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Diffstat (limited to 'doc/classes/AStar.xml')
| -rw-r--r-- | doc/classes/AStar.xml | 89 |
1 files changed, 77 insertions, 12 deletions
diff --git a/doc/classes/AStar.xml b/doc/classes/AStar.xml index 2695e86f47..0cd7d3dc25 100644 --- a/doc/classes/AStar.xml +++ b/doc/classes/AStar.xml @@ -7,7 +7,8 @@ A* (A star) is a computer algorithm that is widely 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 three-dimensional space and Euclidean distances by default. You must add points manually with [method add_point] and create segments manually with [method connect_points]. Then you can test if there is a path between two points with the [method are_points_connected] function, get a path containing indices by [method get_id_path], or one containing actual coordinates with [method get_point_path]. It is also possible to use non-Euclidean distances. To do so, create a class that extends [code]AStar[/code] and override methods [method _compute_cost] and [method _estimate_cost]. Both take two indices and return a length, as is shown in the following example. - [codeblock] + [codeblocks] + [gdscript] class MyAStar: extends AStar @@ -16,7 +17,21 @@ func _estimate_cost(u, v): return min(0, abs(u - v) - 1) - [/codeblock] + [/gdscript] + [csharp] + public class MyAStar : AStar + { + public override float _ComputeCost(int u, int v) + { + return Mathf.Abs(u - v); + } + public override float _EstimateCost(int u, int v) + { + return Mathf.Min(0, Mathf.Abs(u - v) - 1); + } + } + [/csharp] + [/codeblocks] [method _estimate_cost] should return a lower bound of the distance, i.e. [code]_estimate_cost(u, v) <= _compute_cost(u, v)[/code]. This serves as a hint to the algorithm because the custom [code]_compute_cost[/code] might be computation-heavy. If this is not the case, make [method _estimate_cost] return the same value as [method _compute_cost] to provide the algorithm with the most accurate information. </description> <tutorials> @@ -57,10 +72,16 @@ </argument> <description> Adds a new point at the given position with the given identifier. The algorithm prefers points with lower [code]weight_scale[/code] to form a path. The [code]id[/code] must be 0 or larger, and the [code]weight_scale[/code] must be 1 or larger. - [codeblock] + [codeblocks] + [gdscript] 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 - [/codeblock] + [/gdscript] + [csharp] + var astar = new AStar(); + astar.AddPoint(1, new Vector3(1, 0, 0), 4); // Adds the point (1, 0, 0) with weight_scale 4 and id 1 + [/csharp] + [/codeblocks] If there already exists a point for the given [code]id[/code], its position and weight scale are updated to the given values. </description> </method> @@ -95,12 +116,20 @@ </argument> <description> Creates a segment between the given points. If [code]bidirectional[/code] is [code]false[/code], only movement from [code]id[/code] to [code]to_id[/code] is allowed, not the reverse direction. - [codeblock] + [codeblocks] + [gdscript] 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) - [/codeblock] + [/gdscript] + [csharp] + var astar = new AStar(); + astar.AddPoint(1, new Vector3(1, 1, 0)); + astar.AddPoint(2, new Vector3(0, 5, 0)); + astar.ConnectPoints(1, 2, false); + [/csharp] + [/codeblocks] </description> </method> <method name="disconnect_points"> @@ -142,13 +171,22 @@ </argument> <description> Returns the closest position to [code]to_position[/code] that resides inside a segment between two connected points. - [codeblock] + [codeblocks] + [gdscript] 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) - [/codeblock] + [/gdscript] + [csharp] + var astar = new AStar(); + 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) + [/csharp] + [/codeblocks] The result is in the segment that goes from [code]y = 0[/code] to [code]y = 5[/code]. It's the closest position in the segment to the given point. </description> </method> @@ -161,7 +199,8 @@ </argument> <description> 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. - [codeblock] + [codeblocks] + [gdscript] 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 @@ -174,7 +213,20 @@ astar.connect_points(1, 4, false) var res = astar.get_id_path(1, 3) # Returns [1, 2, 3] - [/codeblock] + [/gdscript] + [csharp] + var astar = new AStar(); + 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] + [/csharp] + [/codeblocks] If you change the 2nd point's weight to 3, then the result will be [code][1, 4, 3][/code] instead, because now even though the distance is longer, it's "easier" to get through point 4 than through point 2. </description> </method> @@ -192,7 +244,8 @@ </argument> <description> Returns an array with the IDs of the points that form the connection with the given point. - [codeblock] + [codeblocks] + [gdscript] var astar = AStar.new() astar.add_point(1, Vector3(0, 0, 0)) astar.add_point(2, Vector3(0, 1, 0)) @@ -203,7 +256,19 @@ astar.connect_points(1, 3, true) var neighbors = astar.get_point_connections(1) # Returns [2, 3] - [/codeblock] + [/gdscript] + [csharp] + var astar = new AStar(); + 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] + [/csharp] + [/codeblocks] </description> </method> <method name="get_point_count" qualifiers="const"> |