fix: NetworkTransform initial synchronization, parenting, smooth transitions between transform spaces, and UI updates (#3013)

* fix

This fixes a synchronization issue with owner authoritative instances when running in client-server mode and parenting. When the server sends a parent sync message back with the position of the client's owned object it is out of sync with the client's position by the time the message is received. This fix gives users the option to not synchronize the transform position of a NetworkObject when using an owner authoritative motion mode.

* fix

This fix provides users with the option to have child `NetworkTransform`(s) tick synchronized with their parent. When the parent has `TickSyncChildren` enabled, any child `NetworkTransform`(s) that the local client has authority over will force a synchronization of their transform state. When a client is not the authority of the parent but it is the authority of one or more children, then when the parent sends a state update it will force the child/children the client has authority over to send a state update. Children will still send state updates if the transform has a delta that exceeds an axis threshold and the parent has yet to send a synchronization, but if a parent sends a synchronization within the same tick period the child/children will still send another state update.

* wip

Better approach, but still flawed.
I think converting any remaining items in the interpolators when the transform space changes will yield consistent results.

* fix

Seamless transform space transitions when parenting.

* update

We no longer need to send lossy scale since we defer applying the initial synchronization data until the non-authority side has finished synchronizing.

* fix

Fixing some minor issues with nested `NetworkTransforms` (i.e. under the same `NetworkObject`) and adding additional comments.
Reverting back to just checking `InLocalSpace` (as opposed to the interpolator's) when applying a position on the non-authority side.

* test fix

Fixing some issues with `NestedNetworkTransformTests` assets to account for some past updates.
Fixing an issue with `NetworkTransformTests` where it needs to not just advance the tick (for updates) but needs to also advance to the next tick.

* fix

caught scenario where `NetworkObject.NetworkTransforms` could not be set properly.

* fix

This fixes a minor "blip" when transitioning from world to local space,

* test

disabling two tests that need to be reviewed by Kitty and/or re-written.

* fix

Updating all NetworkTransform instances that belong to a specific NetworkObject as opposed to just the root.
Also not updating when not spawned or disabled NetworkTransforms.

* test

Making test asset adjustments for recent updates in NetworkTransform.

* update

Adding change log entry.

* update

mid-point check-in

* test

Updating interpolation test to recent NetworkTransform updates.

* update

wip towards getting a cleaner divide between the two modes.

* update

Some adjustments to when nested children check their own state updates or exit early.

* update

Cleaning up some Rigidbody references and making Rigidbody & Rigidbody2D accessible via NetworkRigidbody and NetworkRigidbody2D.

* update

Adding an internal InternalOnNetworkObjectParentChanged method that gets invoked ahead of OnNetworkObjectParentChanged so user code can't override any NGO components that need this kind of notification.

* update

Adding InternalOnNetworkSessionSynchronized to be invoked by NGO components to assure they don't get overridden by user script.

* update

Renaming some internal properties that are common names and would conflict with serialization if a user defined them in a derived class.

Making sure both the position and rotation interpolators are configured for the transform space when reset.

Adding the ability to change the parent locally when running with a client-server network topology.
Adding SwitchTransformSpaceWhenParented property to the NetworkTransformEditor.
Shifting all of the non-authority's final synchronization logic to occur either once a client's initial connection synchronization is complete or when all of the NetworkObject's components have run through the spawn process.

* update

Adding some improved and needed UI updates to NetworkBehaviour derived components and NetworkManager.
This includes a new NetcodeEditorBase class that allows users to more easily create customized, multi-generation, components that have their properties organized based on the generation of each child.

* fix

Wrapping the NetworkRigidbodyBaseEditor within physics defines.

* style

>.<

(sigh) null checks can be simplified style/standards update.

* update

switching from TT as a class to TT as a MonoBehaviour.

* fix

This fixes an issue where a server instance parenting with AllowOwnerToParent set would send to itself.
Adding check within the NetworkObject parenting logic to pass through to the server portion of sending the parenting message.

