Unity NavMesh (AI Navigation)

Give NPCs pathfinding in Unity 6: bake walkable surfaces and move agents around obstacles.
Targets Unity 6 (6000.0 LTS) with the AI Navigation package 2.x.

> Version trap (Unity 2022+/6): the old built-in Navigation window (Object/Bake tabs)
> is gone. Baking is now component-based via the AI Navigation package
> (com.unity.ai.navigation): add a NavMeshSurface to your level geometry and click
> Bake. The runtime NavMeshAgent/NavMesh API stays in built-in UnityEngine.AI.

When to use

• Use when an agent needs to walk/chase/patrol to a target, when baking a navigable surface,
  adding dynamic blockers (NavMeshObstacle), or checking whether a destination is reachable.
• Use when the project has the AI Navigation package, a NavMeshSurface component, or scripts
  using UnityEngine.AI.NavMeshAgent.

When not to use: the decision logic of when/where to move (FSMs, behaviour trees,
steering) → game-ai (this skill is the Unity movement/pathing mechanism). Force-driven or
kinematic movement that isn't pathfinding → unity-physics.

Core workflow

1. Install the AI Navigation package (Package Manager → com.unity.ai.navigation).
2. Bake a surface: select the static level geometry, Add Component → Navigation → NavMesh
   Surface, set the agent type/area settings, and click Bake. Re-bake whenever geometry,
   NavMeshModifiers, or agent settings change.
3. Add a NavMeshAgent to each moving NPC; its radius/height/speed must match the baked
   agent type, and it must spawn on the baked mesh.
4. Drive it from script with SetDestination(targetPos); the agent steers and avoids other
   agents automatically. Detect arrival with remainingDistance/pathPending.
5. Handle dynamic blockers with NavMeshObstacle (carving) so closed doors/crates block
   paths without a full re-bake.
6. Verify with the AI Navigation overlay (the baked mesh is drawn in the Scene view) and by
   watching agents path around obstacles to the goal; check NavMeshPath.status for
   unreachable targets.

Patterns

1. Chase/seek with a NavMeshAgent

using UnityEngine;
using UnityEngine.AI;

[RequireComponent(typeof(NavMeshAgent))]
public class Chaser : MonoBehaviour
{
    [SerializeField] private Transform target;
    private NavMeshAgent _agent;

    private void Awake() => _agent = GetComponent<NavMeshAgent>();

    private void Update()
    {
        if (target) _agent.SetDestination(target.position);   // re-path toward the target
    }

    // Arrived? pathPending guards the first frame before a path exists.
    private bool HasArrived() =>
        !_agent.pathPending && _agent.remainingDistance <= _agent.stoppingDistance;
}

2. Check reachability before committing

using UnityEngine.AI;

public bool CanReach(NavMeshAgent agent, Vector3 destination)
{
    var path = new NavMeshPath();
    agent.CalculatePath(destination, path);
    return path.status == NavMeshPathStatus.PathComplete;   // vs Partial / Invalid
}

3. Bake at runtime (for procedurally built or streamed levels)

using Unity.AI.Navigation;   // the package namespace (NavMeshSurface)

[SerializeField] private NavMeshSurface surface;

// After spawning level geometry, build the navmesh in code.
public void RebuildNav() => surface.BuildNavMesh();

4. Dynamic obstacle that carves the mesh

// Add a NavMeshObstacle (Carve = true) to a door/crate. While present it cuts a hole in the
// navmesh so agents route around it; remove/disable it to reopen the path — no re-bake needed.

Pitfalls

• Looking for the Navigation window — it no longer exists in Unity 6. Use the AI Navigation
  package's NavMeshSurface component + Bake.
• Agent doesn't move / warps to origin — it isn't on the baked mesh, or no surface was
  baked. Bake the surface and spawn the agent on it (NavMesh.SamplePosition to snap).
• Agent ignores new geometry — the navmesh is baked; runtime-spawned obstacles need a
  NavMeshObstacle (carving) or a surface.BuildNavMesh() re-bake.
• SetDestination every frame is wasteful — for a slow-moving target, re-path on a timer
  (e.g. every 0.2s) instead of each frame.
• Agent radius/height mismatch — if the NavMeshAgent's size differs from the baked agent
  type, it gets stuck in gaps or floats; keep them consistent.
• Agents jitter against each other — tune avoidancePriority and quality, or use an
  obstacle for truly static blockers rather than relying on agent avoidance.

References

• Primary docs: AI Navigation package manual
  (https://docs.unity3d.com/Packages/com.unity.ai.navigation@2.0/manual/index.html) and
  ScriptReference/AI.NavMeshAgent, ScriptReference/AI.NavMesh.

Related skills

• game-ai — engine-agnostic decision-making (FSM, behaviour trees, steering) that uses this.
• unity-csharp-scripting — the MonoBehaviour structure around the agent.
• tower-defense / fps-shooter — genres that compose pathfinding with gameplay.