Codechange: Use an enum for vehicle acceleration model.

src/build_vehicle_gui.cpp

@@ -637,7 +637,7 @@ static int DrawRailEnginePurchaseInfo(int left, int right, int y, EngineID engin
 	y += GetCharacterHeight(FS_NORMAL);
 
 	/* Max tractive effort - not applicable if old acceleration or maglev */
-	if (_settings_game.vehicle.train_acceleration_model != AM_ORIGINAL && GetRailTypeInfo(rvi->railtype)->acceleration_type != 2) {
+	if (_settings_game.vehicle.train_acceleration_model != AM_ORIGINAL && GetRailTypeInfo(rvi->railtype)->acceleration_type != VehicleAccelerationModel::Maglev) {
 		DrawString(left, right, y, GetString(STR_PURCHASE_INFO_MAX_TE, e->GetDisplayMaxTractiveEffort()));
 		y += GetCharacterHeight(FS_NORMAL);
 	}

src/engine_gui.cpp

@@ -181,7 +181,7 @@ static std::string GetTrainEngineInfoString(const Engine &e)
 	res << GetString(STR_ENGINE_PREVIEW_COST_WEIGHT, e.GetCost(), e.GetDisplayWeight());
 	res << '\n';
 
-	if (_settings_game.vehicle.train_acceleration_model != AM_ORIGINAL && GetRailTypeInfo(e.u.rail.railtype)->acceleration_type != 2) {
+	if (_settings_game.vehicle.train_acceleration_model != AM_ORIGINAL && GetRailTypeInfo(e.u.rail.railtype)->acceleration_type != VehicleAccelerationModel::Maglev) {
 		res << GetString(STR_ENGINE_PREVIEW_SPEED_POWER_MAX_TE, PackVelocity(e.GetDisplayMaxSpeed(), e.type), e.GetPower(), e.GetDisplayMaxTractiveEffort());
 		res << '\n';
 	} else {

src/engine_type.h

@@ -43,6 +43,13 @@ enum EngineClass : uint8_t {
 	EC_MAGLEV,   ///< Maglev engine.
 };
 
+/** Acceleration model of a vehicle. */
+enum class VehicleAccelerationModel : uint8_t {
+	Normal,   ///< Default acceleration model.
+	Monorail, ///< Monorail acceleration model.
+	Maglev,   ///< Maglev acceleration model.
+};
+
 /** Information about a rail vehicle. */
 struct RailVehicleInfo {
 	uint8_t image_index = 0;

src/ground_vehicle.cpp

@@ -131,7 +131,7 @@ int GroundVehicle<T, Type>::GetAcceleration() const
 	 */
 	int64_t resistance = 0;
 
-	bool maglev = v->GetAccelerationType() == 2;
+	bool maglev = v->GetAccelerationType() == VehicleAccelerationModel::Maglev;
 
 	const int area = v->GetAirDragArea();
 	if (!maglev) {

src/newgrf/newgrf_act0_railtypes.cpp

@@ -117,7 +117,7 @@ static ChangeInfoResult RailTypeChangeInfo(uint first, uint last, int prop, Byte
 				break;
 
 			case 0x15: // Acceleration model
-				rti->acceleration_type = Clamp(buf.ReadByte(), 0, 2);
+				rti->acceleration_type = static_cast<VehicleAccelerationModel>(Clamp(buf.ReadByte(), 0, 2));
 				break;
 
 			case 0x16: // Map colour

src/rail.h

@@ -214,7 +214,7 @@ public:
 	/**
 	 * Acceleration type of this rail type
 	 */
-	uint8_t acceleration_type;
+	VehicleAccelerationModel acceleration_type;
 
 	/**
 	 * Maximum speed for vehicles travelling on this rail type

src/roadveh.h

@@ -250,11 +250,11 @@ protected: // These functions should not be called outside acceleration code.
 
