src/ground_vehicle.hpp

   1 /*
   2  * This file is part of OpenTTD.
   3  * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
   4  * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   5  * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
   6  */
   7
   8 /** @file ground_vehicle.hpp Base class and functions for all vehicles that move through ground. */
   9
  10 #ifndef GROUND_VEHICLE_HPP
  11 #define GROUND_VEHICLE_HPP
  12
  13 #include "vehicle_base.h"
  14 #include "vehicle_gui.h"
  15 #include "landscape.h"
  16 #include "window_func.h"
  17 #include "widgets/vehicle_widget.h"
  18
  19 /** What is the status of our acceleration? */
  20 enum AccelStatus {
  21         AS_ACCEL, ///< We want to go faster, if possible of course.
  22         AS_BRAKE, ///< We want to stop.
  23 };
  24
  25 /**
  26  * Cached, frequently calculated values.
  27  * All of these values except cached_slope_resistance are set only for the first part of a vehicle.
  28  */
  29 struct GroundVehicleCache {
  30         /* Cached acceleration values, recalculated when the cargo on a vehicle changes (in addition to the conditions below) */
  31         uint32 cached_weight;           ///< Total weight of the consist (valid only for the first engine).
  32         uint32 cached_slope_resistance; ///< Resistance caused by weight when this vehicle part is at a slope.
  33         uint32 cached_max_te;           ///< Maximum tractive effort of consist (valid only for the first engine).
  34         uint16 cached_axle_resistance;  ///< Resistance caused by the axles of the vehicle (valid only for the first engine).
  35
  36         /* Cached acceleration values, recalculated on load and each time a vehicle is added to/removed from the consist. */
  37         uint16 cached_max_track_speed;  ///< Maximum consist speed (in internal units) limited by track type (valid only for the first engine).
  38         uint32 cached_power;            ///< Total power of the consist (valid only for the first engine).
  39         uint32 cached_air_drag;         ///< Air drag coefficient of the vehicle (valid only for the first engine).
  40
  41         /* Cached NewGRF values, recalculated on load and each time a vehicle is added to/removed from the consist. */
  42         uint16 cached_total_length;     ///< Length of the whole vehicle (valid only for the first engine).
  43         EngineID first_engine;          ///< Cached EngineID of the front vehicle. INVALID_ENGINE for the front vehicle itself.
  44         uint8 cached_veh_length;        ///< Length of this vehicle in units of 1/VEHICLE_LENGTH of normal length. It is cached because this can be set by a callback.
  45
  46         /* Cached UI information. */
  47         uint16 last_speed;              ///< The last speed we did display, so we only have to redraw when this changes.
  48 };
  49
  50 /** Ground vehicle flags. */
  51 enum GroundVehicleFlags {
  52         GVF_GOINGUP_BIT              = 0,  ///< Vehicle is currently going uphill. (Cached track information for acceleration)
  53         GVF_GOINGDOWN_BIT            = 1,  ///< Vehicle is currently going downhill. (Cached track information for acceleration)
  54         GVF_SUPPRESS_IMPLICIT_ORDERS = 2,  ///< Disable insertion and removal of automatic orders until the vehicle completes the real order.
  55 };
  56
  57 /**
  58  * Base class for all vehicles that move through ground.
  59  *
  60  * Child classes must define all of the following functions.
  61  * These functions are not defined as pure virtual functions at this class to improve performance.
  62  *
  63  * virtual uint16      GetPower() const = 0;
  64  * virtual uint16      GetPoweredPartPower(const T *head) const = 0;
  65  * virtual uint16      GetWeight() const = 0;
  66  * virtual byte        GetTractiveEffort() const = 0;
  67  * virtual byte        GetAirDrag() const = 0;
  68  * virtual byte        GetAirDragArea() const = 0;
  69  * virtual AccelStatus GetAccelerationStatus() const = 0;
  70  * virtual uint16      GetCurrentSpeed() const = 0;
  71  * virtual uint32      GetRollingFriction() const = 0;
  72  * virtual int         GetAccelerationType() const = 0;
  73  * virtual int32       GetSlopeSteepness() const = 0;
  74  * virtual int         GetDisplayMaxSpeed() const = 0;
  75  * virtual uint16      GetMaxTrackSpeed() const = 0;
  76  * virtual bool        TileMayHaveSlopedTrack() const = 0;
  77  */
  78 template <class T, VehicleType Type>
  79 struct GroundVehicle : public SpecializedVehicle<T, Type> {
  80         GroundVehicleCache gcache; ///< Cache of often calculated values.
  81         uint16 gv_flags;           ///< @see GroundVehicleFlags.
