newgrf_engine.cpp

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/*
 * 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/>.
 */
 
#include "stdafx.h"
#include "debug.h"
#include "train.h"
#include "roadveh.h"
#include "company_func.h"
#include "newgrf_badge.h"
#include "newgrf_cargo.h"
#include "newgrf_spritegroup.h"
#include "timer/timer_game_calendar.h"
#include "vehicle_func.h"
#include "core/random_func.hpp"
#include "core/container_func.hpp"
#include "aircraft.h"
#include "station_base.h"
#include "company_base.h"
#include "newgrf_railtype.h"
#include "newgrf_roadtype.h"
#include "ship.h"
 
#include "safeguards.h"
 
void SetWagonOverrideSprites(EngineID engine, CargoType cargo, const SpriteGroup *group, std::span<EngineID> engine_ids)
{
  Engine *e = Engine::Get(engine);
 
  assert(cargo < NUM_CARGO + 2); // Include SpriteGroupCargo::SG_DEFAULT and SpriteGroupCargo::SG_PURCHASE pseudo cargoes.
 
  WagonOverride *wo = &e->overrides.emplace_back();
  wo->group = group;
  wo->cargo = cargo;
  wo->engines.assign(engine_ids.begin(), engine_ids.end());
}
 
const SpriteGroup *GetWagonOverrideSpriteSet(EngineID engine, CargoType cargo, EngineID overriding_engine)
{
  const Engine *e = Engine::Get(engine);
 
  for (const WagonOverride &wo : e->overrides) {
    if (wo.cargo != cargo && wo.cargo != SpriteGroupCargo::SG_DEFAULT) continue;
    if (std::ranges::find(wo.engines, overriding_engine) != wo.engines.end()) return wo.group;
  }
  return nullptr;
}
 
void SetCustomEngineSprites(EngineID engine, CargoType cargo, const SpriteGroup *group)
{
  Engine *e = Engine::Get(engine);
 
  if (e->grf_prop.GetSpriteGroup(cargo) != nullptr) {
    GrfMsg(6, "SetCustomEngineSprites: engine {} cargo {} already has group -- replacing", engine, cargo);
  }
  e->grf_prop.SetSpriteGroup(cargo, group);
}
 
 
void SetEngineGRF(EngineID engine, const GRFFile *file)
{
  Engine *e = Engine::Get(engine);
  e->grf_prop.SetGRFFile(file);
}
 
 
static int MapOldSubType(const Vehicle *v)
{
  switch (v->type) {
    case VEH_TRAIN:
      if (Train::From(v)->IsEngine()) return 0;
      if (Train::From(v)->IsFreeWagon()) return 4;
      return 2;
    case VEH_ROAD:
    case VEH_SHIP:     return 0;
    case VEH_AIRCRAFT:
    case VEH_DISASTER: return v->subtype;
    case VEH_EFFECT:   return v->subtype << 1;
    default: NOT_REACHED();
  }
}
 
 
/* TTDP style aircraft movement states for GRF Action 2 Var 0xE2 */
enum TTDPAircraftMovementStates : uint8_t {
  AMS_TTDP_HANGAR,
  AMS_TTDP_TO_HANGAR,
  AMS_TTDP_TO_PAD1,
  AMS_TTDP_TO_PAD2,
  AMS_TTDP_TO_PAD3,
  AMS_TTDP_TO_ENTRY_2_AND_3,
  AMS_TTDP_TO_ENTRY_2_AND_3_AND_H,
  AMS_TTDP_TO_JUNCTION,
  AMS_TTDP_LEAVE_RUNWAY,
  AMS_TTDP_TO_INWAY,
  AMS_TTDP_TO_RUNWAY,
  AMS_TTDP_TO_OUTWAY,
  AMS_TTDP_WAITING,
  AMS_TTDP_TAKEOFF,
  AMS_TTDP_TO_TAKEOFF,
  AMS_TTDP_CLIMBING,
  AMS_TTDP_FLIGHT_APPROACH,
  AMS_TTDP_UNUSED_0x11,
  AMS_TTDP_FLIGHT_TO_TOWER,
  AMS_TTDP_UNUSED_0x13,
  AMS_TTDP_FLIGHT_FINAL,
  AMS_TTDP_FLIGHT_DESCENT,
  AMS_TTDP_BRAKING,
  AMS_TTDP_HELI_TAKEOFF_AIRPORT,
  AMS_TTDP_HELI_TO_TAKEOFF_AIRPORT,
  AMS_TTDP_HELI_LAND_AIRPORT,
  AMS_TTDP_HELI_TAKEOFF_HELIPORT,
  AMS_TTDP_HELI_TO_TAKEOFF_HELIPORT,
  AMS_TTDP_HELI_LAND_HELIPORT,
};
 
