Enable recolouring of custom signal graphics (global and per-railtype)

docs/newgrf-additions.html

@@ -227,10 +227,20 @@
 	<p>This applies to <a href="https://newgrf-specs.tt-wiki.net/wiki/Action3/Railtypes#Signal_sprites_.280B.29">Action 2/3 - Railtype custom signal sprites</a>.<br />
 	When enabled, bit 24 of variable 18 (extra callback info) is set if the signal is restricted (has a routing restriction program attached).<br />
 	When enabled, the "Show restricted electric signals using default graphics" client setting and signal post recolouring is not applied.<br />
-	This flag should only be set if the Action 2/3 actually returns a different sprite when bit 24 of variable 18 is set.
+	This flag should only be set if the Action 2/3 actually returns a different sprite when bit 24 of variable 18 is set.<br />
 	The property length is 1 byte. 0 is disabled (default). 1 is enabled.
 	</p>
 	<p>This is indicated by the feature name: <font face="monospace">action0_railtype_restricted_signals</font>, version 1</p>
+	<h4 id="railtype_enable_signal_recolour">Enable recolouring for custom signal sprites (mappable property: railtype_enable_signal_recolour)</h4>
+	<p>This applies to <a href="https://newgrf-specs.tt-wiki.net/wiki/Action3/Railtypes#Signal_sprites_.280B.29">Action 2/3 - Railtype custom signal sprites</a>.<br />
+	When enabled, in addition to returning a sprite, register 0x100 may be set to the following:
+	<table>
+	<tr><th>Bits</th><th>Meaning</th></tr>
+	<tr><td>0 - 23</td><td>Recolour sprite to use. Set to 0 for no recolouring.</td></tr>
+	<tr><td>24 - 31</td><td>Reserved, set to zero. </td></tr>
+	</table></p>
+	<p>The property length is 1 byte. 0 is disabled (default). 1 is enabled.</p>
+	<p>This is indicated by the feature name: <font face="monospace">action0_railtype_recolour</font>, version 1</p>
 	<h4 id="railtype_disable_realistic_braking">Disable use of realistic braking with this rail type (mappable property: railtype_disable_realistic_braking)</h4>
 	<p>When this property is set realistic braking is disabled for trains of this railtype even when realistic braking is otherwise in effect.<br />
 	The property length is 1 byte. 0 is realistic braking is not disabled for this railtype. 1 is disable realistic braking for this railtype.
@@ -297,6 +307,18 @@
 	The Action 0 Id field is not used, the value is ignored.
 	</p>
 	<p>This is indicated by the feature name: <font face="monospace">action0_signals_restricted_signals</font>, version 1</p>
+	<h4 id="signals_enable_signal_recolour">Enable recolouring for custom signal sprites (mappable property: signals_enable_signal_recolour)</h4>
+	<p>This applies to <a href="#a3signals_custom_signal_sprites">Action 2/3 Signals (Feature 0E) custom signal sprites</a> for this GRF.<br />
+	When enabled, in addition to returning a sprite, register 0x100 may be set to the following:
+	<table>
+	<tr><th>Bits</th><th>Meaning</th></tr>
+	<tr><td>0 - 23</td><td>Recolour sprite to use. Set to 0 for no recolouring.</td></tr>
+	<tr><td>24 - 31</td><td>Reserved, set to zero. </td></tr>
+	</table></p>
+	<p>The property length is 1 byte. 0 is disabled (default). 1 is enabled.<br />
+	The Action 0 Id field is not used, the value is ignored.
+	</p>
+	<p>This is indicated by the feature name: <font face="monospace">action0_signals_recolour</font>, version 1</p>
 	<br />
 	<br />
 	<h3 id="varaction2_station"><a href="https://newgrf-specs.tt-wiki.net/wiki/VariationalAction2/Stations">Variational Action 2 - Stations</a></h3>

src/newgrf.cpp

@@ -4083,6 +4083,11 @@ static ChangeInfoResult SignalsChangeInfo(uint id, int numinfo, int prop, const
 				SB(_cur.grffile->new_signal_ctrl_flags, NSCF_RESTRICTEDSIG, 1, (buf->ReadByte() != 0 ? 1 : 0));
 				break;
 