  82
  83         typedef GroundVehicle<T, Type> GroundVehicleBase; ///< Our type
  84
  85         /**
  86          * The constructor at SpecializedVehicle must be called.
  87          */
  88         GroundVehicle() : SpecializedVehicle<T, Type>() {}
  89
  90         void PowerChanged();
  91         void CargoChanged();
  92         int GetAcceleration() const;
  93         bool IsChainInDepot() const override;
  94
  95         /**
  96          * Common code executed for crashed ground vehicles
  97          * @param flooded was this vehicle flooded?
  98          * @return number of victims
  99          */
 100         uint Crash(bool flooded) override
 101         {
 102                 /* Crashed vehicles aren't going up or down */
 103                 for (T *v = T::From(this); v != nullptr; v = v->Next()) {
 104                         ClrBit(v->gv_flags, GVF_GOINGUP_BIT);
 105                         ClrBit(v->gv_flags, GVF_GOINGDOWN_BIT);
 106                 }
 107                 return this->Vehicle::Crash(flooded);
 108         }
 109
 110         /**
 111          * Calculates the total slope resistance for this vehicle.
 112          * @return Slope resistance.
 113          */
 114         inline int64 GetSlopeResistance() const
 115         {
 116                 int64 incl = 0;
 117
 118                 for (const T *u = T::From(this); u != nullptr; u = u->Next()) {
 119                         if (HasBit(u->gv_flags, GVF_GOINGUP_BIT)) {
 120                                 incl += u->gcache.cached_slope_resistance;
 121                         } else if (HasBit(u->gv_flags, GVF_GOINGDOWN_BIT)) {
 122                                 incl -= u->gcache.cached_slope_resistance;
 123                         }
 124                 }
 125
 126                 return incl;
 127         }
 128
 129         /**
 130          * Updates vehicle's Z position and inclination.
 131          * Used when the vehicle entered given tile.
 132          * @pre The vehicle has to be at (or near to) a border of the tile,
 133          *      directed towards tile centre
 134          */
 135         inline void UpdateZPositionAndInclination()
 136         {
 137                 this->z_pos = GetSlopePixelZ(this->x_pos, this->y_pos);
 138                 ClrBit(this->gv_flags, GVF_GOINGUP_BIT);
 139                 ClrBit(this->gv_flags, GVF_GOINGDOWN_BIT);
 140
 141                 if (T::From(this)->TileMayHaveSlopedTrack()) {
 142                         /* To check whether the current tile is sloped, and in which
 143                          * direction it is sloped, we get the 'z' at the center of
 144                          * the tile (middle_z) and the edge of the tile (old_z),
 145                          * which we then can compare. */
 146                         int middle_z = GetSlopePixelZ((this->x_pos & ~TILE_UNIT_MASK) | (TILE_SIZE / 2), (this->y_pos & ~TILE_UNIT_MASK) | (TILE_SIZE / 2));
 147
 148                         if (middle_z != this->z_pos) {
 149                                 SetBit(this->gv_flags, (middle_z > this->z_pos) ? GVF_GOINGUP_BIT : GVF_GOINGDOWN_BIT);
 150                         }
 151                 }
 152         }
 153
 154         /**
 155          * Updates vehicle's Z position.
 156          * Inclination can't change in the middle of a tile.
 157          * The faster code is used for trains and road vehicles unless they are
 158          * reversing on a sloped tile.
 159          */
 160         inline void UpdateZPosition()
 161         {
 162 #if 0
 163                 /* The following code does this: */
 164
 165                 if (HasBit(this->gv_flags, GVF_GOINGUP_BIT)) {
 166                         switch (this->direction) {
 167                                 case DIR_NE:
 168                                         this->z_pos += (this->x_pos & 1); break;
 169                                 case DIR_SW:
 170                                         this->z_pos += (this->x_pos & 1) ^ 1; break;
 171                                 case DIR_NW:
 172                                         this->z_pos += (this->y_pos & 1); break;
 173                                 case DIR_SE:
 174                                         this->z_pos += (this->y_pos & 1) ^ 1; break;
 175                                 default: break;
 176                         }
 177                 } else if (HasBit(this->gv_flags, GVF_GOINGDOWN_BIT)) {
 178                         switch (this->direction) {
 179                                 case DIR_NE:
 180                                         this->z_pos -= (this->x_pos & 1); break;
 181                                 case DIR_SW:
 182                                         this->z_pos -= (this->x_pos & 1) ^ 1; break;
 183                                 case DIR_NW:
 184                                         this->z_pos -= (this->y_pos & 1); break;
 185                                 case DIR_SE:
 186                                         this->z_pos -= (this->y_pos & 1) ^ 1; break;
 187                                 default: break;
 188                         }
 189                 }
 190
 191                 /* But gcc 4.4.5 isn't able to nicely optimise it, and the resulting
 192                  * code is full of conditional jumps. */
 193 #endif
 194
 195                 /* Vehicle's Z position can change only if it has GVF_GOINGUP_BIT or GVF_GOINGDOWN_BIT set.
