AStar

Inherits: Reference < Object

Category: Core

Brief Description

AStar class representation that uses vectors as edges.

Methods

Description

A* (A star) is a computer algorithm that is widely used in pathfinding and graph traversal, the process of plotting an efficiently directed path between multiple points. It enjoys widespread use due to its performance and accuracy. Godot’s A* implementation make use of vectors as points.

You must add points manually with add_point and create segments manually with connect_points. So you can test if there is a path between two points with the are_points_connected function, get the list of existing ids in the found path with get_id_path, or the points list with get_point_path.

Method Descriptions

• float _compute_cost ( int from_id, int to_id ) virtual

Called when computing the cost between two connected points.

• float _estimate_cost ( int from_id, int to_id ) virtual

Called when estimating the cost between a point and the path’s ending point.

• void add_point ( int id, Vector3 position, float weight_scale=1.0 )

Adds a new point at the given position with the given identifier. The algorithm prefers points with lower weight_scale to form a path. The id must be 0 or larger, and the weight_scale must be 1 or larger.

var astar = AStar.new()
astar.add_point(1, Vector3(1, 0, 0), 4) # Adds the point (1, 0, 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.

• bool are_points_connected ( int id, int to_id ) const

Returns whether there is a connection/segment between the given points.

• void clear ( )

Clears all the points and segments.

• void connect_points ( int id, int to_id, bool bidirectional=true )

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 = AStar.new()
astar.add_point(1, Vector3(1, 1, 0))
astar.add_point(2, Vector3(0, 5, 0))
astar.connect_points(1, 2, false)

• void disconnect_points ( int id, int to_id )

Deletes the segment between the given points.

• int get_available_point_id ( ) const

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

• int get_closest_point ( Vector3 to_position ) const

Returns the id of the closest point to to_position. Returns -1 if there are no points in the points pool.

• Vector3 get_closest_position_in_segment ( Vector3 to_position ) const

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

var astar = AStar.new()
astar.add_point(1, Vector3(0, 0, 0))
astar.add_point(2, Vector3(0, 5, 0))
astar.connect_points(1, 2)
var res = astar.get_closest_position_in_segment(Vector3(3, 3, 0)) # Returns (0, 3, 0)

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.

• PoolIntArray get_id_path ( int from_id, int to_id )

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

var astar = AStar.new()
astar.add_point(1, Vector3(0, 0, 0))
astar.add_point(2, Vector3(0, 1, 0), 1) # Default weight is 1
astar.add_point(3, Vector3(1, 1, 0))
astar.add_point(4, Vector3(2, 0, 0))
astar.connect_points(1, 2, false)
astar.connect_points(2, 3, false)
astar.connect_points(4, 3, false)
astar.connect_points(1, 4, false)
var res = astar.get_id_path(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.

• PoolIntArray get_point_connections ( int id )

Returns an array with the ids of the points that form the connect with the given point.

var astar = AStar.new()
astar.add_point(1, Vector3(0, 0, 0))
astar.add_point(2, Vector3(0, 1, 0))
astar.add_point(3, Vector3(1, 1, 0))
astar.add_point(4, Vector3(2, 0, 0))
astar.connect_points(1, 2, true)
astar.connect_points(1, 3, true)
var neighbors = astar.get_point_connections(1) # Returns [2, 3]

• PoolVector3Array get_point_path ( int from_id, int to_id )

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

• Vector3 get_point_position ( int id ) const

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

• float get_point_weight_scale ( int id ) const

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

• Array get_points ( )

Returns an array of all points.

• bool has_point ( int id ) const

Returns whether a point associated with the given id exists.

• bool is_point_disabled ( int id ) const

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

• void remove_point ( int id )

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

• void set_point_disabled ( int id, bool disabled=true )

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

• void set_point_position ( int id, Vector3 position )

Sets the position for the point with the given id.

• void set_point_weight_scale ( int id, float weight_scale )

Sets the weight_scale for the point with the given id.