From 3e8625b78b83a56ae3f9557060f3e9bf4387517b Mon Sep 17 00:00:00 2001
From: mbalfour <mbalfour@amazon.com>
Date: Wed, 14 Apr 2021 16:09:02 -0500
Subject: [PATCH] Added "IsReadyToSpawn" to help detect when a spawner is ready
 to start spawning.  Also added a small optimization to
 SetDynamicSliceByAssetId so that it doesn't do anything when setting it to
 the same value as before.

(cherry picked from commit ff8a93e71f3017e8555012855f3e2155ec74a405)
---
 .../Source/Scripting/SpawnerComponent.cpp     | 25 +++++++++++--------
 .../Code/Source/Scripting/SpawnerComponent.h  |  3 ++-
 .../Scripting/SpawnerComponentBus.h           |  3 +++
 3 files changed, 20 insertions(+), 11 deletions(-)

diff --git a/Gems/LmbrCentral/Code/Source/Scripting/SpawnerComponent.cpp b/Gems/LmbrCentral/Code/Source/Scripting/SpawnerComponent.cpp
index 2595fc09fd..7b76a1465c 100644
--- a/Gems/LmbrCentral/Code/Source/Scripting/SpawnerComponent.cpp
+++ b/Gems/LmbrCentral/Code/Source/Scripting/SpawnerComponent.cpp
@@ -148,6 +148,7 @@ namespace LmbrCentral
                 ->Event("GetCurrentEntitiesFromSpawnedSlice", &SpawnerComponentRequestBus::Events::GetCurrentEntitiesFromSpawnedSlice)
                 ->Event("GetAllCurrentlySpawnedEntities", &SpawnerComponentRequestBus::Events::GetAllCurrentlySpawnedEntities)
                 ->Event("SetDynamicSlice", &SpawnerComponentRequestBus::Events::SetDynamicSliceByAssetId)
+                ->Event("IsReadyToSpawn", &SpawnerComponentRequestBus::Events::IsReadyToSpawn)
                 ;
 
             behaviorContext->EBus<SpawnerComponentNotificationBus>("SpawnerComponentNotificationBus")
@@ -250,17 +251,15 @@ namespace LmbrCentral
     //=========================================================================
     void SpawnerComponent::SetDynamicSliceByAssetId(AZ::Data::AssetId& assetId)
     {
-        auto sliceAsset = AZ::Data::AssetManager::Instance().GetAsset(assetId, AZ::AzTypeInfo<AZ::DynamicSliceAsset>::Uuid(), m_sliceAsset.GetAutoLoadBehavior());
+        if (m_sliceAsset.GetId() == assetId)
+        {
+            return;
+        }
 
-        if (sliceAsset.IsReady())
-        {
-            m_sliceAsset = sliceAsset;
-        }
-        else
-        {
-            AZ::Data::AssetBus::Handler::BusDisconnect();
-            AZ::Data::AssetBus::Handler::BusConnect(assetId);
-        }
+        m_sliceAsset = AZ::Data::AssetManager::Instance().GetAsset(
+            assetId, AZ::AzTypeInfo<AZ::DynamicSliceAsset>::Uuid(), m_sliceAsset.GetAutoLoadBehavior());
+        AZ::Data::AssetBus::Handler::BusDisconnect();
+        AZ::Data::AssetBus::Handler::BusConnect(assetId);
     }
 
     //=========================================================================
@@ -444,6 +443,12 @@ namespace LmbrCentral
         return entities;
     }
 
+    //=========================================================================
+    bool SpawnerComponent::IsReadyToSpawn()
+    {
+        return m_sliceAsset.IsReady();
+    }
+
     //=========================================================================
     void SpawnerComponent::OnSlicePreInstantiate(const AZ::Data::AssetId& /*sliceAssetId*/, [[maybe_unused]] const AZ::SliceComponent::SliceInstanceAddress& sliceAddress)
     {
diff --git a/Gems/LmbrCentral/Code/Source/Scripting/SpawnerComponent.h b/Gems/LmbrCentral/Code/Source/Scripting/SpawnerComponent.h
index 3dee332df3..75f5db8df2 100644
--- a/Gems/LmbrCentral/Code/Source/Scripting/SpawnerComponent.h
+++ b/Gems/LmbrCentral/Code/Source/Scripting/SpawnerComponent.h
@@ -70,7 +70,8 @@ namespace LmbrCentral
         AZStd::vector<AzFramework::SliceInstantiationTicket> GetCurrentlySpawnedSlices() override;
         bool HasAnyCurrentlySpawnedSlices() override;
         AZStd::vector<AZ::EntityId> GetCurrentEntitiesFromSpawnedSlice(const AzFramework::SliceInstantiationTicket& ticket) override;
-        AZStd::vector<AZ::EntityId> GetAllCurrentlySpawnedEntities();
+        AZStd::vector<AZ::EntityId> GetAllCurrentlySpawnedEntities() override;
+        bool IsReadyToSpawn() override;
         //////////////////////////////////////////////////////////////////////////
 
         //////////////////////////////////////////////////////////////////////////
diff --git a/Gems/LmbrCentral/Code/include/LmbrCentral/Scripting/SpawnerComponentBus.h b/Gems/LmbrCentral/Code/include/LmbrCentral/Scripting/SpawnerComponentBus.h
index 6122a747f3..92ca003300 100644
--- a/Gems/LmbrCentral/Code/include/LmbrCentral/Scripting/SpawnerComponentBus.h
+++ b/Gems/LmbrCentral/Code/include/LmbrCentral/Scripting/SpawnerComponentBus.h
@@ -91,6 +91,9 @@ namespace LmbrCentral
         //! Note that spawning is not instant, if a slice hasn't finished spawning then none of its entities are returned.
         //! If an entity has been destroyed since it was spawned, its ID is not returned.
         virtual AZStd::vector<AZ::EntityId> GetAllCurrentlySpawnedEntities() = 0;
+
+        //! Returns whether or not the spawner is in a state that's ready to spawn.
+        virtual bool IsReadyToSpawn() = 0;
     };
 
     using SpawnerComponentRequestBus = AZ::EBus<SpawnerComponentRequests>;