(svn r20126) -Fix [FS#3883]: Make railtype Terrain Type variable aware of RAIL_GROUND_HALF_SNOW. That is, resolve the sprites for upper and lower part of the foundation independently.

7 files changed, 46 insertions, 18 deletions

diff --git a/src/elrail.cpp b/src/elrail.cpp
index 1474ff932..757790312 100644
--- a/src/elrail.cpp
+++ b/src/elrail.cpp
@@ -165,20 +165,20 @@ static TrackBits MaskWireBits(TileIndex t, TrackBits tracks)
 /**
  * Get the base wire sprite to use.
  */
-static inline SpriteID GetWireBase(TileIndex tile)
+static inline SpriteID GetWireBase(TileIndex tile, bool upper_halftile = false)
 {
 	const RailtypeInfo *rti = GetRailTypeInfo(GetRailType(tile));
-	SpriteID wires = GetCustomRailSprite(rti, tile, RTSG_WIRES);
+	SpriteID wires = GetCustomRailSprite(rti, tile, RTSG_WIRES, upper_halftile);
 	return wires == 0 ? SPR_WIRE_BASE : wires;
 }
 
 /**
  * Get the base pylon sprite to use.
  */
-static inline SpriteID GetPylonBase(TileIndex tile)
+static inline SpriteID GetPylonBase(TileIndex tile, bool upper_halftile = false)
 {
 	const RailtypeInfo *rti = GetRailTypeInfo(GetRailType(tile));
-	SpriteID pylons = GetCustomRailSprite(rti, tile, RTSG_PYLONS);
+	SpriteID pylons = GetCustomRailSprite(rti, tile, RTSG_PYLONS, upper_halftile);
 	return pylons == 0 ? SPR_PYLON_BASE : pylons;
 }
 
@@ -274,7 +274,11 @@ static void DrawCatenaryRailway(const TileInfo *ti)
 
 	/* Half tile slopes coincide only with horizontal/vertical track.
 	 * Faking a flat slope results in the correct sprites on positions. */
-	if (IsHalftileSlope(tileh[TS_HOME])) tileh[TS_HOME] = SLOPE_FLAT;
+	Corner halftile_corner = CORNER_INVALID;
+	if (IsHalftileSlope(tileh[TS_HOME])) {
+		halftile_corner = GetHighestSlopeCorner(tileh[TS_HOME]);
+		tileh[TS_HOME] = SLOPE_FLAT;
+	}
 
 	TLG tlg = GetTLG(ti->tile);
 	byte PCPstatus = 0;
@@ -295,9 +299,17 @@ static void DrawCatenaryRailway(const TileInfo *ti)
 
 	AdjustTileh(ti->tile, &tileh[TS_HOME]);
 
-	SpriteID pylon_base = GetPylonBase(ti->tile);
+	SpriteID pylon_normal = GetPylonBase(ti->tile);
+	SpriteID pylon_halftile = (halftile_corner != CORNER_INVALID) ? GetPylonBase(ti->tile, true) : pylon_normal;
 
 	for (DiagDirection i = DIAGDIR_BEGIN; i < DIAGDIR_END; i++) {
+		static const uint edge_corners[] = {
+			1 << CORNER_N | 1 << CORNER_E, // DIAGDIR_NE
+			1 << CORNER_S | 1 << CORNER_E, // DIAGDIR_SE
+			1 << CORNER_S | 1 << CORNER_W, // DIAGDIR_SW
+			1 << CORNER_N | 1 << CORNER_W, // DIAGDIR_NW
+		};
+		SpriteID pylon_base = (halftile_corner != CORNER_INVALID && HasBit(edge_corners[i], halftile_corner)) ? pylon_halftile : pylon_normal;
 		TileIndex neighbour = ti->tile + TileOffsByDiagDir(i);
 		Foundation foundation = FOUNDATION_NONE;
 		byte elevation = GetPCPElevation(ti->tile, i);
@@ -426,11 +438,21 @@ static void DrawCatenaryRailway(const TileInfo *ti)
 		if (height <= GetTileMaxZ(ti->tile) + TILE_HEIGHT) return;
 	}
 