 196                  * Furthermore, if this function is called once every time the vehicle's position changes,
 197                  * we know the Z position changes by +/-1 at certain moments - when x_pos, y_pos is odd/even,
 198                  * depending on orientation of the slope and vehicle's direction */
 199
 200                 if (HasBit(this->gv_flags, GVF_GOINGUP_BIT) || HasBit(this->gv_flags, GVF_GOINGDOWN_BIT)) {
 201                         if (T::From(this)->HasToUseGetSlopePixelZ()) {
 202                                 /* In some cases, we have to use GetSlopePixelZ() */
 203                                 this->z_pos = GetSlopePixelZ(this->x_pos, this->y_pos);
 204                                 return;
 205                         }
 206                         /* DirToDiagDir() is a simple right shift */
 207                         DiagDirection dir = DirToDiagDir(this->direction);
 208                         /* Read variables, so the compiler knows the access doesn't trap */
 209                         int8 x_pos = this->x_pos;
 210                         int8 y_pos = this->y_pos;
 211                         /* DiagDirToAxis() is a simple mask */
 212                         int8 d = DiagDirToAxis(dir) == AXIS_X ? x_pos : y_pos;
 213                         /* We need only the least significant bit */
 214                         d &= 1;
 215                         /* Conditional "^ 1". Optimised to "(dir - 1) <= 1". */
 216                         d ^= (int8)(dir == DIAGDIR_SW || dir == DIAGDIR_SE);
 217                         /* Subtraction instead of addition because we are testing for GVF_GOINGUP_BIT.
 218                          * GVF_GOINGUP_BIT is used because it's bit 0, so simple AND can be used,
 219                          * without any shift */
 220                         this->z_pos += HasBit(this->gv_flags, GVF_GOINGUP_BIT) ? d : -d;
 221                 }
 222
 223                 assert(this->z_pos == GetSlopePixelZ(this->x_pos, this->y_pos));
 224         }
 225
 226         /**
 227          * Checks if the vehicle is in a slope and sets the required flags in that case.
 228          * @param new_tile True if the vehicle reached a new tile.
 229          * @param update_delta Indicates to also update the delta.
 230          * @return Old height of the vehicle.
 231          */
 232         inline int UpdateInclination(bool new_tile, bool update_delta)
 233         {
 234                 int old_z = this->z_pos;
 235
 236                 if (new_tile) {
 237                         this->UpdateZPositionAndInclination();
 238                 } else {
 239                         this->UpdateZPosition();
 240                 }
 241
 242                 this->UpdateViewport(true, update_delta);
 243                 return old_z;
 244         }
 245
 246         /**
 247          * Set front engine state.
 248          */
 249         inline void SetFrontEngine() { SetBit(this->subtype, GVSF_FRONT); }
 250
 251         /**
 252          * Remove the front engine state.
 253          */
 254         inline void ClearFrontEngine() { ClrBit(this->subtype, GVSF_FRONT); }
 255
 256         /**
 257          * Set a vehicle to be an articulated part.
 258          */
 259         inline void SetArticulatedPart() { SetBit(this->subtype, GVSF_ARTICULATED_PART); }
 260
 261         /**
 262          * Clear a vehicle from being an articulated part.
 263          */
 264         inline void ClearArticulatedPart() { ClrBit(this->subtype, GVSF_ARTICULATED_PART); }
 265
 266         /**
 267          * Set a vehicle to be a wagon.
 268          */
 269         inline void SetWagon() { SetBit(this->subtype, GVSF_WAGON); }
 270
 271         /**
 272          * Clear wagon property.
 273          */
 274         inline void ClearWagon() { ClrBit(this->subtype, GVSF_WAGON); }
 275
 276         /**
 277          * Set engine status.
 278          */
 279         inline void SetEngine() { SetBit(this->subtype, GVSF_ENGINE); }
 280
 281         /**
 282          * Clear engine status.
 283          */
 284         inline void ClearEngine() { ClrBit(this->subtype, GVSF_ENGINE); }
 285
 286         /**
 287          * Set a vehicle as a free wagon.
