src/ground_vehicle.cpp

   1 /* $Id$ */
   2
   3 /*
   4  * This file is part of OpenTTD.
   5  * 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.
   6  * 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.
   7  * 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/>.
   8  */
   9
  10 /** @file ground_vehicle.cpp Implementation of GroundVehicle. */
  11
  12 #include "stdafx.h"
  13 #include "train.h"
  14 #include "roadveh.h"
  15 #include "depot_map.h"
  16 #include "tunnel_base.h"
  17 #include "slope_type.h"
  18
  19 #include "safeguards.h"
  20
  21 /**
  22  * Recalculates the cached total power of a vehicle. Should be called when the consist is changed.
  23  */
  24 template <class T, VehicleType Type>
  25 void GroundVehicle<T, Type>::PowerChanged()
  26 {
  27         assert(this->First() == this);
  28         const T *v = T::From(this);
  29
  30         uint32 total_power = 0;
  31         uint32 max_te = 0;
  32         uint32 number_of_parts = 0;
  33         uint16 max_track_speed = v->GetDisplayMaxSpeed();
  34
  35         for (const T *u = v; u != nullptr; u = u->Next()) {
  36                 uint32 current_power = u->GetPower() + u->GetPoweredPartPower(u);
  37                 total_power += current_power;
  38
  39                 /* Only powered parts add tractive effort. */
  40                 if (current_power > 0) max_te += u->GetWeight() * u->GetTractiveEffort();
  41                 number_of_parts++;
  42
  43                 /* Get minimum max speed for this track. */
  44                 uint16 track_speed = u->GetMaxTrackSpeed();
  45                 if (track_speed > 0) max_track_speed = min(max_track_speed, track_speed);
  46         }
  47
  48         byte air_drag;
  49         byte air_drag_value = v->GetAirDrag();
  50
  51         /* If air drag is set to zero (default), the resulting air drag coefficient is dependent on max speed. */
  52         if (air_drag_value == 0) {
  53                 uint16 max_speed = v->GetDisplayMaxSpeed();
  54                 /* Simplification of the method used in TTDPatch. It uses <= 10 to change more steadily from 128 to 196. */
  55                 air_drag = (max_speed <= 10) ? 192 : max(2048 / max_speed, 1);
  56         } else {
  57                 /* According to the specs, a value of 0x01 in the air drag property means "no air drag". */
  58                 air_drag = (air_drag_value == 1) ? 0 : air_drag_value;
  59         }
  60
  61         this->gcache.cached_air_drag = air_drag + 3 * air_drag * number_of_parts / 20;
  62
  63         max_te *= 10000; // Tractive effort in (tonnes * 1000 * 10 =) N.
  64         max_te /= 256;   // Tractive effort is a [0-255] coefficient.
  65         if (this->gcache.cached_power != total_power || this->gcache.cached_max_te != max_te) {
  66                 /* Stop the vehicle if it has no power. */
  67                 if (total_power == 0)
  68                         this->vehstatus |= VS_STOPPED;
  69
  70                 this->gcache.cached_power = total_power;
  71                 this->gcache.cached_max_te = max_te;
  72                 SetWindowDirty(WC_VEHICLE_DETAILS, this->index);
  73                 SetWindowWidgetDirty(WC_VEHICLE_VIEW, this->index, WID_VV_START_STOP);
  74         }
  75
  76         this->gcache.cached_max_track_speed = max_track_speed;
  77 }
  78
  79 /**
  80  * Recalculates the cached weight of a vehicle and its parts. Should be called each time the cargo on
  81  * the consist changes.
  82  */
  83 template <class T, VehicleType Type>
  84 void GroundVehicle<T, Type>::CargoChanged()
  85 {
  86         assert(this->First() == this);
  87         uint32 weight = 0;
  88
  89         for (T *u = T::From(this); u != nullptr; u = u->Next()) {
  90                 uint32 current_weight = u->GetWeight();
  91                 weight += current_weight;
  92                 /* Slope steepness is in percent, result in N. */
  93                 u->gcache.cached_slope_resistance = current_weight * u->GetSlopeSteepness() * 100;
  94         }
  95
  96         /* Store consist weight in cache. */
  97         this->gcache.cached_weight = max<uint32>(1, weight);
  98
  99         /* Now update vehicle power (tractive effort is dependent on weight). */
 100         this->PowerChanged();
 101 }
 102
 103 /**
 104  * Calculates the acceleration of the vehicle under its current conditions.
