Function GraphUtilities.GetContours

void GetContours (

GridGraph	grid	The grid to find the contours of
System.Action<Vector3[]>	callback	The callback will be called once for every contour that is found with the vertices of the contour. The contour always forms a cycle.
float	yMergeThreshold	Contours will be simplified if the y coordinates for adjacent vertices differ by no more than this value.
GridNodeBase[]	nodes=null	Only these nodes will be searched. If this parameter is null then all nodes in the grid graph will be searched.
System.Func<GraphNode,GraphNode, bool>	connectionFilter=null	Allows you to disable connections between nodes. If null, no additional filtering will be done. The filter must be symmetric, so that f(A,B) == f(B,A). A contour edge will be generated between two adjacent nodes if this function returns false for the pair.

)

Finds all contours of a collection of nodes in a grid graph.

var grid = AstarPath.active.data.gridGraph;

// Find all contours in the graph and draw them using debug lines
GraphUtilities.GetContours(grid, vertices => {
for (int i = 0; i < vertices.Length; i++) {
Debug.DrawLine(vertices[i], vertices[(i+1)%vertices.Length], Color.red, 4);
}
}, 0);
In the image below you can see the contour of a graph.

In the image below you can see the contour of just a part of a grid graph (when the nodes parameter is supplied)

Contour of a hexagon graph

List<Vector3> GetContours (

NavGraph

graph

)

Convenience method to get a list of all segments of the contours of a graph.

This method works for navmesh, recast, grid graphs and layered grid graphs. For other graph types it will return an empty list.

If you need more information about how the contours are connected you can take a look at the other variants of this method.

// Get the first graph
var navmesh = AstarPath.active.graphs[0];

// Get all contours of the graph (works for grid, navmesh and recast graphs)
var segments = GraphUtilities.GetContours(navmesh);

// Every 2 elements form a line segment. The first segment is (segments[0], segments[1]), the second one is (segments[2], segments[3]) etc.
// The line segments are oriented so that the navmesh is on the right side of the segments when seen from above.
for (int i = 0; i < segments.Count; i += 2) {
var start = segments[i];
var end = segments[i+1];
Debug.DrawLine(start, end, Color.red, 3);
}


void GetContours (

NavmeshBase	navmesh	The navmesh-like object to trace. This can be a recast or navmesh graph or it could be a single tile in one such graph.
System.Action<List<Int3>, bool>	results	Will be called once for each contour with the contour as a parameter as well as a boolean indicating if the contour is a cycle or a chain (see second image).

)

Traces the contour of a navmesh.

This image is just used to illustrate the difference between chains and cycles. That it shows a grid graph is not relevant.