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AStarGrid2D¶

Inherits: RefCounted < Object

An implementation of A* for finding the shortest path between two points on a partial 2D grid.

Description¶

AStarGrid2D is a variant of AStar2D that is specialized for partial 2D grids. It is simpler to use because it doesn't require you to manually create points and connect them together. This class also supports multiple types of heuristics, modes for diagonal movement, and a jumping mode to speed up calculations.

To use AStarGrid2D, you only need to set the region of the grid, optionally set the cell_size, and then call the update method:

var astar_grid = AStarGrid2D.new()
astar_grid.region = Rect2i(0, 0, 32, 32)
astar_grid.cell_size = Vector2(16, 16)
astar_grid.update()
print(astar_grid.get_id_path(Vector2i(0, 0), Vector2i(3, 4))) # prints (0, 0), (1, 1), (2, 2), (3, 3), (3, 4)
print(astar_grid.get_point_path(Vector2i(0, 0), Vector2i(3, 4))) # prints (0, 0), (16, 16), (32, 32), (48, 48), (48, 64)

AStarGrid2D astarGrid = new AStarGrid2D();
astarGrid.Region = new Rect2I(0, 0, 32, 32);
astarGrid.CellSize = new Vector2I(16, 16);
astarGrid.Update();
GD.Print(astarGrid.GetIdPath(Vector2I.Zero, new Vector2I(3, 4))); // prints (0, 0), (1, 1), (2, 2), (3, 3), (3, 4)
GD.Print(astarGrid.GetPointPath(Vector2I.Zero, new Vector2I(3, 4))); // prints (0, 0), (16, 16), (32, 32), (48, 48), (48, 64)

To remove a point from the pathfinding grid, it must be set as "solid" with set_point_solid.

Properties¶

Vector2	cell_size	`Vector2(1, 1)`
Heuristic	default_compute_heuristic	`0`
Heuristic	default_estimate_heuristic	`0`
DiagonalMode	diagonal_mode	`0`
bool	jumping_enabled	`false`
Vector2	offset	`Vector2(0, 0)`
Rect2i	region	`Rect2i(0, 0, 0, 0)`
Vector2i	size	`Vector2i(0, 0)`

Methods¶

float	_compute_cost ( Vector2i from_id, Vector2i to_id ) virtual const
float	_estimate_cost ( Vector2i from_id, Vector2i to_id ) virtual const
void	clear ( )
void	fill_solid_region ( Rect2i region, bool solid=true )
void	fill_weight_scale_region ( Rect2i region, float weight_scale )
Vector2i[]	get_id_path ( Vector2i from_id, Vector2i to_id )
PackedVector2Array	get_point_path ( Vector2i from_id, Vector2i to_id )
Vector2	get_point_position ( Vector2i id ) const
float	get_point_weight_scale ( Vector2i id ) const
bool	is_dirty ( ) const
bool	is_in_bounds ( int x, int y ) const
bool	is_in_boundsv ( Vector2i id ) const
bool	is_point_solid ( Vector2i id ) const
void	set_point_solid ( Vector2i id, bool solid=true )
void	set_point_weight_scale ( Vector2i id, float weight_scale )
void	update ( )

Enumerations¶

enum Heuristic:

Heuristic HEURISTIC_EUCLIDEAN = 0

The Euclidean heuristic to be used for the pathfinding using the following formula:

dx = abs(to_id.x - from_id.x)
dy = abs(to_id.y - from_id.y)
result = sqrt(dx * dx + dy * dy)

Note: This is also the internal heuristic used in AStar3D and AStar2D by default (with the inclusion of possible z-axis coordinate).

Heuristic HEURISTIC_MANHATTAN = 1

The Manhattan heuristic to be used for the pathfinding using the following formula:

dx = abs(to_id.x - from_id.x)
dy = abs(to_id.y - from_id.y)
result = dx + dy

Note: This heuristic is intended to be used with 4-side orthogonal movements, provided by setting the diagonal_mode to DIAGONAL_MODE_NEVER.