+			case A0RPI_SIGNALS_ENABLE_SIGNAL_RECOLOUR:
+				if (MappedPropertyLengthMismatch(buf, 1, mapping_entry)) break;
+				SB(_cur.grffile->new_signal_ctrl_flags, NSCF_RECOLOUR_ENABLED, 1, (buf->ReadByte() != 0 ? 1 : 0));
+				break;
+
 			default:
 				ret = HandleAction0PropertyDefault(buf, prop);
 				break;
@@ -4416,6 +4421,11 @@ static ChangeInfoResult RailTypeChangeInfo(uint id, int numinfo, int prop, const
 				SB(rti->ctrl_flags, RTCF_NOREALISTICBRAKING, 1, (buf->ReadByte() != 0 ? 1 : 0));
 				break;
 
+			case A0RPI_RAILTYPE_ENABLE_SIGNAL_RECOLOUR:
+				if (MappedPropertyLengthMismatch(buf, 1, mapping_entry)) break;
+				SB(rti->ctrl_flags, RTCF_RECOLOUR_ENABLED, 1, (buf->ReadByte() != 0 ? 1 : 0));
+				break;
+
 			default:
 				ret = HandleAction0PropertyDefault(buf, prop);
 				break;
@@ -4499,6 +4509,7 @@ static ChangeInfoResult RailTypeReserveInfo(uint id, int numinfo, int prop, cons
 			case A0RPI_RAILTYPE_ENABLE_PROGRAMMABLE_SIGNALS:
 			case A0RPI_RAILTYPE_ENABLE_RESTRICTED_SIGNALS:
 			case A0RPI_RAILTYPE_DISABLE_REALISTIC_BRAKING:
+			case A0RPI_RAILTYPE_ENABLE_SIGNAL_RECOLOUR:
 				buf->Skip(buf->ReadExtendedByte());
 				break;
 
@@ -8468,10 +8479,12 @@ static const GRFFeatureInfo _grf_feature_list[] = {
 	GRFFeatureInfo("action0_railtype_programmable_signals", 1),
 	GRFFeatureInfo("action0_railtype_restricted_signals", 1),
 	GRFFeatureInfo("action0_railtype_disable_realistic_braking", 1),
+	GRFFeatureInfo("action0_railtype_recolour", 1),
 	GRFFeatureInfo("action0_roadtype_extra_flags", 1),
 	GRFFeatureInfo("action0_global_extra_station_names", 1),
 	GRFFeatureInfo("action0_signals_programmable_signals", 1),
 	GRFFeatureInfo("action0_signals_restricted_signals", 1),
+	GRFFeatureInfo("action0_signals_recolour", 1),
 	GRFFeatureInfo("action3_signals_custom_signal_sprites", 1),
 	GRFFeatureInfo(),
 };
@@ -8592,11 +8605,13 @@ static const GRFPropertyMapDefinition _grf_action0_remappable_properties[] = {
 	GRFPropertyMapDefinition(GSF_RAILTYPES, A0RPI_RAILTYPE_ENABLE_PROGRAMMABLE_SIGNALS, "railtype_enable_programmable_signals"),
 	GRFPropertyMapDefinition(GSF_RAILTYPES, A0RPI_RAILTYPE_ENABLE_RESTRICTED_SIGNALS, "railtype_enable_restricted_signals"),
 	GRFPropertyMapDefinition(GSF_RAILTYPES, A0RPI_RAILTYPE_DISABLE_REALISTIC_BRAKING, "railtype_disable_realistic_braking"),
+	GRFPropertyMapDefinition(GSF_RAILTYPES, A0RPI_RAILTYPE_ENABLE_SIGNAL_RECOLOUR, "railtype_enable_signal_recolour"),
 	GRFPropertyMapDefinition(GSF_ROADTYPES, A0RPI_ROADTYPE_EXTRA_FLAGS, "roadtype_extra_flags"),
 	GRFPropertyMapDefinition(GSF_TRAMTYPES, A0RPI_ROADTYPE_EXTRA_FLAGS, "roadtype_extra_flags"),
 	GRFPropertyMapDefinition(GSF_GLOBALVAR, A0RPI_GLOBALVAR_EXTRA_STATION_NAMES, "global_extra_station_names"),
 	GRFPropertyMapDefinition(GSF_SIGNALS, A0RPI_SIGNALS_ENABLE_PROGRAMMABLE_SIGNALS, "signals_enable_programmable_signals"),
 	GRFPropertyMapDefinition(GSF_SIGNALS, A0RPI_SIGNALS_ENABLE_RESTRICTED_SIGNALS, "signals_enable_restricted_signals"),
+	GRFPropertyMapDefinition(GSF_SIGNALS, A0RPI_SIGNALS_ENABLE_SIGNAL_RECOLOUR, "signals_enable_signal_recolour"),
 	GRFPropertyMapDefinition(),
 };
 

