A* Pathfinding Project
3.8.5
The A* Pathfinding Project for Unity 3D
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Basic path, finds the shortest path from A to B. More...
Basic path, finds the shortest path from A to B.
This is the most basic path object it will try to find the shortest path from A to B.
Many other path types inherit from this type.
Public Member Functions | |
override void | CalculateStep (long targetTick) |
Calculates the path until completed or until the time has passed targetTick. | |
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. | |
override void | Reset () |
Reset all values to their default values. | |
void | ResetCosts (Path p) |
Resets End Node Costs. | |
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. | |
Public Attributes | |
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 | |
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. | |
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. | |
Protected Attributes | |
int[] | endNodeCosts |
Saved original costs for the end node. | |
PathNode | partialBestTarget |
Current best target for the partial path. | |
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. | |
float | maxFrameTime |
The max number of milliseconds per iteration (frame, in case of non-multithreading) | |
Properties | |
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 Member Functions | |
void | CompleteWith (GraphNode node) |
Completes the path using the specified target node. | |
void | SetFlagOnSurroundingGridNodes (GridNode gridNode, int flag, bool flagState) |
Helper method to set PathNode.flag1 to a specific value for all nodes adjacent to a grid node. | |
Private Attributes | |
GridNode | gridSpecialCaseNode |
Used in EndPointGridGraphSpecialCase. | |
Constructors | |
ABPath () | |
Default constructor. | |
static ABPath | Construct (Vector3 start, Vector3 end, OnPathDelegate callback=null) |
Construct a path with a start and end point. | |
void | Setup (Vector3 start, Vector3 end, OnPathDelegate callbackDelegate) |
Additional Inherited Members | |
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. | |
ABPath | ( | ) |
Default constructor.
Do not use this. Instead use the static Construct method which can handle path pooling.
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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).
Implements Path.
Reimplemented in MultiTargetPath, RandomPath, FloodPathTracer, and XPath.
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virtual |
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.
Reimplemented from Path.
Reimplemented in MultiTargetPath.
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protectedvirtual |
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private |
Completes the path using the specified target node.
This method assumes that the node is a target node of the path not just any random node.
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static |
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virtual |
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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.
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 in XPath.
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.
a | Moving from this node |
b | Moving to this node |
currentCost | The cost of moving between the nodes. Return this value if there is no meaningful special cost to return. |
Reimplemented from Path.
Vector3 GetMovementVector | ( | Vector3 | point | ) |
Returns in which direction to move from a point on the path.
A simple and quite slow (well, compared to more optimized algorithms) algorithm first finds the closest path segment (from vectorPath) and then returns the direction to the next point from there. The direction is not normalized.
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Initializes the path.
Sets up the open list and adds the first node to it
Implements Path.
Reimplemented in MultiTargetPath, RandomPath, and FloodPathTracer.
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Prepares the path.
Searches for start and end nodes and does some simple checking if a path is at all possible
Implements Path.
Reimplemented in MultiTargetPath, and RandomPath.
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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 Path.
Reimplemented in RandomPath, FloodPathTracer, and XPath.
void ResetCosts | ( | Path | p | ) |
Resets End Node Costs.
Costs are updated on the end node at the start of the search to better reflect the end point passed to the path, the previous ones are saved in endNodeCosts and are reset in this function which is called after the path search is complete
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Helper method to set PathNode.flag1 to a specific value for all nodes adjacent to a grid node.
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Sets the start and end points.
Sets originalStartPoint, originalEndPoint, startPoint, endPoint, startIntPoint and hTarget (to end )
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.
GraphNode endHint |
Hints can be set to enable faster Get Nearest Node queries.
Only applies to some graph types
GraphNode endNode |
End node of the path.
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protected |
Saved original costs for the end node.
Vector3 endPoint |
End point of the path.
This is the closest point on the endNode to originalEndPoint
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private |
Used in EndPointGridGraphSpecialCase.
Vector3 originalEndPoint |
End Point exactly as in the path request.
Vector3 originalStartPoint |
Start Point exactly as in the path request.
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protected |
Current best target for the partial path.
This is the node with the lowest H score.
bool recalcStartEndCosts = true |
Defines if start and end nodes will have their connection costs recalculated for this path.
These connection costs will be more accurate and based on the exact start point and target point, however it should not be used when connection costs are not the default ones (all build in graph generators currently generate default connection costs).
GraphNode startHint |
Hints can be set to enable faster Get Nearest Node queries.
Only applies to some graph types
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
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getprotected |
Determines if a search for an end node should be done.
Set by different path types.