 105  * @return Current acceleration of the vehicle.
 106  */
 107 template <class T, VehicleType Type>
 108 int GroundVehicle<T, Type>::GetAcceleration() const
 109 {
 110         /* Templated class used for function calls for performance reasons. */
 111         const T *v = T::From(this);
 112
 113         int64 speed = (v->GetCurrentSpeed() * 5) / 18; // [m/s-ish]
 114
 115         /* Weight is stored in tonnes. */
 116         int32 mass = this->gcache.cached_weight;
 117
 118         /* Power is stored in HP, we need it in watts.
 119          * Each vehicle can have U16 power, 128 vehicles, HP -> watt
 120          * and km/h to m/s conversion below result in a maximum of
 121          * about 1.1E11, way more than 4.3E9 of int32. */
 122         int64 power = this->gcache.cached_power * 746ll;
 123
 124         /* This is constructed from:
 125          *  - axle resistance:  U16 power * 10 for 128 vehicles.
 126          *     * 8.3E7
 127          *  - rolling friction: U16 power * 144 for 128 vehicles.
 128          *     * 1.2E9
 129          *  - slope resistance: U16 weight * 100 * 10 (steepness) for 128 vehicles.
 130          *     * 8.4E9
 131          *  - air drag: 28 * (U8 drag + 3 * U8 drag * 128 vehicles / 20) * U16 speed * U16 speed
 132          *     * 6.2E14 before dividing by 1000
 133          * Sum is 6.3E11, more than 4.3E9 of int32, so int64 is needed.
 134          */
 135         int64 resistance = 0;
 136
 137         bool maglev = v->GetAccelerationType() == 2;
 138
 139         const int area = v->GetAirDragArea();
 140         if (!maglev) {
 141                 resistance += mass * v->GetRollingFriction();
 142         }
 143
 144         /* Air drag; the air drag coefficient is in an arbitrary NewGRF-unit,
 145          * so we need some magic conversion factor. */
 146         resistance += (area * this->gcache.cached_air_drag * speed * speed) / 1000;
 147
 148         resistance += this->GetSlopeResistance();
 149
 150         /* This value allows to know if the vehicle is accelerating or braking. */
 151         AccelStatus mode = v->GetAccelerationStatus();
 152
 153         int max_te = this->gcache.cached_max_te; // [N]
 154
 155         /* Constructed from power, with need to multiply by 18 and assuming
 156          * low speed, it needs to be a 64 bit integer too. */
 157         int64 force;
 158         if (speed > 0) {
 159                 if (!maglev) {
 160                         force = power / speed;
 161                         if (mode == AS_ACCEL && force > max_te) force = max_te;
 162                 } else {
 163                         force = power / 25;
 164                 }
 165         } else {
 166                 /* "Kickoff" acceleration. */
 167                 force = (mode == AS_ACCEL && !maglev) ? min(max_te, power) : power;
 168                 force = max(force, (mass * 8) + resistance);
 169         }
 170
 171         if (mode == AS_ACCEL) {
 172                 /* Easy way out when there is no acceleration. */
 173                 if (force == resistance) return 0;
 174
 175                 /* When we accelerate, make sure we always keep doing that, even when
 176                  * the excess force is more than the mass. Otherwise a vehicle going
 177                  * down hill will never slow down enough, and a vehicle that came up
 178                  * a hill will never speed up enough to (eventually) get back to the
 179                  * same (maximum) speed. */
 180                 int accel = ClampToI32((force - resistance) / mass);
 181
 182                 return force < resistance ? min(-1, accel) : max(1, accel);
 183         } else {
 184                 return ClampToI32(min(-force - resistance, -10000) / mass);
 185         }
 186 }
 187
 188 /**
 189  * Check whether the whole vehicle chain is in the depot.
