fix: Auto configure rigidbody based on physics mode selection (#4229)

* fix

Fixing issue with rigidbody and physics mode.

* update

Adding minor blurb about the rigidbody adjustments

* style

Adding whitespace

* fix: scope physics mode workarounds to hybrid sessions and keep them across authority changes

- AlwaysRun interpolation override now applies only when the session has hybrid prefabs (N4E defaults to AlwaysRun, so plain NGO sessions were affected), only to 3D Rigidbodies, and is reapplied on every kinematic/ownership update instead of being reset to the authored value.
- Restores the authored kinematic capture for hybrid prefabs to Awake only, so OnDestroy no longer restores the runtime kinematic state.
- Guards both NetcodeConfig.Global reads against a missing config, and compiles the full tick smoothing change only when a physics module is present.

Author: NoelStephensUnity

com.unity.netcode.gameobjects/Documentation~/ghostobjects.md

@@ -86,6 +86,13 @@ To convert a hybrid object back into a prefab that uses only one package, remove
 > [!NOTE]
 > Unity might prevent you from removing a **GhostObject** or **NetworkObject** component while the GameObject has `GhostBehaviour` or `NetworkBehaviour` components that depend on it. Remove the dependent components first.
 
+## Mixed mode objects and physics
+
+To avoid visual anomalies, NGO automatically adjusts some Rigidbody settings based on the **Physics Run Mode** of the `NetcodeConfig` asset:
+
+- **Always Run**: In a session that has hybrid prefabs, non-hybrid NGO prefabs with a NetworkRigidbody and a 3D Rigidbody have the Rigidbody's **Interpolate** value set to **Extrapolate** on the authority instance and to **None** on all non-authority instances. The authority instance is the server or host for a server-authoritative NetworkTransform, or the owner for an owner-authoritative one. The value follows authority when ownership changes, and the original value is restored when the instance despawns.
+- **User Controlled**: Hybrid NGO prefabs with a NetworkRigidbody have **Full Tick Smoothing** set to **Disabled**.
+
 ## Additional resources
 
 - [GhostObjects in Unity Netcode](https://docs.unity3d.com/Packages/com.unity.netcode@latest?subfolder=/manual/ghostobject/ghostobject.html)

com.unity.netcode.gameobjects/Runtime/Components/NetworkRigidBodyBase.cs

@@ -298,6 +298,25 @@ private bool InitializeHybrid()
             return true;
         }
 
+        // Overrides the authored interpolation while spawned when the NetcodeConfig physics mode requires it.
+        private bool m_UsePhysicsModeInterpolation;
+
+        /// <summary>
+        /// Prevents the jitter an interpolated Rigidbody that is not a GhostObject shows in a hybrid session with <see cref="PhysicGroupRunMode.AlwaysRun"/>.
+        /// </summary>
+        private void SetPhysicsModeInterpolation()
+        {
+            var netcodeConfig = NetcodeConfig.Global;
+            m_UsePhysicsModeInterpolation = !m_IsRigidbody2D && m_LocalNetworkManager.NetworkConfig.Prefabs.HasGhostPrefabs
+                && netcodeConfig != null && netcodeConfig.PhysicsRunMode == PhysicGroupRunMode.AlwaysRun;
+        }
+
+        // The authority extrapolates and every other peer does not interpolate.
+        private void ApplyPhysicsModeInterpolation()
+        {
+            SetInterpolation(m_IsAuthority ? InterpolationTypes.Extrapolate : InterpolationTypes.None);
+        }
+
         /// <summary>
         /// Kinematic on every peer except the server. Called at spawn because an in-scene placed instance has no session during Awake.
         /// </summary>
@@ -956,6 +975,14 @@ private void PostSetIsKinematic()
                 return;
             }
 
+#if UNIFIED_NETCODE
+            if (m_UsePhysicsModeInterpolation)
+            {
+                ApplyPhysicsModeInterpolation();
+                return;
+            }
+#endif
+
             if (UseRigidBodyForMotion)
             {
                 // Exit early if the original interpolation type is not set to extrapolate or NetworkTransform interpolate is disabled
@@ -1103,6 +1130,12 @@ internal void UpdateOwnershipAuthority()
             {
                 SetIsKinematic(!m_IsAuthority);
             }
+#if UNIFIED_NETCODE
+            else if (m_UsePhysicsModeInterpolation)
+            {
+                ApplyPhysicsModeInterpolation();
+            }
+#endif
         }
 
         internal override void InternalOnNetworkPreSpawn(ref NetworkManager networkManager)
@@ -1122,6 +1155,9 @@ public override void OnNetworkSpawn()
 #endif
             m_TickFrequency = 1.0f / m_LocalNetworkManager.NetworkConfig.TickRate;
             m_TickRate = m_LocalNetworkManager.NetworkConfig.TickRate;
+#if UNIFIED_NETCODE
+            SetPhysicsModeInterpolation();
+#endif
             UpdateOwnershipAuthority();
         }
 

com.unity.netcode.gameobjects/Runtime/Configuration/NetworkPrefab.cs

@@ -179,6 +179,18 @@ public bool Validate(int index = -1)
 #if UNIFIED_NETCODE
                 // Mark this network prefab as having to be registered via the unified API
                 HasGhost = networkObject.HasGhost;
+
+#if COM_UNITY_MODULES_PHYSICS || COM_UNITY_MODULES_PHYSICS2D
+                // With UserControlled physics, full tick smoothing holds a hybrid Rigidbody in place on the host.
+                var netcodeConfig = NetcodeConfig.Global;
+                if (HasGhost && netcodeConfig != null && netcodeConfig.PhysicsRunMode == PhysicGroupRunMode.UserControlled
+                    && networkObject.GhostObject.FullTickSmoothing != FullTickSmoothingMode.Disabled
+                    && networkObject.GetComponent<Components.NetworkRigidbodyBase>() != null)
+                {
+                    NetworkLog.LogWarning(new Logging.Context(LogLevel.Developer, $"Disabling full tick smoothing on {networkObject.name} because the {nameof(NetcodeConfig)} physics mode is {PhysicGroupRunMode.UserControlled}.").AddNetworkObject(networkObject));
+                    networkObject.GhostObject.FullTickSmoothing = FullTickSmoothingMode.Disabled;
+                }
+#endif
 #endif
                 if (networkObject.InScenePlaced)
                 {