Support railtype-dependant GRF train speed limits with realistic braking

See: #389

src/newgrf_commons.h

@@ -339,6 +339,7 @@ enum SpriteGroupCallbacksUsed : uint8 {
 	SGCU_VEHICLE_32DAY_CALLBACK         = 1 << 0,
 	SGCU_VEHICLE_REFIT_COST             = 1 << 1,
 	SGCU_RANDOM_TRIGGER                 = 1 << 2,
+	SGCU_CB36_SPEED_RAILTYPE            = 1 << 3,
 };
 DECLARE_ENUM_AS_BIT_SET(SpriteGroupCallbacksUsed)
 

src/newgrf_spritegroup.cpp

@@ -354,6 +354,7 @@ void DeterministicSpriteGroup::AnalyseCallbacks(AnalyseCallbackOperation &op) co
 									cb36_op.mode = ACOM_CB36_PROP;
 									range.group->AnalyseCallbacks(cb36_op);
 									op.properties_used |= cb36_op.properties_used;
+									op.callbacks_used |= cb36_op.callbacks_used;
 								}
 								break;
 						}
@@ -370,7 +371,18 @@ void DeterministicSpriteGroup::AnalyseCallbacks(AnalyseCallbackOperation &op) co
 				for (const auto &range : this->ranges) {
 					if (range.low == range.high) {
 						if (range.low < 64) {
-							if (find_cb_result()) SetBit(op.properties_used, range.low);
+							if (find_cb_result()) {
+								SetBit(op.properties_used, range.low);
+								if (range.low == 0x9) {
+									/* Speed */
+									if (range.group != nullptr) {
+										AnalyseCallbackOperation cb36_speed;
+										cb36_speed.mode = ACOM_CB36_SPEED;
+										range.group->AnalyseCallbacks(cb36_speed);
+										op.callbacks_used |= cb36_speed.callbacks_used;
+									}
+								}
+							}
 						}
 					} else {
 						if (range.group != nullptr) range.group->AnalyseCallbacks(op);
@@ -392,6 +404,10 @@ void DeterministicSpriteGroup::AnalyseCallbacks(AnalyseCallbackOperation &op) co
 				return;
 			}
 		}
+		if (op.mode == ACOM_CB36_SPEED && adjust.variable == 0x4A) {
+			op.callbacks_used |= SGCU_CB36_SPEED_RAILTYPE;
+			return;
+		}
 	}
 	for (const auto &adjust : this->adjusts) {
 		if (op.mode == ACOM_CB_VAR && adjust.variable == 0xC) {

src/newgrf_spritegroup.h

@@ -53,6 +53,7 @@ enum AnalyseCallbackOperationMode {
 	ACOM_CB_VAR,
 	ACOM_CB36_PROP,
 	ACOM_FIND_CB_RESULT,
+	ACOM_CB36_SPEED,
 };
 
 struct AnalyseCallbackOperation {

src/pbs.cpp

@@ -386,6 +386,26 @@ static uint16 ApplyTunnelBridgeLookaheadSignalSpeedRestriction(TileIndex tile, T
 	return speed_restriction;
 }
 
+static uint16 GetTrainSpeedLimitForRailtype(const Train *v, RailType rt, TileIndex tile, Track track)
+{
+	uint16 speed = GetRailTypeInfo(rt)->max_speed;
+	if (v->tcache.cached_tflags & TCF_SPD_RAILTYPE) {
+		for (const Train *u = v; u != nullptr; u = u->Next()) {
+			if (u->GetEngine()->callbacks_used & SGCU_CB36_SPEED_RAILTYPE) {
+				const TileIndex prev_tile = u->tile;
+				const TrackBits prev_track = u->track;
+				const_cast<Train *>(u)->tile = tile;
+				const_cast<Train *>(u)->track = TrackToTrackBits(track);
+				uint16 cb_speed = GetVehicleProperty(u, PROP_TRAIN_SPEED, speed);
+				if (cb_speed != 0 && (cb_speed < speed || speed == 0)) speed = cb_speed;
+				const_cast<Train *>(u)->tile = prev_tile;
+				const_cast<Train *>(u)->track = prev_track;
+			}
+		}
+	}
+	return speed;
+}
+
 /** Follow a reservation starting from a specific tile to the end. */
 static PBSTileInfo FollowReservation(Owner o, RailTypes rts, TileIndex tile, Trackdir trackdir, FollowReservationFlags flags, const Train *v, TrainReservationLookAhead *lookahead)
 {
@@ -431,7 +451,7 @@ static PBSTileInfo FollowReservation(Owner o, RailTypes rts, TileIndex tile, Tra
 	auto check_rail_type = [&](TileIndex t, Trackdir td, int offset) {
 		RailType new_rt = GetRailTypeByTrack(t, TrackdirToTrack(td));
 		if (new_rt != rt) {
-			uint16 rail_speed = GetRailTypeInfo(new_rt)->max_speed;
+			uint16 rail_speed = GetTrainSpeedLimitForRailtype(v, new_rt, t, TrackdirToTrack(td));
 			if (rail_speed > 0) lookahead->AddTrackSpeedLimit(rail_speed, offset, 4, z);
 			if (GetRailTypeInfo(rt)->curve_speed != GetRailTypeInfo(new_rt)->curve_speed) {
 				CheckCurveLookAhead(v, lookahead, lookahead->RealEndPosition() + 4 + offset, z, new_rt);
@@ -870,9 +890,10 @@ static int ScanTrainPositionForLookAheadStation(Train *t, TileIndex start_tile)
 				if (u == t) {
 					for (uint i = 1; i < forward_length; i++) {
 						/* Check for mid platform rail type change */
-						RailType new_rt = GetRailTypeByTrack(tile + (i * diff), TrackdirToTrack(trackdir));
+						TileIndex new_tile = tile + (i * diff);
+						RailType new_rt = GetRailTypeByTrack(new_tile, TrackdirToTrack(trackdir));
 						if (new_rt != rt) {
-							uint16 rail_speed = GetRailTypeInfo(new_rt)->max_speed;
+							uint16 rail_speed = GetTrainSpeedLimitForRailtype(t, new_rt, new_tile, TrackdirToTrack(trackdir));
 							if (rail_speed > 0) t->lookahead->AddTrackSpeedLimit(rail_speed, (i - 1) * TILE_SIZE, 4, z);
 							rt = new_rt;
 						}

