RecastGraph recenter

General Recast graph
#1

Hi, I have a question regarding recentering of RecastGraph by reusing the ProceduralGraphMover. I read the following in the documentation for the ‘TranslateInDirection’ method:

/// <summary>
/// Moves the recast graph by a number of tiles, discarding old tiles and scanning new ones.
///
/// Note: Only translation in a single direction is supported. dx == 0 || dz == 0 must hold.
/// If you need to move the graph diagonally, then you can call this function twice, once for each axis.
/// </summary>
public IGraphUpdatePromise TranslateInDirection (int dx, int dz) {
	return new RecastMovePromise(this, new Int2(dx, dz));
}

Let’s say I wanted to recenter/move the RecastGraph to the closest tile given a position. Either when an agent is spawned outside the graph bounds, or when the player is teleported to a new area outside the graph bounds.

Is polling a similar method as ‘ProceduralGraphMover.UpdateGraph’ still my best option here, or could I combine the graph shift done in ‘ProceduralGraphMover.UpdateRecastGraph’ somehow’?

void UpdateRecastGraph (RecastGraph graph, Int2 delta, bool async) {
	updatingGraph = true;
	List<(IGraphUpdatePromise, IEnumerator<JobHandle>)> promises = new List<(IGraphUpdatePromise, IEnumerator<JobHandle>)>();
	AstarPath.active.AddWorkItem(new AstarWorkItem(
		ctx => {
		var promise = graph.TranslateInDirection(delta.x, delta.y);
		promises.Add((promise, promise.Prepare()));
	},
		(ctx, force) => {
		if (GraphUpdateProcessor.ProcessGraphUpdatePromises(promises, ctx, force)) {
			updatingGraph = false;
			return true;
		}
		return false;
	}
		));
	if (!async) AstarPath.active.FlushWorkItems();
}
#2

Hi

I take it you want to move it along a non-zero dx and non-zero dz?
In that case, you can add two promises to the list, like in the UpdateRecastGraph method:

var promise1 = graph.TranslateInDirection(2, 0);
promises.Add((promise1, promise1.Prepare()));
var promise2 = graph.TranslateInDirection(0, 5);
promises.Add((promise2, promise2.Prepare()));
#3

Thank you! Apologies for the late reply. Is it possible to move the graph while retaining previously scanned tiles, but excluding the newly added ones from scanning? I assume this is done within the ‘ReplaceTile’ method during the Apply stage?

#4

Well, yes. That’s what the TranslateInDirection method does. It moves the graph, and recalculates only the tiles that need to be recalculated.
Or are you referring to something else?

#5

Well, I have a ‘GraphArea’ script which periodically requests graph translations when moved out of the graph bounds. It also performs GraphUpdates within its own bounds when necessary.

However when I perform graph translations, all of the newly added tiles will be scanned. I’m not sure if this is intended or if I am doing something wrong. In any case I’d like to avoid this and let all GraphUpdates/Scans to be handled by my ‘GraphArea’ script. Sorry if I’m not being clear.

RecastGraph with GraphArea

GraphArea
GraphArea890×890 616 KB

RecastGraph after running TranslateInDirection
Graph_TranslateInDirection
Graph_TranslateInDirection890×890 39.1 KB

#6

It sounds like you might want to use RecastGraph - A* Pathfinding Project instead

#7

Thank you for your time. The following code seems to work for my use case I’m not sure if the early return is necessary anymore though:

public void RecenterGraph()
{
    if (updatingGraph) return;

    updatingGraph = true;

    AstarPath.active.AddWorkItem(ctx =>
    {
        Int2 shiftDelta = CalculateTileShift(recenterTarget);
        IntRect newTileBounds = new(shiftDelta.x, shiftDelta.y, graph.tileXCount - 1 + shiftDelta.x, graph.tileZCount - 1 + shiftDelta.y);
        graph.Resize(newTileBounds);
        recenterScheduled = false;
        updatingGraph = false;
    });
}
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