 190  * @return true if and only if the whole chain is in the depot.
 191  */
 192 template <class T, VehicleType Type>
 193 bool GroundVehicle<T, Type>::IsChainInDepot() const
 194 {
 195         const T *v = this->First();
 196         /* Is the front engine stationary in the depot? */
 197         assert_compile((int)TRANSPORT_RAIL == (int)VEH_TRAIN);
 198         assert_compile((int)TRANSPORT_ROAD == (int)VEH_ROAD);
 199         if (!IsDepotTypeTile(v->tile, (TransportType)Type) || v->cur_speed != 0) return false;
 200
 201         /* Check whether the rest is also already trying to enter the depot. */
 202         for (; v != nullptr; v = v->Next()) {
 203                 if (!v->T::IsInDepot() || v->tile != this->tile) return false;
 204         }
 205
 206         return true;
 207 }
 208
 209 /**
 210  * Updates vehicle's Z inclination inside a wormhole, where applicable.
 211  */
 212 template <class T, VehicleType Type>
 213 void GroundVehicle<T, Type>::UpdateZPositionInWormhole()
 214 {
 215         if (!IsTunnel(this->tile)) return;
 216
 217         const Tunnel *t = Tunnel::GetByTile(this->tile);
 218         if (!t->is_chunnel) return;
 219
 220         TileIndex pos_tile = TileVirtXY(this->x_pos, this->y_pos);
 221
 222         ClrBit(this->gv_flags, GVF_GOINGUP_BIT);
 223         ClrBit(this->gv_flags, GVF_GOINGDOWN_BIT);
 224
 225         if (pos_tile == t->tile_n || pos_tile == t->tile_s) {
 226                 this->z_pos = 0;
 227                 return;
 228         }
 229
 230         int north_coord, south_coord, pos_coord;
 231         bool going_north;
 232         Slope slope_north;
 233         if (t->tile_s - t->tile_n > MapMaxX()) {
 234                 // tunnel extends along Y axis (DIAGDIR_SE from north end), has same X values
 235                 north_coord = TileY(t->tile_n);
 236                 south_coord = TileY(t->tile_s);
 237                 pos_coord = TileY(pos_tile);
 238                 going_north = (this->direction == DIR_NW);
 239                 slope_north = SLOPE_NW;
 240         } else {
 241                 // tunnel extends along X axis (DIAGDIR_SW from north end), has same Y values
 242                 north_coord = TileX(t->tile_n);
 243                 south_coord = TileX(t->tile_s);
 244                 pos_coord = TileX(pos_tile);
 245                 going_north = (this->direction == DIR_NE);
 246                 slope_north = SLOPE_NE;
 247         }
 248
 249         Slope slope = SLOPE_FLAT;
 250
 251         int delta;
 252         if ((delta = pos_coord - north_coord) <= 3) {
 253                 this->z_pos = TILE_HEIGHT * (delta == 3 ? -2 : -1);
 254                 if (delta != 2) {
 255                         slope = slope_north;
 256                         SetBit(this->gv_flags, going_north ? GVF_GOINGUP_BIT : GVF_GOINGDOWN_BIT);
 257                 }
 258         } else if ((delta = south_coord - pos_coord) <= 3) {
 259                 this->z_pos = TILE_HEIGHT * (delta == 3 ? -2 : -1);
 260                 if (delta != 2) {
 261                         slope = SLOPE_ELEVATED ^ slope_north;
 262                         SetBit(this->gv_flags, going_north ? GVF_GOINGDOWN_BIT : GVF_GOINGUP_BIT);
 263                 }
 264         }
 265
 266         if (slope != SLOPE_FLAT) this->z_pos += GetPartialPixelZ(this->x_pos & 0xF, this->y_pos & 0xF, slope);
 267 }
 268
 269 /* Instantiation for Train */
 270 template struct GroundVehicle<Train, VEH_TRAIN>;
 271 /* Instantiation for RoadVehicle */
 272 template struct GroundVehicle<RoadVehicle, VEH_ROAD>;