class_astar.rst

AStar

Inherits: Reference<class_reference> < Object<class_object>

Category: Core

Brief Description

AStar class representation that uses vectors as edges.

Member Functions

float<class_float>	_compute_cost<class_AStar__compute_cost> ( int<class_int> from_id, int<class_int> to_id ) virtual
float<class_float>	_estimate_cost<class_AStar__estimate_cost> ( int<class_int> from_id, int<class_int> to_id ) virtual
void	add_point<class_AStar_add_point> ( int<class_int> id, Vector3<class_vector3> position, float<class_float> weight_scale=1.0 )
bool<class_bool>	are_points_connected<class_AStar_are_points_connected> ( int<class_int> id, int<class_int> to_id ) const
void	clear<class_AStar_clear> ( )
void	connect_points<class_AStar_connect_points> ( int<class_int> id, int<class_int> to_id, bool<class_bool> bidirectional=true )
void	disconnect_points<class_AStar_disconnect_points> ( int<class_int> id, int<class_int> to_id )
int<class_int>	get_available_point_id<class_AStar_get_available_point_id> ( ) const
int<class_int>	get_closest_point<class_AStar_get_closest_point> ( Vector3<class_vector3> to_position ) const
Vector3<class_vector3>	get_closest_position_in_segment<class_AStar_get_closest_position_in_segment> ( Vector3<class_vector3> to_position ) const
PoolIntArray<class_poolintarray>	get_id_path<class_AStar_get_id_path> ( int<class_int> from_id, int<class_int> to_id )
PoolIntArray<class_poolintarray>	get_point_connections<class_AStar_get_point_connections> ( int<class_int> id )
PoolVector3Array<class_poolvector3array>	get_point_path<class_AStar_get_point_path> ( int<class_int> from_id, int<class_int> to_id )
Vector3<class_vector3>	get_point_position<class_AStar_get_point_position> ( int<class_int> id ) const
float<class_float>	get_point_weight_scale<class_AStar_get_point_weight_scale> ( int<class_int> id ) const
Array<class_array>	get_points<class_AStar_get_points> ( )
bool<class_bool>	has_point<class_AStar_has_point> ( int<class_int> id ) const
void	remove_point<class_AStar_remove_point> ( int<class_int> id )
void	set_point_position<class_AStar_set_point_position> ( int<class_int> id, Vector3<class_vector3> position )
void	set_point_weight_scale<class_AStar_set_point_weight_scale> ( int<class_int> id, float<class_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<class_AStar_add_point> and create segments manually with AStar.connect_points<class_AStar_connect_points>. So you can test if there is a path between two points with the AStar.are_points_connected<class_AStar_are_points_connected> function, get the list of existing ids in the found path with AStar.get_id_path<class_AStar_get_id_path>, or the points list with AStar.get_point_path<class_AStar_get_point_path>.

Member Function Description

• float<class_float> _compute_cost ( int<class_int> from_id, int<class_int> to_id ) virtual

Called when computing the cost between two connected points.

• float<class_float> _estimate_cost ( int<class_int> from_id, int<class_int> to_id ) virtual

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

• void add_point ( int<class_int> id, Vector3<class_vector3> position, float<class_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 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<class_bool> are_points_connected ( int<class_int> id, int<class_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<class_int> id, int<class_int> to_id, bool<class_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<class_int> id, int<class_int> to_id )

Deletes the segment between the given points.

• int<class_int> get_available_point_id ( ) const

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

• int<class_int> get_closest_point ( Vector3<class_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<class_vector3> get_closest_position_in_segment ( Vector3<class_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.

• PoolIntArray<class_poolintarray> get_id_path ( int<class_int> from_id, int<class_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 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.

• PoolIntArray<class_poolintarray> get_point_connections ( int<class_int> id )

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]

• PoolVector3Array<class_poolvector3array> get_point_path ( int<class_int> from_id, int<class_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<class_vector3> get_point_position ( int<class_int> id ) const

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

• float<class_float> get_point_weight_scale ( int<class_int> id ) const

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

• Array<class_array> get_points ( )

Returns an array of all points.

• bool<class_bool> has_point ( int<class_int> id ) const

Returns whether a point associated with the given id exists.

• void remove_point ( int<class_int> id )

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

• void set_point_position ( int<class_int> id, Vector3<class_vector3> position )

Sets the position for the point with the given id.

• void set_point_weight_scale ( int<class_int> id, float<class_float> weight_scale )

Sets the weight_scale for the point with the given id.