Add railtype variable for adjacent crossing information

docs/newgrf-additions-nml.html

@@ -216,6 +216,17 @@
 			If there is no bridge above, the value is 0xFF.
 		</td>
 	</tr>
+	<tr><td>adjacent_crossing</td><td>bitmask(RAILTYPE_ADJACENT_CROSSING_XXX, ...)</td>
+		<td>
+			Adjacent level crossing information:
+			<dl>
+				<dt>SOUTH</dt>
+				<dd>This level crossing tile is part of a continuous adjacent crossing with the tile to the south (SW or SE)</dd>
+				<dt>NORTH</dt>
+				<dd>This level crossing tile is part of a continuous adjacent crossing with the tile to the north (NW or NE)</dd>
+			</dl>
+		</td>
+	</tr>
 	</table>
 	<h3 id="roadtype-properties"><a href="https://newgrf-specs.tt-wiki.net/wiki/NML:Roadtypes#Roadtype_properties">Roadtype properties</a></h3>
 	<table>

docs/newgrf-additions.html

@@ -872,6 +872,16 @@
 	</table>
 	</p>
 	<p>This is indicated by the feature name: <font face="monospace">varaction2_railtype_signal_vertical_clearance</font>, version 1</p>
+	<h4 id="railtype_adjacent_crossing">Adjacent level crossing information (mappable variable: railtype_adjacent_crossing)</h4>
+	<p>
+	<table>
+	<tr><th>Bit</th><th>Meaning</th></tr>
+	<tr><td>0</td><td>This level crossing tile is part of a continuous adjacent crossing with the tile to the south (SW or SE)</td></tr>
+	<tr><td>1</td><td>This level crossing tile is part of a continuous adjacent crossing with the tile to the north (NW or NE)</td></tr>
+	</table>
+	The value is 0 for non level crossing tiles.
+	</p>
+	<p>This is indicated by the feature name: <font face="monospace">varaction2_railtype_adjacent_crossing</font>, version 1</p>
 	<br />
 	<h3 id="varaction2_object"><a href="https://newgrf-specs.tt-wiki.net/wiki/VariationalAction2/Objects">Variational Action 2 - Objects</a></h3>
 	<h4 id="object_foundation_tile_slope">Tile slope after foundation applied (mappable variable: object_foundation_tile_slope)</h4>

src/newgrf_extension.cpp

@@ -44,6 +44,7 @@ extern const GRFFeatureInfo _grf_feature_list[] = {
 	GRFFeatureInfo("varaction2_railtype_signal_context", 1),
 	GRFFeatureInfo("varaction2_railtype_signal_side", 1),
 	GRFFeatureInfo("varaction2_railtype_signal_vertical_clearance", 1),
+	GRFFeatureInfo("varaction2_railtype_adjacent_crossing", 1),
 	GRFFeatureInfo("action0_global_extra_station_names", 2),
 	GRFFeatureInfo("action0_global_default_object_generate_amount", 1),
 	GRFFeatureInfo("action0_global_allow_rocks_in_desert", 1),
@@ -175,6 +176,7 @@ extern const GRFVariableMapDefinition _grf_action2_remappable_variables[] = {
 	GRFVariableMapDefinition(GSF_RAILTYPES, A2VRI_RAILTYPE_SIGNAL_CONTEXT, "railtype_signal_context"),
 	GRFVariableMapDefinition(GSF_RAILTYPES, A2VRI_RAILTYPE_SIGNAL_SIDE, "railtype_signal_side"),
 	GRFVariableMapDefinition(GSF_RAILTYPES, A2VRI_RAILTYPE_SIGNAL_VERTICAL_CLEARANCE, "railtype_signal_vertical_clearance"),
+	GRFVariableMapDefinition(GSF_RAILTYPES, A2VRI_RAILTYPE_ADJACENT_CROSSING, "railtype_adjacent_crossing"),
 	GRFVariableMapDefinition(GSF_SIGNALS, A2VRI_SIGNALS_SIGNAL_RESTRICTION_INFO, "signals_signal_restriction_info"),
 	GRFVariableMapDefinition(GSF_SIGNALS, A2VRI_SIGNALS_SIGNAL_CONTEXT, "signals_signal_context"),
 	GRFVariableMapDefinition(GSF_SIGNALS, A2VRI_SIGNALS_SIGNAL_STYLE, "signals_signal_style"),

