Merge pull request #578 from aws-lumberyard-dev/hultonha_LYN-3496_whitebox_freezing

Fix for level loading hangs with White Box Component and Atom

Gems/WhiteBox/Code/Source/Asset/EditorWhiteBoxMeshAsset.cpp

@@ -181,6 +181,9 @@ namespace WhiteBox
         // disconnect from any previously connected asset id
         AZ::Data::AssetBus::Handler::BusDisconnect();
         WhiteBoxMeshAssetNotificationBus::Handler::BusDisconnect();
+
+        // ensure we're disconnected from the tick bus
+        AZ::TickBus::Handler::BusDisconnect();
     }
 
     void EditorWhiteBoxMeshAsset::Release()
@@ -215,11 +218,20 @@ namespace WhiteBox
         if (asset == m_meshAsset)
         {
             m_meshAsset = asset;
-            EditorWhiteBoxComponentRequestBus::Event(
-                m_entityComponentIdPair, &EditorWhiteBoxComponentRequestBus::Events::RebuildWhiteBox);
+
+            // defer rebuilding the mesh by a frame by connecting to the tick bus - this prevents issues
+            // with reentrancy when rebuilding the white box mesh
+            AZ::TickBus::Handler::BusConnect();
         }
     }
 
+    void EditorWhiteBoxMeshAsset::OnTick([[maybe_unused]] float deltaTime, [[maybe_unused]] AZ::ScriptTimePoint time)
+    {
+        // after rebuilding the white box mesh, immediately disconnect from the tick bus (we only use it for deferred rebuilding)
+        EditorWhiteBoxComponentRequestBus::Event(m_entityComponentIdPair, &EditorWhiteBoxComponentRequestBus::Events::RebuildWhiteBox);
+        AZ::TickBus::Handler::BusDisconnect();
+    }
+
     void EditorWhiteBoxMeshAsset::OnAssetReloaded(AZ::Data::Asset<AZ::Data::AssetData> asset)
     {
         OnAssetReady(asset);

Gems/WhiteBox/Code/Source/Asset/EditorWhiteBoxMeshAsset.h

@@ -16,6 +16,7 @@
 #include "Asset/WhiteBoxMeshAssetBus.h"
 
 #include <AzCore/Component/ComponentBus.h>
+#include <AzCore/Component/TickBus.h>
 #include <IEditor.h>
 
 namespace WhiteBox
@@ -26,6 +27,7 @@ namespace WhiteBox
         : private AZ::Data::AssetBus::Handler
         , private WhiteBoxMeshAssetNotificationBus::Handler
         , private IEditorNotifyListener
+        , private AZ::TickBus::Handler
     {
     public:
         AZ_CLASS_ALLOCATOR_DECL
@@ -93,6 +95,9 @@ namespace WhiteBox
         //! Disconnect from buses/listeners before either releasing or destroying the asset.
         void Disconnect();
 
+        // AZ::TickBus overrides ...
+        void OnTick(float deltaTime, AZ::ScriptTimePoint time) override;
+
         // Listeners for legacy editor events when the level is saved.
         void RegisterForEditorEvents();
         void UnregisterForEditorEvents();

Gems/WhiteBox/Code/Source/Rendering/Atom/WhiteBoxAtomRenderMesh.cpp

@@ -120,9 +120,7 @@ namespace WhiteBox
         modelLodCreator.SetMeshAabb(meshData.GetAabb());
 
         // set the default material
-        auto materialAsset =
-            AZ::RPI::AssetUtils::LoadAssetByProductPath<AZ::RPI::MaterialAsset>(TexturedMaterialPath.data());
-        if (materialAsset)
+        if (auto materialAsset = AZ::RPI::AssetUtils::LoadAssetByProductPath<AZ::RPI::MaterialAsset>(TexturedMaterialPath.data()))
         {
             modelLodCreator.SetMeshMaterialAsset(materialAsset);
         }