* test

adding some validation tests for the updates made in #3013

* update

adding changelog entries

* fix

This fixes the two failing tests within NetworkTransformAnticipationTest and updates AnticipatedNetworkTransform to account for #3013's updates/changes.

* fix

Removing the added base.OnInspectorGUI() call (was causing duplicated properties)

* update

Assure the callouts and call-to-action buttons show up outside of the Foldout Group when extending NetworkManager.
Assure that the NetworkManager has no Foldout Group when it is not extended.

Author: NoelStephensUnity

com.unity.netcode.gameobjects/CHANGELOG.md

@@ -11,14 +11,26 @@ Additional documentation and release notes are available at [Multiplayer Documen
 ### Added
 
 - Added "Check for NetworkObject Component" property to the Multiplayer->Netcode for GameObjects project settings. When disabled, this will bypass the in-editor `NetworkObject` check on `NetworkBehaviour` components. (#3031)
+- Added `NetworkTransform.SwitchTransformSpaceWhenParented` property that, when enabled, will handle the world to local, local to world, and local to local transform space transitions when interpolation is enabled. (#3013)
+- Added `NetworkTransform.TickSyncChildren` that, when enabled, will tick synchronize nested and/or child `NetworkTransform` components to eliminate any potential visual jittering that could occur if the `NetworkTransform` instances get into a state where their state updates are landing on different network ticks. (#3013)
+- Added `NetworkObject.AllowOwnerToParent` property to provide the ability to allow clients to parent owned objects when running in a client-server network topology. (#3013)
+- Added `NetworkObject.SyncOwnerTransformWhenParented` property to provide a way to disable applying the server's transform information in the parenting message on the client owner instance which can be useful for owner authoritative motion models. (#3013)
+- Added `NetcodeEditorBase` editor helper class to provide easier modification and extension of the SDK's components. (#3013)
 
 ### Fixed
 
--Fixed issue where the `NetworkSpawnManager.HandleNetworkObjectShow` could throw an exception if one of the `NetworkObject` components to show was destroyed during the same frame. (#3030)
+- Fixed issue where the `NetworkSpawnManager.HandleNetworkObjectShow` could throw an exception if one of the `NetworkObject` components to show was destroyed during the same frame. (#3030)
 - Fixed issue where the `NetworkManagerHelper` was continuing to check for hierarchy changes when in play mode. (#3026)
+- Fixed issue with newly/late joined clients and `NetworkTransform` synchronization of parented `NetworkObject` instances. (#3013)
+- Fixed issue with smooth transitions between transform spaces when interpolation is enabled (requires `NetworkTransform.SwitchTransformSpaceWhenParented` to be enabled). (#3013)
 
 ### Changed
 
+- Changed `NetworkTransformEditor` so it now derives from `NetcodeEditorBase`. (#3013)
+- Changed `NetworkRigidbodyBaseEditor` so it now derives from `NetcodeEditorBase`. (#3013)
+- Changed `NetworkManagerEditor` so it now derives from `NetcodeEditorBase`. (#3013)
+
+
 ## [2.0.0-pre.4] - 2024-08-21
 
