fix: NetworkTransform dropped packets can cause interpolation stutter [MTT-7551] (#2713)

* update

Adding OnOwnershipChanged(ulong previous, ulong current)

* fix

This resolves the issue with client authoritative network transforms and the random "noise" that would occur when transitioning ownership from a remote client back to the host-server.
- Latent messages from the client would still be received and processed after ownership changed.
- Ownership changed messages would proceed the NetworkTransform initialization state update message. Now ownership changed messages precede the NetworkTransform initialization state update message.
- Clients could sometimes have the same network tick value even when the tick event had triggered, which for NetworkDeltaPosition would cause dropped state updates.

* test

minor adjustment to a test that would fail from time to time due to precision.

* Merge branch 'develop' into fix/networktransform-halffloat-ownership-sync

* fix - validation bug

This is another bug in the validation test suite where removing an override of a virtual method that can still be overridden will throw an API validation error.

* update

Send deltas unreliable but synchronization and teleporting reliably.

* style

white space fixes

* test

Fixing issue with changes that require a NetworkManager to be present.

* fix

Fixing new issues (due to changes) with position not synchronizing to the target position when half float precision was enabled.

* test

minor adjustments to account for minor precision delta when quaternion compression is enabled in the NetworkTransformTests.ParentedNetworkTransformTest

* update

Resolves the api validation issue.

* update

Updating rotation and scale delta checks when sending unreliable messages.

* update

Was doing some profiling and found a few low hanging fruit areas that helps improve performance.

* style

removing whitespace

* fix

More adjustments to handle sending unreliable deltas. These changes will (when sending unreliable deltas):
- Stagger NetworkTransform axial frame synchronization
  - Axial frame synchronization is sent reliably
  - Axial frame synchronization is sent only if deltas have been sent (once to assure when an object stops it no longer sends syncs)

This also adjusts the "one tick event updates all NetworkTransform authority instances" addition.

* test

Fixing an issue with precision adjustments for rotation.
Adding integration test to validate the handling of dropped packets.

* update and style

Removing unused namespace.
Removing reference to static variable that no longer exists (was for debugging)

* style

removed whitespaces

* test

Removing UseUnreliableDeltas when running the TestRotationThresholdDeltaCheck as the synchronization frame could cause this test to fail.

* fix

Noticed a potential timing related parenting issue where a parented object should be fully synchronized by  NetworkTransform (even though it sends transform information when parenting).

* test

Some additional tweaks to the parenting portion of the NetworkTransform tests.

* revert

Reverting the parenting adjustment, that was a bad idea.
Only reset and update interpolators if interpolation is enabled seems to resolve the earlier issue.

* test

removing unused methods.
adding 100ms latency to the NetworkTransformUTPTests.

* test

Renaming NetworkTransformUTPTests to NetworkTransformPacketLossTests

* update

Exposing the UseUnreliableDeltas property and adding UI/UX to provide users a way to disable this via the inspector view.

* test

Making NetworkTransformTests run with UseUnreliableDeltas disabled to validate this operation mode of NetworkTransform.

* test

Adding additional wait for added latency.

* update

adding change log entries.

* update

Removing some todo statements and finalizing a bit flag to assure non-authoritative instances mirror the authoritative instance's UseUnreliableDeltas settings (i.e. if owner authoritative and ownership changes the same settings should apply).

* update

Updating change log entry

* Update CHANGELOG.md

Fixing bad changelog merge

* Update CHANGELOG.md

adding CR/LF

* fix

Discovered a long time standing parenting issue with the initial synchronization (while working on something else). The issue involves WorldPositionStays, InLocalSpace,  and the initial synchronization. Added comments to describe the adjustments.
Basically, when synchronizing, ignore the InLocalSpace setting and only use the WorldPositionStays value to determine which position space to use on the authoritative side only when building the initial synchronization state update.

* Update NetworkTransformStateTests.cs

Just adjusting the way a test asserts on null based on suggested review feedback.

* update

minor adjustments to when we need to send a reliable packet when sending unreliable deltas.

Author: NoelStephensUnity

com.unity.netcode.gameobjects/CHANGELOG.md

@@ -14,8 +14,12 @@ Additional documentation and release notes are available at [Multiplayer Documen
 