 
static uint8_t MapAircraftMovementState(const Aircraft *v)
{
  const Station *st = GetTargetAirportIfValid(v);
  if (st == nullptr) return AMS_TTDP_FLIGHT_TO_TOWER;
 
  const AirportFTAClass *afc = st->airport.GetFTA();
  AirportMovingDataFlags amdflag = afc->MovingData(v->pos)->flags;
 
  switch (v->state) {
    case HANGAR:
      /* The international airport is a special case as helicopters can land in
       * front of the hangar. Helicopters also change their air.state to
       * AirportMovingDataFlag::HeliLower some time before actually descending. */
 
      /* This condition only occurs for helicopters, during descent,
       * to a landing by the hangar of an international airport. */
      if (amdflag.Test(AirportMovingDataFlag::HeliLower)) return AMS_TTDP_HELI_LAND_AIRPORT;
 
      /* This condition only occurs for helicopters, before starting descent,
       * to a landing by the hangar of an international airport. */
      if (amdflag.Test(AirportMovingDataFlag::SlowTurn)) return AMS_TTDP_FLIGHT_TO_TOWER;
 
      /* The final two conditions apply to helicopters or aircraft.
       * Has reached hangar? */
      if (amdflag.Test(AirportMovingDataFlag::ExactPosition)) return AMS_TTDP_HANGAR;
 
      /* Still moving towards hangar. */
      return AMS_TTDP_TO_HANGAR;
 
    case TERM1:
      if (amdflag.Test(AirportMovingDataFlag::ExactPosition)) return AMS_TTDP_TO_PAD1;
      return AMS_TTDP_TO_JUNCTION;
 
    case TERM2:
      if (amdflag.Test(AirportMovingDataFlag::ExactPosition)) return AMS_TTDP_TO_PAD2;
      return AMS_TTDP_TO_ENTRY_2_AND_3_AND_H;
 
    case TERM3:
    case TERM4:
    case TERM5:
    case TERM6:
    case TERM7:
    case TERM8:
      /* TTDPatch only has 3 terminals, so treat these states the same */
      if (amdflag.Test(AirportMovingDataFlag::ExactPosition)) return AMS_TTDP_TO_PAD3;
      return AMS_TTDP_TO_ENTRY_2_AND_3_AND_H;
 
    case HELIPAD1:
    case HELIPAD2:
    case HELIPAD3:
      /* Will only occur for helicopters.*/
      if (amdflag.Test(AirportMovingDataFlag::HeliLower)) return AMS_TTDP_HELI_LAND_AIRPORT; // Descending.
      if (amdflag.Test(AirportMovingDataFlag::SlowTurn)) return AMS_TTDP_FLIGHT_TO_TOWER;   // Still hasn't started descent.
      return AMS_TTDP_TO_JUNCTION; // On the ground.
 
    case TAKEOFF: // Moving to takeoff position.
      return AMS_TTDP_TO_OUTWAY;
 
    case STARTTAKEOFF: // Accelerating down runway.
      return AMS_TTDP_TAKEOFF;
 
    case ENDTAKEOFF: // Ascent
      return AMS_TTDP_CLIMBING;
 
    case HELITAKEOFF: // Helicopter is moving to take off position.
      if (afc->delta_z == 0) {
        return amdflag.Test(AirportMovingDataFlag::HeliRaise) ?
          AMS_TTDP_HELI_TAKEOFF_AIRPORT : AMS_TTDP_TO_JUNCTION;
      } else {
        return AMS_TTDP_HELI_TAKEOFF_HELIPORT;
      }
 
    case FLYING:
      return amdflag.Test(AirportMovingDataFlag::Hold) ? AMS_TTDP_FLIGHT_APPROACH : AMS_TTDP_FLIGHT_TO_TOWER;
 