 ### Added

com.unity.netcode.gameobjects/Editor/NetcodeEditorBase.cs

@@ -0,0 +1,62 @@
+using System;
+using UnityEditor;
+using UnityEngine;
+
+namespace Unity.Netcode.Editor
+{
+    /// <summary>
+    /// The base Netcode Editor helper class to display derived <see cref="MonoBehaviour"/> based components <br />
+    /// where each child generation's properties will be displayed within a FoldoutHeaderGroup.
+    /// </summary>
+    [CanEditMultipleObjects]
+    public partial class NetcodeEditorBase<TT> : UnityEditor.Editor where TT : MonoBehaviour
+    {
+        /// <inheritdoc/>
+        public virtual void OnEnable()
+        {
+        }
+
+        /// <summary>
+        /// Helper method to draw the properties of the specified child type <typeparamref name="T"/> component within a FoldoutHeaderGroup.
+        /// </summary>
+        /// <typeparam name="T">The specific child type that should have its properties drawn.</typeparam>
+        /// <param name="type">The component type of the <see cref="UnityEditor.Editor.target"/>.</param>
+        /// <param name="displayProperties">The <see cref="Action"/> to invoke that will draw the type <typeparamref name="T"/> properties.</param>
+        /// <param name="expanded">The <typeparamref name="T"/> current expanded property value</param>
+        /// <param name="setExpandedProperty">The <see cref="Action{bool}"/> invoked to apply the updated <paramref name="expanded"/> value.</param>
+        protected void DrawFoldOutGroup<T>(Type type, Action displayProperties, bool expanded, Action<bool> setExpandedProperty)
+        {
+            var baseClass = target as TT;
+            EditorGUI.BeginChangeCheck();
+            serializedObject.Update();
+            var currentClass = typeof(T);
+            if (type.IsSubclassOf(currentClass) || (!type.IsSubclassOf(currentClass) && currentClass.IsSubclassOf(typeof(TT))))
+            {
+                var expandedValue = EditorGUILayout.BeginFoldoutHeaderGroup(expanded, $"{currentClass.Name} Properties");
+                if (expandedValue)
+                {
+                    EditorGUILayout.EndFoldoutHeaderGroup();
+                    displayProperties.Invoke();
+                }
+                else
+                {
+                    EditorGUILayout.EndFoldoutHeaderGroup();
+                }
+                EditorGUILayout.Space();
+                setExpandedProperty.Invoke(expandedValue);
+            }
+            else
+            {
+                displayProperties.Invoke();
+            }
+            serializedObject.ApplyModifiedProperties();
+            EditorGUI.EndChangeCheck();
+        }
+
+        /// <inheritdoc/>
+        public override void OnInspectorGUI()
+        {
+            serializedObject.ApplyModifiedProperties();
+        }
+    }
+}

com.unity.netcode.gameobjects/Editor/NetcodeEditorBase.cs.meta

@@ -301,9 +301,8 @@ public override void OnInspectorGUI()
 
                 expanded = false;
             }
-
-            serializedObject.ApplyModifiedProperties();
             EditorGUI.EndChangeCheck();
+            serializedObject.ApplyModifiedProperties();
         }
 
         /// <summary>

com.unity.netcode.gameobjects/Editor/NetworkBehaviourEditor.cs

@@ -13,7 +13,7 @@ namespace Unity.Netcode.Editor
     /// </summary>
     [CustomEditor(typeof(NetworkManager), true)]
     [CanEditMultipleObjects]
-    public class NetworkManagerEditor : UnityEditor.Editor
+    public class NetworkManagerEditor : NetcodeEditorBase<NetworkManager>
     {
         private static GUIStyle s_CenteredWordWrappedLabelStyle;
         private static GUIStyle s_HelpBoxStyle;
@@ -168,16 +168,8 @@ private void CheckNullProperties()
                 .FindPropertyRelative(nameof(NetworkPrefabs.NetworkPrefabsLists));
         }
 
-        /// <inheritdoc/>
-        public override void OnInspectorGUI()
+        private void DisplayNetworkManagerProperties()
         {
-            Initialize();
-            CheckNullProperties();
-
-#if !MULTIPLAYER_TOOLS
-            DrawInstallMultiplayerToolsTip();
-#endif
-
             if (!m_NetworkManager.IsServer && !m_NetworkManager.IsClient)
             {
                 serializedObject.Update();
@@ -298,48 +290,50 @@ public override void OnInspectorGUI()
                 }
 
                 serializedObject.ApplyModifiedProperties();
+            }
+        }
 
+        private void DisplayCallToActionButtons()
+        {
+            if (!m_NetworkManager.IsServer && !m_NetworkManager.IsClient)
+            {
+                string buttonDisabledReasonSuffix = "";
 