-	SpriteID wire_base = GetWireBase(ti->tile);
+	SpriteID wire_normal = GetWireBase(ti->tile);
+	SpriteID wire_halftile = (halftile_corner != CORNER_INVALID) ? GetWireBase(ti->tile, true) : wire_normal;
+	Track halftile_track;
+	switch (halftile_corner) {
+		case CORNER_W: halftile_track = TRACK_LEFT; break;
+		case CORNER_S: halftile_track = TRACK_LOWER; break;
+		case CORNER_E: halftile_track = TRACK_RIGHT; break;
+		case CORNER_N: halftile_track = TRACK_UPPER; break;
+		default:       halftile_track = INVALID_TRACK; break;
+	}
 
 	/* Drawing of pylons is finished, now draw the wires */
 	Track t;
 	FOR_EACH_SET_TRACK(t, wireconfig[TS_HOME]) {
+		SpriteID wire_base = (t == halftile_track) ? wire_halftile : wire_normal;
 		byte PCPconfig = HasBit(PCPstatus, PCPpositions[t][0]) +
 			(HasBit(PCPstatus, PCPpositions[t][1]) << 1);
 
diff --git a/src/newgrf_commons.cpp b/src/newgrf_commons.cpp
index ec4810461..821d1362d 100644
--- a/src/newgrf_commons.cpp
+++ b/src/newgrf_commons.cpp
@@ -280,9 +280,10 @@ void IndustryTileOverrideManager::SetEntitySpec(const IndustryTileSpec *its)
 /** Function used by houses (and soon industries) to get information
  * on type of "terrain" the tile it is queries sits on.
  * @param tile TileIndex of the tile been queried
+ * @param upper_halftile If true, query upper halftile in case of rail tiles.
  * @return value corresponding to the grf expected format:
  *         Terrain type: 0 normal, 1 desert, 2 rainforest, 4 on or above snowline */
-uint32 GetTerrainType(TileIndex tile)
+uint32 GetTerrainType(TileIndex tile, bool upper_halftile)
 {
 	switch (_settings_game.game_creation.landscape) {
 		case LT_TROPIC: return GetTropicZone(tile);
@@ -295,7 +296,7 @@ uint32 GetTerrainType(TileIndex tile)
 
 				case MP_RAILWAY: {
 					RailGroundType ground = GetRailGroundType(tile);
-					has_snow = (ground == RAIL_GROUND_ICE_DESERT);
+					has_snow = (ground == RAIL_GROUND_ICE_DESERT || (upper_halftile && ground == RAIL_GROUND_HALF_SNOW));
 					break;
 				}
 
diff --git a/src/newgrf_commons.h b/src/newgrf_commons.h
index d5b9d9901..a30390603 100644
--- a/src/newgrf_commons.h
+++ b/src/newgrf_commons.h
@@ -123,7 +123,7 @@ extern IndustryTileOverrideManager _industile_mngr;
 extern AirportOverrideManager _airport_mngr;
 extern AirportTileOverrideManager _airporttile_mngr;
 
-uint32 GetTerrainType(TileIndex tile);
+uint32 GetTerrainType(TileIndex tile, bool upper_halftile = false);
 TileIndex GetNearbyTile(byte parameter, TileIndex tile);
 uint32 GetNearbyTileInformation(TileIndex tile);
 
diff --git a/src/newgrf_railtype.cpp b/src/newgrf_railtype.cpp
index 53894dca7..114f31b7c 100644
--- a/src/newgrf_railtype.cpp
+++ b/src/newgrf_railtype.cpp
@@ -49,7 +49,7 @@ static uint32 RailTypeGetVariable(const ResolverObject *object, byte variable, b
 	}
 
 	switch (variable) {
-		case 0x40: return GetTerrainType(tile);
+		case 0x40: return GetTerrainType(tile, object->u.routes.upper_halftile);
 		case 0x41: return 0;
 		case 0x42: return IsLevelCrossingTile(tile) && IsCrossingBarred(tile);
 		case 0x43:
@@ -70,7 +70,7 @@ static const SpriteGroup *RailTypeResolveReal(const ResolverObject *object, cons
 	return NULL;
 }
 
-static inline void NewRailTypeResolver(ResolverObject *res, TileIndex tile)
+static inline void NewRailTypeResolver(ResolverObject *res, TileIndex tile, bool upper_halftile)
 {
 	res->GetRandomBits = &RailTypeGetRandomBits;
 	res->GetTriggers   = &RailTypeGetTriggers;
@@ -79,6 +79,7 @@ static inline void NewRailTypeResolver(ResolverObject *res, TileIndex tile)
 	res->ResolveReal   = &RailTypeResolveReal;
 
 	res->u.routes.tile = tile;
+	res->u.routes.upper_halftile = upper_halftile;
 
 	res->callback        = CBID_NO_CALLBACK;
 	res->callback_param1 = 0;
@@ -89,7 +90,7 @@ static inline void NewRailTypeResolver(ResolverObject *res, TileIndex tile)
 	res->count           = 0;
 }
 