    case LANDING: // Descent
      return AMS_TTDP_FLIGHT_DESCENT;
 
    case ENDLANDING: // On the runway braking
      if (amdflag.Test(AirportMovingDataFlag::Brake)) return AMS_TTDP_BRAKING;
      /* Landed - moving off runway */
      return AMS_TTDP_TO_INWAY;
 
    case HELILANDING:
    case HELIENDLANDING: // Helicoptor is descending.
      if (amdflag.Test(AirportMovingDataFlag::HeliLower)) {
        return afc->delta_z == 0 ?
          AMS_TTDP_HELI_LAND_AIRPORT : AMS_TTDP_HELI_LAND_HELIPORT;
      } else {
        return AMS_TTDP_FLIGHT_TO_TOWER;
      }
 
    default:
      return AMS_TTDP_HANGAR;
  }
}
 
 
/* TTDP style aircraft movement action for GRF Action 2 Var 0xE6 */
enum TTDPAircraftMovementActions : uint8_t {
  AMA_TTDP_IN_HANGAR,
  AMA_TTDP_ON_PAD1,
  AMA_TTDP_ON_PAD2,
  AMA_TTDP_ON_PAD3,
  AMA_TTDP_HANGAR_TO_PAD1,
  AMA_TTDP_HANGAR_TO_PAD2,
  AMA_TTDP_HANGAR_TO_PAD3,
  AMA_TTDP_LANDING_TO_PAD1,
  AMA_TTDP_LANDING_TO_PAD2,
  AMA_TTDP_LANDING_TO_PAD3,
  AMA_TTDP_PAD1_TO_HANGAR,
  AMA_TTDP_PAD2_TO_HANGAR,
  AMA_TTDP_PAD3_TO_HANGAR,
  AMA_TTDP_PAD1_TO_TAKEOFF,
  AMA_TTDP_PAD2_TO_TAKEOFF,
  AMA_TTDP_PAD3_TO_TAKEOFF,
  AMA_TTDP_HANGAR_TO_TAKOFF,
  AMA_TTDP_LANDING_TO_HANGAR,
  AMA_TTDP_IN_FLIGHT,
};
 
 
static uint8_t MapAircraftMovementAction(const Aircraft *v)
{
  switch (v->state) {
    case HANGAR:
      return (v->cur_speed > 0) ? AMA_TTDP_LANDING_TO_HANGAR : AMA_TTDP_IN_HANGAR;
 
    case TERM1:
    case HELIPAD1:
      return (v->current_order.IsType(OT_LOADING)) ? AMA_TTDP_ON_PAD1 : AMA_TTDP_LANDING_TO_PAD1;
 
    case TERM2:
    case HELIPAD2:
      return (v->current_order.IsType(OT_LOADING)) ? AMA_TTDP_ON_PAD2 : AMA_TTDP_LANDING_TO_PAD2;
 
    case TERM3:
    case TERM4:
    case TERM5:
    case TERM6:
    case TERM7:
    case TERM8:
    case HELIPAD3:
      return (v->current_order.IsType(OT_LOADING)) ? AMA_TTDP_ON_PAD3 : AMA_TTDP_LANDING_TO_PAD3;
 
    case TAKEOFF:      // Moving to takeoff position
    case STARTTAKEOFF: // Accelerating down runway
    case ENDTAKEOFF:   // Ascent
    case HELITAKEOFF:
      /* @todo Need to find which terminal (or hangar) we've come from. How? */
      return AMA_TTDP_PAD1_TO_TAKEOFF;
 
    case FLYING:
      return AMA_TTDP_IN_FLIGHT;
 
    case LANDING:    // Descent
    case ENDLANDING: // On the runway braking
    case HELILANDING:
    case HELIENDLANDING:
      /* @todo Need to check terminal we're landing to. Is it known yet? */
      return (v->current_order.IsType(OT_GOTO_DEPOT)) ?
        AMA_TTDP_LANDING_TO_HANGAR : AMA_TTDP_LANDING_TO_PAD1;
 
    default:
      return AMA_TTDP_IN_HANGAR;
  }
}
 
 
/* virtual */ uint32_t VehicleScopeResolver::GetRandomBits() const
{
  return this->v == nullptr ? 0 : this->v->random_bits;
}
 
