AStar

Inherits: Reference < Object

Category: Core

Brief Description

AStar class representation that uses vectors as edges.

Member Functions

void _compute_cost ( int from_id, int to_id ) virtual
void _estimate_cost ( int from_id, int to_id ) virtual
void add_point ( int id, Vector3 position, float weight_scale=1.0 )
bool are_points_connected ( int id, int to_id ) const
void clear ( )
void connect_points ( int id, int to_id, bool bidirectional=true )
void disconnect_points ( int id, int to_id )
int get_available_point_id ( ) const
int get_closest_point ( Vector3 to_position ) const
Vector3 get_closest_position_in_segment ( Vector3 to_position ) const
PoolIntArray get_id_path ( int from_id, int to_id )
PoolIntArray get_point_connections ( int arg0 )
PoolVector3Array get_point_path ( int from_id, int to_id )
Vector3 get_point_position ( int id ) const
float get_point_weight_scale ( int id ) const
Array get_points ( )
bool has_point ( int id ) const
void remove_point ( int id )
void set_point_position ( int id, Vector3 position )
void set_point_weight_scale ( int id, float weight_scale )

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

Member Function Description

  • void _compute_cost ( int from_id, int to_id ) virtual

Called when computing the cost between two connected points.

  • void _estimate_cost ( int from_id, int to_id ) virtual

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

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 as = AStar.new()

as.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.

var as = AStar.new()

as.add_point(1, Vector3(1,1,0))
as.add_point(2, Vector3(0,5,0))

as.connect_points(1, 2, false) # If bidirectional=false it's only possible to go from point 1 to point 2
                               # and not from point 2 to point 1.
  • 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 as = AStar.new()

as.add_point(1, Vector3(0,0,0))
as.add_point(2, Vector3(0,5,0))

as.connect_points(1, 2)

var res = as.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.

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 as = AStar.new()

as.add_point(1, Vector3(0,0,0))
as.add_point(2, Vector3(0,1,0), 1) # default weight is 1
as.add_point(3, Vector3(1,1,0))
as.add_point(4, Vector3(2,0,0))

as.connect_points(1, 2, false)
as.connect_points(2, 3, false)
as.connect_points(4, 3, false)
as.connect_points(1, 4, false)
as.connect_points(5, 4, false)

var res = as.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.

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

var as = AStar.new()

as.add_point(1, Vector3(0,0,0))
as.add_point(2, Vector3(0,1,0))
as.add_point(3, Vector3(1,1,0))
as.add_point(4, Vector3(2,0,0))

as.connect_points(1, 2, true)
as.connect_points(1, 3, true)

var neighbors = as.get_point_connections(1) # returns [2, 3]

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.

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.

Returns an array of all points.

Returns whether a point associated with the given id exists.

  • void remove_point ( int id )

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

  • 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.