-SpriteID GetCustomRailSprite(const RailtypeInfo *rti, TileIndex tile, RailTypeSpriteGroup rtsg)
+SpriteID GetCustomRailSprite(const RailtypeInfo *rti, TileIndex tile, RailTypeSpriteGroup rtsg, bool upper_halftile)
 {
 	assert(rtsg < RTSG_END);
 
@@ -98,7 +99,7 @@ SpriteID GetCustomRailSprite(const RailtypeInfo *rti, TileIndex tile, RailTypeSp
 	const SpriteGroup *group;
 	ResolverObject object;
 
-	NewRailTypeResolver(&object, tile);
+	NewRailTypeResolver(&object, tile, upper_halftile);
 
 	group = SpriteGroup::Resolve(rti->group[rtsg], &object);
 	if (group == NULL || group->GetNumResults() == 0) return 0;
@@ -128,5 +129,5 @@ uint8 GetReverseRailTypeTranslation(RailType railtype, const GRFFile *grffile)
  */
 void GetRailTypeResolver(ResolverObject *ro, uint index)
 {
-	NewRailTypeResolver(ro, index);
+	NewRailTypeResolver(ro, index, false);
 }
diff --git a/src/newgrf_railtype.h b/src/newgrf_railtype.h
index 8dcd4fed0..40f772c03 100644
--- a/src/newgrf_railtype.h
+++ b/src/newgrf_railtype.h
@@ -5,7 +5,7 @@
 
 #include "rail.h"
 
-SpriteID GetCustomRailSprite(const RailtypeInfo *rti, TileIndex tile, RailTypeSpriteGroup rtsg);
+SpriteID GetCustomRailSprite(const RailtypeInfo *rti, TileIndex tile, RailTypeSpriteGroup rtsg, bool upper_halftile = false);
 
 uint8 GetReverseRailTypeTranslation(RailType railtype, const GRFFile *grffile);
 
diff --git a/src/newgrf_spritegroup.h b/src/newgrf_spritegroup.h
index 4ee77a29a..ed8eac529 100644
--- a/src/newgrf_spritegroup.h
+++ b/src/newgrf_spritegroup.h
@@ -343,6 +343,7 @@ struct ResolverObject {
 		} generic;
 		struct {
 			TileIndex tile;
+			bool upper_halftile;           ///< Are we resolving sprites for the upper halftile?
 		} routes;
 		struct {
 			const struct Station *st;
diff --git a/src/rail_cmd.cpp b/src/rail_cmd.cpp
index 0bcae1a66..ab3444cbd 100644
--- a/src/rail_cmd.cpp
+++ b/src/rail_cmd.cpp
@@ -1791,8 +1791,9 @@ static void DrawTrackFence_WE_2(const TileInfo *ti, SpriteID base_image)
 
 static void DrawTrackDetails(const TileInfo *ti, const RailtypeInfo *rti)
 {
-	/* Base sprite for track fences. */
-	SpriteID base_image = GetCustomRailSprite(rti, ti->tile, RTSG_FENCES);
+	/* Base sprite for track fences.
+	 * Note: Halftile slopes only have fences on the upper part. */
+	SpriteID base_image = GetCustomRailSprite(rti, ti->tile, RTSG_FENCES, IsHalftileSlope(ti->tileh));
 	if (base_image == 0) base_image = SPR_TRACK_FENCE_FLAT_X;
 
 	switch (GetRailGroundType(ti->tile)) {
@@ -1951,6 +1952,8 @@ static void DrawTrackBitsOverlay(TileInfo *ti, TrackBits track, const RailtypeIn
 
 	if (IsValidCorner(halftile_corner)) {
 		DrawFoundation(ti, HalftileFoundation(halftile_corner));
+		overlay = GetCustomRailSprite(rti, ti->tile, RTSG_OVERLAY, true);
+		ground = GetCustomRailSprite(rti, ti->tile, RTSG_GROUND, true);
 
 		/* Draw higher halftile-overlay: Use the sloped sprites with three corners raised. They probably best fit the lightning. */
 		Slope fake_slope = SlopeWithThreeCornersRaised(OppositeCorner(halftile_corner));