/* virtual */ uint32_t VehicleScopeResolver::GetTriggers() const
{
  return this->v == nullptr ? 0 : this->v->waiting_triggers;
}
 
 
/* virtual */ ScopeResolver *VehicleResolverObject::GetScope(VarSpriteGroupScope scope, uint8_t relative)
{
  switch (scope) {
    case VSG_SCOPE_SELF:   return &this->self_scope;
    case VSG_SCOPE_PARENT: return &this->parent_scope;
    case VSG_SCOPE_RELATIVE: {
      int32_t count = GB(relative, 0, 4);
      if (this->self_scope.v != nullptr && (relative != this->cached_relative_count || count == 0)) {
        /* Note: This caching only works as long as the VSG_SCOPE_RELATIVE cannot be used in
         *       VarAct2 with procedure calls. */
        if (count == 0) count = GetRegister(0x100);
 
        const Vehicle *v = nullptr;
        switch (GB(relative, 6, 2)) {
          default: NOT_REACHED();
          case 0x00: // count back (away from the engine), starting at this vehicle
            v = this->self_scope.v;
            break;
          case 0x01: // count forward (toward the engine), starting at this vehicle
            v = this->self_scope.v;
            count = -count;
            break;
          case 0x02: // count back, starting at the engine
            v = this->parent_scope.v;
            break;
          case 0x03: { // count back, starting at the first vehicle in this chain of vehicles with the same ID, as for vehicle variable 41
            const Vehicle *self = this->self_scope.v;
            for (const Vehicle *u = self->First(); u != self; u = u->Next()) {
              if (u->engine_type != self->engine_type) {
                v = nullptr;
              } else {
                if (v == nullptr) v = u;
              }
            }
            if (v == nullptr) v = self;
            break;
          }
        }
        this->relative_scope.SetVehicle(v->Move(count));
      }
      return &this->relative_scope;
    }
    default: return ResolverObject::GetScope(scope, relative);
  }
}
 
static const Livery *LiveryHelper(EngineID engine, const Vehicle *v)
{
  const Livery *l;
 
  if (v == nullptr) {
    if (!Company::IsValidID(_current_company)) return nullptr;
    l = GetEngineLivery(engine, _current_company, EngineID::Invalid(), nullptr, LIT_ALL);
  } else if (v->IsGroundVehicle()) {
    l = GetEngineLivery(v->engine_type, v->owner, v->GetGroundVehicleCache()->first_engine, v, LIT_ALL);
  } else {
    l = GetEngineLivery(v->engine_type, v->owner, EngineID::Invalid(), v, LIT_ALL);
  }
 
  return l;
}
 
static uint32_t PositionHelper(const Vehicle *v, bool consecutive)
{
  const Vehicle *u;
  uint8_t chain_before = 0;
  uint8_t chain_after  = 0;
 
  for (u = v->First(); u != v; u = u->Next()) {
    chain_before++;
    if (consecutive && u->engine_type != v->engine_type) chain_before = 0;
  }
 
  while (u->Next() != nullptr && (!consecutive || u->Next()->engine_type == v->engine_type)) {
    chain_after++;
    u = u->Next();
  }
 
  return chain_before | chain_after << 8 | (chain_before + chain_after + consecutive) << 16;
}
 
static uint32_t VehicleGetVariable(Vehicle *v, const VehicleScopeResolver *object, uint8_t variable, uint32_t parameter, bool &available)
{
  /* Calculated vehicle parameters */
  switch (variable) {
    case 0x25: // Get engine GRF ID
      return v->GetGRFID();
 
    case 0x40: // Get length of consist
      if (!HasBit(v->grf_cache.cache_valid, NCVV_POSITION_CONSIST_LENGTH)) {
        v->grf_cache.position_consist_length = PositionHelper(v, false);
        SetBit(v->grf_cache.cache_valid, NCVV_POSITION_CONSIST_LENGTH);
      }
      return v->grf_cache.position_consist_length;
 
    case 0x41: // Get length of same consecutive wagons
      if (!HasBit(v->grf_cache.cache_valid, NCVV_POSITION_SAME_ID_LENGTH)) {
        v->grf_cache.position_same_id_length = PositionHelper(v, true);
        SetBit(v->grf_cache.cache_valid, NCVV_POSITION_SAME_ID_LENGTH);
      }
      return v->grf_cache.position_same_id_length;
 
    case 0x42: { // Consist cargo information
      if (!HasBit(v->grf_cache.cache_valid, NCVV_CONSIST_CARGO_INFORMATION)) {
        std::array<uint8_t, NUM_CARGO> common_cargoes{};
        uint8_t cargo_classes = 0;
        uint8_t user_def_data = 0;
 
        for (const Vehicle *u = v; u != nullptr; u = u->Next()) {
          if (v->type == VEH_TRAIN) user_def_data |= Train::From(u)->tcache.user_def_data;
 
