How to setup FleePath with FollowerEntity w/DestinationSetter?

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  • A* version: 5.3.8
  • Unity version: 2022.3.41

Hi there,

I am attempting to get a FleePath working for my NPCs and have the current code below.

fleePath = FleePath.Construct(npc.transform.position, npc.witnessedCrime.transform.position, 10000);

fleePath.aimStrength = 1;
fleePath.spread = 4000;

npc.SetCustomTarget(fleePath.endPoint);

The SetCustomTarget function just sets the position of an empty transform that is always assigned in the AIDestinationSetter component.

The example on the docs using the seeker component has a callback for path complete when doing SetPath(), but the FollowerEntity version doesn’t, so I don’t think I can use it this way.

Looking at the docs it seems the Path may not be calculated immediately, so I tried doing a similar thing in the callback (which looks to be when the path has finished calculating), but that only passes the Path class, and not the FleePath class, therefore I cannot read the “endPoint” location.

fleePath = FleePath.Construct(npc.transform.position, npc.witnessedCrime.transform.position, 10000, OnPathCalculated);

private void OnPathCalculated(Path path)
{
    if (path.error)
    {
        Debug.LogError("Flee path calculation failed: " + path.errorLog);
        return;
    }
//"endPoint" doesn't exist :(
    //npc.SetCustomTarget(path.endPoint);
}

For this version I also tried to cast the Path as a FleePath, but I don’t think the callback is ever being called.

What’s the best way to handle this? Ideally I wouldn’t want to keep enabling and disabling my AIDestinationSetter component and directly do FollowerEntity.SetPath()?

2

What behavior are you seeing exactly? I just tried this exact thing- FollowerEntity with a FleePath being set as their AIDestinationSetter destination with no issue.

    [Button]
    public void SetFleePath(GameObject fleeFrom){
        var fleePath = FleePath.Construct(transform.position, fleeFrom.transform.position, 10000);
        // follower.SetPath(fleePath);

        GameObject newObj = new GameObject();
        newObj.transform.position = fleePath.endPoint;

        GetComponent<AIDestinationSetter>().target = newObj.transform;
    }
1 Like
3

If you use ai.SetPath(myFleePath) you’ll need to disable the AIDestinationSetter, as otherwise it will try to override the FleePath immediately afterward.

But you can also do something similar to what @tealtxgr showed.

1 Like
4

For some reason my “endPoint” is always 0,0,0.

For optimisation reasons i’d prefer to keep the empty transform as the target, and just move it if possible.

5

Ok, so in the end I had to write my own code which I will share below. I never could figure out why the fleepath was always returning 0,0,0. I did look into it more, and fleePath.IsDone(); was never returning true. Not sure what I was doing wrong.

private Vector3 GetFleePosition(Vector3 startPosition, Vector3 avoidPosition, float fleeDistance)
{
    // Calculate the flee direction
    Vector3 fleeDir = (startPosition - avoidPosition).normalized;
    if (fleeDir == Vector3.zero)
    {
        // Fall back to a random direction if the input is invalid (e.g., overlapping positions)
        fleeDir = Random.insideUnitSphere.normalized;
    }

    // Target position in the opposite direction
    Vector3 rawFleePosition = startPosition + fleeDir * fleeDistance;

    // Use the A* Pathfinding Project to find nearest valid position on navmesh
    NNConstraint nnConstraint = NNConstraint.Walkable;
    GraphNode node = AstarPath.active.GetNearest(rawFleePosition, nnConstraint).node;

    // If valid node found, return its closest point
    if (node != null && node.Walkable)
    {
        return (Vector3)node.position;
    }

    // If no valid flee node is found, fallback to original start position
    return startPosition;
}