Heuristic HEURISTIC_OCTILE = 2

The Octile heuristic to be used for the pathfinding using the following formula:

dx = abs(to_id.x - from_id.x)
dy = abs(to_id.y - from_id.y)
f = sqrt(2) - 1
result = (dx < dy) ? f * dx + dy : f * dy + dx;

Heuristic HEURISTIC_CHEBYSHEV = 3

The Chebyshev heuristic to be used for the pathfinding using the following formula:

dx = abs(to_id.x - from_id.x)
dy = abs(to_id.y - from_id.y)
result = max(dx, dy)

Heuristic HEURISTIC_MAX = 4

Represents the size of the Heuristic enum.

enum DiagonalMode:

DiagonalMode DIAGONAL_MODE_ALWAYS = 0

The pathfinding algorithm will ignore solid neighbors around the target cell and allow passing using diagonals.

DiagonalMode DIAGONAL_MODE_NEVER = 1

The pathfinding algorithm will ignore all diagonals and the way will be always orthogonal.

DiagonalMode DIAGONAL_MODE_AT_LEAST_ONE_WALKABLE = 2

The pathfinding algorithm will avoid using diagonals if at least two obstacles have been placed around the neighboring cells of the specific path segment.

DiagonalMode DIAGONAL_MODE_ONLY_IF_NO_OBSTACLES = 3

The pathfinding algorithm will avoid using diagonals if any obstacle has been placed around the neighboring cells of the specific path segment.

DiagonalMode DIAGONAL_MODE_MAX = 4

Represents the size of the DiagonalMode enum.

Property Descriptions¶

Vector2 cell_size = Vector2(1, 1)

void set_cell_size ( Vector2 value )
Vector2 get_cell_size ( )

The size of the point cell which will be applied to calculate the resulting point position returned by get_point_path. If changed, update needs to be called before finding the next path.

Heuristic default_compute_heuristic = 0

void set_default_compute_heuristic ( Heuristic value )
Heuristic get_default_compute_heuristic ( )

The default Heuristic which will be used to calculate the cost between two points if _compute_cost was not overridden.

Heuristic default_estimate_heuristic = 0

void set_default_estimate_heuristic ( Heuristic value )
Heuristic get_default_estimate_heuristic ( )

The default Heuristic which will be used to calculate the cost between the point and the end point if _estimate_cost was not overridden.

DiagonalMode diagonal_mode = 0

void set_diagonal_mode ( DiagonalMode value )
DiagonalMode get_diagonal_mode ( )

A specific DiagonalMode mode which will force the path to avoid or accept the specified diagonals.

bool jumping_enabled = false

void set_jumping_enabled ( bool value )
bool is_jumping_enabled ( )

Enables or disables jumping to skip up the intermediate points and speeds up the searching algorithm.

Note: Currently, toggling it on disables the consideration of weight scaling in pathfinding.

Vector2 offset = Vector2(0, 0)

void set_offset ( Vector2 value )
Vector2 get_offset ( )

The offset of the grid which will be applied to calculate the resulting point position returned by get_point_path. If changed, update needs to be called before finding the next path.

Rect2i region = Rect2i(0, 0, 0, 0)

void set_region ( Rect2i value )
Rect2i get_region ( )

The region of grid cells available for pathfinding. If changed, update needs to be called before finding the next path.

Vector2i size = Vector2i(0, 0)

void set_size ( Vector2i value )
Vector2i get_size ( )

The size of the grid (number of cells of size cell_size on each axis). If changed, update needs to be called before finding the next path.

Deprecated. Use region instead.

Method Descriptions¶

float _compute_cost ( Vector2i from_id, Vector2i to_id ) virtual const

Called when computing the cost between two connected points.

Note that this function is hidden in the default AStarGrid2D class.

float _estimate_cost ( Vector2i from_id, Vector2i 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 AStarGrid2D class.

void clear ( )

Clears the grid and sets the region to Rect2i(0, 0, 0, 0).

void fill_solid_region ( Rect2i region, bool solid=true )

Fills the given region on the grid with the specified value for the solid flag.</