godot-docs/classes/class_astar2d.rst

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.. _class_AStar2D:

AStar2D
=======

**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 2D space.

.. rst-class:: classref-introduction-group

Description
-----------

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

See :ref:`AStar3D<class_AStar3D>` for a more thorough explanation on how to use this class. **AStar2D** is a wrapper for :ref:`AStar3D<class_AStar3D>` that enforces 2D coordinates.

.. rst-class:: classref-reftable-group

Methods
-------

.. table::
   :widths: auto

   +-----------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | :ref:`float<class_float>`                           | :ref:`_compute_cost<class_AStar2D_private_method__compute_cost>` **(** :ref:`int<class_int>` from_id, :ref:`int<class_int>` to_id **)** |virtual| |const|                                    |
   +-----------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | :ref:`float<class_float>`                           | :ref:`_estimate_cost<class_AStar2D_private_method__estimate_cost>` **(** :ref:`int<class_int>` from_id, :ref:`int<class_int>` to_id **)** |virtual| |const|                                  |
   +-----------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | void                                                | :ref:`add_point<class_AStar2D_method_add_point>` **(** :ref:`int<class_int>` id, :ref:`Vector2<class_Vector2>` position, :ref:`float<class_float>` weight_scale=1.0 **)**                    |
   +-----------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | :ref:`bool<class_bool>`                             | :ref:`are_points_connected<class_AStar2D_method_are_points_connected>` **(** :ref:`int<class_int>` id, :ref:`int<class_int>` to_id, :ref:`bool<class_bool>` bidirectional=true **)** |const| |
   +-----------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | void                                                | :ref:`clear<class_AStar2D_method_clear>` **(** **)**                                                                                                                                         |
   +-----------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | void                                                | :ref:`connect_points<class_AStar2D_method_connect_points>` **(** :ref:`int<class_int>` id, :ref:`int<class_int>` to_id, :ref:`bool<class_bool>` bidirectional=true **)**                     |
   +-----------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | void                                                | :ref:`disconnect_points<class_AStar2D_method_disconnect_points>` **(** :ref:`int<class_int>` id, :ref:`int<class_int>` to_id, :ref:`bool<class_bool>` bidirectional=true **)**               |
   +-----------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | :ref:`int<class_int>`                               | :ref:`get_available_point_id<class_AStar2D_method_get_available_point_id>` **(** **)** |const|                                                                                               |
   +-----------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | :ref:`int<class_int>`                               | :ref:`get_closest_point<class_AStar2D_method_get_closest_point>` **(** :ref:`Vector2<class_Vector2>` to_position, :ref:`bool<class_bool>` include_disabled=false **)** |const|               |
   +-----------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | :ref:`Vector2<class_Vector2>`                       | :ref:`get_closest_position_in_segment<class_AStar2D_method_get_closest_position_in_segment>` **(** :ref:`Vector2<class_Vector2>` to_position **)** |const|                                   |
   +-----------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | :ref:`PackedInt64Array<class_PackedInt64Array>`     | :ref:`get_id_path<class_AStar2D_method_get_id_path>` **(** :ref:`int<class_int>` from_id, :ref:`int<class_int>` to_id **)**                                                                  |
   +-----------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | :ref:`int<class_int>`                               | :ref:`get_point_capacity<class_AStar2D_method_get_point_capacity>` **(** **)** |const|                                                                                                       |
   +-----------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | :ref:`PackedInt64Array<class_PackedInt64Array>`     | :ref:`get_point_connections<class_AStar2D_method_get_point_connections>` **(** :ref:`int<class_int>` id **)**                                                                                |
   +-----------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | :ref:`int<class_int>`                               | :ref:`get_point_count<class_AStar2D_method_get_point_count>` **(** **)** |const|                                                                                                             |
   +-----------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | :ref:`PackedInt64Array<class_PackedInt64Array>`     | :ref:`get_point_ids<class_AStar2D_method_get_point_ids>` **(** **)**                                                                                                                         |
   +-----------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | :ref:`PackedVector2Array<class_PackedVector2Array>` | :ref:`get_point_path<class_AStar2D_method_get_point_path>` **(** :ref:`int<class_int>` from_id, :ref:`int<class_int>` to_id **)**                                                            |
   +-----------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | :ref:`Vector2<class_Vector2>`                       | :ref:`get_point_position<class_AStar2D_method_get_point_position>` **(** :ref:`int<class_int>` id **)** |const|                                                                              |
   +-----------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | :ref:`float<class_float>`                           | :ref:`get_point_weight_scale<class_AStar2D_method_get_point_weight_scale>` **(** :ref:`int<class_int>` id **)** |const|                                                                      |
   +-----------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | :ref:`bool<class_bool>`                             | :ref:`has_point<class_AStar2D_method_has_point>` **(** :ref:`int<class_int>` id **)** |const|                                                                                                |
   +-----------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | :ref:`bool<class_bool>`                             | :ref:`is_point_disabled<class_AStar2D_method_is_point_disabled>` **(** :ref:`int<class_int>` id **)** |const|                                                                                |
   +-----------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | void                                                | :ref:`remove_point<class_AStar2D_method_remove_point>` **(** :ref:`int<class_int>` id **)**                                                                                                  |
   +-----------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | void                                                | :ref:`reserve_space<class_AStar2D_method_reserve_space>` **(** :ref:`int<class_int>` num_nodes **)**                                                                                         |
   +-----------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | void                                                | :ref:`set_point_disabled<class_AStar2D_method_set_point_disabled>` **(** :ref:`int<class_int>` id, :ref:`bool<class_bool>` disabled=true **)**                                               |
   +-----------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | void                                                | :ref:`set_point_position<class_AStar2D_method_set_point_position>` **(** :ref:`int<class_int>` id, :ref:`Vector2<class_Vector2>` position **)**                                              |
   +-----------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   | void                                                | :ref:`set_point_weight_scale<class_AStar2D_method_set_point_weight_scale>` **(** :ref:`int<class_int>` id, :ref:`float<class_float>` weight_scale **)**                                      |
   +-----------------------------------------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

