/* $Id$ */ /* * This file is part of OpenTTD. * 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. * 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. * 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/>. */ /** @file ground_vehicle.cpp Implementation of GroundVehicle. */ #include "stdafx.h" #include "train.h" #include "roadveh.h" #include "depot_map.h" #include "safeguards.h" /** * Recalculates the cached total power of a vehicle. Should be called when the consist is changed. */ template <class T, VehicleType Type> void GroundVehicle<T, Type>::PowerChanged() { assert(this->First() == this); const T *v = T::From(this); uint32 total_power = 0; uint32 max_te = 0; uint32 number_of_parts = 0; uint16 max_track_speed = v->GetDisplayMaxSpeed(); for (const T *u = v; u != NULL; u = u->Next()) { uint32 current_power = u->GetPower() + u->GetPoweredPartPower(u); total_power += current_power; /* Only powered parts add tractive effort. */ if (current_power > 0) max_te += u->GetWeight() * u->GetTractiveEffort(); number_of_parts++; /* Get minimum max speed for this track. */ uint16 track_speed = u->GetMaxTrackSpeed(); if (track_speed > 0) max_track_speed = min(max_track_speed, track_speed); } byte air_drag; byte air_drag_value = v->GetAirDrag(); /* If air drag is set to zero (default), the resulting air drag coefficient is dependent on max speed. */ if (air_drag_value == 0) { uint16 max_speed = v->GetDisplayMaxSpeed(); /* Simplification of the method used in TTDPatch. It uses <= 10 to change more steadily from 128 to 196. */ air_drag = (max_speed <= 10) ? 192 : max(2048 / max_speed, 1); } else { /* According to the specs, a value of 0x01 in the air drag property means "no air drag". */ air_drag = (air_drag_value == 1) ? 0 : air_drag_value; } this->gcache.cached_air_drag = air_drag + 3 * air_drag * number_of_parts / 20; max_te *= 10000; // Tractive effort in (tonnes * 1000 * 10 =) N. max_te /= 256; // Tractive effort is a [0-255] coefficient. if (this->gcache.cached_power != total_power || this->gcache.cached_max_te != max_te) { /* Stop the vehicle if it has no power. */ if (total_power == 0) this->vehstatus |= VS_STOPPED; this->gcache.cached_power = total_power; this->gcache.cached_max_te = max_te; SetWindowDirty(WC_VEHICLE_DETAILS, this->index); SetWindowWidgetDirty(WC_VEHICLE_VIEW, this->index, WID_VV_START_STOP); } this->gcache.cached_max_track_speed = max_track_speed; } /** * Recalculates the cached weight of a vehicle and its parts. Should be called each time the cargo on * the consist changes. */ template <class T, VehicleType Type> void GroundVehicle<T, Type>::CargoChanged() { assert(this->First() == this); uint32 weight = 0; for (T *u = T::From(this); u != NULL; u = u->Next()) { uint32 current_weight = u->GetWeight(); weight += current_weight; /* Slope steepness is in percent, result in N. */ u->gcache.cached_slope_resistance = current_weight * u->GetSlopeSteepness() * 100; } /* Store consist weight in cache. */ this->gcache.cached_weight = max<uint32>(1, weight); /* Friction in bearings and other mechanical parts is 0.1% of the weight (result in N). */ this->gcache.cached_axle_resistance = 10 * weight; /* Now update vehicle power (tractive effort is dependent on weight). */ this->PowerChanged(); } /** * Calculates the acceleration of the vehicle under its current conditions. * @return Current acceleration of the vehicle. */ template <class T, VehicleType Type> int GroundVehicle<T, Type>::GetAcceleration() const { /* Templated class used for function calls for performance reasons. */ const T *v = T::From(this); /* Speed is used squared later on, so U16 * U16, and then multiplied by other values. */ int64 speed = v->GetCurrentSpeed(); // [km/h-ish] /* Weight is stored in tonnes. */ int32 mass = this->gcache.cached_weight; /* Power is stored in HP, we need it in watts. * Each vehicle can have U16 power, 128 vehicles, HP -> watt * and km/h to m/s conversion below result in a maxium of * about 1.1E11, way more than 4.3E9 of int32. */ int64 power = this->gcache.cached_power * 746ll; /* This is constructed from: * - axle resistance: U16 power * 10 for 128 vehicles. * * 8.3E7 * - rolling friction: U16 power * 144 for 128 vehicles. * * 1.2E9 * - slope resistance: U16 weight * 100 * 10 (steepness) for 128 vehicles. * * 8.4E9 * - air drag: 28 * (U8 drag + 3 * U8 drag * 128 vehicles / 20) * U16 speed * U16 speed * * 6.2E14 before dividing by 1000 * Sum is 6.3E11, more than 4.3E9 of int32, so int64 is needed. */ int64 resistance = 0; bool maglev = v->GetAccelerationType() == 2; const int area = v->GetAirDragArea(); if (!maglev) { /* Static resistance plus rolling friction. */ resistance = this->gcache.cached_axle_resistance; resistance += mass * v->GetRollingFriction(); } /* Air drag; the air drag coefficient is in an arbitrary NewGRF-unit, * so we need some magic conversion factor. */ resistance += (area * this->gcache.cached_air_drag * speed * speed) / 1000; resistance += this->GetSlopeResistance(); /* This value allows to know if the vehicle is accelerating or braking. */ AccelStatus mode = v->GetAccelerationStatus(); const int max_te = this->gcache.cached_max_te; // [N] /* Constructued from power, with need to multiply by 18 and assuming * low speed, it needs to be a 64 bit integer too. */ int64 force; if (speed > 0) { if (!maglev) { /* Conversion factor from km/h to m/s is 5/18 to get [N] in the end. */ force = power * 18 / (speed * 5); if (mode == AS_ACCEL && force > max_te) force = max_te; } else { force = power / 25; } } else { /* "Kickoff" acceleration. */ force = (mode == AS_ACCEL && !maglev) ? min(max_te, power) : power; force = max(force, (mass * 8) + resistance); } if (mode == AS_ACCEL) { /* Easy way out when there is no acceleration. */ if (force == resistance) return 0; /* When we accelerate, make sure we always keep doing that, even when * the excess force is more than the mass. Otherwise a vehicle going * down hill will never slow down enough, and a vehicle that came up * a hill will never speed up enough to (eventually) get back to the * same (maximum) speed. */ int accel = ClampToI32((force - resistance) / (mass * 4)); return force < resistance ? min(-1, accel) : max(1, accel); } else { return ClampToI32(min(-force - resistance, -10000) / mass); } } /** * Check whether the whole vehicle chain is in the depot. * @return true if and only if the whole chain is in the depot. */ template <class T, VehicleType Type> bool GroundVehicle<T, Type>::IsChainInDepot() const { const T *v = this->First(); /* Is the front engine stationary in the depot? */ assert_compile((int)TRANSPORT_RAIL == (int)VEH_TRAIN); assert_compile((int)TRANSPORT_ROAD == (int)VEH_ROAD); if (!IsDepotTypeTile(v->tile, (TransportType)Type) || v->cur_speed != 0) return false; /* Check whether the rest is also already trying to enter the depot. */ for (; v != NULL; v = v->Next()) { if (!v->T::IsInDepot() || v->tile != this->tile) return false; } return true; } /* Instantiation for Train */ template struct GroundVehicle<Train, VEH_TRAIN>; /* Instantiation for RoadVehicle */ template struct GroundVehicle<RoadVehicle, VEH_ROAD>;