Class FloodPathTracer Extends ABPath

FloodPathTracer ()

Default constructor.

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

void Trace (

GraphNode

from

)

Traces the calculated path from the start node to the end.

This will build an array (path) of the nodes this path will pass through and also set the vectorPath array to the path arrays positions. This implementation will use the flood (FloodPath) to trace the path from precalculated data.

FloodPathTracer Construct (

Vector3	start
FloodPath	flood
OnPathDelegate	callback=null

)

void BlockUntilCalculated ()

Blocks until this path has been calculated and returned.

Normally it takes a few frames for a path to be calculated and returned. This function will ensure that the path will be calculated when this function returns and that the callback for that path has been called.

Use this function only if you really need to. There is a point to spreading path calculations out over several frames. It smoothes out the framerate and makes sure requesting a large number of paths at the same time does not cause lag.

Path p = seeker.StartPath (transform.position, transform.position + Vector3.forward * 10);
p.BlockUntilCalculated();
// The path is calculated now


bool CanTraverse (

GraphNode

node

)

Returns if the node can be traversed.

This per default equals to if the node is walkable and if the node's tag is included in enabledTags

void Claim (

System.Object

o

)

Claim this path (pooling).

A claim on a path will ensure that it is not pooled. If you are using a path, you will want to claim it when you first get it and then release it when you will not use it anymore. When there are no claims on the path, it will be reset and put in a pool.

This is essentially just reference counting.

The object passed to this method is merely used as a way to more easily detect when pooling is not done correctly. It can be any object, when used from a movement script you can just pass "this". This class will throw an exception if you try to call Claim on the same path twice with the same object (which is usually not what you want) or if you try to call Release with an object that has not been used in a Claim call for that path. The object passed to the Claim method needs to be the same as the one you pass to this method.

PathCompleteState CompleteState

Current state of the path.

ABPath Construct (

Vector3	start
Vector3	end
OnPathDelegate	callback=null

)

Construct a path with a start and end point.

The delegate will be called when the path has been calculated. Do not confuse it with the Seeker callback as they are sent at different times. If you are using a Seeker to start the path you can set callback to null.

void Error ()

Aborts the path because of an error.

Sets error to true. This function is called when an error has occurred (e.g a valid path could not be found).

void FailWithError (

string

msg

)

Causes the path to fail and sets errorLog to msg.

ABPath FakePath (

List<Vector3>	vectorPath
List<GraphNode>	nodePath=null

)

Creates a fake path.

Creates a path that looks almost exactly like it would if the pathfinding system had calculated it.

This is useful if you want your agents to follow some known path that cannot be calculated using the pathfinding system for some reason.

var path = ABPath.FakePath(new List<Vector3> { new Vector3(1, 2, 3), new Vector3(4, 5, 6) });

ai.SetPath(path);
You can use it to combine existing paths like this:

var a = Vector3.zero;
var b = new Vector3(1, 2, 3);
var c = new Vector3(2, 3, 4);
var path1 = ABPath.Construct(a, b);
var path2 = ABPath.Construct(b, c);

AstarPath.StartPath(path1);
AstarPath.StartPath(path2);
path1.BlockUntilCalculated();
path2.BlockUntilCalculated();

// Combine the paths
// Note: Skip the first element in the second path as that will likely be the last element in the first path
var newVectorPath = path1.vectorPath.Concat(path2.vectorPath.Skip(1)).ToList();
var newNodePath = path1.path.Concat(path2.path.Skip(1)).ToList();
var combinedPath = ABPath.FakePath(newVectorPath, newNodePath);


bool FloodingPath

True for paths that want to search all nodes and not jump over nodes as optimizations.

This disables Jump Point Search when that is enabled to prevent e.g ConstantPath and FloodPath to become completely useless.

uint GetConnectionSpecialCost (

GraphNode	a	Moving from this node
GraphNode	b	Moving to this node
uint	currentCost	The cost of moving between the nodes. Return this value if there is no meaningful special cost to return.

)

May be called by graph nodes to get a special cost for some connections.

Nodes may call it when PathNode.flag2 is set to true, for example mesh nodes, which have a very large area can be marked on the start and end nodes, this method will be called to get the actual cost for moving from the start position to its neighbours instead of as would otherwise be the case, from the start node's position to its neighbours. The position of a node and the actual start point on the node can vary quite a lot.

The default behaviour of this method is to return the previous cost of the connection, essentiall making no change at all.

This method should return the same regardless of the order of a and b. That is f(a,b) == f(b,a) should hold.

uint GetTagPenalty (

int

tag

A value between 0 (inclusive) and 32 (exclusive).

)

Returns penalty for the given tag.

float GetTotalLength ()

Total Length of the path.

Calculates the total length of the vectorPath. Cache this rather than call this function every time since it will calculate the length every time, not just return a cached value.

uint GetTraversalCost (

GraphNode

node

)

Returns the cost of traversing the given node.

bool IsDone ()

True if this path is done calculating.

PathState PipelineState

Returns the state of the path in the pathfinding pipeline.

void Release (

System.Object	o
bool	silent=false

)

Releases a path claim (pooling).

Removes the claim of the path by the specified object. When the claim count reaches zero, the path will be pooled, all variables will be cleared and the path will be put in a pool to be used again. This is great for performance since fewer allocations are made.

If the silent parameter is true, this method will remove the claim by the specified object but the path will not be pooled if the claim count reches zero unless a Release call (not silent) has been made earlier. This is used by the internal pathfinding components such as Seeker and AstarPath so that they will not cause paths to be pooled. This enables users to skip the claim/release calls if they want without the path being pooled by the Seeker or AstarPath and thus causing strange bugs.

