Initializer

init(bufferRadius:minCoordinate:maxCoordinate:nodeClass:)

Initializes a graph to cover the specified area, using the specified node class.

Declaration

init(bufferRadius: Float, minCoordinate min: vector_float2, maxCoordinate max: vector_float2, nodeClass: AnyClass)

Parameters

bufferRadius

The distance from obstacle edges that should also be considered impassable.

min

The minimum coordinate of the space to be covered by the graph.

max

The maximum coordinate of the space to be covered by the graph.

nodeClass

The GKGraphNode2D subclass to use for nodes in the graph.

Return Value

A new mesh graph.

Discussion

A newly created graph contains no obstacles and no graph nodes. First, use the addObstacles(_:) method to add obstacles. Next, use the triangulate() method to fill the open space between obstacles with a web of graph nodes, allowing pathfinding operations to result in smooth paths around obstacles.

Use the bufferRadius parameter to take the size of potential travelers into account when determining navigability. For example, if a game character that will use pathfinding has a radius of 20 units (in the same coordinate space you use to define obstacles), specify a buffer radius of 20. As a result, the graph will consider any points within 20 units of an obstacle non-navigable—that is, pathfinding in the graph will not result in any positions that lie inside this buffer region, so you can safely set the character’s center point to the location of a node returned from the findPath(from:to:) method without the character overlapping any obstacles.

Use the nodeClass parameter to create a graph using a custom subclass of GKGraphNode2D. For example, your custom node class might override the cost(to:) method so that some nodes are more costly than others to travel through. Pathfinding in such a graph would favor indirect routes when a direct route has a higher cost.

See Also

Creating a Graph