AStar2D

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 Go to latest Published: Sep 16, 2025 License: MIT Imports: 23 Imported by: 0

Documentation

Overview

An implementation of the A* algorithm, used to find the shortest path between two vertices on a connected graph in 2D space.

See graphics.gd/classdb/AStar3D for a more thorough explanation on how to use this class. graphics.gd/classdb/AStar2D is a wrapper for graphics.gd/classdb/AStar3D that enforces 2D coordinates.

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

This section is empty.

Types

type Advanced 

type Advanced = class

Advanced exposes a 1:1 low-level instance of the class, undocumented, for those who know what they are doing.

type Any 

type Any interface {
	gd.IsClass
	AsAStar2D() Instance
}

type Expanded 

type Expanded [1]gdclass.AStar2D

func (Expanded) AddPoint 

func (self Expanded) AddPoint(id Point, position Vector2.XY, weight_scale Float.X)

Adds a new point at the given position with the given identifier. The 'id' must be 0 or larger, and the 'weight_scale' must be 0.0 or greater.

The 'weight_scale' is multiplied by the result of [Interface.ComputeCost] when determining the overall cost of traveling across a segment from a neighboring point to this point. Thus, all else being equal, the algorithm prefers points with lower 'weight_scale's to form a path. 

var astar = AStar2D.New()
AStar2D.Expanded(astar).AddPoint(1, Vector2.New(1, 0), 4) // Adds the point (1, 0) with weight_scale 4 and id 1

If there already exists a point for the given 'id', its position and weight scale are updated to the given values.

func (Expanded) ArePointsConnected 

func (self Expanded) ArePointsConnected(id Point, to_id Point, bidirectional bool) bool

Returns whether there is a connection/segment between the given points. If 'bidirectional' is false, returns whether movement from 'id' to 'to_id' is possible through this segment.

func (Expanded) ConnectPoints 

func (self Expanded) ConnectPoints(id Point, to_id Point, bidirectional bool)

Creates a segment between the given points. If 'bidirectional' is false, only movement from 'id' to 'to_id' is allowed, not the reverse direction. 

var astar = AStar2D.New()
astar.AddPoint(1, Vector2.New(1, 1))
astar.AddPoint(2, Vector2.New(0, 5))
AStar2D.Expanded(astar).ConnectPoints(1, 2, false)

func (Expanded) DisconnectPoints 

func (self Expanded) DisconnectPoints(id Point, to_id Point, bidirectional bool)

Deletes the segment between the given points. If 'bidirectional' is false, only movement from 'id' to 'to_id' is prevented, and a unidirectional segment possibly remains.

func (Expanded) GetClosestPoint 

func (self Expanded) GetClosestPoint(to_position Vector2.XY, include_disabled bool) int

Returns the ID of the closest point to 'to_position', optionally taking disabled points into account. Returns -1 if there are no points in the points pool.

Note: If several points are the closest to 'to_position', the one with the smallest ID will be returned, ensuring a deterministic result.

func (Expanded) GetIdPath 

func (self Expanded) GetIdPath(from_id Point, to_id Point, allow_partial_path bool) []Point

Returns an array with the IDs of the points that form the path found by AStar2D between the given points. The array is ordered from the starting point to the ending point of the path.

If there is no valid path to the target, and 'allow_partial_path' is true, returns a path to the point closest to the target that can be reached.