-                // Start buttons below
+                if (!EditorApplication.isPlaying)
                 {
-                    string buttonDisabledReasonSuffix = "";
+                    buttonDisabledReasonSuffix = ". This can only be done in play mode";
+                    GUI.enabled = false;
+                }
 
-                    if (!EditorApplication.isPlaying)
+                if (m_NetworkManager.NetworkConfig.NetworkTopology == NetworkTopologyTypes.ClientServer)
+                {
+                    if (GUILayout.Button(new GUIContent("Start Host", "Starts a host instance" + buttonDisabledReasonSuffix)))
                     {
-                        buttonDisabledReasonSuffix = ". This can only be done in play mode";
-                        GUI.enabled = false;
+                        m_NetworkManager.StartHost();
                     }
 
-                    if (m_NetworkManager.NetworkConfig.NetworkTopology == NetworkTopologyTypes.ClientServer)
+                    if (GUILayout.Button(new GUIContent("Start Server", "Starts a server instance" + buttonDisabledReasonSuffix)))
                     {
-                        if (GUILayout.Button(new GUIContent("Start Host", "Starts a host instance" + buttonDisabledReasonSuffix)))
-                        {
-                            m_NetworkManager.StartHost();
-                        }
-
-                        if (GUILayout.Button(new GUIContent("Start Server", "Starts a server instance" + buttonDisabledReasonSuffix)))
-                        {
-                            m_NetworkManager.StartServer();
-                        }
+                        m_NetworkManager.StartServer();
+                    }
 
-                        if (GUILayout.Button(new GUIContent("Start Client", "Starts a client instance" + buttonDisabledReasonSuffix)))
-                        {
-                            m_NetworkManager.StartClient();
-                        }
+                    if (GUILayout.Button(new GUIContent("Start Client", "Starts a client instance" + buttonDisabledReasonSuffix)))
+                    {
+                        m_NetworkManager.StartClient();
                     }
-                    else
+                }
+                else
+                {
+                    if (GUILayout.Button(new GUIContent("Start Client", "Starts a distributed authority client instance" + buttonDisabledReasonSuffix)))
                     {
-                        if (GUILayout.Button(new GUIContent("Start Client", "Starts a distributed authority client instance" + buttonDisabledReasonSuffix)))
-                        {
-                            m_NetworkManager.StartClient();
-                        }
+                        m_NetworkManager.StartClient();
                     }
+                }
 
 
-                    if (!EditorApplication.isPlaying)
-                    {
-                        GUI.enabled = true;
-                    }
+                if (!EditorApplication.isPlaying)
+                {
+                    GUI.enabled = true;
                 }
             }
             else
@@ -368,6 +362,21 @@ public override void OnInspectorGUI()
             }
         }
 
+        /// <inheritdoc/>
+        public override void OnInspectorGUI()
+        {
+            var networkManager = target as NetworkManager;
+            Initialize();
+            CheckNullProperties();
+#if !MULTIPLAYER_TOOLS
+            DrawInstallMultiplayerToolsTip();
+#endif
+            void SetExpanded(bool expanded) { networkManager.NetworkManagerExpanded = expanded; };
+            DrawFoldOutGroup<NetworkManager>(networkManager.GetType(), DisplayNetworkManagerProperties, networkManager.NetworkManagerExpanded, SetExpanded);
+            DisplayCallToActionButtons();
+            base.OnInspectorGUI();
+        }
+
         private static void DrawInstallMultiplayerToolsTip()
         {
             const string getToolsText = "Access additional tools for multiplayer development by installing the Multiplayer Tools package in the Package Manager.";

