Class AStar2D
An implementation of A* for finding the shortest path between two vertices on a connected graph in 2D space.
- Inheritance
-
AStar2D
Remarks
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
_compute_cost(int, int)
Qualifiers: virtualconst
Called when computing the cost between two connected points.
Note that this function is hidden in the default AStar2D class.
float _compute_cost(int from_id, int to_id)Parameters
_estimate_cost(int, int)
Qualifiers: virtualconst
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.
float _estimate_cost(int from_id, int end_id)Parameters
add_point(int, Vector2, float)
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 AStar2D._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.
void add_point(int id, Vector2 position, float weight_scale)Parameters
are_points_connected(int, int, bool)
Qualifiers: 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.
bool are_points_connected(int id, int to_id, bool bidirectional)Parameters
clear
Clears all the points and segments.
void clearconnect_points(int, int, 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.
void connect_points(int id, int to_id, bool bidirectional)Parameters
disconnect_points(int, int, 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.
void disconnect_points(int id, int to_id, bool bidirectional)Parameters
get_available_point_id
Qualifiers: const
Returns the next available point ID with no point associated to it.
int get_available_point_idget_closest_point(Vector2, bool)
Qualifiers: 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.
int get_closest_point(Vector2 to_position, bool include_disabled)Parameters
get_closest_position_in_segment(Vector2)
Qualifiers: 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.
Vector2 get_closest_position_in_segment(Vector2 to_position)Parameters
to_positionVector2
get_id_path(int, int, bool)
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.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.
PackedInt64Array get_id_path(int from_id, int to_id, bool allow_partial_path)Parameters
get_point_capacity
Qualifiers: const
Returns the capacity of the structure backing the points, useful in conjunction with AStar2D.reserve_space.
int get_point_capacityget_point_connections(int)
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]
PackedInt64Array get_point_connections(int id)Parameters
idint
get_point_count
Qualifiers: const
Returns the number of points currently in the points pool.
int get_point_countget_point_ids
Returns an array of all point IDs.
PackedInt64Array get_point_idsget_point_path(int, int, bool)
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. If called from a Thread, it will return an empty array and will print an error message.
Additionally, when allow_partial_path is true and to_id is disabled the search may take an unusually long time to finish.
PackedVector2Array get_point_path(int from_id, int to_id, bool allow_partial_path)Parameters
get_point_position(int)
Qualifiers: const
Returns the position of the point associated with the given id.
Vector2 get_point_position(int id)Parameters
idint
get_point_weight_scale(int)
Qualifiers: const
Returns the weight scale of the point associated with the given id.
float get_point_weight_scale(int id)Parameters
idint
has_point(int)
Qualifiers: const
Returns whether a point associated with the given id exists.
bool has_point(int id)Parameters
idint
is_point_disabled(int)
Qualifiers: const
Returns whether a point is disabled or not for pathfinding. By default, all points are enabled.
bool is_point_disabled(int id)Parameters
idint
remove_point(int)
Removes the point associated with the given id from the points pool.
void remove_point(int id)Parameters
idint
reserve_space(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. The new capacity must be greater or equal to the old capacity.
void reserve_space(int num_nodes)Parameters
num_nodesint
set_point_disabled(int, bool)
Disables or enables the specified point for pathfinding. Useful for making a temporary obstacle.
void set_point_disabled(int id, bool disabled)Parameters
set_point_position(int, Vector2)
Sets the position for the point with the given id.
void set_point_position(int id, Vector2 position)Parameters
set_point_weight_scale(int, float)
Sets the weight_scale for the point with the given id. The weight_scale is multiplied by the result of AStar2D._compute_cost when determining the overall cost of traveling across a segment from a neighboring point to this point.
void set_point_weight_scale(int id, float weight_scale)