.. rst-class:: classref-section-separator

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.. rst-class:: classref-descriptions-group

Method Descriptions
-------------------

.. _class_AStar2D_private_method__compute_cost:

.. rst-class:: classref-method

: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 **AStar2D** class.

.. rst-class:: classref-item-separator

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.. _class_AStar2D_private_method__estimate_cost:

.. rst-class:: classref-method

: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 **AStar2D** class.

.. rst-class:: classref-item-separator

----

.. _class_AStar2D_method_add_point:

.. rst-class:: classref-method

void **add_point** **(** :ref:`int<class_int>` id, :ref:`Vector2<class_Vector2>` 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_AStar2D_private_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_scale``\ s to form a path.


.. tabs::

 .. code-tab:: gdscript

    var astar = AStar2D.new()
    astar.add_point(1, Vector2(1, 0), 4) # Adds the point (1, 0) with weight_scale 4 and id 1

 .. code-tab:: csharp

    var astar = new AStar2D();
    astar.AddPoint(1, new 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.

.. rst-class:: classref-item-separator

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.. _class_AStar2D_method_are_points_connected:

.. rst-class:: classref-method

: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 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.

.. rst-class:: classref-item-separator

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.. _class_AStar2D_method_clear:

.. rst-class:: classref-method

void **clear** **(** **)**

Clears all the points and segments.

.. rst-class:: classref-item-separator

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.. _class_AStar2D_method_connect_points:

.. rst-class:: classref-method

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.


.. tabs::

 .. code-tab:: gdscript

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

 .. code-tab:: csharp

    var astar = new AStar2D();
    astar.AddPoint(1, new Vector2(1, 1));
    astar.AddPoint(2, new Vector2(0, 5));
    astar.ConnectPoints(1, 2, false);



.. rst-class:: classref-item-separator

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.. _class_AStar2D_method_disconnect_points:

.. rst-class:: classref-method

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.

.. rst-class:: classref-item-separator

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.. _class_AStar2D_method_get_available_point_id:

.. rst-class:: classref-method

:ref:`int<class_int>` **get_available_point_id** **(** **)** |const|

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

.. rst-class:: classref-item-separator

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.. _class_AStar2D_method_get_closest_point:

.. rst-class:: classref-method

:ref:`int<class_int>` **get_closest_point** **(** :ref:`Vector2<class_Vector2>` 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.

.. rst-class:: classref-item-separator

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.. _class_AStar2D_method_get_closest_position_in_segment:

.. rst-class:: classref-method

:ref:`Vector2<class_Vector2>` **get_closest_position_in_segment** **(** :ref:`Vector2<class_Vector2>` to_position **)** |const|

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


.. tabs::

 .. code-tab:: gdscript

    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)

 .. code-tab:: csharp

    var astar = new AStar2D();
    astar.AddPoint(1, new Vector2(0, 0));
    astar.AddPoint(2, new Vector2(0, 5));
    astar.ConnectPoints(1, 2);
    Vector2 res = astar.GetClosestPositionInSegment(new 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.

.. rst-class:: classref-item-separator

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.. _class_AStar2D_method_get_id_path:

.. rst-class:: classref-method

: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 AStar2D between the given points. The array is ordered from the starting point to the ending point of the path.


