Add airport tile variables to get airport type local ID and layout

docs/newgrf-additions-nml.html

@@ -45,6 +45,7 @@
 	<li><a href="#object-ids">Object IDs</a></li>
 	<li><a href="#object-properties">Object properties</a></li>
 	<li><a href="#object-variables">Object variables</a></li>
+	<li><a href="#airport-tile-variables">Airport tile variables</a></li>
 	<li><a href="#global-variable-properties">Global variables properties</a></li>
 	<li><a href="#replace-new-sprites">Replace new sprites</a></li>
 	<li><a href="#signal-graphics">Signal graphics using switches</a></li>
@@ -382,6 +383,17 @@
 		This is useful for xoring with the tile_slope variable, because if this variable is unavailable then the result is still the underlying tile slope.
 	</td></tr>
 	</table>
+	<h3 id="airport-tile-variables"><a href="https://newgrf-specs.tt-wiki.net/wiki/NML:Airports#Airport_tile_variables">Airport tile variables</a></h3>
+	<p>Variables in the table below which are not supported by the version of OpenTTD being used return a value of 0.</p>
+	<table>
+	<tr><th>Variable</th><th>Value range</th><th>Comment</th></tr>
+	<tr><td>airport_id</td><td>0..255</td><td>
+		Local GRF ID of the airport type.
+	</td></tr>
+	<tr><td>airport_layout</td><td>0..255</td><td>
+		Airport layout number (as defined in layouts).
+	</td></tr>
+	</table>
 	<h3 id="global-variable-properties">Global variables properties</h3>
 	<p>The variables listed below should set inside an item and property block of the form:<pre class="code">
 item (FEAT_GLOBALVARS) {

docs/newgrf-additions.html

@@ -52,6 +52,7 @@
 	<li><a href="#varaction2_station">Variational Action 2 - Stations</a></li>
 	<li><a href="#varaction2_railtypes">Variational Action 2 - Railtypes</a></li>
 	<li><a href="#varaction2_object">Variational Action 2 - Objects</a></li>
+	<li><a href="#varaction2_airporttiles">Variational Action 2 - Airport tiles</a></li>
 	<li><a href="#varaction2_signals">Variational Action 2 - Signals (Feature 0E)</a></li>
 	<li><a href="#callbacks_ships">Callbacks - Ships</a></li>
 	<li><a href="#a3objects">Action 3 - Objects</a></li>
@@ -882,6 +883,14 @@
 	This is useful for xoring with bits 8-12 of variable 41, because if this variable is unavailable then the result is still the underlying tile slope.</p>
 	<p>This is indicated by the feature name: <font face="monospace">action0_object_edge_foundation_mode</font>, version 2</p>
 	<br />
+	<h3 id="varaction2_airporttiles"><a href="https://newgrf-specs.tt-wiki.net/wiki/VariationalAction2/Airport_Tiles">Variational Action 2 - Airport Tiles</a></h3>
+	<h4 id="airporttiles_airport_id">Airport ID (mappable variable: airporttiles_airport_id)</h4>
+	<p>This is the local GRF ID of the airport type.</p>
+	<p>This is indicated by the feature name: <font face="monospace">varaction2_airporttiles_airport_info</font>, version 1</p>
+	<h4 id="airporttiles_airport_layout">Airport layout number (mappable variable: airporttiles_airport_layout)</h4>
+	<p>This is the airport layout number (as defined in <a href="https://newgrf-specs.tt-wiki.net/wiki/Action0/Airports#Set_airportlayout.28s.29_.280A.29">airport property 0A</a>).</p>
+	<p>This is indicated by the feature name: <font face="monospace">varaction2_airporttiles_airport_info</font>, version 1</p>
+	<br />
 	<h3 id="varaction2_signals"><a href="https://newgrf-specs.tt-wiki.net/wiki/VariationalAction2">Variational Action 2 - Signals (Feature 0E)</a></h3>
 	<h4 id="signals_signal_restriction_info">Signal routing restriction information (mappable variable: signals_signal_restriction_info)</h4>
 	<p>This applies to <a href="#a3signals_custom_signal_sprites">Action 2/3 Signals (Feature 0E) custom signal sprites</a>.<br />

src/newgrf_airporttiles.cpp

@@ -10,6 +10,7 @@
 #include "stdafx.h"
 #include "debug.h"
 #include "newgrf_airporttiles.h"
+#include "newgrf_extension.h"
 #include "newgrf_spritegroup.h"
 #include "newgrf_sound.h"
 #include "station_base.h"
@@ -192,6 +193,12 @@ static uint32 GetAirportTileIDAtOffset(TileIndex tile, const Station *st, uint32
 