src/newgrf.h

@@ -118,10 +118,12 @@ enum Action0RemapPropertyIds {
 	A0RPI_RAILTYPE_ENABLE_PROGRAMMABLE_SIGNALS,
 	A0RPI_RAILTYPE_ENABLE_RESTRICTED_SIGNALS,
 	A0RPI_RAILTYPE_DISABLE_REALISTIC_BRAKING,
+	A0RPI_RAILTYPE_ENABLE_SIGNAL_RECOLOUR,
 	A0RPI_ROADTYPE_EXTRA_FLAGS,
 	A0RPI_GLOBALVAR_EXTRA_STATION_NAMES,
 	A0RPI_SIGNALS_ENABLE_PROGRAMMABLE_SIGNALS,
 	A0RPI_SIGNALS_ENABLE_RESTRICTED_SIGNALS,
+	A0RPI_SIGNALS_ENABLE_SIGNAL_RECOLOUR,
 };
 
 enum GRFPropertyMapFallbackMode {
@@ -222,6 +224,7 @@ enum NewSignalCtrlFlags {
 	NSCF_GROUPSET               = 0,                          ///< Custom signal sprites group set.
 	NSCF_PROGSIG                = 1,                          ///< Custom signal sprites enabled for programmable pre-signals.
 	NSCF_RESTRICTEDSIG          = 2,                          ///< Custom signal sprite flag enabled for restricted signals.
+	NSCF_RECOLOUR_ENABLED       = 3,                          ///< Recolour sprites enabled
 };
 
 /** New signal control flags. */

src/newgrf_railtype.cpp

@@ -115,10 +115,10 @@ SpriteID GetCustomRailSprite(const RailtypeInfo *rti, TileIndex tile, RailTypeSp
 	return group->GetResult();
 }
 
-static SpriteID GetRailTypeCustomSignalSprite(const RailtypeInfo *rti, TileIndex tile, SignalType type, SignalVariant var, SignalState state, bool gui, bool restricted)
+static PalSpriteID GetRailTypeCustomSignalSprite(const RailtypeInfo *rti, TileIndex tile, SignalType type, SignalVariant var, SignalState state, bool gui, bool restricted)
 {
-	if (rti->group[RTSG_SIGNALS] == nullptr) return 0;
+	if (rti->group[RTSG_SIGNALS] == nullptr) return { 0, PAL_NONE };
-	if (type == SIGTYPE_PROG && !HasBit(rti->ctrl_flags, RTCF_PROGSIG)) return 0;
+	if (type == SIGTYPE_PROG && !HasBit(rti->ctrl_flags, RTCF_PROGSIG)) return { 0, PAL_NONE };
 
 	uint32 param1 = gui ? 0x10 : 0x00;
 	uint32 param2 = (type << 16) | (var << 8) | state;
@@ -126,9 +126,10 @@ static SpriteID GetRailTypeCustomSignalSprite(const RailtypeInfo *rti, TileIndex
 	RailTypeResolverObject object(rti, tile, TCX_NORMAL, RTSG_SIGNALS, param1, param2);
 
 	const SpriteGroup *group = object.Resolve();
-	if (group == nullptr || group->GetNumResults() == 0) return 0;
+	if (group == nullptr || group->GetNumResults() == 0) return { 0, PAL_NONE };
 
