Merge pull request #7

Update ModuleCoPFollowTransform to use part prefabs better. Thanks @JonnyOThan

Author: SofieBrink

Source/Modules/ModuleCoPFollowTransform.cs

@@ -15,21 +15,43 @@ public class ModuleCoPFollowTransform : PartModule
         [KSPField]
         public string transformName;
 
+        [SerializeField]
         private Transform followTransform;
 
         public override void OnLoad(ConfigNode node)
         {
-            base.OnLoad(node);
-            if (HighLogic.LoadedScene != GameScenes.LOADING)
+            if (followTransform == null || followTransform.name != transformName)
             {
                 if (transformName != null) followTransform = part.FindModelTransform(transformName);
-                if (followTransform == null) Debug.LogError($"[{MODULENAME}] transformName was empty or does not exist.");
+                if (followTransform == null) Debug.LogError($"[{MODULENAME}] transformName '{transformName}' was empty or does not exist on part '{part.partInfo?.name}'");
             }
+
+            if (followTransform == null && part.partInfo != null)
+            {
+                // this may be important if someone is swapping out versions of this module with B9PS
+                // Note this probably isn't correct for parts that also have modules that mess with this field (e.g. ModuleProceduralFairing)
+                part.CoPOffset = part.partInfo.partPrefab.CoPOffset;
+            }
+
+            // NOTE: isEnabled will be persisted to the save file, but we want to treat it purely as runtime state
+            this.isEnabled = followTransform != null;
+            this.enabled = followTransform != null && HighLogic.LoadedSceneIsFlight;
         }
 
         public void FixedUpdate()
         {
-            if (followTransform != null) part.CoPOffset = part.transform.InverseTransformPoint(followTransform.position);
+            // Note that we shouldn't ever get here if the transform just didn't exist
+            // But it's certainly possible for *something* to delete it later
+            if (followTransform == null)
+            {
+                isEnabled = false;
+                enabled = false;
+                // should we reset CoPOffset here?   Not sure.
+            }
+            else    
+            {
+                part.CoPOffset = part.transform.InverseTransformPoint(followTransform.position);
+            }
         }
     }
 }