 		/* Get airport tile ID at offset */
 		case 0x62: return GetAirportTileIDAtOffset(GetNearbyTile(parameter, this->tile), this->st, this->ro.grffile->grfid);
+
+		case A2VRI_AIRPORTTILES_AIRPORT_LAYOUT:
+			return this->st->airport.layout;
+
+		case A2VRI_AIRPORTTILES_AIRPORT_ID:
+			return this->st->airport.GetSpec()->grf_prop.local_id;
 	}
 
 	DEBUG(grf, 1, "Unhandled airport tile variable 0x%X", variable);

src/newgrf_extension.cpp

@@ -61,6 +61,7 @@ extern const GRFFeatureInfo _grf_feature_list[] = {
 	GRFFeatureInfo("action0_object_edge_foundation_mode", 2),
 	GRFFeatureInfo("action0_object_flood_resistant", 1),
 	GRFFeatureInfo("action0_object_viewport_map_tile_type", 1),
+	GRFFeatureInfo("varaction2_airporttiles_airport_info", 1),
 	GRFFeatureInfo("road_stops", 9, GFTOF_ROAD_STOPS),
 	GRFFeatureInfo("new_landscape", 2),
 	GRFFeatureInfo("more_objects_per_grf", 1),
@@ -179,6 +180,8 @@ extern const GRFVariableMapDefinition _grf_action2_remappable_variables[] = {
 	GRFVariableMapDefinition(GSF_SIGNALS, A2VRI_SIGNALS_SIGNAL_STYLE, "signals_signal_style"),
 	GRFVariableMapDefinition(GSF_SIGNALS, A2VRI_SIGNALS_SIGNAL_SIDE, "signals_signal_side"),
 	GRFVariableMapDefinition(GSF_SIGNALS, A2VRI_SIGNALS_SIGNAL_VERTICAL_CLEARANCE, "signals_signal_vertical_clearance"),
+	GRFVariableMapDefinition(GSF_AIRPORTTILES, A2VRI_AIRPORTTILES_AIRPORT_LAYOUT, "airporttiles_airport_layout"),
+	GRFVariableMapDefinition(GSF_AIRPORTTILES, A2VRI_AIRPORTTILES_AIRPORT_ID, "airporttiles_airport_id"),
 	GRFVariableMapDefinition(GSF_FAKE_TOWNS, A2VRI_TOWNS_HOUSE_COUNT, "town_house_count"),
 	GRFVariableMapDefinition(GSF_FAKE_TOWNS, A2VRI_TOWNS_POPULATION, "town_population"),
 	GRFVariableMapDefinition(GSF_FAKE_TOWNS, A2VRI_TOWNS_ZONE_0, "town_zone_0_radius_square"),

src/newgrf_extension.h

@@ -91,6 +91,8 @@ enum Action2VariableRemapIds {
 	A2VRI_SIGNALS_SIGNAL_STYLE,
 	A2VRI_SIGNALS_SIGNAL_SIDE,
 	A2VRI_SIGNALS_SIGNAL_VERTICAL_CLEARANCE,
+	A2VRI_AIRPORTTILES_AIRPORT_LAYOUT,
+	A2VRI_AIRPORTTILES_AIRPORT_ID,
 	A2VRI_TOWNS_HOUSE_COUNT,
 	A2VRI_TOWNS_POPULATION,
 	A2VRI_TOWNS_ZONE_0,

src/table/newgrf_debug_data.h

@@ -1702,6 +1702,19 @@ static const NICallback _nic_airporttiles[] = {
 	NIC_END()
 };
 
+static const NIVariable _niv_airporttiles[] = {
+	NIV(0x41, "ground type"),
+	NIV(0x42, "current town zone in nearest town"),
+	NIV(0x43, "relative position"),
+	NIV(0x44, "animation frame"),
+	NIV(0x60, "land info of nearby tiles"),
+	NIV(0x61, "animation stage of nearby tiles"),
+	NIV(0x62, "get industry or airport tile ID at offset"),
+	NIV(A2VRI_AIRPORTTILES_AIRPORT_LAYOUT, "airport layout"),
+	NIV(A2VRI_AIRPORTTILES_AIRPORT_ID, "airport local ID"),
+	NIV_END()
+};
+
 class NIHAirportTile : public NIHelper {
 	bool IsInspectable(uint index) const override        { return AirportTileSpec::Get(GetAirportGfx(index))->grf_prop.grffile != nullptr; }
 	uint GetParent(uint index) const override            { return GetTownInspectWindowNumber(Station::GetByTile(index)->town); }
@@ -1733,7 +1746,7 @@ class NIHAirportTile : public NIHelper {
 static const NIFeature _nif_airporttile = {
 	nullptr,
 	_nic_airporttiles,
-	_niv_industrytiles, // Yes, they share this (at least now)
+	_niv_airporttiles,
 	new NIHAirportTile(),
 };