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Inherits: :ref:`RefCounted<class_RefCounted>` < :ref:`Object<class_Object>`
An implementation of A* for finding the shortest path between two vertices on a connected graph in 3D space.
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A* (A star) is a computer algorithm used in pathfinding and graph traversal, the process of plotting short paths among vertices (points), passing through a given set of edges (segments). It enjoys widespread use due to its performance and accuracy. Godot's A* implementation uses points in 3D space and Euclidean distances by default.
You must add points manually with :ref:`add_point<class_AStar3D_method_add_point>` and create segments manually with :ref:`connect_points<class_AStar3D_method_connect_points>`. Once done, you can test if there is a path between two points with the :ref:`are_points_connected<class_AStar3D_method_are_points_connected>` function, get a path containing indices by :ref:`get_id_path<class_AStar3D_method_get_id_path>`, or one containing actual coordinates with :ref:`get_point_path<class_AStar3D_method_get_point_path>`.
It is also possible to use non-Euclidean distances. To do so, create a class that extends AStar3D and override methods :ref:`_compute_cost<class_AStar3D_method__compute_cost>` and :ref:`_estimate_cost<class_AStar3D_method__estimate_cost>`. Both take two indices and return a length, as is shown in the following example.
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.. code-tab:: gdscript
class MyAStar:
extends AStar3D
func _compute_cost(u, v):
return abs(u - v)
func _estimate_cost(u, v):
return min(0, abs(u - v) - 1)
.. code-tab:: csharp
public partial class MyAStar : AStar3D
{
public override float _ComputeCost(long fromId, long toId)
{
return Mathf.Abs((int)(fromId - toId));
}
public override float _EstimateCost(long fromId, long toId)
{
return Mathf.Min(0, Mathf.Abs((int)(fromId - toId)) - 1);
}
}
:ref:`_estimate_cost<class_AStar3D_method__estimate_cost>` should return a lower bound of the distance, i.e. _estimate_cost(u, v) <= _compute_cost(u, v). This serves as a hint to the algorithm because the custom _compute_cost might be computation-heavy. If this is not the case, make :ref:`_estimate_cost<class_AStar3D_method__estimate_cost>` return the same value as :ref:`_compute_cost<class_AStar3D_method__compute_cost>` to provide the algorithm with the most accurate information.
If the default :ref:`_estimate_cost<class_AStar3D_method__estimate_cost>` and :ref:`_compute_cost<class_AStar3D_method__compute_cost>` methods are used, or if the supplied :ref:`_estimate_cost<class_AStar3D_method__estimate_cost>` method returns a lower bound of the cost, then the paths returned by A* will be the lowest-cost paths. Here, the cost of a path equals the sum of the :ref:`_compute_cost<class_AStar3D_method__compute_cost>` results of all segments in the path multiplied by the weight_scales of the endpoints of the respective segments. If the default methods are used and the weight_scales of all points are set to 1.0, then this equals the sum of Euclidean distances of all segments in the path.
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:ref:`float<class_float>` _compute_cost ( :ref:`int<class_int>` from_id, :ref:`int<class_int>` to_id ) |virtual| |const|
Called when computing the cost between two connected points.
Note that this function is hidden in the default AStar3D class.
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:ref:`float<class_float>` _estimate_cost ( :ref:`int<class_int>` from_id, :ref:`int<class_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 AStar3D class.
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void add_point ( :ref:`int<class_int>` id, :ref:`Vector3<class_Vector3>` position, :ref:`float<class_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 :ref:`_compute_cost<class_AStar3D_method__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.
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.. code-tab:: gdscript
var astar = AStar3D.new()
astar.add_point(1, Vector3(1, 0, 0), 4) # Adds the point (1, 0, 0) with weight_scale 4 and id 1
.. code-tab:: csharp
var astar = new AStar3D();
astar.AddPoint(1, new 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.
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:ref:`bool<class_bool>` are_points_connected ( :ref:`int<class_int>` id, :ref:`int<class_int>` to_id, :ref:`bool<class_bool>` bidirectional=true ) |const|
Returns whether the two given points are directly connected by a segment. If bidirectional is false, returns whether movement from id to to_id is possible through this segment.
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void clear ( )
Clears all the points and segments.
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void connect_points ( :ref:`int<class_int>` id, :ref:`int<class_int>` to_id, :ref:`bool<class_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.
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.. code-tab:: gdscript
var astar = AStar3D.new()
astar.add_point(1, Vector3(1, 1, 0))
astar.add_point(2, Vector3(0, 5, 0))
astar.connect_points(1, 2, false)
.. code-tab:: csharp
var astar = new AStar3D();
astar.AddPoint(1, new Vector3(1, 1, 0));
astar.AddPoint(2, new Vector3(0, 5, 0));
astar.ConnectPoints(1, 2, false);
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void disconnect_points ( :ref:`int<class_int>` id, :ref:`int<class_int>` to_id, :ref:`bool<class_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.