-	return group->GetResult();
+	PaletteID pal = HasBit(rti->ctrl_flags, RTCF_RECOLOUR_ENABLED) ? GB(GetRegister(0x100), 0, 24) : PAL_NONE;
+	return { group->GetResult(), pal };
 }
 
 /**
@@ -143,8 +144,8 @@ static SpriteID GetRailTypeCustomSignalSprite(const RailtypeInfo *rti, TileIndex
  */
 CustomSignalSpriteResult GetCustomSignalSprite(const RailtypeInfo *rti, TileIndex tile, SignalType type, SignalVariant var, SignalState state, bool gui, bool restricted)
 {
-	SpriteID spr = GetRailTypeCustomSignalSprite(rti, tile, type, var, state, gui, restricted);
+	PalSpriteID spr = GetRailTypeCustomSignalSprite(rti, tile, type, var, state, gui, restricted);
-	if (spr != 0) return { spr, HasBit(rti->ctrl_flags, RTCF_PROGSIG) };
+	if (spr.sprite != 0) return { spr, HasBit(rti->ctrl_flags, RTCF_PROGSIG) };
 
 	for (const GRFFile *grf : _new_signals_grfs) {
 		if (type == SIGTYPE_PROG && !HasBit(grf->new_signal_ctrl_flags, NSCF_PROGSIG)) continue;
@@ -155,10 +156,13 @@ CustomSignalSpriteResult GetCustomSignalSprite(const RailtypeInfo *rti, TileInde
 		NewSignalsResolverObject object(grf, tile, TCX_NORMAL, param1, param2);
 
 		const SpriteGroup *group = object.Resolve();
-		if (group != nullptr && group->GetNumResults() != 0) return { group->GetResult(), HasBit(grf->new_signal_ctrl_flags, NSCF_RESTRICTEDSIG) };
+		if (group != nullptr && group->GetNumResults() != 0) {
+			PaletteID pal = HasBit(grf->new_signal_ctrl_flags, NSCF_RECOLOUR_ENABLED) ? GB(GetRegister(0x100), 0, 24) : PAL_NONE;
+			return { { group->GetResult(), pal }, HasBit(grf->new_signal_ctrl_flags, NSCF_RESTRICTEDSIG) };
+		}
 	}
 
-	return { 0, false };
+	return { { 0, PAL_NONE }, false };
 }
 
 /**

src/newgrf_railtype.h

@@ -56,7 +56,7 @@ struct RailTypeResolverObject : public ResolverObject {
 };
 
 struct CustomSignalSpriteResult {
-	SpriteID sprite_id;
+	PalSpriteID sprite;
 	bool restricted_valid;
 };
 

src/rail.h

@@ -46,6 +46,7 @@ enum RailTypeCtrlFlags {
 	RTCF_PROGSIG                = 0,                          ///< Custom signal sprites enabled for programmable pre-signals.
 	RTCF_RESTRICTEDSIG          = 1,                          ///< Custom signal sprite flag enabled for restricted signals.
 	RTCF_NOREALISTICBRAKING     = 2,                          ///< Realistic braking disabled for this track type
+	RTCF_RECOLOUR_ENABLED       = 3,                          ///< Recolour sprites enabled
 };
 
 struct SpriteGroup;
@@ -163,7 +164,7 @@ public:
 		SpriteID build_depot;        ///< button for building depots
 		SpriteID build_tunnel;       ///< button for building a tunnel
 		SpriteID convert_rail;       ///< button for converting rail
-		SpriteID signals[SIGTYPE_END][2][2]; ///< signal GUI sprites (type, variant, state)
+		PalSpriteID signals[SIGTYPE_END][2][2]; ///< signal GUI sprites (type, variant, state)
 	} gui_sprites;
 