Note: When 'allow_partial_path' is true and 'to_id' is disabled the search may take an unusually long time to finish. 

var astar = AStar2D.New()
astar.AddPoint(1, Vector2.New(0, 0))
AStar2D.Expanded(astar).AddPoint(2, Vector2.New(0, 1), 1) // Default weight is 1
astar.AddPoint(3, Vector2.New(1, 1))
astar.AddPoint(4, Vector2.New(2, 0))

AStar2D.Expanded(astar).ConnectPoints(1, 2, false)
AStar2D.Expanded(astar).ConnectPoints(2, 3, false)
AStar2D.Expanded(astar).ConnectPoints(4, 3, false)
AStar2D.Expanded(astar).ConnectPoints(1, 4, false)

var res = astar.GetIdPath(1, 3) // Returns [1, 2, 3]

If you change the 2nd point's weight to 3, then the result will be [1, 4, 3] instead, because now even though the distance is longer, it's "easier" to get through point 4 than through point 2.

func (Expanded) GetPointPath 

func (self Expanded) GetPointPath(from_id Point, to_id Point, allow_partial_path bool) []Vector2.XY

Returns an array with the points that are in the path found by AStar2D between the given points. The array is ordered from the starting point to the ending point of the path.

If there is no valid path to the target, and 'allow_partial_path' is true, returns a path to the point closest to the target that can be reached.

Note: This method is not thread-safe; it can only be used from a single graphics.gd/classdb/Thread at a given time. Consider using graphics.gd/classdb/Mutex to ensure exclusive access to one thread to avoid race conditions.

Additionally, when 'allow_partial_path' is true and 'to_id' is disabled the search may take an unusually long time to finish.

func (Expanded) SetPointDisabled 

func (self Expanded) SetPointDisabled(id Point, disabled bool)

Disables or enables the specified point for pathfinding. Useful for making a temporary obstacle.

type Extension 

type Extension[T gdclass.Interface] struct{ gdclass.Extension[T, Instance] }

Extension can be embedded in a new struct to create an extension of this class. T should be the type that is embedding this [Extension]See Interface for methods that can be overridden by T.

func (*Extension[T]) AsAStar2D 

func (self *Extension[T]) AsAStar2D() Instance

func (*Extension[T]) AsObject 

func (self *Extension[T]) AsObject() [1]gd.Object

func (*Extension[T]) AsRefCounted 

func (self *Extension[T]) AsRefCounted() [1]gd.RefCounted

type ID 

type ID Object.ID

ID is a typed object ID (reference) to an instance of this class, use it to store references to objects with unknown lifetimes, as an ID will not panic on use if the underlying object has been destroyed.

func (ID) Instance 

func (id ID) Instance() (Instance, bool)

type Implementation 

type Implementation = implementation

Implementation implements Interface with empty methods.

type Instance 

type Instance [1]gdclass.AStar2D

Instance of the class with convieniently typed arguments and results. 

var Nil Instance

Nil is a nil/null instance of the class. Equivalent to the zero value.

func New 

func New() Instance

func (Instance) AddPoint 

func (self Instance) AddPoint(id Point, position Vector2.XY)

Adds a new point at the given position with the given identifier. The 'id' must be 0 or larger, and the 'weight_scale' must be 0.0 or greater.

The 'weight_scale' is multiplied by the result of [Interface.ComputeCost] when determining the overall cost of traveling across a segment from a neighboring point to this point. Thus, all else being equal, the algorithm prefers points with lower 'weight_scale's to form a path. 

var astar = AStar2D.New()
AStar2D.Expanded(astar).AddPoint(1, Vector2.New(1, 0), 4) // Adds the point (1, 0) with weight_scale 4 and id 1

If there already exists a point for the given 'id', its position and weight scale are updated to the given values.

func (Instance) ArePointsConnected 

func (self Instance) ArePointsConnected(id Point, to_id Point) bool

Returns whether there is a connection/segment between the given points. If 'bidirectional' is false, returns whether movement from 'id' to 'to_id' is possible through this segment.

func (Instance) AsAStar2D 

func (self Instance) AsAStar2D() Instance

func (Instance) AsObject 

func (self Instance) AsObject() [1]gd.Object

func (Instance) AsRefCounted 

func (self Instance) AsRefCounted() [1]gd.RefCounted

func (Instance) Clear 

func (self Instance) Clear()

Clears all the points and segments.

