AStar2D

Inherits: RefCounted < Object

An implementation of A* for finding the shortest path between two vertices on a connected graph in 2D space.

Description

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

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

Methods

float

_compute_cost ( int from_id, int to_id ) virtual const

float

_estimate_cost ( int from_id, int to_id ) virtual const

void

add_point ( int id, Vector2 position, float weight_scale=1.0 )

bool

are_points_connected ( int id, int to_id, bool bidirectional=true ) const

void

clear ( )

void

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

void

disconnect_points ( int id, int to_id, bool bidirectional=true )

int

get_available_point_id ( ) const

int

get_closest_point ( Vector2 to_position, bool include_disabled=false ) const

Vector2

get_closest_position_in_segment ( Vector2 to_position ) const

PackedInt64Array

get_id_path ( int from_id, int to_id )

int

get_point_capacity ( ) const

PackedInt64Array

get_point_connections ( int id )

int

get_point_count ( ) const

PackedInt64Array

get_point_ids ( )

PackedVector2Array

get_point_path ( int from_id, int to_id )

Vector2

get_point_position ( int id ) const

float

get_point_weight_scale ( int id ) const

bool

has_point ( int id ) const

bool

is_point_disabled ( int id ) const

void

remove_point ( int id )

void

reserve_space ( int num_nodes )

void

set_point_disabled ( int id, bool disabled=true )

void

set_point_position ( int id, Vector2 position )

void

set_point_weight_scale ( int id, float weight_scale )

Method Descriptions

float _compute_cost ( int from_id, int to_id ) virtual const

Called when computing the cost between two connected points.

Note that this function is hidden in the default AStar2D class.

float _estimate_cost ( int from_id, int to_id ) virtual const

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

Note that this function is hidden in the default AStar2D class.

void add_point ( int id, Vector2 position, float weight_scale=1.0 )

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 _compute_cost 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_scales to form a path.

var astar = AStar2D.new()
astar.add_point(1, Vector2(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.

bool are_points_connected ( int id, int to_id, bool bidirectional=true ) const

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.

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 = AStar2D.new()
astar.add_point(1, Vector2(1, 1))
astar.add_point(2, Vector2(0, 5))
astar.connect_points(1, 2, false)

void disconnect_points ( int id, int to_id, bool bidirectional=true )

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.

int get_available_point_id ( ) const

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

int get_closest_point ( Vector2 to_position, bool include_disabled=false ) const

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.

Vector2 get_closest_position_in_segment ( Vector2 to_position ) const

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

var astar = AStar2D.new()
astar.add_point(1, Vector2(0, 0))
astar.add_point(2, Vector2(0, 5))
astar.connect_points(1, 2)
var res = astar.get_closest_position_in_segment(Vector2(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.

PackedInt64Array get_id_path ( int from_id, int to_id )

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.

var astar = AStar2D.new()
astar.add_point(1, Vector2(0, 0))
astar.add_point(2, Vector2(0, 1), 1) # Default weight is 1
astar.add_point(3, Vector2(1, 1))
astar.add_point(4, Vector2(2, 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.

int get_point_capacity ( ) const

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

PackedInt64Array get_point_connections ( int id )

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

var astar = AStar2D.new()
astar.add_point(1, Vector2(0, 0))
astar.add_point(2, Vector2(0, 1))
astar.add_point(3, Vector2(1, 1))
astar.add_point(4, Vector2(2, 0))

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

var neighbors = astar.get_point_connections(1) # Returns [2, 3]

int get_point_count ( ) const

Returns the number of points currently in the points pool.

PackedInt64Array get_point_ids ( )

Returns an array of all point IDs.

PackedVector2Array get_point_path ( int from_id, int to_id )

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.

Note: This method is not thread-safe. If called from a Thread, it will return an empty PackedVector2Array and will print an error message.

Vector2 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.

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 reserve_space ( int num_nodes )

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. New capacity must be greater or equals to old capacity.

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, Vector2 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. The weight_scale is multiplied by the result of _compute_cost when determining the overall cost of traveling across a segment from a neighboring point to this point.