src/newgrf_extension.h

@@ -86,6 +86,7 @@ enum Action2VariableRemapIds {
 	A2VRI_RAILTYPE_SIGNAL_CONTEXT,
 	A2VRI_RAILTYPE_SIGNAL_SIDE,
 	A2VRI_RAILTYPE_SIGNAL_VERTICAL_CLEARANCE,
+	A2VRI_RAILTYPE_ADJACENT_CROSSING,
 	A2VRI_SIGNALS_SIGNAL_RESTRICTION_INFO,
 	A2VRI_SIGNALS_SIGNAL_CONTEXT,
 	A2VRI_SIGNALS_SIGNAL_STYLE,

src/newgrf_optimiser.cpp

@@ -108,6 +108,7 @@ static bool IsExpensiveRailtypeVariable(uint16 variable)
 {
 	switch (variable) {
 		case A2VRI_RAILTYPE_SIGNAL_VERTICAL_CLEARANCE:
+		case A2VRI_RAILTYPE_ADJACENT_CROSSING:
 			return true;
 
 		default:

src/newgrf_railtype.cpp

@@ -17,6 +17,7 @@
 #include "depot_base.h"
 #include "town.h"
 #include "signal_func.h"
+#include "road.h"
 
 #include "safeguards.h"
 
@@ -39,6 +40,7 @@
 			case A2VRI_RAILTYPE_SIGNAL_CONTEXT: return this->signal_context;
 			case A2VRI_RAILTYPE_SIGNAL_SIDE: return GetNewSignalsSideVariable();
 			case A2VRI_RAILTYPE_SIGNAL_VERTICAL_CLEARANCE: return 0xFF;
+			case A2VRI_RAILTYPE_ADJACENT_CROSSING: return 0;
 		}
 	}
 
@@ -66,6 +68,31 @@
 			return GetNewSignalsSideVariable();
 		case A2VRI_RAILTYPE_SIGNAL_VERTICAL_CLEARANCE:
 			return GetNewSignalsVerticalClearanceInfo(this->tile, this->z);
+		case A2VRI_RAILTYPE_ADJACENT_CROSSING: {
+			if (!IsLevelCrossingTile(this->tile) || !_settings_game.vehicle.adjacent_crossings) return 0;
+
+			auto is_usable_crossing = [&](TileIndex t) -> bool {
+				if (HasRoadTypeRoad(t) && !HasBit(_roadtypes_non_train_colliding, GetRoadTypeRoad(t))) return true;
+				if (HasRoadTypeTram(t) && !HasBit(_roadtypes_non_train_colliding, GetRoadTypeTram(t))) return true;
+				return false;
+			};
+			if (!is_usable_crossing(this->tile)) return 0;
+
+			const Axis axis = GetCrossingRoadAxis(this->tile);
+			const DiagDirection dir_s = AxisToDiagDir(axis);
+			const DiagDirection dir_n = ReverseDiagDir(dir_s);
+
+			uint32 result = 0;
+			auto test_dir = [&](DiagDirection dir, uint bit) {
+				const TileIndex t = TileAddByDiagDir(this->tile, dir);
+				if (t < MapSize() && IsLevelCrossingTile(t) && GetCrossingRoadAxis(t) == axis && is_usable_crossing(t)) {
+					SetBit(result, bit);
+				}
+			};
+			test_dir(dir_s, 0);
+			test_dir(dir_n, 1);
+			return result;
+		}
 	}
 
 	DEBUG(grf, 1, "Unhandled rail type tile variable 0x%X", variable);

src/table/newgrf_debug_data.h

@@ -1599,6 +1599,7 @@ static const NIVariable _niv_railtypes[] = {
 	NIV(0x42, "level crossing status"),
 	NIV(0x43, "construction date"),
 	NIV(0x44, "town zone"),
+	NIV(A2VRI_RAILTYPE_ADJACENT_CROSSING, "adjacent crossing"),
 	NIV_END()
 };