.. tabs::

 .. code-tab:: gdscript

    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]

 .. code-tab:: csharp

    var astar = new AStar2D();
    astar.AddPoint(1, new Vector2(0, 0));
    astar.AddPoint(2, new Vector2(0, 1), 1); // Default weight is 1
    astar.AddPoint(3, new Vector2(1, 1));
    astar.AddPoint(4, new Vector2(2, 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.

.. rst-class:: classref-item-separator

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.. _class_AStar2D_method_get_point_capacity:

.. rst-class:: classref-method

:ref:`int<class_int>` **get_point_capacity** **(** **)** |const|

Returns the capacity of the structure backing the points, useful in conjunction with :ref:`reserve_space<class_AStar2D_method_reserve_space>`.

.. rst-class:: classref-item-separator

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.. _class_AStar2D_method_get_point_connections:

.. rst-class:: classref-method

: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 = 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]

 .. code-tab:: csharp

    var astar = new AStar2D();
    astar.AddPoint(1, new Vector2(0, 0));
    astar.AddPoint(2, new Vector2(0, 1));
    astar.AddPoint(3, new Vector2(1, 1));
    astar.AddPoint(4, new Vector2(2, 0));
    
    astar.ConnectPoints(1, 2, true);
    astar.ConnectPoints(1, 3, true);
    
    int[] neighbors = astar.GetPointConnections(1); // Returns [2, 3]



.. rst-class:: classref-item-separator

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.. _class_AStar2D_method_get_point_count:

.. rst-class:: classref-method

:ref:`int<class_int>` **get_point_count** **(** **)** |const|

Returns the number of points currently in the points pool.

.. rst-class:: classref-item-separator

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.. _class_AStar2D_method_get_point_ids:

.. rst-class:: classref-method

:ref:`PackedInt64Array<class_PackedInt64Array>` **get_point_ids** **(** **)**

Returns an array of all point IDs.

.. rst-class:: classref-item-separator

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.. _class_AStar2D_method_get_point_path:

.. rst-class:: classref-method

:ref:`PackedVector2Array<class_PackedVector2Array>` **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 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 :ref:`Thread<class_Thread>`, it will return an empty :ref:`PackedVector2Array<class_PackedVector2Array>` and will print an error message.

.. rst-class:: classref-item-separator

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.. _class_AStar2D_method_get_point_position:

.. rst-class:: classref-method

:ref:`Vector2<class_Vector2>` **get_point_position** **(** :ref:`int<class_int>` id **)** |const|

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

.. rst-class:: classref-item-separator

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.. _class_AStar2D_method_get_point_weight_scale:

.. rst-class:: classref-method

: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``.

.. rst-class:: classref-item-separator

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.. _class_AStar2D_method_has_point:

.. rst-class:: classref-method

:ref:`bool<class_bool>` **has_point** **(** :ref:`int<class_int>` id **)** |const|

Returns whether a point associated with the given ``id`` exists.

.. rst-class:: classref-item-separator

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.. _class_AStar2D_method_is_point_disabled:

.. rst-class:: classref-method

: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.

.. rst-class:: classref-item-separator

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.. _class_AStar2D_method_remove_point:

.. rst-class:: classref-method

void **remove_point** **(** :ref:`int<class_int>` id **)**

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

.. rst-class:: classref-item-separator

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.. _class_AStar2D_method_reserve_space:

.. rst-class:: classref-method

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.

.. rst-class:: classref-item-separator

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.. _class_AStar2D_method_set_point_disabled:

.. rst-class:: classref-method

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.

.. rst-class:: classref-item-separator

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.. _class_AStar2D_method_set_point_position:

.. rst-class:: classref-method

void **set_point_position** **(** :ref:`int<class_int>` id, :ref:`Vector2<class_Vector2>` position **)**

Sets the ``position`` for the point with the given ``id``.

.. rst-class:: classref-item-separator

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.. _class_AStar2D_method_set_point_weight_scale:

.. rst-class:: classref-method

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_AStar2D_private_method__compute_cost>` when determining the overall cost of traveling across a segment from a neighboring point to this point.

.. |virtual| replace:: :abbr:`virtual (This method should typically be overridden by the user to have any effect.)`
.. |const| replace:: :abbr:`const (This method has no side effects. It doesn't modify any of the instance's member variables.)`
.. |vararg| replace:: :abbr:`vararg (This method accepts any number of arguments after the ones described here.)`
.. |constructor| replace:: :abbr:`constructor (This method is used to construct a type.)`
.. |static| replace:: :abbr:`static (This method doesn't need an instance to be called, so it can be called directly using the class name.)`
.. |operator| replace:: :abbr:`operator (This method describes a valid operator to use with this type as left-hand operand.)`
.. |bitfield| replace:: :abbr:`BitField (This value is an integer composed as a bitmask of the following flags.)`