How to set maximum path length

General
1
  • A* version: [5.4.4]
  • Unity version: [6000.2.6f1]

Hi

I’m using AIPath (and AIDestinationSetter) to move my agents on a Recast Graph and I’m trying to find a way to set a maximum score/cost limit to the pathfinder.
In the example below, there is a viable path from the starting point (red square) to the target (blue square) but I don’t want my agents to find such paths when they exceed a certain distance.

ejemplo_pathfinder
ejemplo_pathfinder273×102 356 Bytes

Case A is what happens now, case B is what I want to happen: I want my agents to find the node closest to the target that doesn’t exceed the maximum cost.

I found a thread asking the same thing, “How to limit searched for path length” (can’t post the link) but it seems to be outdated

2

You can test with this a bit, maybe it helps;

using UnityEngine;
using Pathfinding;
using System.Collections.Generic;

public class LimitedRangePathfinder : MonoBehaviour
{
    [Header("Settings")]
    public Transform target;
    [Tooltip("Max walking distance in World Units")]
    public float maxDistance = 20f; 
    
    private IAstarAI ai;

    private void Awake()
    {
        ai = GetComponent<IAstarAI>(); 
    }

    private void Update()
    {
        if (Input.GetKeyDown(KeyCode.Space)) 
        {
            FindPathWithinLimit();
        }
    }

    public void FindPathWithinLimit()
    {
        // 1. Convert World Distance to Cost
        int maxCost = (int)(maxDistance * 1000f);

        // 2. Create the path manually
        ConstantPath cPath = ConstantPath.Construct(transform.position, maxCost, OnConstantPathComplete);
        
        // 3. IMPORTANT FIX: Send it directly to the A* System, NOT the Seeker component.
        // The Seeker component tries to automatically assign the result to the AIPath/FollowerEntity,
        // which crashes because they can't "follow" a flood-fill result.
        AstarPath.StartPath(cPath);
    }

    private void OnConstantPathComplete(Path p)
    {
        if (p.error) return;

        ConstantPath cPath = p as ConstantPath;
        List<GraphNode> reachableNodes = cPath.allNodes;

        GraphNode bestNode = null;
        float bestDistance = float.MaxValue;
        Vector3 targetPos = target.position;

        // 4. Find closest node to target in the reachable set
        foreach (GraphNode node in reachableNodes)
        {
            Vector3 nodePos = (Vector3)node.position;
            float distToTarget = Vector3.SqrMagnitude(nodePos - targetPos);

            if (distToTarget < bestDistance)
            {
                bestDistance = distToTarget;
                bestNode = node;
            }
        }

        if (bestNode != null)
        {
            // 5. Now we give the AI a valid destination
            // The AI will calculate a standard ABPath to this new, valid point.
            ai.destination = (Vector3)bestNode.position;
            ai.SearchPath(); 
            
            Debug.DrawLine(transform.position, (Vector3)bestNode.position, Color.green, 2f);
        }
    }
}
1 Like
3

That worked, thanks

1 Like