AStar¶
Category: Core
Brief Description¶
AStar class representation that uses vectors as edges.
Methods¶
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 add_point and create segments manually with connect_points. So you can test if there is a path between two points with the are_points_connected function, get the list of existing ids in the found path with get_id_path, or the points list with get_point_path.
Method Descriptions¶
Called when computing the cost between two connected points.
Called when estimating the cost between a point and the path’s ending point.
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 astar = AStar.new()
astar.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.
Returns whether there is a connection/segment between the given points.
- void clear ( )
Clears all the points and segments.
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 = AStar.new()
astar.add_point(1, Vector3(1, 1, 0))
astar.add_point(2, Vector3(0, 5, 0))
astar.connect_points(1, 2, false)
Deletes the segment between the given points.
- int get_available_point_id ( ) const
Returns the next available point id with no point associated to it.
Returns the id of the closest point to to_position
. Returns -1 if there are no points in the points pool.
Returns the closest position to to_position
that resides inside a segment between two connected points.
var astar = AStar.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)
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 get_id_path ( int from_id, 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 astar = AStar.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]
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 get_point_connections ( int id )
Returns an array with the ids of the points that form the connect with the given point.
var astar = AStar.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]
- PoolVector3Array get_point_path ( int from_id, 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.
Returns the position of the point associated with the given id.
Returns the weight scale of the point associated with the given id.
- Array get_points ( )
Returns an array of all points.
Returns whether a point associated with the given id exists.
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.
Disables or enables the specified point for pathfinding. Useful for making a temporary obstacle.
Sets the position for the point with the given id.
Sets the weight_scale
for the point with the given id.