IEnumerator WaitForPath ()

Waits until this path has been calculated and returned.

Allows for very easy scripting. IEnumerator Start () {
var path = seeker.StartPath(transform.position, transform.position + transform.forward*10, null);
yield return StartCoroutine(path.WaitForPath());
// The path is calculated now
}


bool calculatePartial

Calculate partial path if the target node cannot be reached.

If the target node cannot be reached, the node which was closest (given by heuristic) will be chosen as target node and a partial path will be returned. This only works if a heuristic is used (which is the default). If a partial path is found, CompleteState is set to Partial.

The endNode and endPoint will be modified and be set to the node which ends up being closest to the target.

OnPathDelegate callback

Callback to call when the path is complete.

This is usually sent to the Seeker component which post processes the path and then calls a callback to the script which requested the path

float duration

How long it took to calculate this path in milliseconds.

int enabledTags = -1

Which graph tags are traversable.

This is a bitmask so -1 = all bits set = all tags traversable. For example, to set bit 5 to true, you would do myPath.enabledTags |= 1 << 5;
To set it to false, you would do myPath.enabledTags &= ~(1 << 5);


The Seeker has a popup field where you can set which tags to use.

GraphNode endNode

End node of the path.

Vector3 endPoint

End point of the path.

This is the closest point on the endNode to originalEndPoint

bool error

If the path failed, this is true.

string errorLog

Additional info on why a path failed.

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.

Vector3 originalEndPoint

End Point exactly as in the path request.

Vector3 originalStartPoint

Start Point exactly as in the path request.

List<GraphNode> path

Holds the path as a Node array.

All nodes the path traverses. This may not be the same nodes as the post processed path traverses.

ushort pathID

ID of this path.

Used to distinguish between different paths

int searchedNodes

Number of nodes this path has searched.

Int3 startIntPoint

Start point in integer coordinates.

GraphNode startNode

Start node of the path.

Vector3 startPoint

Start point of the path.

This is the closest point on the startNode to originalStartPoint

int[] tagPenalties

Penalties for each tag.

Tag 0 which is the default tag, will have added a penalty of tagPenalties[0]. These should only be positive values since the A* algorithm cannot handle negative penalties.

When assigning an array to this property it must have a length of 32.

ITraversalProvider traversalProvider

Provides additional traversal information to a path request.

List<Vector3> vectorPath

Holds the (possibly post processed) path as a Vector3 list.

uint CalculateHScore (

GraphNode

node

)

Estimated cost from the specified node to the target.

void CalculateStep (

long

targetTick

)

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 occurred
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


void Cleanup ()

Always called after the path has been calculated.

Guaranteed to be called before other paths have been calculated on the same thread. Use for cleaning up things like node tagging and similar.

void CompletePathIfStartIsValidTarget ()

Checks if the start node is the target and complete the path if that is the case.

This is necessary so that subclasses (e.g XPath) can override this behaviour.

If the start node is a valid target point, this method should set CompleteState to Complete and trace the path.

string DebugString (

PathLog

logMode

)

Returns a debug string for this 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 EndPointGridGraphSpecialCase (

GraphNode

closestWalkableEndNode

)

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.

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

Image below shows paths when this special case has been disabled

Int3 GetHTarget ()

void Initialize ()

Initializes the path.

Traces the path from the start node.

void OnEnterPool ()

Called when the path enters the pool.

This method should release e.g pooled lists and other pooled resources The base version of this method releases vectorPath and path lists. Reset() will be called after this function, not before.

void Prepare ()

Prepares the path.

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

void PrepareBase (

PathHandler

pathHandler

)

Prepares low level path variables for calculation.

Called before a path search will take place. Always called before the Prepare, Initialize and CalculateStep functions

void Reset ()

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 ();

void ReturnPath ()

Calls callback to return the calculated path.

void Setup (

Vector3	start
Vector3	end
OnPathDelegate	callbackDelegate

)

void Setup (

Vector3	start
FloodPath	flood
OnPathDelegate	callback

)

void Trace (

PathNode

from

)

Traces the calculated path from the end node to the start.

This will build an array (path) of the nodes this path will pass through and also set the vectorPath array to the path arrays positions. Assumes the vectorPath and path are empty and not null (which will be the case for a correctly initialized path).

void UpdateStartEnd (

Vector3	start
Vector3	end

)

Sets the start and end points.

Sets originalStartPoint, originalEndPoint, startPoint, endPoint, startIntPoint and hTarget (to end )

PathCompleteState completeState

Backing field for CompleteState.

PathNode currentR

The node currently being processed.

int[] endNodeCosts

Saved original costs for the end node.

FloodPath flood

Reference to the FloodPath which searched the path originally.

Int3 hTarget

Target to use for H score calculations.

GraphNode hTargetNode

Target to use for H score calculation.

Used alongside hTarget.

bool hasBeenReset

True if the Reset function has been called.

Used to alert users when they are doing something wrong.

bool hasEndPoint

Determines if a search for an end node should be done.

Set by different path types.

bool hasEndPoint

int[] internalTagPenalties

The tag penalties that are actually used.

If manualTagPenalties is null, this will be ZeroTagPenalties

int[] manualTagPenalties

Tag penalties set by other scripts.

Path next

Internal linked list implementation.

PathNode partialBestTarget

Current best target for the partial path.

This is the node with the lowest H score.

PathHandler pathHandler

Data for the thread calculating this path.