com.unity.netcode.gameobjects/Editor/NetworkManagerEditor.cs

@@ -0,0 +1,42 @@
+#if COM_UNITY_MODULES_PHYSICS || COM_UNITY_MODULES_PHYSICS2D
+using Unity.Netcode.Components;
+using UnityEditor;
+
+namespace Unity.Netcode.Editor
+{
+    [CustomEditor(typeof(NetworkRigidbodyBase), true)]
+    [CanEditMultipleObjects]
+    public class NetworkRigidbodyBaseEditor : NetcodeEditorBase<NetworkBehaviour>
+    {
+        private SerializedProperty m_UseRigidBodyForMotion;
+        private SerializedProperty m_AutoUpdateKinematicState;
+        private SerializedProperty m_AutoSetKinematicOnDespawn;
+
+
+        public override void OnEnable()
+        {
+            m_UseRigidBodyForMotion = serializedObject.FindProperty(nameof(NetworkRigidbodyBase.UseRigidBodyForMotion));
+            m_AutoUpdateKinematicState = serializedObject.FindProperty(nameof(NetworkRigidbodyBase.AutoUpdateKinematicState));
+            m_AutoSetKinematicOnDespawn = serializedObject.FindProperty(nameof(NetworkRigidbodyBase.AutoSetKinematicOnDespawn));
+
+            base.OnEnable();
+        }
+
+        private void DisplayNetworkRigidbodyProperties()
+        {
+            EditorGUILayout.PropertyField(m_UseRigidBodyForMotion);
+            EditorGUILayout.PropertyField(m_AutoUpdateKinematicState);
+            EditorGUILayout.PropertyField(m_AutoSetKinematicOnDespawn);
+        }
+
+        /// <inheritdoc/>
+        public override void OnInspectorGUI()
+        {
+            var networkRigidbodyBase = target as NetworkRigidbodyBase;
+            void SetExpanded(bool expanded) { networkRigidbodyBase.NetworkRigidbodyBaseExpanded = expanded; };
+            DrawFoldOutGroup<NetworkRigidbodyBase>(networkRigidbodyBase.GetType(), DisplayNetworkRigidbodyProperties, networkRigidbodyBase.NetworkRigidbodyBaseExpanded, SetExpanded);
+            base.OnInspectorGUI();
+        }
+    }
+}
+#endif

com.unity.netcode.gameobjects/Editor/NetworkRigidbodyBaseEditor.cs

@@ -8,8 +8,11 @@ namespace Unity.Netcode.Editor
     /// The <see cref="CustomEditor"/> for <see cref="NetworkTransform"/>
     /// </summary>
     [CustomEditor(typeof(NetworkTransform), true)]
-    public class NetworkTransformEditor : UnityEditor.Editor
+    [CanEditMultipleObjects]
+    public class NetworkTransformEditor : NetcodeEditorBase<NetworkBehaviour>
     {
+        private SerializedProperty m_SwitchTransformSpaceWhenParented;
+        private SerializedProperty m_TickSyncChildren;
         private SerializedProperty m_UseUnreliableDeltas;
         private SerializedProperty m_SyncPositionXProperty;
         private SerializedProperty m_SyncPositionYProperty;
@@ -39,8 +42,10 @@ public class NetworkTransformEditor : UnityEditor.Editor
         private static GUIContent s_ScaleLabel = EditorGUIUtility.TrTextContent("Scale");
 
         /// <inheritdoc/>
-        public virtual void OnEnable()
+        public override void OnEnable()
         {
+            m_SwitchTransformSpaceWhenParented = serializedObject.FindProperty(nameof(NetworkTransform.SwitchTransformSpaceWhenParented));
+            m_TickSyncChildren = serializedObject.FindProperty(nameof(NetworkTransform.TickSyncChildren));
             m_UseUnreliableDeltas = serializedObject.FindProperty(nameof(NetworkTransform.UseUnreliableDeltas));
             m_SyncPositionXProperty = serializedObject.FindProperty(nameof(NetworkTransform.SyncPositionX));
             m_SyncPositionYProperty = serializedObject.FindProperty(nameof(NetworkTransform.SyncPositionY));
@@ -61,10 +66,10 @@ public virtual void OnEnable()
             m_UseHalfFloatPrecision = serializedObject.FindProperty(nameof(NetworkTransform.UseHalfFloatPrecision));
             m_SlerpPosition = serializedObject.FindProperty(nameof(NetworkTransform.SlerpPosition));
             m_AuthorityMode = serializedObject.FindProperty(nameof(NetworkTransform.AuthorityMode));
+            base.OnEnable();
         }
 
