From f9a06ae01b0d01a0258a5615aec5fbd5ccaeedac Mon Sep 17 00:00:00 2001
From: Michael Steenbeek <1478678+Gymnasiast@users.noreply.github.com>
Date: Fri, 21 Jun 2024 20:50:15 +0200
Subject: [PATCH] Fix #21496: RCT1 scenery hidden after reloading (#22181)

---
 distribution/changelog.txt     |  1 +
 src/openrct2/world/Scenery.cpp | 69 +++++++++++++++++++++++-----------
 2 files changed, 48 insertions(+), 22 deletions(-)

diff --git a/distribution/changelog.txt b/distribution/changelog.txt
index 4b9927f87f..2a4fc131f9 100644
--- a/distribution/changelog.txt
+++ b/distribution/changelog.txt
@@ -30,6 +30,7 @@
 - Fix: [#13234] Vehicle weight sometimes wrong after using Remove All Guests cheat.
 - Fix: [#13294] Map corners are cut off in some directions (original bug).
 - Fix: [#14630] Non-ASCII thousands and decimal separators not processed correctly.
+- Fix: [#21496] Some RCT1 scenery is hidden after saving and reloading.
 - Fix: [#21974] No reason specified when attempting to place benches, lamps, or bins on path with no unconnected edges (original bug).
 - Fix: [#21987] [Plugin] API cannot handle negative removal prices.
 - Fix: [#22008] Uninverted Lay-down roller coaster uses the wrong support type.
diff --git a/src/openrct2/world/Scenery.cpp b/src/openrct2/world/Scenery.cpp
index 86418f2e83..73ed9b9424 100644
--- a/src/openrct2/world/Scenery.cpp
+++ b/src/openrct2/world/Scenery.cpp
@@ -425,17 +425,26 @@ bool ObjectTypeCanBeRestricted(ObjectType objectType)
     }
 }
 
-static std::vector<ScenerySelection> GetAllMiscScenery()
+struct MiscScenery
 {
-    std::vector<ScenerySelection> miscScenery;
-    std::vector<ScenerySelection> nonMiscScenery;
+    // Scenery that will end up on the ‘?’ tab
+    std::vector<ScenerySelection> miscScenery{};
+    // Scenery that has attached itself to an existing group, but is not referenced directly.
+    std::vector<ScenerySelection> additionalGroupScenery{};
+};
+
+static MiscScenery GetAllMiscScenery()
+{
+    MiscScenery ret;
+    std::vector<ScenerySelection> referencedBySceneryGroups;
     std::vector<ObjectEntryIndex> sceneryGroupIds;
     for (ObjectEntryIndex i = 0; i < MAX_SCENERY_GROUP_OBJECTS; i++)
     {
         const auto* sgEntry = OpenRCT2::ObjectManager::GetObjectEntry<SceneryGroupEntry>(i);
         if (sgEntry != nullptr)
         {
-            nonMiscScenery.insert(nonMiscScenery.end(), sgEntry->SceneryEntries.begin(), sgEntry->SceneryEntries.end());
+            referencedBySceneryGroups.insert(
+                referencedBySceneryGroups.end(), sgEntry->SceneryEntries.begin(), sgEntry->SceneryEntries.end());
             sceneryGroupIds.emplace_back(i);
         }
     }
@@ -487,50 +496,66 @@ static std::vector<ScenerySelection> GetAllMiscScenery()
                     break;
             }
 
-            // An object may be link itself against a scenery group, in which case it should not be marked as miscellaneous.
+            const ScenerySelection sceneryItem = { sceneryType, i };
+            if (!IsSceneryEntryValid(sceneryItem))
+                continue;
+
+            const bool isReferencedBySceneryGroup = std::find(
+                                                        std::begin(referencedBySceneryGroups),
+                                                        std::end(referencedBySceneryGroups), sceneryItem)
+                != std::end(referencedBySceneryGroups);
+            if (isReferencedBySceneryGroup)
+                continue;
+
+            // An object may link itself against a scenery group, in which case it should not be marked as miscellaneous.
+            bool isLinkedToKnownSceneryGroup = false;
             if (linkedSceneryGroup != OBJECT_ENTRY_INDEX_NULL)
             {
                 if (std::find(std::begin(sceneryGroupIds), std::end(sceneryGroupIds), linkedSceneryGroup)
                     != std::end(sceneryGroupIds))
                 {
-                    continue;
+                    isLinkedToKnownSceneryGroup = true;
                 }
             }
 
-            const ScenerySelection sceneryItem = { sceneryType, i };
-            if (IsSceneryEntryValid(sceneryItem))
-            {
-                if (std::find(std::begin(nonMiscScenery), std::end(nonMiscScenery), sceneryItem) == std::end(nonMiscScenery))
-                {
-                    miscScenery.push_back(sceneryItem);
-                }
-            }
+            if (isLinkedToKnownSceneryGroup)
+                ret.additionalGroupScenery.push_back(sceneryItem);
+            else
+                ret.miscScenery.push_back(sceneryItem);
         }
     }
-    return miscScenery;
+    return ret;
 }
 
 void RestrictAllMiscScenery()
 {
     auto& gameState = GetGameState();
-    auto miscScenery = GetAllMiscScenery();
+    auto miscScenery = GetAllMiscScenery().miscScenery;
     gameState.RestrictedScenery.insert(gameState.RestrictedScenery.begin(), miscScenery.begin(), miscScenery.end());
 }
 
-void MarkAllUnrestrictedSceneryAsInvented()
+static void MarkAllUnrestrictedSceneryInVectorInvented(const std::vector<ScenerySelection>& vector)
 {
-    auto& gameState = GetGameState();
-    auto miscScenery = GetAllMiscScenery();
-    for (const auto& sceneryItem : miscScenery)
+    auto& restrictedScenery = GetGameState().RestrictedScenery;
+
+    for (const auto& sceneryItem : vector)
     {
-        if (std::find(gameState.RestrictedScenery.begin(), gameState.RestrictedScenery.end(), sceneryItem)
-            == gameState.RestrictedScenery.end())
+        const bool isNotRestricted = std::find(restrictedScenery.begin(), restrictedScenery.end(), sceneryItem)
+            == restrictedScenery.end();
+        if (isNotRestricted)
         {
             ScenerySetInvented(sceneryItem);
         }
     }
 }
 
+void MarkAllUnrestrictedSceneryAsInvented()
+{
+    auto scenery = GetAllMiscScenery();
+    MarkAllUnrestrictedSceneryInVectorInvented(scenery.miscScenery);
+    MarkAllUnrestrictedSceneryInVectorInvented(scenery.additionalGroupScenery);
+}
+
 ObjectType GetObjectTypeFromSceneryType(uint8_t type)
 {
     switch (type)