetTick)
void	Cleanup ()
void	Initialize ()
void	OnEnterPool ()
void	Prepare ()
void	PrepareBase (PathHandler handler)
void	Reset ()
void	ReturnPath ()

Static Public Member Functions
static FloodPath	Construct (Vector3 start, OnPathDelegate callback=null)
static FloodPath	Construct (GraphNode start, OnPathDelegate callback=null)

Public Attributes
Vector3	originalStartPoint
bool	saveParents = true
	If false, will not save any information.
GraphNode	startNode
Vector3	startPoint
Public Attributes inherited from Path
OnPathDelegate	callback
	Callback to call when the path is complete.
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.
ITraversalProvider	traversalProvider
	Provides additional traversal information to a path request.
List< Vector3 >	vectorPath
	Holds the (possibly post processed) path as a Vector3 list.

Protected Member Functions
override void	CalculateStep (long targetTick)
	Opens nodes until there are none left to search (or until the max time limit has been exceeded)
override void	Initialize ()
	Initializes the path.
override void	Prepare ()
	Called before the path is started.
override void	Reset ()
	Reset all values to their default values.
void	Setup (Vector3 start, OnPathDelegate callback)
void	Setup (GraphNode start, OnPathDelegate callback)
Protected Member Functions inherited from Path
virtual void	Cleanup ()
	Always called after the path has been calculated.
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.
virtual void	OnEnterPool ()
	Called when the path enters the pool.
void	PrepareBase (PathHandler pathHandler)
	Prepares low level path variables for calculation.
virtual void	ReturnPath ()
	Calls callback to return the calculated path.
virtual void	Trace (PathNode from)
	Traces the calculated path from the end node to the start.

Protected Attributes
Dictionary< GraphNode, GraphNode >	parents
Protected Attributes inherited from Path
PathNode	currentR
	The node currently being processed.
bool	hasBeenReset
	True if the Reset function has been called.
Int3	hTarget
	Target to use for H score calculations.
GraphNode	hTargetNode
	Target to use for H score calculation.
int[]	internalTagPenalties
	The tag penalties that are actually used.
int[]	manualTagPenalties
	Tag penalties set by other scripts.
PathHandler	pathHandler
	Data for the thread calculating this path.

Properties
override bool	FloodingPath [get]
Properties inherited from Path
PathCompleteState	CompleteState [get, set]
	Current state of the path.
bool	error [get]
	If the path failed, this is true.
string	errorLog [get, set]
	Additional info on why a path failed.
virtual bool	FloodingPath [get]
	True for paths that want to search all nodes and not jump over nodes as optimizations.
PathHandler IPathInternals.	PathHandler [get]
ushort	pathID [get, set]
	ID of this path.
PathState	PipelineState [get, set]
	Returns the state of the path in the pathfinding pipeline.
bool IPathInternals.	Pooled [get, set]
	True if the path is currently pooled.
bool	recycled [get]
	True if the path is currently recycled (i.e in the path pool).
int[]	tagPenalties [get, set]
	Penalties for each tag.
Properties inherited from IPathInternals
PathHandler	PathHandler [get]
bool	Pooled [get, set]

Additional Inherited Members
Package Functions inherited from Path
uint	CalculateHScore (GraphNode node)
	Estimated cost from the specified node to the target.
bool	CanTraverse (GraphNode node)
	Returns if the node can be traversed.
virtual string	DebugString (PathLog logMode)
	Returns a string with information about it.
void	FailWithError (string msg)
	Causes the path to fail and sets errorLog to msg.
virtual uint	GetConnectionSpecialCost (GraphNode a, GraphNode b, uint currentCost)
	May be called by graph nodes to get a special cost for some connections.
Int3	GetHTarget ()
uint	GetTagPenalty (int tag)
	Returns penalty for the given tag.
uint	GetTraversalCost (GraphNode node)
void	Log (string msg)
	Appends a message to the errorLog.
void	LogError (string msg)
	Logs an error.
void	ReleaseSilent (System.Object o)
	Releases the path silently (pooling).
Package Attributes inherited from Path
float	duration
	How long it took to calculate this path in milliseconds.
Path	next
	Internal linked list implementation.
int	searchedNodes
	Number of nodes this path has searched.

Constructor & Destructor Documentation

FloodPath

(

)

Default constructor.

Do not use this. Instead use the static Construct method which can handle path pooling.

Member Function Documentation

override void CalculateStep ( long  targetTick )

protectedvirtual

Opens nodes until there are none left to search (or until the max time limit has been exceeded)

Implements Path.

static FloodPath Construct ( Vector3  start, OnPathDelegate  callback = null  )

static

static FloodPath Construct ( GraphNode  start, OnPathDelegate  callback = null  )

static

GraphNode GetParent

(

GraphNode

node

)

bool HasPathTo

(

GraphNode

node

)

override void Initialize ( )

protectedvirtual

Initializes the path.

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

Implements Path.

override void Prepare ( )

protectedvirtual

Called before the path is started.

Called right before Initialize

Implements Path.

override void Reset ( )

protectedvirtual

Reset all values to their default values.

Note

All inheriting path types (e.g ConstantPath, RandomPath, etc.) which declare their own variables need to override this function, resetting ALL their variables to enable pooling of paths. If this is not done, trying to use that path type for pooling could result in weird behaviour. The best way is to reset to default values the variables declared in the extended path type and then call the base function in inheriting types with base.Reset().

Reimplemented from Path.

void Setup ( Vector3  start, OnPathDelegate  callback  )

protected

void Setup ( GraphNode  start, OnPathDelegate  callback  )

protected

Member Data Documentation

Vector3 originalStartPoint

Dictionary<GraphNode, GraphNode> parents

protected

bool saveParents = true

If false, will not save any information.

Used by some internal parts of the system which doesn't need it.

GraphNode startNode

Vector3 startPoint

Property Documentation

override bool FloodingPath

getpackage

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

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