From bc2e1302818ad77a5e0e874ea413414c8549510a Mon Sep 17 00:00:00 2001
From: Wojtek Figat <wojtek@figat.pl>
Date: Mon, 18 Dec 2023 21:43:13 +0100
Subject: [PATCH] Fix calling script `OnDestroy` when removing actors or
 scripts from the scene

---
 Source/Engine/Level/Actor.cpp      | 24 ++++++++++++++++++------
 Source/Engine/Scripting/Script.cpp | 28 ++++++++++++++++++++++------
 Source/Engine/Scripting/Script.h   |  1 +
 3 files changed, 41 insertions(+), 12 deletions(-)

diff --git a/Source/Engine/Level/Actor.cpp b/Source/Engine/Level/Actor.cpp
index 00ca485d2..bf544d9ad 100644
--- a/Source/Engine/Level/Actor.cpp
+++ b/Source/Engine/Level/Actor.cpp
@@ -206,10 +206,18 @@ void Actor::OnDeleteObject()
 #endif
     for (int32 i = 0; i < Scripts.Count(); i++)
     {
-        auto e = Scripts[i];
-        ASSERT(e->_parent == this);
-        e->_parent = nullptr;
-        e->DeleteObject();
+        auto script = Scripts[i];
+        ASSERT(script->_parent == this);
+        if (script->_wasAwakeCalled)
+        {
+            script->_wasAwakeCalled = false;
+            CHECK_EXECUTE_IN_EDITOR
+            {
+                script->OnDestroy();
+            }
+        }
+        script->_parent = nullptr;
+        script->DeleteObject();
     }
 #if BUILD_DEBUG
     ASSERT(callsCheck == Scripts.Count());
@@ -889,9 +897,13 @@ void Actor::EndPlay()
 
     for (auto* script : Scripts)
     {
-        CHECK_EXECUTE_IN_EDITOR
+        if (script->_wasAwakeCalled)
         {
-            script->OnDestroy();
+            script->_wasAwakeCalled = false;
+            CHECK_EXECUTE_IN_EDITOR
+            {
+                script->OnDestroy();
+            }
         }
     }
 
diff --git a/Source/Engine/Scripting/Script.cpp b/Source/Engine/Scripting/Script.cpp
index 8eaff42de..e9cc2a0a8 100644
--- a/Source/Engine/Scripting/Script.cpp
+++ b/Source/Engine/Scripting/Script.cpp
@@ -27,6 +27,7 @@ Script::Script(const SpawnParams& params)
     , _tickUpdate(false)
     , _tickLateUpdate(false)
     , _tickLateFixedUpdate(false)
+    , _wasAwakeCalled(false)
     , _wasStartCalled(false)
     , _wasEnableCalled(false)
 {
@@ -86,7 +87,7 @@ void Script::SetParent(Actor* value, bool canBreakPrefabLink)
     // Unlink from the old one
     if (_parent)
     {
-        if (!value && _parent->IsDuringPlay() && _parent->IsActiveInHierarchy() && GetEnabled())
+        if (!value && _parent->IsDuringPlay() && _parent->IsActiveInHierarchy() && GetEnabled() && _wasEnableCalled)
         {
             // Call disable when script is removed from actor (new actor is null)
             Disable();
@@ -241,19 +242,31 @@ String Script::ToString() const
 
 void Script::OnDeleteObject()
 {
-    // Ensure to unlink from the parent (it will call Disable event if required)
-    SetParent(nullptr);
-
-    // Check if remove object from game
-    if (IsDuringPlay())
+    // Call OnDisable
+    if (_wasEnableCalled)
     {
+        Disable();
+    }
+
+    // Call OnDestroy
+    if (_wasAwakeCalled)
+    {
+        _wasAwakeCalled = false;
         CHECK_EXECUTE_IN_EDITOR
         {
             OnDestroy();
         }
+    }
+
+    // End play
+    if (IsDuringPlay())
+    {
         EndPlay();
     }
 
+    // Unlink from parent
+    SetParent(nullptr);
+
     // Base
     SceneObject::OnDeleteObject();
 }
@@ -274,6 +287,9 @@ void Script::Initialize()
     if (!IsRegistered())
         RegisterObject();
 
+    // Call OnAwake
+    ASSERT(!_wasAwakeCalled);
+    _wasAwakeCalled = true;
     CHECK_EXECUTE_IN_EDITOR
     {
         OnAwake();
diff --git a/Source/Engine/Scripting/Script.h b/Source/Engine/Scripting/Script.h
index 8cf1d0670..919f3ecdd 100644
--- a/Source/Engine/Scripting/Script.h
+++ b/Source/Engine/Scripting/Script.h
@@ -20,6 +20,7 @@ protected:
     uint16 _tickUpdate : 1;
     uint16 _tickLateUpdate : 1;
     uint16 _tickLateFixedUpdate : 1;
+    uint16 _wasAwakeCalled : 1;
     uint16 _wasStartCalled : 1;
     uint16 _wasEnableCalled : 1;
 #if USE_EDITOR