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:ref:`int<class_int>` get_available_point_id ( ) |const|
Returns the next available point ID with no point associated to it.
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:ref:`int<class_int>` get_closest_point ( :ref:`Vector3<class_Vector3>` to_position, :ref:`bool<class_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.
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:ref:`Vector3<class_Vector3>` get_closest_position_in_segment ( :ref:`Vector3<class_Vector3>` to_position ) |const|
Returns the closest position to to_position that resides inside a segment between two connected points.
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.. code-tab:: gdscript
var astar = AStar3D.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)
.. code-tab:: csharp
var astar = new AStar3D();
astar.AddPoint(1, new Vector3(0, 0, 0));
astar.AddPoint(2, new Vector3(0, 5, 0));
astar.ConnectPoints(1, 2);
Vector3 res = astar.GetClosestPositionInSegment(new 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.
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:ref:`PackedInt64Array<class_PackedInt64Array>` get_id_path ( :ref:`int<class_int>` from_id, :ref:`int<class_int>` to_id )
Returns an array with the IDs of the points that form the path found by AStar3D between the given points. The array is ordered from the starting point to the ending point of the path.
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.. code-tab:: gdscript
var astar = AStar3D.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]
.. code-tab:: csharp
var astar = new AStar3D();
astar.AddPoint(1, new Vector3(0, 0, 0));
astar.AddPoint(2, new Vector3(0, 1, 0), 1); // Default weight is 1
astar.AddPoint(3, new Vector3(1, 1, 0));
astar.AddPoint(4, new Vector3(2, 0, 0));
astar.ConnectPoints(1, 2, false);
astar.ConnectPoints(2, 3, false);
astar.ConnectPoints(4, 3, false);
astar.ConnectPoints(1, 4, false);
int[] res = astar.GetIdPath(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.
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:ref:`int<class_int>` get_point_capacity ( ) |const|
Returns the capacity of the structure backing the points, useful in conjunction with reserve_space.
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:ref:`PackedInt64Array<class_PackedInt64Array>` get_point_connections ( :ref:`int<class_int>` id )
Returns an array with the IDs of the points that form the connection with the given point.
.. tabs::
.. code-tab:: gdscript
var astar = AStar3D.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]
.. code-tab:: csharp
var astar = new AStar3D();
astar.AddPoint(1, new Vector3(0, 0, 0));
astar.AddPoint(2, new Vector3(0, 1, 0));
astar.AddPoint(3, new Vector3(1, 1, 0));
astar.AddPoint(4, new Vector3(2, 0, 0));
astar.ConnectPoints(1, 2, true);
astar.ConnectPoints(1, 3, true);
int[] neighbors = astar.GetPointConnections(1); // Returns [2, 3]
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:ref:`int<class_int>` get_point_count ( ) |const|
Returns the number of points currently in the points pool.
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:ref:`PackedInt64Array<class_PackedInt64Array>` get_point_ids ( )
Returns an array of all point IDs.
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:ref:`PackedVector3Array<class_PackedVector3Array>` get_point_path ( :ref:`int<class_int>` from_id, :ref:`int<class_int>` to_id )
Returns an array with the points that are in the path found by AStar3D 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 :ref:`Thread<class_Thread>`, it will return an empty :ref:`PackedVector3Array<class_PackedVector3Array>` and will print an error message.
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:ref:`Vector3<class_Vector3>` get_point_position ( :ref:`int<class_int>` id ) |const|
Returns the position of the point associated with the given id.
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:ref:`float<class_float>` get_point_weight_scale ( :ref:`int<class_int>` id ) |const|
Returns the weight scale of the point associated with the given id.
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:ref:`bool<class_bool>` has_point ( :ref:`int<class_int>` id ) |const|
Returns whether a point associated with the given id exists.
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:ref:`bool<class_bool>` is_point_disabled ( :ref:`int<class_int>` id ) |const|
Returns whether a point is disabled or not for pathfinding. By default, all points are enabled.
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void remove_point ( :ref:`int<class_int>` id )
Removes the point associated with the given id from the points pool.
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void reserve_space ( :ref:`int<class_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.
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void set_point_disabled ( :ref:`int<class_int>` id, :ref:`bool<class_bool>` disabled=true )
Disables or enables the specified point for pathfinding. Useful for making a temporary obstacle.
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void set_point_position ( :ref:`int<class_int>` id, :ref:`Vector3<class_Vector3>` position )
Sets the position for the point with the given id.
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void set_point_weight_scale ( :ref:`int<class_int>` id, :ref:`float<class_float>` weight_scale )
Sets the weight_scale for the point with the given id. The weight_scale is multiplied by the result of :ref:`_compute_cost<class_AStar3D_method__compute_cost>` when determining the overall cost of traveling across a segment from a neighboring point to this point.