Core/Transports: Delayed adding transport model to next tick after teleporting to fix race conditions happening when teleporting transport happens at the same time as destination map balances its dynamic LoS tree

src/server/game/Entities/GameObject/GameObject.cpp

@@ -143,7 +143,12 @@ void GameObject::AddToWorld()
         // The state can be changed after GameObject::Create but before GameObject::AddToWorld
         bool toggledState = GetGoType() == GAMEOBJECT_TYPE_CHEST ? getLootState() == GO_READY : (GetGoState() == GO_STATE_READY || IsTransport());
         if (m_model)
-            GetMap()->InsertGameObjectModel(*m_model);
+        {
+            if (Transport* trans = ToTransport())
+                trans->SetDelayedAddModelToMap();
+            else
+                GetMap()->InsertGameObjectModel(*m_model);
+        }
 
         EnableCollision(toggledState);
         WorldObject::AddToWorld();

src/server/game/Entities/Transport/Transport.cpp

@@ -35,7 +35,8 @@
 
 Transport::Transport() : GameObject(),
     _transportInfo(NULL), _isMoving(true), _pendingStop(false),
-    _triggeredArrivalEvent(false), _triggeredDepartureEvent(false), _passengerTeleportItr(_passengers.begin())
+    _triggeredArrivalEvent(false), _triggeredDepartureEvent(false),
+    _passengerTeleportItr(_passengers.begin()), _delayedAddModel(false)
 {
     m_updateFlag = UPDATEFLAG_TRANSPORT | UPDATEFLAG_LOWGUID | UPDATEFLAG_STATIONARY_POSITION | UPDATEFLAG_ROTATION;
 }
@@ -186,6 +187,14 @@ void Transport::Update(uint32 diff)
                 return; // Update more in new map thread
     }
 
+    // Add model to map after we are fully done with moving maps
+    if (_delayedAddModel)
+    {
+        _delayedAddModel = false;
+        if (m_model)
+            GetMap()->InsertGameObjectModel(*m_model);
+    }
+
     // Set position
     _positionChangeTimer.Update(diff);
     if (_positionChangeTimer.Passed())
@@ -625,7 +634,6 @@ bool Transport::TeleportTransport(uint32 newMapid, float x, float y, float z, fl
         }
 
         Relocate(x, y, z, o);
-        UpdateModelPosition();
         GetMap()->AddToMap<Transport>(this);
         return true;
     }

src/server/game/Entities/Transport/Transport.h

@@ -95,6 +95,8 @@ class Transport : public GameObject, public TransportBase
 
         void EnableMovement(bool enabled);
 
+        void SetDelayedAddModelToMap() { _delayedAddModel = true; }
+
         TransportTemplate const* GetTransportTemplate() const { return _transportInfo; }
 
     private:
@@ -123,6 +125,8 @@ class Transport : public GameObject, public TransportBase
         PassengerSet _passengers;
         PassengerSet::iterator _passengerTeleportItr;
         PassengerSet _staticPassengers;
+
+        bool _delayedAddModel;
 };
 
 #endif