-        /// <inheritdoc/>
-        public override void OnInspectorGUI()
+        private void DisplayNetworkTransformProperties()
         {
             var networkTransform = target as NetworkTransform;
             EditorGUILayout.LabelField("Axis to Synchronize", EditorStyles.boldLabel);
@@ -141,9 +146,15 @@ public override void OnInspectorGUI()
             EditorGUILayout.PropertyField(m_ScaleThresholdProperty);
             EditorGUILayout.Space();
             EditorGUILayout.LabelField("Delivery", EditorStyles.boldLabel);
+            EditorGUILayout.PropertyField(m_TickSyncChildren);
             EditorGUILayout.PropertyField(m_UseUnreliableDeltas);
             EditorGUILayout.Space();
             EditorGUILayout.LabelField("Configurations", EditorStyles.boldLabel);
+            EditorGUILayout.PropertyField(m_SwitchTransformSpaceWhenParented);
+            if (m_SwitchTransformSpaceWhenParented.boolValue)
+            {
+                m_TickSyncChildren.boolValue = true;
+            }
             EditorGUILayout.PropertyField(m_InLocalSpaceProperty);
             if (!networkTransform.HideInterpolateValue)
             {
@@ -163,23 +174,31 @@ public override void OnInspectorGUI()
 
 #if COM_UNITY_MODULES_PHYSICS
             // if rigidbody is present but network rigidbody is not present
-            var go = ((NetworkTransform)target).gameObject;
-            if (go.TryGetComponent<Rigidbody>(out _) && go.TryGetComponent<NetworkRigidbody>(out _) == false)
+            if (networkTransform.TryGetComponent<Rigidbody>(out _) && networkTransform.TryGetComponent<NetworkRigidbody>(out _) == false)
             {
                 EditorGUILayout.HelpBox("This GameObject contains a Rigidbody but no NetworkRigidbody.\n" +
                     "Add a NetworkRigidbody component to improve Rigidbody synchronization.", MessageType.Warning);
             }
 #endif // COM_UNITY_MODULES_PHYSICS
 
 #if COM_UNITY_MODULES_PHYSICS2D
-            if (go.TryGetComponent<Rigidbody2D>(out _) && go.TryGetComponent<NetworkRigidbody2D>(out _) == false)
+            if (networkTransform.TryGetComponent<Rigidbody2D>(out _) && networkTransform.TryGetComponent<NetworkRigidbody2D>(out _) == false)
             {
                 EditorGUILayout.HelpBox("This GameObject contains a Rigidbody2D but no NetworkRigidbody2D.\n" +
                     "Add a NetworkRigidbody2D component to improve Rigidbody2D synchronization.", MessageType.Warning);
             }
 #endif // COM_UNITY_MODULES_PHYSICS2D
+        }
+
 
-            serializedObject.ApplyModifiedProperties();
+
+        /// <inheritdoc/>
+        public override void OnInspectorGUI()
+        {
+            var networkTransform = target as NetworkTransform;
+            void SetExpanded(bool expanded) { networkTransform.NetworkTransformExpanded = expanded; };
+            DrawFoldOutGroup<NetworkTransform>(networkTransform.GetType(), DisplayNetworkTransformProperties, networkTransform.NetworkTransformExpanded, SetExpanded);
+            base.OnInspectorGUI();
         }
     }
 }