func (Instance) ConnectPoints 

func (self Instance) ConnectPoints(id Point, to_id Point)

Creates a segment between the given points. If 'bidirectional' is false, only movement from 'id' to 'to_id' is allowed, not the reverse direction. 

var astar = AStar2D.New()
astar.AddPoint(1, Vector2.New(1, 1))
astar.AddPoint(2, Vector2.New(0, 5))
AStar2D.Expanded(astar).ConnectPoints(1, 2, false)

func (Instance) DisconnectPoints 

func (self Instance) DisconnectPoints(id Point, to_id Point)

Deletes the segment between the given points. If 'bidirectional' is false, only movement from 'id' to 'to_id' is prevented, and a unidirectional segment possibly remains.

func (Instance) GetAvailablePointId 

func (self Instance) GetAvailablePointId() int

Returns the next available point ID with no point associated to it.

func (Instance) GetClosestPoint 

func (self Instance) GetClosestPoint(to_position Vector2.XY) int

Returns the ID of the closest point to 'to_position', optionally taking disabled points into account. Returns -1 if there are no points in the points pool.

Note: If several points are the closest to 'to_position', the one with the smallest ID will be returned, ensuring a deterministic result.

func (Instance) GetClosestPositionInSegment 

func (self Instance) GetClosestPositionInSegment(to_position Vector2.XY) Vector2.XY

Returns the closest position to 'to_position' that resides inside a segment between two connected points. 

var astar = AStar2D.New()
astar.AddPoint(1, Vector2.New(0, 0))
astar.AddPoint(2, Vector2.New(0, 5))
astar.ConnectPoints(1, 2)
var res = astar.GetClosestPositionInSegment(Vector2.New(3, 3)) // Returns (0, 3)

The result is in the segment that goes from y = 0 to y = 5. It's the closest position in the segment to the given point.

func (Instance) GetIdPath 

func (self Instance) GetIdPath(from_id Point, to_id Point) []Point

Returns an array with the IDs of the points that form the path found by AStar2D between the given points. The array is ordered from the starting point to the ending point of the path.

If there is no valid path to the target, and 'allow_partial_path' is true, returns a path to the point closest to the target that can be reached.

Note: When 'allow_partial_path' is true and 'to_id' is disabled the search may take an unusually long time to finish. 

var astar = AStar2D.New()
astar.AddPoint(1, Vector2.New(0, 0))
AStar2D.Expanded(astar).AddPoint(2, Vector2.New(0, 1), 1) // Default weight is 1
astar.AddPoint(3, Vector2.New(1, 1))
astar.AddPoint(4, Vector2.New(2, 0))

AStar2D.Expanded(astar).ConnectPoints(1, 2, false)
AStar2D.Expanded(astar).ConnectPoints(2, 3, false)
AStar2D.Expanded(astar).ConnectPoints(4, 3, false)
AStar2D.Expanded(astar).ConnectPoints(1, 4, false)

var res = astar.GetIdPath(1, 3) // Returns [1, 2, 3]

If you change the 2nd point's weight to 3, then the result will be [1, 4, 3] instead, because now even though the distance is longer, it's "easier" to get through point 4 than through point 2.

func (Instance) GetPointCapacity 

func (self Instance) GetPointCapacity() int

Returns the capacity of the structure backing the points, useful in conjunction with Instance.ReserveSpace.

func (Instance) GetPointConnections 

func (self Instance) GetPointConnections(id Point) []Point

Returns an array with the IDs of the points that form the connection with the given point. 

var astar = AStar2D.New()
astar.AddPoint(1, Vector2.New(0, 0))
astar.AddPoint(2, Vector2.New(0, 1))
astar.AddPoint(3, Vector2.New(1, 1))
astar.AddPoint(4, Vector2.New(2, 0))

AStar2D.Expanded(astar).ConnectPoints(1, 2, true)
AStar2D.Expanded(astar).ConnectPoints(1, 3, true)

var neighbors = astar.GetPointConnections(1) // Returns [2, 3]

func (Instance) GetPointCount 

func (self Instance) GetPointCount() int

Returns the number of points currently in the points pool.

func (Instance) GetPointIds 

func (self Instance) GetPointIds() []Point

Returns an array of all point IDs.

func (Instance) GetPointPath 

func (self Instance) GetPointPath(from_id Point, to_id Point) []Vector2.XY

Returns an array with the points that are in the path found by AStar2D between the given points. The array is ordered from the starting point to the ending point of the path.