          /* Skip empty engines */
          if (!u->GetEngine()->CanCarryCargo()) continue;
 
          cargo_classes |= CargoSpec::Get(u->cargo_type)->classes.base();
          common_cargoes[u->cargo_type]++;
        }
 
        /* Pick the most common cargo type */
        auto cargo_it = std::max_element(std::begin(common_cargoes), std::end(common_cargoes));
        /* Return INVALID_CARGO if nothing is carried */
        CargoType common_cargo_type = (*cargo_it == 0) ? INVALID_CARGO : static_cast<CargoType>(std::distance(std::begin(common_cargoes), cargo_it));
 
        /* Count subcargo types of common_cargo_type */
        std::array<uint8_t, UINT8_MAX + 1> common_subtypes{};
        for (const Vehicle *u = v; u != nullptr; u = u->Next()) {
          /* Skip empty engines and engines not carrying common_cargo_type */
          if (u->cargo_type != common_cargo_type || !u->GetEngine()->CanCarryCargo()) continue;
 
          common_subtypes[u->cargo_subtype]++;
        }
 
        /* Pick the most common subcargo type*/
        auto subtype_it = std::max_element(std::begin(common_subtypes), std::end(common_subtypes));
        /* Return UINT8_MAX if nothing is carried */
        uint8_t common_subtype = (*subtype_it == 0) ? UINT8_MAX : static_cast<uint8_t>(std::distance(std::begin(common_subtypes), subtype_it));
 
        /* Note: We have to store the untranslated cargotype in the cache as the cache can be read by different NewGRFs,
         *       which will need different translations */
        v->grf_cache.consist_cargo_information = cargo_classes | (common_cargo_type << 8) | (common_subtype << 16) | (user_def_data << 24);
        SetBit(v->grf_cache.cache_valid, NCVV_CONSIST_CARGO_INFORMATION);
      }
 
      /* The cargo translation is specific to the accessing GRF, and thus cannot be cached. */
      CargoType common_cargo_type = (v->grf_cache.consist_cargo_information >> 8) & 0xFF;
 
      /* Note:
       *  - Unlike everywhere else the cargo translation table is only used since grf version 8, not 7.
       *  - For translating the cargo type we need to use the GRF which is resolving the variable, which
       *    is object->ro.grffile.
       *    In case of CBID_TRAIN_ALLOW_WAGON_ATTACH this is not the same as v->GetGRF().
       *  - The grffile == nullptr case only happens if this function is called for default vehicles.
       *    And this is only done by CheckCaches().
       */
      const GRFFile *grffile = object->ro.grffile;
      uint8_t common_bitnum = (common_cargo_type == INVALID_CARGO) ? 0xFF :
        (grffile == nullptr || grffile->grf_version < 8) ? CargoSpec::Get(common_cargo_type)->bitnum : grffile->cargo_map[common_cargo_type];
 
      return (v->grf_cache.consist_cargo_information & 0xFFFF00FF) | common_bitnum << 8;
    }
 
    case 0x43: // Company information
      if (!HasBit(v->grf_cache.cache_valid, NCVV_COMPANY_INFORMATION)) {
        v->grf_cache.company_information = GetCompanyInfo(v->owner, LiveryHelper(v->engine_type, v));
        SetBit(v->grf_cache.cache_valid, NCVV_COMPANY_INFORMATION);
      }
      return v->grf_cache.company_information;
 
    case 0x44: // Aircraft information
      if (v->type != VEH_AIRCRAFT || !Aircraft::From(v)->IsNormalAircraft()) return UINT_MAX;
 