 	struct {

src/rail_cmd.cpp

@@ -113,10 +113,18 @@ void ResolveRailTypeGUISprites(RailtypeInfo *rti)
 
 	for (SignalType type = SIGTYPE_NORMAL; type < SIGTYPE_END; type = (SignalType)(type + 1)) {
 		for (SignalVariant var = SIG_ELECTRIC; var <= SIG_SEMAPHORE; var = (SignalVariant)(var + 1)) {
-			SpriteID red   = GetCustomSignalSprite(rti, INVALID_TILE, type, var, SIGNAL_STATE_RED, true).sprite_id;
+			PalSpriteID red   = GetCustomSignalSprite(rti, INVALID_TILE, type, var, SIGNAL_STATE_RED, true).sprite;
-			SpriteID green = GetCustomSignalSprite(rti, INVALID_TILE, type, var, SIGNAL_STATE_GREEN, true).sprite_id;
+			PalSpriteID green = GetCustomSignalSprite(rti, INVALID_TILE, type, var, SIGNAL_STATE_GREEN, true).sprite;
-			rti->gui_sprites.signals[type][var][0] = (red != 0)   ? red + SIGNAL_TO_SOUTH   : _signal_lookup[var][type];
+			if (red.sprite != 0) {
-			rti->gui_sprites.signals[type][var][1] = (green != 0) ? green + SIGNAL_TO_SOUTH : _signal_lookup[var][type] + 1;
+				rti->gui_sprites.signals[type][var][0] = { red.sprite + SIGNAL_TO_SOUTH, red.pal };
+			} else {
+				rti->gui_sprites.signals[type][var][0] = { _signal_lookup[var][type], PAL_NONE };
+			}
+			if (green.sprite != 0) {
+				rti->gui_sprites.signals[type][var][1] = { green.sprite + SIGNAL_TO_SOUTH, green.pal };
+			} else {
+				rti->gui_sprites.signals[type][var][1] = { _signal_lookup[var][type] + 1, PAL_NONE };
+			}
 		}
 	}
 }
@@ -2671,10 +2679,12 @@ void DrawSingleSignal(TileIndex tile, const RailtypeInfo *rti, Track track, Sign
 	GetSignalXY(tile, pos, x, y);
 
 	const CustomSignalSpriteResult result = GetCustomSignalSprite(rti, tile, type, variant, condition, false, show_restricted);
-	SpriteID sprite = result.sprite_id;
+	SpriteID sprite = result.sprite.sprite;
+	PaletteID pal = PAL_NONE;
 	bool is_custom_sprite = (sprite != 0);
 	if (sprite != 0) {
 		sprite += image;
+		pal = result.sprite.pal;
 	} else if (type == SIGTYPE_PROG) {
 		if (variant == SIG_SEMAPHORE) {
 			sprite = SPR_PROGSIGNAL_BASE + image * 2 + condition;
@@ -2705,6 +2715,7 @@ void DrawSingleSignal(TileIndex tile, const RailtypeInfo *rti, Track track, Sign
 			sprite = (type == SIGTYPE_NORMAL && variant == SIG_ELECTRIC) ? SPR_DUP_ORIGINAL_SIGNALS_BASE : SPR_DUP_SIGNALS_BASE - 16;
 			sprite += type * 16 + variant * 64 + image * 2 + condition + (IsSignalSpritePBS(type) ? 64 : 0);
 		}
+		pal = PAL_NONE;
 		is_custom_sprite = false;
 	}
 
