Added obj parse queue as a workaround for obj parser mixing up meshes

Assets/_Functionalities/ObjImporter/Scripts/OBJParseQueue.cs

@@ -0,0 +1,88 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+
+namespace Netherlands3D.Twin.Layers
+{
+    public class OBJParseQueue : MonoBehaviour
+    {
+        public static OBJParseQueue Instance;
+
+        public static bool IsParsing = false; //todo: the obj parser currently mixes up meshes if multiple are parsed at once. As a quick fix, only parse one at a time.
+        public static Queue<ObjSpawner> ParseQueue = new();
+        public static Coroutine QueueCoroutine;
+
+        private void Awake()
+        {
+            if (Instance != null && Instance != this)
+            {
+                Destroy(gameObject);
+                return;
+            }
+
+            Instance = this;
+        }
+
+        public static void Enqueue(ObjSpawner spawner)
+        {
+            if (spawner == null) return;
+
+            ParseQueue.Enqueue(spawner);
+
+            // Start processing if not already active
+            if (!IsParsing)
+            {
+                Instance.StartCoroutine(Instance.ProcessQueue());
+            }
+        }
+
+        public static void Remove(ObjSpawner spawner)
+        {
+            if (ParseQueue.Contains(spawner))
+            {
+                // Rebuild the queue without the removed spawner
+                var tempQueue = new Queue<ObjSpawner>();
+                while (ParseQueue.Count > 0)
+                {
+                    var item = ParseQueue.Dequeue();
+                    if (item != spawner)
+                    {
+                        tempQueue.Enqueue(item);
+                    }
+                }
+
+                foreach (var item in tempQueue)
+                {
+                    ParseQueue.Enqueue(item);
+                }
+            }
+        }
+
+        private IEnumerator ProcessQueue()
+        {
+            IsParsing = true;
+
+            while (ParseQueue.Count > 0)
+            {
+                ObjSpawner currentSpawner = ParseQueue.Dequeue();
+
+                // Skip null or destroyed OBJSpawners
+                if (currentSpawner == null)
+                {
+                    continue;
+                }
+
+                currentSpawner.StartImport();
+
+                // Wait until the current spawner signals completion
+                while (!currentSpawner.IsImportComplete)
+                {
+                    yield return null;
+                }
+            }
+
+            IsParsing = false;
+        }
+    }
+}

Assets/_Functionalities/ObjImporter/Scripts/ObjSpawner.cs

@@ -28,6 +28,8 @@ public class ObjSpawner : MonoBehaviour, ILayerWithPropertyData
         public bool HasMtl => GetMtlPathFromPropertyData() != string.Empty;
         public UnityEvent<bool> MtlImportSuccess = new();
 
+        public bool IsImportComplete { get; private set; } = false;
+
         private void Awake()
         {
             gameObject.transform.position = ObjectPlacementUtility.GetSpawnPoint();
@@ -47,7 +49,17 @@ public void LoadProperties(List<LayerPropertyData> properties)
 
         private void Start()
         {
-            StartImport(); //called after loading properties or after setting the file path through the import adapter
+            if (!OBJParseQueue.Instance)
+            {
+                var queue = new GameObject("OBJParseQueue").AddComponent<OBJParseQueue>();
+            }
+
+            OBJParseQueue.Enqueue(this);
+        }
+
+        private void OnDestroy()
+        {
+            OBJParseQueue.Remove(this);
         }
 
         public void StartImport()
@@ -110,10 +122,11 @@ private void OnObjImported(GameObject returnedGameObject)
             }
 
             // In case the returned object is georeferenced, or this (parent) object has its transform set from a property, we will use either of those positionings, and need to retain the world position.
-            returnedGameObject.transform.SetParent(this.transform, isGeoReferenced || hasTransformProperty);
+            returnedGameObject.transform.SetParent(this.transform, isGeoReferenced );
             returnedGameObject.AddComponent<MeshCollider>();
 
             DisposeImporter();
+            IsImportComplete = true;
         }
 
         private void SetObjectPosition(GameObject returnedGameObject, bool hasTransformProperty)