 	/**
 	 * Allows to know the acceleration type of a vehicle.
-	 * @return Zero, road vehicles always use a normal acceleration method.
+	 * @return \c VehicleAccelerationModel::Normal, road vehicles always use a normal acceleration method.
 	 */
-	inline int GetAccelerationType() const
+	inline VehicleAccelerationModel GetAccelerationType() const
 	{
-		return 0;
+		return VehicleAccelerationModel::Normal;
 	}
 
 	/**

src/table/railtypes.h

@@ -86,7 +86,7 @@ static const RailTypeInfo _original_railtypes[] = {
 		8,
 
 		/* acceleration type */
-		0,
+		VehicleAccelerationModel::Normal,
 
 		/* max speed */
 		0,
@@ -188,7 +188,7 @@ static const RailTypeInfo _original_railtypes[] = {
 		12,
 
 		/* acceleration type */
-		0,
+		VehicleAccelerationModel::Normal,
 
 		/* max speed */
 		0,
@@ -286,7 +286,7 @@ static const RailTypeInfo _original_railtypes[] = {
 		16,
 
 		/* acceleration type */
-		1,
+		VehicleAccelerationModel::Monorail,
 
 		/* max speed */
 		0,
@@ -384,7 +384,7 @@ static const RailTypeInfo _original_railtypes[] = {
 		24,
 
 		/* acceleration type */
-		2,
+		VehicleAccelerationModel::Maglev,
 
 		/* max speed */
 		0,

src/train.h

@@ -302,7 +302,7 @@ protected: // These functions should not be called outside acceleration code.
 	 * Allows to know the acceleration type of a vehicle.
 	 * @return Acceleration type of the vehicle.
 	 */
-	inline int GetAccelerationType() const
+	inline VehicleAccelerationModel GetAccelerationType() const
 	{
 		return GetRailTypeInfo(this->railtype)->acceleration_type;
 	}

src/train_cmd.cpp

@@ -3083,7 +3083,7 @@ static inline void AffectSpeedByZChange(Train *v, int old_z)
 {
 	if (old_z == v->z_pos || _settings_game.vehicle.train_acceleration_model != AM_ORIGINAL) return;
 
-	const AccelerationSlowdownParams *asp = &_accel_slowdown[GetRailTypeInfo(v->railtype)->acceleration_type];
+	const AccelerationSlowdownParams *asp = &_accel_slowdown[static_cast<int>(GetRailTypeInfo(v->railtype)->acceleration_type)];
 
 	if (old_z < v->z_pos) {
 		v->cur_speed -= (v->cur_speed * asp->z_up >> 8);
@@ -3490,7 +3490,7 @@ bool TrainController(Train *v, Vehicle *nomove, bool reverse)
 
 				if (chosen_dir != v->direction) {
 					if (prev == nullptr && _settings_game.vehicle.train_acceleration_model == AM_ORIGINAL) {
-						const AccelerationSlowdownParams *asp = &_accel_slowdown[GetRailTypeInfo(v->railtype)->acceleration_type];
+						const AccelerationSlowdownParams *asp = &_accel_slowdown[static_cast<int>(GetRailTypeInfo(v->railtype)->acceleration_type)];
 						DirDiff diff = DirDifference(v->direction, chosen_dir);
 						v->cur_speed -= (diff == DIRDIFF_45RIGHT || diff == DIRDIFF_45LEFT ? asp->small_turn : asp->large_turn) * v->cur_speed >> 8;
 					}

src/vehicle_gui.cpp

@@ -2596,7 +2596,7 @@ struct VehicleDetailsWindow : Window {
 						(v->type == VEH_ROAD && _settings_game.vehicle.roadveh_acceleration_model != AM_ORIGINAL)) {
 					const GroundVehicleCache *gcache = v->GetGroundVehicleCache();
 					if (v->type == VEH_TRAIN && (_settings_game.vehicle.train_acceleration_model == AM_ORIGINAL ||
-							GetRailTypeInfo(Train::From(v)->railtype)->acceleration_type == 2)) {
+							GetRailTypeInfo(Train::From(v)->railtype)->acceleration_type == VehicleAccelerationModel::Maglev)) {
 						DrawString(tr, GetString(STR_VEHICLE_INFO_WEIGHT_POWER_MAX_SPEED, gcache->cached_weight, gcache->cached_power, max_speed));
 					} else {
 						DrawString(tr, GetString(STR_VEHICLE_INFO_WEIGHT_POWER_MAX_SPEED_MAX_TE, gcache->cached_weight, gcache->cached_power, max_speed, gcache->cached_max_te));