 - Fixed a bug where having a class with Rpcs that inherits from a class without Rpcs that inherits from NetworkVariable would cause a compile error. (#2751)
 - Fixed issue where `NetworkBehaviour.Synchronize` was not truncating the write buffer if nothing was serialized during `NetworkBehaviour.OnSynchronize` causing an additional 6 bytes to be written per `NetworkBehaviour` component instance. (#2749)
+- Fixed issue where a parented in-scene placed NetworkObject would be destroyed upon a client or server exiting a network session but not unloading the original scene in which the NetworkObject was placed. (#2737)
+- Fixed issue where during client synchronization and scene loading, when client synchronization or the scene loading mode are set to `LoadSceneMode.Single`, a `CreateObjectMessage` could be received, processed, and the resultant spawned `NetworkObject` could be instantiated in the client's currently active scene that could, towards the end of the client synchronization or loading process, be unloaded and cause the newly created `NetworkObject` to be destroyed (and throw and exception). (#2735)
+- Fixed issue where a `NetworkTransform` instance with interpolation enabled would result in wide visual motion gaps (stuttering) under above normal latency conditions and a 1-5% or higher packet are drop rate. (#2713)
 
 ### Changed
+- Changed `NetworkTransform` authoritative instance tick registration so a single `NetworkTransform` specific tick event update will update all authoritative instances to improve perofmance. (#2713)
 
 ## [1.7.0] - 2023-10-11
 

com.unity.netcode.gameobjects/Components/NetworkDeltaPosition.cs

@@ -23,12 +23,20 @@ public struct NetworkDeltaPosition : INetworkSerializable
         internal Vector3 DeltaPosition;
         internal int NetworkTick;
 
+        internal bool SynchronizeBase;
+
+        internal bool CollapsedDeltaIntoBase;
+
         /// <summary>
         /// The serialization implementation of <see cref="INetworkSerializable"/>
         /// </summary>
         public void NetworkSerialize<T>(BufferSerializer<T> serializer) where T : IReaderWriter
         {
             HalfVector3.NetworkSerialize(serializer);
+            if (SynchronizeBase)
+            {
+                serializer.SerializeValue(ref CurrentBasePosition);
+            }
         }
 
         /// <summary>
@@ -122,6 +130,7 @@ public Vector3 GetDeltaPosition()
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public void UpdateFrom(ref Vector3 vector3, int networkTick)
         {
+            CollapsedDeltaIntoBase = false;
             NetworkTick = networkTick;
             DeltaPosition = (vector3 + PrecisionLossDelta) - CurrentBasePosition;
             for (int i = 0; i < HalfVector3.Length; i++)
@@ -136,6 +145,7 @@ public void UpdateFrom(ref Vector3 vector3, int networkTick)
                         CurrentBasePosition[i] += HalfDeltaConvertedBack[i];
                         HalfDeltaConvertedBack[i] = 0.0f;
                         DeltaPosition[i] = 0.0f;
+                        CollapsedDeltaIntoBase = true;
                     }
                 }
             }
@@ -164,6 +174,8 @@ public NetworkDeltaPosition(Vector3 vector3, int networkTick, bool3 axisToSynchr
             DeltaPosition = Vector3.zero;
             HalfDeltaConvertedBack = Vector3.zero;
             HalfVector3 = new HalfVector3(vector3, axisToSynchronize);
+            SynchronizeBase = false;
+            CollapsedDeltaIntoBase = false;
             UpdateFrom(ref vector3, networkTick);
         }
 

com.unity.netcode.gameobjects/Components/NetworkTransform.cs

@@ -10,6 +10,7 @@ namespace Unity.Netcode.Editor
     [CustomEditor(typeof(NetworkTransform), true)]
     public class NetworkTransformEditor : UnityEditor.Editor
     {
+        private SerializedProperty m_UseUnreliableDeltas;
         private SerializedProperty m_SyncPositionXProperty;
         private SerializedProperty m_SyncPositionYProperty;
         private SerializedProperty m_SyncPositionZProperty;
@@ -39,6 +40,7 @@ public class NetworkTransformEditor : UnityEditor.Editor
         /// <inheritdoc/>
         public void OnEnable()
         {
+            m_UseUnreliableDeltas = serializedObject.FindProperty(nameof(NetworkTransform.UseUnreliableDeltas));
             m_SyncPositionXProperty = serializedObject.FindProperty(nameof(NetworkTransform.SyncPositionX));
             m_SyncPositionYProperty = serializedObject.FindProperty(nameof(NetworkTransform.SyncPositionY));
             m_SyncPositionZProperty = serializedObject.FindProperty(nameof(NetworkTransform.SyncPositionZ));
@@ -129,7 +131,9 @@ public override void OnInspectorGUI()
             EditorGUILayout.PropertyField(m_PositionThresholdProperty);
             EditorGUILayout.PropertyField(m_RotAngleThresholdProperty);
             EditorGUILayout.PropertyField(m_ScaleThresholdProperty);
-
+            EditorGUILayout.Space();
+            EditorGUILayout.LabelField("Delivery", EditorStyles.boldLabel);
+            EditorGUILayout.PropertyField(m_UseUnreliableDeltas);
             EditorGUILayout.Space();
             EditorGUILayout.LabelField("Configurations", EditorStyles.boldLabel);
             EditorGUILayout.PropertyField(m_InLocalSpaceProperty);