Fix bridges not being redrawn after all signals reset when cleared

src/bridge_map.cpp

@@ -107,17 +107,22 @@ void SetBridgeEntranceSimulatedSignalStateExtended(TileIndex t, uint16 signal, S
 	_m[t].m2 |= BRIDGE_M2_SIGNAL_STATE_EXT_FLAG;
 }
 
-void SetAllBridgeEntranceSimulatedSignalsGreenExtended(TileIndex t)
+bool SetAllBridgeEntranceSimulatedSignalsGreenExtended(TileIndex t)
 {
+	bool changed = GB(_m[t].m2, BRIDGE_M2_SIGNAL_STATE_OFFSET, BRIDGE_M2_SIGNAL_STATE_COUNT) != 0;
 	SB(_m[t].m2, BRIDGE_M2_SIGNAL_STATE_OFFSET, BRIDGE_M2_SIGNAL_STATE_FIELD_SIZE, 0);
 	auto it = _long_bridge_signal_sim_map.find(t);
 	if (it != _long_bridge_signal_sim_map.end()) {
 		LongBridgeSignalStorage &lbss = it->second;
 		for (auto &it : lbss.signal_red_bits) {
-			it = 0;
+			if (it != 0) {
+				changed = true;
+				it = 0;
+			}
 		}
 		_m[t].m2 |= BRIDGE_M2_SIGNAL_STATE_EXT_FLAG;
 	}
+	return changed;
 }
 
 void ClearBridgeEntranceSimulatedSignalsExtended(TileIndex t)

src/bridge_signal_map.h

@@ -53,14 +53,16 @@ static inline void SetBridgeEntranceSimulatedSignalState(TileIndex t, uint16 sig
 	}
 }
 
-void SetAllBridgeEntranceSimulatedSignalsGreenExtended(TileIndex t);
+bool SetAllBridgeEntranceSimulatedSignalsGreenExtended(TileIndex t);
 
-static inline void SetAllBridgeEntranceSimulatedSignalsGreen(TileIndex t)
+static inline bool SetAllBridgeEntranceSimulatedSignalsGreen(TileIndex t)
 {
 	if (_m[t].m2 & BRIDGE_M2_SIGNAL_STATE_EXT_FLAG) {
-		SetAllBridgeEntranceSimulatedSignalsGreenExtended(t);
+		return SetAllBridgeEntranceSimulatedSignalsGreenExtended(t);
 	} else {
+		bool changed = GB(_m[t].m2, BRIDGE_M2_SIGNAL_STATE_OFFSET, BRIDGE_M2_SIGNAL_STATE_FIELD_SIZE) != 0;
 		SB(_m[t].m2, BRIDGE_M2_SIGNAL_STATE_OFFSET, BRIDGE_M2_SIGNAL_STATE_FIELD_SIZE, 0);
+		return changed;
 	}
 }
 

src/train_cmd.cpp

@@ -2763,8 +2763,14 @@ static void HandleLastTunnelBridgeSignals(TileIndex tile, TileIndex end, DiagDir
 	if (free) {
 	/* Open up the wormhole and clear m2. */
 		if (IsBridge(end)) {
-			if (IsTunnelBridgeSignalSimulationEntrance(tile)) SetAllBridgeEntranceSimulatedSignalsGreen(tile);
-			if (IsTunnelBridgeSignalSimulationEntrance(end)) SetAllBridgeEntranceSimulatedSignalsGreen(end);
+			bool redraw = false;
+			if (IsTunnelBridgeSignalSimulationEntrance(tile)) {
+				redraw |= SetAllBridgeEntranceSimulatedSignalsGreen(tile);
+			}
+			if (IsTunnelBridgeSignalSimulationEntrance(end)) {
+				redraw |= SetAllBridgeEntranceSimulatedSignalsGreen(end);
+			}
+			if (redraw) MarkBridgeDirty(tile, end, GetTunnelBridgeDirection(tile), GetBridgeHeight(tile), VMDF_NOT_MAP_MODE);
 		}
 
 		if (IsTunnelBridgeSignalSimulationEntrance(end) && GetTunnelBridgeEntranceSignalState(end) == SIGNAL_STATE_RED) {