using System.Collections;
using System.Collections.Generic;
using Pathfinding;
using Pathfinding.ECS;
using UnityEngine;
using static AnimatorTags;
using static AnimatorParameters;
[ExecuteAlways]
public class LadderLink : MonoBehaviour, IOffMeshLinkHandler, IOffMeshLinkStateMachine
{
[Tooltip("The ladder mesh object (contains rotation, top & bottom points).")]
public GameObject ladderObj;
[Header("Setup State")]
[Tooltip("If true, this ladder is placeable by a unit. Pre-existing ladders should set this to false.")]
public bool canSetup = false;
public Transform top; // Top of the ladder
public Transform bottom; // Bottom of the ladder
NodeLink2 nodeLink;
[Header("OffMeshLink Points")]
[Tooltip("These points follow the top and bottom automatically.")]
public Transform bottomLink, topLink;
public readonly float offset = 0.4f; // Offset between unit and ladder
[HideInInspector] public Vector3 offsetDir;
float ladderLength;
private void Awake()
{
nodeLink = GetComponent<NodeLink2>();
nodeLink.end = topLink;
offsetDir = ladderObj.transform.forward;
offsetDir.y = 0;
offsetDir = -offsetDir.normalized;
SetLinkPositions();
ladderLength = (top.position - bottom.position).magnitude;
// Before the ladder is built: disable the visual and the link
if (Application.isPlaying && canSetup)
{
nodeLink.enabled = false;
ladderObj.SetActive(false);
}
}
private void OnEnable()
{
if (Application.isPlaying)
GetComponent<NodeLink2>().onTraverseOffMeshLink = this;
}
private void OnDisable()
{
if (Application.isPlaying)
GetComponent<NodeLink2>().onTraverseOffMeshLink = null;
}
#if UNITY_EDITOR
private void Update()
{
// In editor: keep link endpoints synced with the ladder transforms
if (!Application.isPlaying)
{
if (!bottomLink || !topLink || !bottom || !top || !ladderObj) return;
offsetDir = ladderObj.transform.forward;
offsetDir.y = 0;
offsetDir = -offsetDir.normalized;
SetLinkPositions();
}
}
#endif
/// <summary>
/// Called when a unit builds the ladder.
/// Smoothly moves the carried ladder into position and then enables the actual link.
/// </summary>
public void StartSmoothPlacement(GameObject carriedLadder, float duration)
{
if (!carriedLadder) return;
canSetup = false;
nodeLink.enabled = true; // Enable the link at start of placement
// NOTE: Timing issue can sometimes cause short delay/error
StartCoroutine(SmoothPlacementRoutine(carriedLadder, duration));
}
private IEnumerator SmoothPlacementRoutine(GameObject carriedLadder, float duration)
{
// Detach from parent and disable physics on the carried mesh
carriedLadder.transform.SetParent(null);
if (carriedLadder.TryGetComponent<Collider>(out var col))
col.enabled = false;
if (carriedLadder.TryGetComponent<Rigidbody>(out var rb))
rb.isKinematic = true;
// Smooth movement & rotation to the final target position
Vector3 startPos = carriedLadder.transform.position;
Quaternion startRot = carriedLadder.transform.rotation;
Vector3 endPos = bottom.position;
Quaternion endRot = ladderObj.transform.rotation;
duration = Mathf.Max(0.01f, duration);
float t = 0f;
while (t < 1f)
{
t += Time.deltaTime / duration;
float e = Mathf.Sqrt(1f - (1f - t) * (1f - t));
carriedLadder.transform.SetPositionAndRotation(
Vector3.Lerp(startPos, endPos, e),
Quaternion.Slerp(startRot, endRot, e)
);
yield return null;
}
// Activate real ladder mesh and destroy carried one
ladderObj.SetActive(true);
Managers.Resource.Destroy(carriedLadder);
}
void SetLinkPositions()
{
bottomLink.position = bottom.position + offset * offsetDir;
topLink.position = top.position - 1.5f * offset * offsetDir;
}
IOffMeshLinkStateMachine IOffMeshLinkHandler.GetOffMeshLinkStateMachine(AgentOffMeshLinkTraversalContext context)
{
Debug.Log("Started OffMeshLink traversal");
return this;
}
void IOffMeshLinkStateMachine.OnFinishTraversingOffMeshLink(AgentOffMeshLinkTraversalContext ctx)
{
if (ctx.gameObject.TryGetComponent<ILadderClimbable>(out var c))
UnitInitOnLinkEnd(c);
}
void IOffMeshLinkStateMachine.OnAbortTraversingOffMeshLink()
{
Debug.Log("Aborted OffMeshLink traversal");
}
IEnumerable IOffMeshLinkStateMachine.OnTraverseOffMeshLink(AgentOffMeshLinkTraversalContext ctx)
{
// If ladder is not active yet, do not allow traversal