 288          */
 289         inline void SetFreeWagon() { SetBit(this->subtype, GVSF_FREE_WAGON); }
 290
 291         /**
 292          * Clear a vehicle from being a free wagon.
 293          */
 294         inline void ClearFreeWagon() { ClrBit(this->subtype, GVSF_FREE_WAGON); }
 295
 296         /**
 297          * Set a vehicle as a multiheaded engine.
 298          */
 299         inline void SetMultiheaded() { SetBit(this->subtype, GVSF_MULTIHEADED); }
 300
 301         /**
 302          * Clear multiheaded engine property.
 303          */
 304         inline void ClearMultiheaded() { ClrBit(this->subtype, GVSF_MULTIHEADED); }
 305
 306         /**
 307          * Check if the vehicle is a free wagon (got no engine in front of it).
 308          * @return Returns true if the vehicle is a free wagon.
 309          */
 310         inline bool IsFreeWagon() const { return HasBit(this->subtype, GVSF_FREE_WAGON); }
 311
 312         /**
 313          * Check if a vehicle is an engine (can be first in a consist).
 314          * @return Returns true if vehicle is an engine.
 315          */
 316         inline bool IsEngine() const { return HasBit(this->subtype, GVSF_ENGINE); }
 317
 318         /**
 319          * Check if a vehicle is a wagon.
 320          * @return Returns true if vehicle is a wagon.
 321          */
 322         inline bool IsWagon() const { return HasBit(this->subtype, GVSF_WAGON); }
 323
 324         /**
 325          * Check if the vehicle is a multiheaded engine.
 326          * @return Returns true if the vehicle is a multiheaded engine.
 327          */
 328         inline bool IsMultiheaded() const { return HasBit(this->subtype, GVSF_MULTIHEADED); }
 329
 330         /**
 331          * Tell if we are dealing with the rear end of a multiheaded engine.
 332          * @return True if the engine is the rear part of a dualheaded engine.
 333          */
 334         inline bool IsRearDualheaded() const { return this->IsMultiheaded() && !this->IsEngine(); }
 335
 336         /**
 337          * Update the GUI variant of the current speed of the vehicle.
 338          * Also mark the widget dirty when that is needed, i.e. when
 339          * the speed of this vehicle has changed.
 340          */
 341         inline void SetLastSpeed()
 342         {
 343                 if (this->cur_speed != this->gcache.last_speed) {
 344                         SetWindowWidgetDirty(WC_VEHICLE_VIEW, this->index, WID_VV_START_STOP);
 345                         this->gcache.last_speed = this->cur_speed;
 346                 }
 347         }
 348
 349 protected:
 350         /**
 351          * Update the speed of the vehicle.
 352          *
 353          * It updates the cur_speed and subspeed variables depending on the state
 354          * of the vehicle; in this case the current acceleration, minimum and
 355          * maximum speeds of the vehicle. It returns the distance that that the
 356          * vehicle can drive this tick. #Vehicle::GetAdvanceDistance() determines
 357          * the distance to drive before moving a step on the map.
 358          * @param accel     The acceleration we would like to give this vehicle.
 359          * @param min_speed The minimum speed here, in vehicle specific units.
 360          * @param max_speed The maximum speed here, in vehicle specific units.
 361          * @return Distance to drive.
 362          */
 363         inline uint DoUpdateSpeed(uint accel, int min_speed, int max_speed)
 364         {
 365                 uint spd = this->subspeed + accel;
 366                 this->subspeed = (byte)spd;
 367
 368                 /* When we are going faster than the maximum speed, reduce the speed
 369                  * somewhat gradually. But never lower than the maximum speed. */
 370                 int tempmax = max_speed;
 371                 if (this->cur_speed > max_speed) {
 372                         tempmax = std::max(this->cur_speed - (this->cur_speed / 10) - 1, max_speed);
 373                 }
 374
 375                 /* Enforce a maximum and minimum speed. Normally we would use something like
 376                  * Clamp for this, but in this case min_speed might be below the maximum speed
 377                  * threshold for some reason. That makes acceleration fail and assertions
 378                  * happen in Clamp. So make it explicit that min_speed overrules the maximum
 379                  * speed by explicit ordering of min and max. */
 380                 this->cur_speed = spd = std::max(std::min(this->cur_speed + ((int)spd >> 8), tempmax), min_speed);
 381
 382                 int scaled_spd = this->GetAdvanceSpeed(spd);
 383
 384                 scaled_spd += this->progress;
 385                 this->progress = 0; // set later in *Handler or *Controller
 386                 return scaled_spd;
 387         }
 388 };
 389
 390 #endif /* GROUND_VEHICLE_HPP */