minor rework of @keveleigh's fixes

Author: David Kline (ANALOG)

Assets/MixedRealityToolkit-SDK/Features/SpatialAwareness/System/Handlers/MixedRealitySpatialAwarenessMeshHandler.cs

@@ -17,19 +17,19 @@ public class MixedRealitySpatialAwarenessMeshHandler : MonoBehaviour, IMixedReal
         /// <inheritdoc />
         public void OnMeshAdded(MixedRealitySpatialAwarenessEventData eventData)
         {
-            eventData.GameObject.SetActive(true);
+            // Custom implementations can use this event to access the mesh data on arrival.
         }
 
         /// <inheritdoc />
         public void OnMeshUpdated(MixedRealitySpatialAwarenessEventData eventData)
         {
-            eventData.GameObject.SetActive(true);
+            // Custom implementations can use this event to access the mesh data on update.
         }
 
         /// <inheritdoc />
         public void OnMeshRemoved(MixedRealitySpatialAwarenessEventData eventData)
         {
-            eventData.GameObject.SetActive(false);
+            // Custom implementations can use this event to respond to mesh removal.
         }
     }
 }

Assets/MixedRealityToolkit/_Core/Devices/MixedReality/WindowsMixedRealitySpatialObserver.cs

@@ -454,23 +454,29 @@ private void SurfaceObserver_OnDataReady(SurfaceData cookedData, bool outputWrit
             }
 
             // Add / update the mesh to our collection
-            if (!meshObjects.ContainsKey(cookedData.id.handle))
-            {
-                meshObjects.Add(cookedData.id.handle, meshObject);
-                MixedRealityManager.SpatialAwarenessSystem.RaiseMeshAdded(cookedData.id.handle, meshObject.GameObject);
-            }
-            else
+            // todo: fix
+            bool sendUpdatedEvent = false;
+            if (meshObjects.ContainsKey(cookedData.id.handle))
             {
                 // Reclaim the old mesh object for future use.
                 ReclaimMeshObject(meshObjects[cookedData.id.handle]);
-                meshObjects[cookedData.id.handle] = meshObject;
+                meshObjects.Remove(cookedData.id.handle);
+
+                sendUpdatedEvent = true;
+            }
+            meshObjects.Add(cookedData.id.handle, meshObject);
+
+            if (sendUpdatedEvent)
+            {
                 MixedRealityManager.SpatialAwarenessSystem.RaiseMeshUpdated(cookedData.id.handle, meshObject.GameObject);
             }
+            else
+            {
+                MixedRealityManager.SpatialAwarenessSystem.RaiseMeshAdded(cookedData.id.handle, meshObject.GameObject);
+            }
         }
 #endif // UNITY_WSA
 
-        // todo: SetObserverOrigin
-
         #endregion IMixedRealitySpatialAwarenessObserver implementation
     }
 }