if (!ladderObj || !ladderObj.activeInHierarchy)
{
ctx.Abort(false);
yield break;
}
if (!ctx.gameObject.TryGetComponent<UnitBase>(out var u) || u is not ILadderClimbable climbable)
{
ctx.Abort(false);
yield break;
}
// If not moving animation state -> abort
if (u.CurrentSMBInfo.tagHash != tagHashMove)
{
ctx.Abort(false);
yield break;
}
// Disable rotation/local avoidance/gravity for climbing
ctx.DisableRotationSmoothing();
ctx.DisableLocalAvoidance();
climbable.AI.enableGravity = false;
bool climbingUp = !ctx.link.isReverse;
Vector3 startPoint = (climbingUp ? bottom.position : top.position) + offsetDir * offset;
Vector3 endPoint = (climbingUp ? top.position : bottom.position) + offsetDir * offset;
// Move to link start
while (!ctx.MoveTowards(
ctx.link.relativeStart,
Quaternion.LookRotation(ctx.link.relativeStart - (Vector3)ctx.transform.Position, ctx.movementPlane.up),
gravity: true,
slowdown: true).reached)
{
if (u.CurrentSMBInfo.tagHash != tagHashMove) { AbortLink(ctx, climbable); yield break; }
yield return null;
}
climbable.SetIsClimbUpOrDown(climbingUp);
climbable.SetOnLadder(true);
int startHash = climbingUp ? SNHLadderUpStart : SNHLadderDownStart;
int endHash = climbingUp ? SNHLadderUpEnd : SNHLadderDownEnd;
// Wait for climbing animation to activate
while (u.CurrentSMBInfo.tagHash == tagHashMove) yield return null;
if (u.CurrentSMBInfo.tagHash != tagHashClimb) { AbortLink(ctx, climbable); yield break; }
while (u.CurrentSMBInfo.tagHash == tagHashClimb)
{
switch (u.CurrentSMBInfo.shortNameHash)
{
case var snh when snh == startHash:
SyncWithLadder(ctx, u.transform, startPoint, endPoint, true);
break;
case var snh when snh == endHash:
if (u.CurrentSMBInfo.normalizedTime > (climbingUp ? 0.35f : 0.5f))
{
RestoreRotation(ctx, u.transform, true);
MoveToward(ctx, ctx.link.relativeEnd);
}
else
{
SyncWithLadder(ctx, u.transform, startPoint, endPoint, false);
}
break;
default:
SyncWithLadder(ctx, u.transform, startPoint, endPoint, false);
float dist = Vector3.Distance(u.Position, endPoint);
bool nearEnd = climbingUp ? dist < 1.23f : dist < 0.4f;
if (nearEnd) climbable.SetOnLadder(false);
break;
}
yield return null;
}
while (u.CurrentSMBInfo.tagHash == tagHashClimb) yield return null;
if (u.CurrentSMBInfo.tagHash != tagHashMove) { AbortLink(ctx, climbable); yield break; }
while (!ctx.MoveTowards(
ctx.link.relativeEnd,
Quaternion.LookRotation(ctx.link.relativeEnd - endPoint, ctx.movementPlane.up),
gravity: false,
slowdown: true).reached)
{
if (u.CurrentSMBInfo.tagHash != tagHashMove && u.CurrentSMBInfo.tagHash != tagHashIdle)
{
FinishLink(ctx, climbable);
break;
}
yield return null;
}
Debug.Log("Finished OffMeshLink traversal");
}
void SyncWithLadder(AgentOffMeshLinkTraversalContext ctx, Transform tr, Vector3 start, Vector3 end, bool smooth)
{
float h = ((Vector3)ctx.transform.Position - start).magnitude;
float ratio = Mathf.Clamp01(h / ladderLength);
Vector3 p = Vector3.Lerp(start, end, ratio);
if (smooth)
{
Vector3 next = Vector3.MoveTowards(ctx.transform.Position, p, ctx.deltaTime * 3f);
ctx.transform.Position = new Vector3(next.x, tr.position.y, next.z);
}
else
{
ctx.transform.Position = new Vector3(p.x, tr.position.y, p.z);
}
Quaternion targetRot = ladderObj.transform.rotation;
tr.rotation = smooth
? Quaternion.Slerp(tr.rotation, targetRot, ctx.deltaTime * 13f)
: targetRot;
}
void MoveToward(AgentOffMeshLinkTraversalContext ctx, Vector3 targetPos)
{
ctx.transform.Position = Vector3.MoveTowards(ctx.transform.Position, targetPos, ctx.deltaTime * 2f);
}
void RestoreRotation(AgentOffMeshLinkTraversalContext ctx, Transform tr, bool smooth)
{
Quaternion look = Quaternion.LookRotation(-offsetDir);
tr.rotation = smooth
? Quaternion.Slerp(tr.rotation, look, ctx.deltaTime * 8f)
: look;
}
void FinishLink(AgentOffMeshLinkTraversalContext ctx, ILadderClimbable c)
{
Debug.Log("Finish Link");
UnitInitOnLinkEnd(c);
ctx.Teleport(ctx.link.relativeEnd);
}
void AbortLink(AgentOffMeshLinkTraversalContext ctx, ILadderClimbable c)
{
Debug.Log("Abort Link");
UnitInitOnLinkEnd(c);
ctx.Abort(false);
}
void UnitInitOnLinkEnd(ILadderClimbable c)
{
c.AI.enableGravity = true;
c.SetOnLadder(false);
}
}
This is my custom ladder off-mesh-link code.