      {
        const Vehicle *w = v->Next();
        assert(w != nullptr);
        uint16_t altitude = ClampTo<uint16_t>(v->z_pos - w->z_pos); // Aircraft height - shadow height
        uint8_t airporttype = ATP_TTDP_LARGE;
 
        const Station *st = GetTargetAirportIfValid(Aircraft::From(v));
 
        if (st != nullptr && st->airport.tile != INVALID_TILE) {
          airporttype = st->airport.GetSpec()->ttd_airport_type;
        }
 
        return (ClampTo<uint8_t>(altitude) << 8) | airporttype;
      }
 
    case 0x45: { // Curvature info
      /* Format: xxxTxBxF
       * F - previous wagon to current wagon, 0 if vehicle is first
       * B - current wagon to next wagon, 0 if wagon is last
       * T - previous wagon to next wagon, 0 in an S-bend
       */
      if (!v->IsGroundVehicle()) return 0;
 
      const Vehicle *u_p = v->Previous();
      const Vehicle *u_n = v->Next();
      DirDiff f = (u_p == nullptr) ?  DIRDIFF_SAME : DirDifference(u_p->direction, v->direction);
      DirDiff b = (u_n == nullptr) ?  DIRDIFF_SAME : DirDifference(v->direction, u_n->direction);
      DirDiff t = ChangeDirDiff(f, b);
 
      return ((t > DIRDIFF_REVERSE ? t | 8 : t) << 16) |
             ((b > DIRDIFF_REVERSE ? b | 8 : b) <<  8) |
             ( f > DIRDIFF_REVERSE ? f | 8 : f);
    }
 
    case 0x46: // Motion counter
      return v->motion_counter;
 
    case 0x47: { // Vehicle cargo info
      /* Format: ccccwwtt
       * tt - the cargo type transported by the vehicle,
       *     translated if a translation table has been installed.
       * ww - cargo unit weight in 1/16 tons, same as cargo prop. 0F.
       * cccc - the cargo class value of the cargo transported by the vehicle.
       */
      const CargoSpec *cs = CargoSpec::Get(v->cargo_type);
 
      /* Note:
       * For translating the cargo type we need to use the GRF which is resolving the variable, which
       * is object->ro.grffile.
       * In case of CBID_TRAIN_ALLOW_WAGON_ATTACH this is not the same as v->GetGRF().
       */
      return (cs->classes.base() << 16) | (cs->weight << 8) | object->ro.grffile->cargo_map[v->cargo_type];
    }
 
    case 0x48: return v->GetEngine()->flags.base(); // Vehicle Type Info
    case 0x49: return v->build_year.base();
 
    case 0x4A:
      switch (v->type) {
        case VEH_TRAIN: {
          RailType rt = GetTileRailType(v->tile);
          const RailTypeInfo *rti = GetRailTypeInfo(rt);
          return (rti->flags.Test(RailTypeFlag::Catenary) ? 0x200 : 0) |
            (HasPowerOnRail(Train::From(v)->railtype, rt) ? 0x100 : 0) |
            GetReverseRailTypeTranslation(rt, object->ro.grffile);
        }
 
        case VEH_ROAD: {
          RoadType rt = GetRoadType(v->tile, GetRoadTramType(RoadVehicle::From(v)->roadtype));
          const RoadTypeInfo *rti = GetRoadTypeInfo(rt);
          return (rti->flags.Test(RoadTypeFlag::Catenary) ? 0x200 : 0) |
            0x100 |
            GetReverseRoadTypeTranslation(rt, object->ro.grffile);
        }
 
        default:
          return 0;
      }
 
    case 0x4B: // Long date of last service
      return v->date_of_last_service_newgrf.base();
 
    case 0x4C: // Current maximum speed in NewGRF units
      if (!v->IsPrimaryVehicle()) return 0;
      return v->GetCurrentMaxSpeed();
 
    case 0x4D: // Position within articulated vehicle
      if (!HasBit(v->grf_cache.cache_valid, NCVV_POSITION_IN_VEHICLE)) {
        uint8_t artic_before = 0;
        for (const Vehicle *u = v; u->IsArticulatedPart(); u = u->Previous()) artic_before++;
        uint8_t artic_after = 0;
        for (const Vehicle *u = v; u->HasArticulatedPart(); u = u->Next()) artic_after++;
        v->grf_cache.position_in_vehicle = artic_before | artic_after << 8;
        SetBit(v->grf_cache.cache_valid, NCVV_POSITION_IN_VEHICLE);
      }
      return v->grf_cache.position_in_vehicle;
 