If there is no valid path to the target, and 'allow_partial_path' is true, returns a path to the point closest to the target that can be reached.

Note: This method is not thread-safe; it can only be used from a single graphics.gd/classdb/Thread at a given time. Consider using graphics.gd/classdb/Mutex to ensure exclusive access to one thread to avoid race conditions.

Additionally, when 'allow_partial_path' is true and 'to_id' is disabled the search may take an unusually long time to finish.

func (Instance) GetPointPosition 

func (self Instance) GetPointPosition(id Point) Vector2.XY

Returns the position of the point associated with the given 'id'.

func (Instance) GetPointWeightScale 

func (self Instance) GetPointWeightScale(id Point) Float.X

Returns the weight scale of the point associated with the given 'id'.

func (Instance) HasPoint 

func (self Instance) HasPoint(id Point) bool

Returns whether a point associated with the given 'id' exists.

func (Instance) ID 

func (self Instance) ID() ID

func (Instance) IsPointDisabled 

func (self Instance) IsPointDisabled(id Point) bool

Returns whether a point is disabled or not for pathfinding. By default, all points are enabled.

func (Instance) NeighborFilterEnabled 

func (self Instance) NeighborFilterEnabled() bool

func (Instance) RemovePoint 

func (self Instance) RemovePoint(id Point)

Removes the point associated with the given 'id' from the points pool.

func (Instance) ReserveSpace 

func (self Instance) ReserveSpace(num_nodes int)

Reserves space internally for 'num_nodes' points. Useful if you're adding a known large number of points at once, such as points on a grid.

func (Instance) SetNeighborFilterEnabled 

func (self Instance) SetNeighborFilterEnabled(value bool)

func (*Instance) SetObject 

func (self *Instance) SetObject(obj [1]gd.Object) bool

func (Instance) SetPointDisabled 

func (self Instance) SetPointDisabled(id Point)

Disables or enables the specified point for pathfinding. Useful for making a temporary obstacle.

func (Instance) SetPointPosition 

func (self Instance) SetPointPosition(id Point, position Vector2.XY)

Sets the 'position' for the point with the given 'id'.

func (Instance) SetPointWeightScale 

func (self Instance) SetPointWeightScale(id Point, weight_scale Float.X)

Sets the 'weight_scale' for the point with the given 'id'. The 'weight_scale' is multiplied by the result of [Interface.ComputeCost] when determining the overall cost of traveling across a segment from a neighboring point to this point.

func (Instance) Virtual 

func (self Instance) Virtual(name string) reflect.Value

type Interface 

type Interface interface {
	// Called when neighboring enters processing and if [Instance.NeighborFilterEnabled] is true. If true is returned the point will not be processed.
	//
	// Note that this function is hidden in the default [graphics.gd/classdb/AStar2D] class.
	FilterNeighbor(from_id Point, neighbor_id Point) bool
	// Called when estimating the cost between a point and the path's ending point.
	//
	// Note that this function is hidden in the default [graphics.gd/classdb/AStar2D] class.
	EstimateCost(from_id Point, end_id Point) Float.X
	// Called when computing the cost between two connected points.
	//
	// Note that this function is hidden in the default [graphics.gd/classdb/AStar2D] class.
	ComputeCost(from_id Point, to_id Point) Float.X
}

type Point 

type Point int64

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