src/table/newgrf_debug_data.h

@@ -182,8 +182,8 @@ class NIHVehicle : public NIHelper {
 		}
 		if (v->type == VEH_TRAIN) {
 			const Train *t = Train::From(v);
-			seprintf(buffer, lastof(buffer), "  T cache: tilt: %d, curve speed mod: %d, engines: %u",
-					(t->tcache.cached_tflags & TCF_TILT) ? 1 : 0, t->tcache.cached_curve_speed_mod, t->tcache.cached_num_engines);
+			seprintf(buffer, lastof(buffer), "  T cache: tilt: %d, speed varies by railtype: %d, curve speed mod: %d, engines: %u",
+					(t->tcache.cached_tflags & TCF_TILT) ? 1 : 0, (t->tcache.cached_tflags & TCF_SPD_RAILTYPE) ? 1 : 0, t->tcache.cached_curve_speed_mod, t->tcache.cached_num_engines);
 			output.print(buffer);
 			seprintf(buffer, lastof(buffer), "  T cache: RL braking: %d, decel: %u, uncapped decel: %u, centre mass: %u",
 					(t->UsingRealisticBraking()) ? 1 : 0, t->tcache.cached_deceleration, t->tcache.cached_uncapped_decel, t->tcache.cached_centre_mass);

src/train.h

@@ -99,6 +99,7 @@ enum TrainCacheFlags : byte {
 	TCF_NONE         = 0,        ///< No flags
 	TCF_TILT         = 0x01,     ///< Train can tilt; feature provides a bonus in curves.
 	TCF_RL_BRAKING   = 0x02,     ///< Train realistic braking (movement physics) in effect for this vehicle
+	TCF_SPD_RAILTYPE = 0x04,     ///< Train speed varies depending on railtype
 };
 DECLARE_ENUM_AS_BIT_SET(TrainCacheFlags)
 

src/train_cmd.cpp

@@ -264,6 +264,7 @@ void Train::ConsistChanged(ConsistChangeFlags allowed_changes)
 	this->tcache.cached_num_engines = 0;
 
 	bool train_can_tilt = true;
+	bool speed_varies_by_railtype = false;
 	int min_curve_speed_mod = INT_MAX;
 
 	for (Train *u = this; u != nullptr; u = u->Next()) {
@@ -304,6 +305,7 @@ void Train::ConsistChanged(ConsistChangeFlags allowed_changes)
 		const RailVehicleInfo *rvi_u = &e_u->u.rail;
 
 		if (!HasBit(e_u->info.misc_flags, EF_RAIL_TILTS)) train_can_tilt = false;
+		if (e_u->callbacks_used & SGCU_CB36_SPEED_RAILTYPE) speed_varies_by_railtype = true;
 		min_curve_speed_mod = std::min(min_curve_speed_mod, u->GetCurveSpeedModifier());
 
 		/* Cache wagon override sprite group. nullptr is returned if there is none */
@@ -390,7 +392,7 @@ void Train::ConsistChanged(ConsistChangeFlags allowed_changes)
 
 	/* store consist weight/max speed in cache */
 	this->vcache.cached_max_speed = max_speed;
-	this->tcache.cached_tflags = (train_can_tilt ? TCF_TILT : TCF_NONE);
+	this->tcache.cached_tflags = (train_can_tilt ? TCF_TILT : TCF_NONE) | (speed_varies_by_railtype ? TCF_SPD_RAILTYPE : TCF_NONE);
 	this->tcache.cached_curve_speed_mod = min_curve_speed_mod;
 	this->tcache.cached_max_curve_speed = this->GetCurveSpeedLimit();