S4: Correctly import supports on ground paths

distribution/changelog.txt

@@ -2,6 +2,7 @@
 ------------------------------------------------------------------------
 - Feature: [#25286] Footpath area dragging tool.
 - Feature: [#25379] Add an option to the command line screenshot function to draw debug segment heights.
+- Improved: [#25297] Paths on the ground in SV4/SC4 no longer block supports of the paths above.
 - Improved: [#25349] ‘Recent Messages’ window can now be fully themed.
 - Change: [#25089] Peep actions and animations that cause them to stop moving no longer trigger when they are on a level crossing.
 - Change: [#25337] Placing track designs with scenery that is obstructed no longer disables all of the scenery.

src/openrct2/rct1/S4Importer.cpp

@@ -74,6 +74,7 @@
 #include "../world/tile_element/EntranceElement.h"
 #include "../world/tile_element/LargeSceneryElement.h"
 #include "../world/tile_element/PathElement.h"
+#include "../world/tile_element/Slope.h"
 #include "../world/tile_element/SmallSceneryElement.h"
 #include "../world/tile_element/SurfaceElement.h"
 #include "../world/tile_element/TileElement.h"
@@ -1630,6 +1631,7 @@ namespace OpenRCT2::RCT1
 
             SetTileElements(gameState, std::move(tileElements));
             FixEntrancePositions(gameState);
+            FixSupportsOnGroundPath(gameState);
         }
 
         size_t ImportTileElement(TileElement* dst, const RCT12TileElement* src)
@@ -2549,6 +2551,39 @@ namespace OpenRCT2::RCT1
             }
         }
 
+        void FixSupportsOnGroundPath(GameState_t& gameState)
+        {
+            TileElementIterator it;
+            TileElementIteratorBegin(&it);
+            while (TileElementIteratorNext(&it))
+            {
+                if (it.element->GetType() != TileElementType::Path)
+                    continue;
+
+                auto* pathElement = it.element->AsPath();
+                if (pathElement->IsSloped())
+                    continue;
+
+                if (pathElement->IsQueue())
+                    continue;
+
+                auto* surface = MapGetSurfaceElementAt(TileCoordsXY(it.x, it.y));
+                if (surface == nullptr)
+                    continue;
+
+                if (surface->GetSlope() != kTileSlopeFlat)
+                    continue;
+
+                if (surface->GetBaseZ() != pathElement->GetBaseZ())
+                    continue;
+
+                // RCT1 would always draw supports around a path if it was flat on the ground.
+                // In RCT2, this depends on the support type of the path, even though that isn’t even visible in this case.
+                // As such, always import footpath that is on the ground with box supports.
+                pathElement->SetRailingsEntryIndex(RCT1_PATH_SUPPORT_TYPE_TRUSS);
+            }
+        }
+
         RCT12::EntryList* GetEntryList(ObjectType objectType)
         {
             switch (objectType)