And here is an example video:
OffMeshLink Issue example
You can see that after the ladder is placed, the agent pauses for a moment, right? At that moment, the following error occurs:
ArgumentOutOfRangeException: Specified argument was out of the range of valid values.
Parameter name: partIndex
Pathfinding.PathTracer.GetLinkInfo (System.Int32 partIndex) (at ./Packages/com.arongranberg.astar/Utilities/PathTracer.cs:1694)
Pathfinding.ECS.TraverseOffMeshLinkSystem.NextLinkToTraverse (Pathfinding.ECS.ManagedState state) (at ./Packages/com.arongranberg.astar/Core/ECS/Systems/TraverseOffMeshLinkSystem.cs:69)
Pathfinding.ECS.TraverseOffMeshLinkSystem.StartOffMeshLinkTraversal (Unity.Entities.SystemState& systemState, Unity.Entities.EntityCommandBuffer commandBuffer) (at ./Packages/com.arongranberg.astar/Core/ECS/Systems/TraverseOffMeshLinkSystem.cs:57)
Pathfinding.ECS.TraverseOffMeshLinkSystem.OnUpdate (Unity.Entities.SystemState& systemState) (at ./Packages/com.arongranberg.astar/Core/ECS/Systems/TraverseOffMeshLinkSystem.cs:42)
Pathfinding.ECS.TraverseOffMeshLinkSystem.__codegen__OnUpdate (System.IntPtr self, System.IntPtr state) (at <0cd40b5daa28465da9e65c4e14d13f5e>:0)
Unity.Entities.SystemBaseRegistry+<>c__DisplayClass9_0.b__0 (System.IntPtr system, System.IntPtr state) (at ./Library/PackageCache/com.unity.entities@e581b903be8e/Unity.Entities/SystemBaseRegistry.cs:249)
UnityEngine.Debug:LogException(Exception)
Unity.Debug:LogException(Exception) (at ./Library/PackageCache/com.unity.entities@e581b903be8e/Unity.Entities/Stubs/Unity/Debug.cs:17)
Unity.Entities.<>c__DisplayClass9_0:b__0(IntPtr, IntPtr) (at ./Library/PackageCache/com.unity.entities@e581b903be8e/Unity.Entities/SystemBaseRegistry.cs:253)
Unity.Entities.UnmanagedUpdate_00001677$BurstDirectCall:wrapper_native_indirect_0x45b35a5f0(IntPtr&, Void*)
Unity.Entities.UnmanagedUpdate_00001677$BurstDirectCall:Invoke(Void*)
Unity.Entities.WorldUnmanagedImpl:UnmanagedUpdate(Void*)
Unity.Entities.WorldUnmanagedImpl:UpdateSystem(SystemHandle) (at ./Library/PackageCache/com.unity.entities@e581b903be8e/Unity.Entities/WorldUnmanaged.cs:891)
Unity.Entities.ComponentSystemGroup:UpdateAllSystems() (at ./Library/PackageCache/com.unity.entities@e581b903be8e/Unity.Entities/ComponentSystemGroup.cs:717)
Unity.Entities.ComponentSystemGroup:OnUpdate() (at ./Library/PackageCache/com.unity.entities@e581b903be8e/Unity.Entities/ComponentSystemGroup.cs:687)
Pathfinding.ECS.AIMovementSystemGroup:OnUpdate() (at ./Packages/com.arongranberg.astar/Core/ECS/Systems/AIMovementSystemGroup.cs:211)
Unity.Entities.SystemBase:Update() (at ./Library/PackageCache/com.unity.entities@e581b903be8e/Unity.Entities/SystemBase.cs:418)
Unity.Entities.ComponentSystemGroup:UpdateAllSystems() (at ./Library/PackageCache/com.unity.entities@e581b903be8e/Unity.Entities/ComponentSystemGroup.cs:723)
Unity.Entities.ComponentSystemGroup:OnUpdate() (at ./Library/PackageCache/com.unity.entities@e581b903be8e/Unity.Entities/ComponentSystemGroup.cs:681)
Unity.Entities.SystemBase:Update() (at ./Library/PackageCache/com.unity.entities@e581b903be8e/Unity.Entities/SystemBase.cs:418)
Unity.Entities.DummyDelegateWrapper:TriggerUpdate() (at ./Library/PackageCache/com.unity.entities@e581b903be8e/Unity.Entities/ScriptBehaviourUpdateOrder.cs:523)
This doesn’t happen every time.
Sometimes it works correctly: after the ladder is placed, the agent immediately uses the link without any error.
By NodeLink.enabled I mean enabling or disabling the NodeLink2 component itself.
When the NodeLink2 component is disabled, the link is not connected.
When it is enabled, the link becomes connected/usable.
