chore: enable unified netcode from N4E 7.2.0, only for hybrid prefab sessions (#4186)

* chore: drop N4E experimental bridge define and OUT_OF_BAND_RPC

N4E is removing NETCODE_GAMEOBJECT_BRIDGE_EXPERIMENTAL and making its GameObject layer public,
so UNIFIED_NETCODE is now the only define the unified path needs. testproject takes N4E from
unity/unity trunk until that change ships in a package, which makes manifest-unified.json redundant.

* Enable the unified path from N4E 7.2.0 and only for hybrid prefab sessions

UNIFIED_NETCODE is now an asmdef versionDefine on com.unity.netcode 7.2.0, the release that makes the
GameObject layer public, so no project define is needed. UNIFIED_NETCODE_7_0_0 is gone since every
supported N4E uses the new namespace.

UnifiedBootstrap is marked DisableBootstrapOverrides and created by NetworkManager only when the session
has hybrid prefabs, so projects without them keep N4E's own startup bootstrap. A hybrid prefab added
after a session started without one is rejected.

testproject takes N4E from the remove-experimental-define branch until that PR merges.

* Register the player prefab before the session decides hybrid mode

A hybrid PlayerPrefab outside the prefab lists was registered after the transport choice and the
session-start rejection, so it was rejected. It now registers with the prefab lists before start, and
distributed authority rejects it like any other hybrid prefab.

* style: format unified netcode code now that UNIFIED_NETCODE compiles in testproject

UNIFIED_NETCODE is now defined automatically from N4E 7.2.0, so the Standards check formats code behind it
for the first time.

* style: format the hybrid code merged from develop-3.x.x

Keeps an implicit bool check where null propagation would call into a destroyed NetworkBehaviour.

* chore: stop tracking the NetcodeConfig assets in testproject and minimalproject

NGO now applies the NetcodeConfig values it needs at session start, so nothing in either asset is required.
Netcode for Entities creates the asset and its project settings entry on first open. The settings file is
removed too, since keeping it tracked would make every fresh checkout rewrite it.

* chore: ignore the NetcodeConfig assets Netcode for Entities creates on first open

The assets are no longer tracked, so the files N4E writes when a project opens would otherwise show up
as untracked changes and could be committed back.

* fix: keep Unity's destroyed-object check where the formatter used null propagation

Implicit bool checks instead of ?. on NetworkTransform and NetworkManager, which the Standards formatter
does not rewrite.

* fix: keep UnifiedBootstrap as the Entities startup bootstrap

[DisableBootstrapOverrides] let Netcode for Entities' own bootstrap run at
startup. Without a NetcodeConfig that disables automatic bootstrapping, it
creates a host world listening on port 7979, so a hybrid host could not bind
the port and the unified tests failed. As the startup bootstrap,
UnifiedBootstrap only creates a local world, which is how #4144 resolved this.

* chore: point the Netcode for Entities git dependency at trunk

The GameObject layer change has merged to trunk, so testproject follows trunk instead of the pull request
branch, and minimalproject gets the same entry so both compile against N4E 7.2.0. These switch to the
published 7.2.0 package once it is available.

Author: NoelStephensUnity

.yamato/unified-tests.yml

@@ -10,7 +10,7 @@
     # 2. For all unified editors (currently a single pinned alpha, see project.metafile)
 
 # QUALITY CONSIDERATIONS--------------------------------------------------------------------
-  # manifest-unified.json takes N4E from unity/unity trunk, so this job can break on N4E changes made outside NGO.
+  # testproject takes N4E from unity/unity trunk, so this job can break on N4E changes made outside NGO.
 
 #------------------------------------------------------------------------------------
 
@@ -34,11 +34,6 @@ unified_test_{{ project.name }}_{{ platform.name }}_{{ editor }}:
     UNIFIED_TESTS: "true"
 
