Merge pull request #23459 from Gymnasiast/fix/1122

Fix #1122: Trains can spawn on cable lift hill

distribution/changelog.txt

@@ -5,6 +5,7 @@
 - Improved: [#23404] Folders are now paired with an icon in the load/save window.
 - Improved: [#23431] Opaque water and Corkscrew Roller Coaster boosters now show up if RCT1 isn’t linked. 
 - Change: [#23413] The max number of park entrance objects has been raised to 255.
+- Fix: [#1122] Trains spawned on a cable lift hill will fall down and crash (original bug).
 - Fix: [#22742, #22793] In game console does not handle format tokens properly.
 - Fix: [#23286] Currency formatted incorrectly in the in game console.
 - Fix: [#23348] Console set commands don't print output properly.

src/openrct2/network/NetworkBase.cpp

@@ -50,7 +50,7 @@ using namespace OpenRCT2;
 // It is used for making sure only compatible builds get connected, even within
 // single OpenRCT2 version.
 
-constexpr uint8_t kNetworkStreamVersion = 2;
+constexpr uint8_t kNetworkStreamVersion = 3;
 
 const std::string kNetworkStreamID = std::string(OPENRCT2_VERSION) + "-" + std::to_string(kNetworkStreamVersion);
 

src/openrct2/ride/Ride.cpp

@@ -3666,6 +3666,23 @@ ResultWithMessage Ride::CreateVehicles(const CoordsXYE& element, bool isApplying
  */
 void Ride::MoveTrainsToBlockBrakes(const CoordsXYZ& firstBlockPosition, TrackElement& firstBlock)
 {
+    // If the ride has a cable lift, we don't want to fetch the cable lift element and the block preceding it
+    TrackElement* cableLiftTileElement = nullptr;
+    TrackElement* cableLiftPreviousBlock = nullptr;
+    if (lifecycle_flags & RIDE_LIFECYCLE_CABLE_LIFT_HILL_COMPONENT_USED)
+    {
+        cableLiftTileElement = MapGetTrackElementAt(CableLiftLoc);
+        if (cableLiftTileElement != nullptr)
+        {
+            cableLiftTileElement = MapGetTrackElementAt(CableLiftLoc);
+            if (cableLiftTileElement != nullptr)
+            {
+                CoordsXYZ location = CableLiftLoc;
+                cableLiftPreviousBlock = TrackGetPreviousBlock(location, reinterpret_cast<TileElement*>(cableLiftTileElement));
+            }
+        }
+    }
+
     for (int32_t i = 0; i < NumTrains; i++)
     {
         auto train = GetEntity<Vehicle>(vehicles[i]);
@@ -3695,6 +3712,14 @@ void Ride::MoveTrainsToBlockBrakes(const CoordsXYZ& firstBlockPosition, TrackEle
                 break;
             }
 
+            // Setting the first block before the cable lift to the same state as the cable lift ensures that any train which
+            // would be placed on the cable lift will instead stop on the block before it. As there can only be one cable lift
+            // per ride and there must always be at least one block left free, there will be enough blocks remaining. This fixes
+            // the bug in #1122.
+            if (cableLiftTileElement != nullptr && cableLiftPreviousBlock != nullptr)
+            {
+                cableLiftPreviousBlock->SetBrakeClosed(cableLiftTileElement->IsBrakeClosed());
+            }
             firstBlock.SetBrakeClosed(true);
             for (Vehicle* car = train; car != nullptr; car = GetEntity<Vehicle>(car->next_vehicle_on_train))
             {
@@ -3722,6 +3747,12 @@ void Ride::MoveTrainsToBlockBrakes(const CoordsXYZ& firstBlockPosition, TrackEle
             }
         }
     }
+
+    // After all trains are in position, set the block preceding the cable lift to open.
+    if (cableLiftPreviousBlock != nullptr)
+    {
+        cableLiftPreviousBlock->SetBrakeClosed(false);
+    }
 }
 
 /**

src/openrct2/ride/Track.cpp

@@ -523,6 +523,58 @@ void TrackGetFront(const CoordsXYE& input, CoordsXYE* output)
     *output = lastTrack;
 }
 
+TrackElement* TrackGetPreviousBlock(CoordsXYZ& location, TileElement* tileElement)
+{
+    CoordsXYZ startLocation = location;
+    TrackBeginEnd trackBeginEnd, slowTrackBeginEnd;
+    TileElement slowTileElement = *tileElement;
+    bool counter = true;
+    CoordsXY slowLocation = location;
+    do
+    {
+        if (!TrackBlockGetPrevious({ location, tileElement }, &trackBeginEnd))
+        {
+            return nullptr;
+        }
+        if (trackBeginEnd.begin_x == startLocation.x && trackBeginEnd.begin_y == startLocation.y
+            && tileElement == trackBeginEnd.begin_element)
+        {
+            return nullptr;
+        }
+
+        location.x = trackBeginEnd.end_x;
+        location.y = trackBeginEnd.end_y;
+        location.z = trackBeginEnd.begin_z;
+        tileElement = trackBeginEnd.begin_element;
+
+        // #2081: prevent infinite loop
+        counter = !counter;
+        if (counter)
+        {
+            TrackBlockGetPrevious({ slowLocation, &slowTileElement }, &slowTrackBeginEnd);
+            slowLocation.x = slowTrackBeginEnd.end_x;
+            slowLocation.y = slowTrackBeginEnd.end_y;
+            slowTileElement = *(slowTrackBeginEnd.begin_element);
+            if (slowLocation == location && slowTileElement.GetBaseZ() == tileElement->GetBaseZ()
+                && slowTileElement.GetType() == tileElement->GetType()
+                && slowTileElement.GetDirection() == tileElement->GetDirection())
+            {
+                return nullptr;
+            }
+        }
+    } while (!(trackBeginEnd.begin_element->AsTrack()->IsBlockStart()));
+
+    // Get the start of the track block instead of the end
+    location = { trackBeginEnd.begin_x, trackBeginEnd.begin_y, trackBeginEnd.begin_z };
+    auto trackOrigin = MapGetTrackElementAtOfTypeSeq(location, trackBeginEnd.begin_element->AsTrack()->GetTrackType(), 0);
+    if (trackOrigin == nullptr)
+    {
+        return nullptr;
+    }
+
+    return trackOrigin->AsTrack();
+}
+
 TrackRoll TrackGetActualBank(TileElement* tileElement, TrackRoll bank)
 {
     auto ride = GetRide(tileElement->AsTrack()->GetRideIndex());

src/openrct2/ride/Track.h

@@ -702,6 +702,8 @@ bool TrackCircuitIteratorsMatch(const TrackCircuitIterator* firstIt, const Track
 void TrackGetBack(const CoordsXYE& input, CoordsXYE* output);
 void TrackGetFront(const CoordsXYE& input, CoordsXYE* output);
 
+TrackElement* TrackGetPreviousBlock(CoordsXYZ& location, TileElement* tileElement);
+
 bool TrackElementIsCovered(OpenRCT2::TrackElemType trackElementType);
 OpenRCT2::TrackElemType UncoverTrackElement(OpenRCT2::TrackElemType trackElementType);
 bool TrackTypeIsStation(OpenRCT2::TrackElemType trackType);