@@ -2719,7 +2730,7 @@ void DrawSingleSignal(TileIndex tile, const RailtypeInfo *rti, Track track, Sign
 			AddSortableSpriteToDraw(sprite, SPR_TRACERESTRICT_BASE + 1, x, y, 1, 1, BB_HEIGHT_UNDER_BRIDGE, GetSaveSlopeZ(x, y, track));
 		}
 	} else {
-		AddSortableSpriteToDraw(sprite, PAL_NONE, x, y, 1, 1, BB_HEIGHT_UNDER_BRIDGE, GetSaveSlopeZ(x, y, track));
+		AddSortableSpriteToDraw(sprite, pal, x, y, 1, 1, BB_HEIGHT_UNDER_BRIDGE, GetSaveSlopeZ(x, y, track));
 	}
 	const Sprite *sp = GetSprite(sprite, ST_NORMAL);
 	if (sp->x_offs < -SIGNAL_DIRTY_LEFT || sp->x_offs + sp->width > SIGNAL_DIRTY_RIGHT || sp->y_offs < -SIGNAL_DIRTY_TOP || sp->y_offs + sp->height > SIGNAL_DIRTY_BOTTOM) {

src/rail_gui.cpp

@@ -1790,17 +1790,17 @@ private:
 	 * @param widget_index index of this widget in the window
 	 * @param image        the sprite to draw
 	 */
-	void DrawSignalSprite(byte widget_index, SpriteID image) const
+	void DrawSignalSprite(byte widget_index, PalSpriteID image) const
 	{
 		Point offset;
-		Dimension sprite_size = GetSpriteSize(image, &offset);
+		Dimension sprite_size = GetSpriteSize(image.sprite, &offset);
 		const NWidgetBase *widget = this->GetWidget<NWidgetBase>(widget_index);
 		int x = widget->pos_x - offset.x +
 				(widget->current_x - sprite_size.width + offset.x) / 2;  // centered
 		int y = widget->pos_y - sig_sprite_bottom_offset + WD_IMGBTN_TOP +
 				(widget->current_y - WD_IMGBTN_TOP - WD_IMGBTN_BOTTOM + sig_sprite_size.height) / 2; // aligned to bottom
 
-		DrawSprite(image, PAL_NONE,
+		DrawSprite(image.sprite, image.pal,
 				x + this->IsWidgetLowered(widget_index),
 				y + this->IsWidgetLowered(widget_index));
 	}
@@ -1847,7 +1847,7 @@ public:
 			for (uint variant = SIG_ELECTRIC; variant <= SIG_SEMAPHORE; variant++) {
 				for (uint lowered = 0; lowered < 2; lowered++) {
 					Point offset;
-					Dimension sprite_size = GetSpriteSize(rti->gui_sprites.signals[type][variant][lowered], &offset);
+					Dimension sprite_size = GetSpriteSize(rti->gui_sprites.signals[type][variant][lowered].sprite, &offset);
 					this->sig_sprite_bottom_offset = std::max<int>(this->sig_sprite_bottom_offset, sprite_size.height);
 					this->sig_sprite_size.width = std::max<int>(this->sig_sprite_size.width, sprite_size.width - offset.x);
 					this->sig_sprite_size.height = std::max<int>(this->sig_sprite_size.height, sprite_size.height - offset.y);
@@ -1882,7 +1882,7 @@ public:
 			/* Extract signal from widget number. */
 			SignalType type = TypeForClick((widget - WID_BS_SEMAPHORE_NORM) % SIGTYPE_END);
 			int var = SIG_SEMAPHORE - (widget - WID_BS_SEMAPHORE_NORM) / SIGTYPE_END; // SignalVariant order is reversed compared to the widgets.
-			SpriteID sprite = GetRailTypeInfo(_cur_railtype)->gui_sprites.signals[type][var][this->IsWidgetLowered(widget)];
+			PalSpriteID sprite = GetRailTypeInfo(_cur_railtype)->gui_sprites.signals[type][var][this->IsWidgetLowered(widget)];
 
 			this->DrawSignalSprite(widget, sprite);
 		}

src/tunnelbridge_cmd.cpp

@@ -1719,22 +1719,22 @@ static void DrawTunnelBridgeRampSingleSignal(const TileInfo *ti, bool is_green,
 	SignalVariant variant = IsTunnelBridgeSemaphore(ti->tile) ? SIG_SEMAPHORE : SIG_ELECTRIC;
 	const RailtypeInfo *rti = GetRailTypeInfo(GetRailType(ti->tile));
 
