Fix #19434, #19509: OpenRCT2 object types not removed by ‘remove_unused_objects’ (#19511)

* Add ObjectTypeIsTransient() and ObjectTypeIsIntransient()

* Fix #19434, #19509: remove_unused_objects does not remove OpenRCT2 types

distribution/changelog.txt

@@ -54,6 +54,7 @@
 - Fix: [#19379] “No platforms” station style shows platforms on the Junior Roller Coaster.
 - Fix: [#19380] Startup crash when no sequences are installed and random sequences are enabled.
 - Fix: [#19391] String corruption caused by an improper buffer handling in ‘GfxWrapString’.
+- Fix: [#19434, #19509] Object types added by OpenRCT2 do not get removed when executing ‘remove_unused_objects’.
 - Fix: [#19475] Cannot increase loan when more than £1000 in debt.
 - Fix: [#19493] SV4 saves not importing the correct vehicle colours.
 - Fix: [#19517] Crash when peeps try to exit or enter hacked rides that have no waypoints specified.

src/openrct2/EditorObjectSelectionSession.cpp

@@ -671,11 +671,13 @@ int32_t EditorRemoveUnusedObjects()
             {
                 const ObjectRepositoryItem* item = &items[i];
                 ObjectType objectType = item->Type;
-
-                if (objectType >= ObjectType::SceneryGroup)
-                {
+                if (ObjectTypeIsIntransient(objectType))
+                    continue;
+
+                // These object types require exactly one object to be selected at all times.
+                // Removing that object can badly break the game state.
+                if (objectType == ObjectType::ParkEntrance || objectType == ObjectType::Water)
                     continue;
-                }
 
                 _numSelectedObjectsForType[EnumValue(objectType)]--;
                 _objectSelectionFlags[i] &= ~ObjectSelectionFlags::Selected;

src/openrct2/libopenrct2.vcxproj

@@ -814,6 +814,7 @@
     <ClCompile Include="object\ObjectList.cpp" />
     <ClCompile Include="object\ObjectManager.cpp" />
     <ClCompile Include="object\ObjectRepository.cpp" />
+    <ClCompile Include="object\ObjectTypes.cpp" />
     <ClCompile Include="object\ResourceTable.cpp" />
     <ClCompile Include="object\RideObject.cpp" />
     <ClCompile Include="object\SceneryGroupObject.cpp" />

src/openrct2/object/ObjectTypes.cpp

@@ -0,0 +1,22 @@
+/*****************************************************************************
+ * Copyright (c) 2014-2023 OpenRCT2 developers
+ *
+ * For a complete list of all authors, please refer to contributors.md
+ * Interested in contributing? Visit https://github.com/OpenRCT2/OpenRCT2
+ *
+ * OpenRCT2 is licensed under the GNU General Public License version 3.
+ *****************************************************************************/
+
+#include "ObjectTypes.h"
+
+#include <algorithm>
+
+bool ObjectTypeIsTransient(ObjectType type)
+{
+    return std::find(TransientObjectTypes.begin(), TransientObjectTypes.end(), type) != std::end(TransientObjectTypes);
+}
+
+bool ObjectTypeIsIntransient(ObjectType type)
+{
+    return std::find(IntransientObjectTypes.begin(), IntransientObjectTypes.end(), type) != std::end(IntransientObjectTypes);
+}

src/openrct2/object/ObjectTypes.h

@@ -72,3 +72,9 @@ constexpr std::array<ObjectType, 16> TransientObjectTypes = {
     ObjectType::ParkEntrance, ObjectType::Water,        ObjectType::TerrainSurface,  ObjectType::TerrainEdge,
     ObjectType::Station,      ObjectType::Music,        ObjectType::FootpathSurface, ObjectType::FootpathRailings,
 };
+
+// Object types that cannot be saved in a park file.
+constexpr std::array<ObjectType, 2> IntransientObjectTypes = { ObjectType::ScenarioText, ObjectType::Audio };
+
+bool ObjectTypeIsTransient(ObjectType type);
+bool ObjectTypeIsIntransient(ObjectType type);