From 92ef82f9331dee683f3d4df7869c27d913321420 Mon Sep 17 00:00:00 2001
From: pereslav <pereslav@amazon.com>
Date: Mon, 10 May 2021 19:52:23 +0100
Subject: [PATCH] Added handling parented net entities

---
 .../EntityReplicationManager.cpp              |  6 ++---
 .../NetworkEntity/NetworkEntityManager.cpp    | 26 ++++++++++++++++++-
 .../Pipeline/NetworkPrefabProcessor.cpp       |  4 +++
 3 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/Gems/Multiplayer/Code/Source/NetworkEntity/EntityReplication/EntityReplicationManager.cpp b/Gems/Multiplayer/Code/Source/NetworkEntity/EntityReplication/EntityReplicationManager.cpp
index 74bdcd5cf0..64eb3fcc6a 100644
--- a/Gems/Multiplayer/Code/Source/NetworkEntity/EntityReplication/EntityReplicationManager.cpp
+++ b/Gems/Multiplayer/Code/Source/NetworkEntity/EntityReplication/EntityReplicationManager.cpp
@@ -550,10 +550,10 @@ namespace Multiplayer
             {
                 replicatorEntity = entityList[0];
             }
-            
-            AZ_Assert(replicatorEntity != nullptr, "Failed to create entity from prefab %s", prefabEntityId.m_prefabName.GetCStr());
-            if (replicatorEntity == nullptr)
+            else
             {
+                AZ_Assert(false, "There should be exactly one created entity out of prefab %s, index %d. Got: %d",
+                    prefabEntityId.m_prefabName.GetCStr(), prefabEntityId.m_entityOffset, entityList.size());
                 return false;
             }
         }
diff --git a/Gems/Multiplayer/Code/Source/NetworkEntity/NetworkEntityManager.cpp b/Gems/Multiplayer/Code/Source/NetworkEntity/NetworkEntityManager.cpp
index ce55f66caa..3bcd613d8b 100644
--- a/Gems/Multiplayer/Code/Source/NetworkEntity/NetworkEntityManager.cpp
+++ b/Gems/Multiplayer/Code/Source/NetworkEntity/NetworkEntityManager.cpp
@@ -334,15 +334,39 @@ namespace Multiplayer
         const AzFramework::Spawnable::EntityList& entities = spawnable.GetEntities();
         size_t entitiesSize = entities.size();
 
+        using EntityIdMap = AZStd::unordered_map<AZ::EntityId, AZ::EntityId>;
+        EntityIdMap originalToCloneIdMap;
+
         for (size_t i = 0; i < entitiesSize; ++i)
         {
-            AZ::Entity* clone = serializeContext->CloneObject(entities[i].get());
+            AZ::Entity* originalEntity = entities[i].get();
+            AZ::Entity* clone = serializeContext->CloneObject(originalEntity);
             AZ_Assert(clone != nullptr, "Failed to clone spawnable entity.");
+
             clone->SetId(AZ::Entity::MakeId());
 
+            originalToCloneIdMap[originalEntity->GetId()] = clone->GetId();
+
             NetBindComponent* netBindComponent = clone->FindComponent<NetBindComponent>();
             if (netBindComponent != nullptr)
             {
+                // Update TransformComponent parent Id. It is guaranteed for the entities array to be sorted from parent->child here.
+                auto* transformComponent = clone->FindComponent<AzFramework::TransformComponent>();
+                AZ::EntityId parentId = transformComponent->GetParentId();
+                if (parentId.IsValid())
+                {
+                    auto it = originalToCloneIdMap.find(parentId);
+                    if (it != originalToCloneIdMap.end())
+                    {
+                        transformComponent->SetParentRelative(it->second);
+                    }
+                    else
+                    {
+                        AZ_Warning("NetworkEntityManager", false, "Entity %s doesn't have the parent entity %s present in network.spawnable",
+                            clone->GetName().c_str(), parentId.ToString().data());
+                    }
+                }
+
                 PrefabEntityId prefabEntityId;
                 prefabEntityId.m_prefabName = m_networkPrefabLibrary.GetPrefabNameFromAssetId(spawnable.GetId());
                 prefabEntityId.m_entityOffset = aznumeric_cast<uint32_t>(i);
diff --git a/Gems/Multiplayer/Code/Source/Pipeline/NetworkPrefabProcessor.cpp b/Gems/Multiplayer/Code/Source/Pipeline/NetworkPrefabProcessor.cpp
index 4962d16fb4..56201bd5fd 100644
--- a/Gems/Multiplayer/Code/Source/Pipeline/NetworkPrefabProcessor.cpp
+++ b/Gems/Multiplayer/Code/Source/Pipeline/NetworkPrefabProcessor.cpp
@@ -59,6 +59,7 @@ namespace Multiplayer
 
         return result;
     }
+
     void NetworkPrefabProcessor::ProcessPrefab(PrefabProcessorContext& context, AZStd::string_view prefabName, PrefabDom& prefab)
     {
         using namespace AzToolsFramework::Prefab;
@@ -175,6 +176,9 @@ namespace Multiplayer
                 (*it)->InvalidateDependencies();
                 (*it)->EvaluateDependencies();
             }
+
+            SpawnableUtils::SortEntitiesByTransformHierarchy(*networkSpawnable);
+
             context.GetProcessedObjects().push_back(AZStd::move(object));
         }
         else