-	SpriteID sprite = GetCustomSignalSprite(rti, ti->tile, type, variant, is_green ? SIGNAL_STATE_GREEN : SIGNAL_STATE_RED).sprite_id;
+	PalSpriteID sprite = GetCustomSignalSprite(rti, ti->tile, type, variant, is_green ? SIGNAL_STATE_GREEN : SIGNAL_STATE_RED).sprite;
-	bool is_custom_sprite = (sprite != 0);
+	bool is_custom_sprite = (sprite.sprite != 0);
 
 	if (is_custom_sprite) {
-		sprite += position;
+		sprite.sprite += position;
 	} else {
 		if (variant == SIG_ELECTRIC && type == SIGTYPE_NORMAL) {
 			/* Normal electric signals are picked from original sprites. */
-			sprite = SPR_ORIGINAL_SIGNALS_BASE + ((position << 1) + is_green);
+			sprite = { SPR_ORIGINAL_SIGNALS_BASE + ((position << 1) + is_green), PAL_NONE };
 		} else {
 			/* All other signals are picked from add on sprites. */
-			sprite = SPR_SIGNALS_BASE + ((type - 1) * 16 + variant * 64 + (position << 1) + is_green) + (IsSignalSpritePBS(type) ? 64 : 0);
+			sprite = { SPR_SIGNALS_BASE + ((type - 1) * 16 + variant * 64 + (position << 1) + is_green) + (IsSignalSpritePBS(type) ? 64 : 0), PAL_NONE };
 		}
 	}
 
-	AddSortableSpriteToDraw(sprite, PAL_NONE, x, y, 1, 1, TILE_HEIGHT, z, false, 0, 0, BB_Z_SEPARATOR);
+	AddSortableSpriteToDraw(sprite.sprite, sprite.pal, x, y, 1, 1, TILE_HEIGHT, z, false, 0, 0, BB_Z_SEPARATOR);
 }
 
 /* Draws a signal on tunnel / bridge entrance tile. */
@@ -1804,21 +1804,22 @@ static void DrawBridgeSignalOnMiddlePart(const TileInfo *ti, TileIndex bridge_st
 			SignalState state = GetBridgeEntranceSimulatedSignalState(bridge_start_tile, m2_position);
 
 			const RailtypeInfo *rti = GetRailTypeInfo(GetRailType(bridge_start_tile));
-			SpriteID sprite = GetCustomSignalSprite(rti, bridge_start_tile, SIGTYPE_NORMAL, variant, state);
+			PalSpriteID sprite = GetCustomSignalSprite(rti, bridge_start_tile, SIGTYPE_NORMAL, variant, state).sprite;
 
-			if (sprite != 0) {
+			if (sprite.sprite != 0) {
-				sprite += position;
+				sprite.sprite += position;
 			} else {
 				if (variant == SIG_ELECTRIC) {
 					/* Normal electric signals are picked from original sprites. */
-					sprite = SPR_ORIGINAL_SIGNALS_BASE + (position << 1) + (state == SIGNAL_STATE_GREEN ? 1 : 0);
+					sprite.sprite = SPR_ORIGINAL_SIGNALS_BASE + (position << 1) + (state == SIGNAL_STATE_GREEN ? 1 : 0);
 				} else {
 					/* All other signals are picked from add on sprites. */
-					sprite = SPR_SIGNALS_BASE + (variant * 64) + (position << 1) - 16 + (state == SIGNAL_STATE_GREEN ? 1 : 0);
+					sprite.sprite = SPR_SIGNALS_BASE + (variant * 64) + (position << 1) - 16 + (state == SIGNAL_STATE_GREEN ? 1 : 0);
 				}
+				sprite.pal = PAL_NONE;
 			}
 
-			AddSortableSpriteToDraw(sprite, PAL_NONE, x, y, 1, 1, TILE_HEIGHT, z, false, 0, 0, BB_Z_SEPARATOR);
+			AddSortableSpriteToDraw(sprite.sprite, sprite.pal, x, y, 1, 1, TILE_HEIGHT, z, false, 0, 0, BB_Z_SEPARATOR);
 		}
 		m2_position++;
 	}