   commands:
-    # Swap in the manifest that takes N4E from unity/unity trunk Workspace/com.unity.netcode.
-    - cp {{ project.path }}/Packages/manifest-unified.json {{ project.path }}/Packages/manifest.json
-    # Turn the unified API on. UNIFIED_NETCODE is opt-in, and N4E keeps its GameObject bridge internal
-    # until NETCODE_GAMEOBJECT_BRIDGE_EXPERIMENTAL is defined, so both are needed here and nowhere else.
-    - sed -i "s/UNITY_NETCODE_NATIVE_COLLECTION_SUPPORT/UNITY_NETCODE_NATIVE_COLLECTION_SUPPORT;NETCODE_GAMEOBJECT_BRIDGE_EXPERIMENTAL;UNIFIED_NETCODE;OUT_OF_BAND_RPC/" {{ project.path }}/ProjectSettings/ProjectSettings.asset
     - unity-downloader-cli --fast --wait -u {{ editor }} -c Editor --arch {{ platform.architecture }}
     - UnifiedTestRunner --testproject={{ project.path }} --suite=playmode --artifacts-path=test-results --editor-location=.Editor --rerun-strategy=Test --retry={{ num_test_retries }} --clean-library-on-rerun --timeout={{ test_timeout }}
   artifacts:

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

@@ -1,11 +1,6 @@
 using System.Collections.Generic;
 #if UNIFIED_NETCODE
-#if UNIFIED_NETCODE_7_0_0
 using Unity.Netcode.Editor;
-#else
-using Unity.NetCode;
-using Unity.NetCode.Editor;
-#endif
 #endif
 using UnityEditor;
 using UnityEngine;

com.unity.netcode.gameobjects/Editor/Unity.Netcode.GameObjects.Editor.asmdef

@@ -23,8 +23,8 @@
     "versionDefines": [
         {
             "name": "com.unity.netcode",
-            "expression": "7.0.0",
-            "define": "UNIFIED_NETCODE_7_0_0"
+            "expression": "7.2.0",
+            "define": "UNIFIED_NETCODE"
         },
         {
             "name": "com.unity.multiplayer.tools",

com.unity.netcode.gameobjects/Runtime/Components/Helpers/NetworkObjectBridge.cs

@@ -1,8 +1,5 @@
 #if UNIFIED_NETCODE
 using Unity.Mathematics;
-#if !UNIFIED_NETCODE_7_0_0
-using Unity.NetCode;
-#endif
 using Unity.Transforms;
 using UnityEngine;
 
@@ -126,11 +123,10 @@ internal void UpdateGhostOwner(NetworkManager networkManager, ulong ownerClientI
         }
     }
 
-#if UNIFIED_NETCODE_7_0_0
     /// <summary>
     /// Stands in for N4E's <c>GhostObject.ApplyPostTransformMatrixScale</c>, which 7.0.0 removed along with the
     /// non-uniform scale rework that gave the GameObject-to-entity transform sync ownership of the
-    /// <see cref="PostTransformMatrix"/>. 6.7.0 still has the method, so this is only compiled against 7.0.0.
+    /// <see cref="PostTransformMatrix"/>.
     /// Remove it once N4E exposes a supported way to push scale to a ghost.
     /// </summary>
     internal static class GhostObjectScaleExtensions
@@ -164,6 +160,5 @@ internal static void ApplyPostTransformMatrixScale(this GhostObject ghost, Vecto
             entityManager.SetComponentData(entity, localTransform);
         }
     }
-#endif
 }
 #endif

com.unity.netcode.gameobjects/Runtime/Components/Helpers/UnifiedBootstrap.cs

@@ -1,13 +1,7 @@
-#if UNIFIED_NETCODE && !NETCODE_GAMEOBJECT_BRIDGE_EXPERIMENTAL
-#error UNIFIED_NETCODE also requires NETCODE_GAMEOBJECT_BRIDGE_EXPERIMENTAL: Netcode for Entities keeps its GameObject bridge (GhostObject, GhostBehaviour, GhostField) internal until that define is set.
-#endif
 #if UNIFIED_NETCODE
 using System;
 using System.Collections.Generic;
 using Unity.Entities;
-#if !UNIFIED_NETCODE_7_0_0
-using Unity.NetCode;
-#endif
 using UnityEngine;
 
 namespace Unity.Netcode
@@ -17,6 +11,11 @@ namespace Unity.Netcode
     /// Handles the bootstrap process for both client and server in unified mode. This is used to create the world and set it on the
     /// NetworkManager during initialization.
     /// </summary>
+    /// <remarks>
+    /// Entities picks this as the startup bootstrap, which only creates a local world. Do not add
+    /// [DisableBootstrapOverrides]: Netcode for Entities' own bootstrap would then run and, unless automatic
+    /// bootstrapping is disabled, create a host world that holds the port a hybrid session listens on.
+    /// </remarks>
     internal class UnifiedBootstrap : ClientServerBootstrap
     {
         public static UnifiedBootstrap Instance { get; private set; }

com.unity.netcode.gameobjects/Runtime/Components/Helpers/UnifiedUpdateConnections.cs

