Delay the initial search for detected sources

to fix a race condition when running in the Editor

Author: keveleigh

Assets/HoloToolkit/Input/Scripts/Utilities/MotionControllerVisualizer.cs

@@ -74,14 +74,6 @@ protected override void Awake()
             base.Awake();
 
 #if UNITY_WSA && UNITY_2017_2_OR_NEWER
-            foreach (var sourceState in InteractionManager.GetCurrentReading())
-            {
-                if (sourceState.source.kind == InteractionSourceKind.Controller)
-                {
-                    StartTrackingController(sourceState.source);
-                }
-            }
-
             Application.onBeforeRender += Application_onBeforeRender;
 
             if (GLTFMaterial == null)
@@ -123,16 +115,29 @@ private void Application_onBeforeRender()
         {
             // NOTE: This work is being done here to present the most correct rendered location of the controller each frame.
             // Any app logic depending on the controller state should happen in Update() or using InteractionManager's events.
-            UpdateControllerState();
+            // We don't want to potentially start loading a new controller model in this call, since onBeforeRender shouldn't
+            // do much work for performance reasons.
+            UpdateControllerState(false);
         }
 
-        private void UpdateControllerState()
+        private void UpdateControllerState(bool createNewControllerIfNeeded = true)
         {
 #if UNITY_WSA && UNITY_2017_2_OR_NEWER
             foreach (var sourceState in InteractionManager.GetCurrentReading())
             {
+                if (sourceState.source.kind != InteractionSourceKind.Controller)
+                {
+                    continue;
+                }
+
+                string key = GenerateKey(sourceState.source);
+                if (createNewControllerIfNeeded && !controllerDictionary.ContainsKey(key) && !loadingControllers.Contains(key))
+                {
+                    StartTrackingController(sourceState.source);
+                }
+
                 MotionControllerInfo currentController;
-                if (sourceState.source.kind == InteractionSourceKind.Controller && controllerDictionary.TryGetValue(GenerateKey(sourceState.source), out currentController))
+                if (controllerDictionary.TryGetValue(key, out currentController))
                 {
                     if (AnimateControllerModel)
                     {
@@ -412,7 +417,7 @@ private void FinishControllerSetup(GameObject controllerModelGameObject, Interac
         {
             var parentGameObject = new GameObject
             {
-                name = handedness + "Controller"
+                name = dictionaryKey + "Controller"
             };
 
             parentGameObject.transform.parent = transform;