@@ -2,9 +2,6 @@
 using System.Collections.Generic;
 using Unity.Collections;
 using Unity.Entities;
-#if !UNIFIED_NETCODE_7_0_0
-using Unity.NetCode;
-#endif
 using UnityEngine;
 
 namespace Unity.Netcode.Components

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

@@ -289,7 +289,7 @@ private bool InitializeHybrid()
             }
 
             // Clears any registration left behind by a prior Initialize call.
-            if (NetworkTransform != null)
+            if (NetworkTransform)
             {
                 NetworkTransform.UnregisterRigidbody();
             }

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

@@ -1,7 +1,4 @@
 #if UNIFIED_NETCODE
-#if !UNIFIED_NETCODE_7_0_0
-using NetcodeConfig = Unity.NetCode.NetCodeConfig;
-#endif
 
 namespace Unity.Netcode
 {

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

@@ -404,11 +404,13 @@ internal void InitializePrefabs()
 
 #if UNIFIED_NETCODE
         /// <summary>
-        /// Registers any prefab list assigned after Awake, and returns false for a distributed authority session with a hybrid prefab registered.
+        /// Registers any prefab list assigned after Awake and the <see cref="PlayerPrefab"/>, and returns false for a distributed authority session with a hybrid prefab registered.
         /// </summary>
-        internal bool InitializePrefabsForStart()
+        internal bool InitializePrefabsForStart(NetworkPrefabHandler prefabHandler)
         {
             InitializePrefabs();
+            // A player prefab outside the prefab lists still decides hybrid mode, so it is registered before the session starts.
+            prefabHandler.RegisterPlayerPrefab();
             return NetworkTopology != NetworkTopologyTypes.DistributedAuthority || Prefabs.ValidateForDistributedAuthority();
         }
 #endif

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

@@ -173,7 +173,7 @@ internal void Shutdown()
                 list.OnRemove -= RemoveTriggeredByNetworkPrefabList;
             }
 #if UNIFIED_NETCODE
-            m_RejectGhostPrefabs = false;
+            m_GhostPrefabRejection = null;
 #endif
         }
 
@@ -367,18 +367,20 @@ public bool Contains(NetworkPrefab prefab)
 
 #if UNIFIED_NETCODE
         internal const string DistributedAuthorityHybridPrefabError = "Distributed authority does not support hybrid prefabs.";
+        internal const string HybridPrefabAfterStartError = "Hybrid prefabs must be registered before the NetworkManager starts.";
 
         internal bool HasGhostPrefabs { get; private set; }
 
-        // Cleared in Shutdown.
-        private bool m_RejectGhostPrefabs;
+        // The error a hybrid prefab added during the session is rejected with, or null. Cleared in Shutdown.
+        private string m_GhostPrefabRejection;
 
         /// <summary>
-        /// A distributed authority session rejects hybrid prefabs added while it runs.
+        /// Hybrid mode is decided when the session starts. A distributed authority session, or one that started without
+        /// hybrid prefabs, rejects hybrid prefabs added while it runs.
         /// </summary>
         internal void OnSessionStarting(bool distributedAuthority)
         {
-            m_RejectGhostPrefabs = distributedAuthority;
+            m_GhostPrefabRejection = distributedAuthority ? DistributedAuthorityHybridPrefabError : HasGhostPrefabs ? null : HybridPrefabAfterStartError;
         }
 
         /// <summary>
@@ -426,9 +428,9 @@ private bool AddPrefabRegistration(NetworkPrefab networkPrefab)
             if (networkPrefab.HasGhost)
             {
                 // Registering a hybrid prefab mid-session would switch NetworkManager into hybrid mode and stop its send queue.
-                if (m_RejectGhostPrefabs)
+                if (m_GhostPrefabRejection != null)
                 {
-                    Debug.LogError($"{DistributedAuthorityHybridPrefabError} {networkPrefab.GetDebugName()} was not added.");
+                    Debug.LogError($"{m_GhostPrefabRejection} {networkPrefab.GetDebugName()} was not added.");
                     return false;
                 }
                 HasGhostPrefabs = true;