    /* Variables which use the parameter */
    case 0x60: // Count consist's engine ID occurrence
      if (v->type != VEH_TRAIN) return v->GetEngine()->grf_prop.local_id == parameter ? 1 : 0;
 
      {
        uint count = 0;
        for (; v != nullptr; v = v->Next()) {
          if (v->GetEngine()->grf_prop.local_id == parameter) count++;
        }
        return count;
      }
 
    case 0x61: // Get variable of n-th vehicle in chain [signed number relative to vehicle]
      if (!v->IsGroundVehicle() || parameter == 0x61) {
        /* Not available */
        break;
      }
 
      /* Only allow callbacks that don't change properties to avoid circular dependencies. */
      if (object->ro.callback == CBID_NO_CALLBACK || object->ro.callback == CBID_RANDOM_TRIGGER || object->ro.callback == CBID_TRAIN_ALLOW_WAGON_ATTACH ||
          object->ro.callback == CBID_VEHICLE_START_STOP_CHECK || object->ro.callback == CBID_VEHICLE_32DAY_CALLBACK || object->ro.callback == CBID_VEHICLE_COLOUR_MAPPING ||
          object->ro.callback == CBID_VEHICLE_SPAWN_VISUAL_EFFECT) {
        Vehicle *u = v->Move((int32_t)GetRegister(0x10F));
        if (u == nullptr) return 0; // available, but zero
 
        if (parameter == 0x5F) {
          /* This seems to be the only variable that makes sense to access via var 61, but is not handled by VehicleGetVariable */
          return (u->random_bits << 8) | u->waiting_triggers;
        } else {
          return VehicleGetVariable(u, object, parameter, GetRegister(0x10E), available);
        }
      }
      /* Not available */
      break;
 
    case 0x62: { // Curvature/position difference for n-th vehicle in chain [signed number relative to vehicle]
      /* Format: zzyyxxFD
       * zz - Signed difference of z position between the selected and this vehicle.
       * yy - Signed difference of y position between the selected and this vehicle.
       * xx - Signed difference of x position between the selected and this vehicle.
       * F  - Flags, bit 7 corresponds to VehState::Hidden.
       * D  - Dir difference, like in 0x45.
       */
      if (!v->IsGroundVehicle()) return 0;
 
      const Vehicle *u = v->Move((int8_t)parameter);
      if (u == nullptr) return 0;
 
      /* Get direction difference. */
      bool prev = (int8_t)parameter < 0;
      uint32_t ret = prev ? DirDifference(u->direction, v->direction) : DirDifference(v->direction, u->direction);
      if (ret > DIRDIFF_REVERSE) ret |= 0x08;
 
      if (u->vehstatus.Test(VehState::Hidden)) ret |= 0x80;
 
      /* Get position difference. */
      ret |= ((prev ? u->x_pos - v->x_pos : v->x_pos - u->x_pos) & 0xFF) << 8;
      ret |= ((prev ? u->y_pos - v->y_pos : v->y_pos - u->y_pos) & 0xFF) << 16;
      ret |= ((prev ? u->z_pos - v->z_pos : v->z_pos - u->z_pos) & 0xFF) << 24;
 
      return ret;
    }
 
    case 0x63:
      /* Tile compatibility wrt. arbitrary track-type
       * Format:
       *  bit 0: Type 'parameter' is known.
       *  bit 1: Engines with type 'parameter' are compatible with this tile.
       *  bit 2: Engines with type 'parameter' are powered on this tile.
       *  bit 3: This tile has type 'parameter' or it is considered equivalent (alternate labels).
       */
      switch (v->type) {
        case VEH_TRAIN: {
          RailType param_type = GetRailTypeTranslation(parameter, object->ro.grffile);
          if (param_type == INVALID_RAILTYPE) return 0x00;
          RailType tile_type = GetTileRailType(v->tile);
          if (tile_type == param_type) return 0x0F;
          return (HasPowerOnRail(param_type, tile_type) ? 0x04 : 0x00) |
              (IsCompatibleRail(param_type, tile_type) ? 0x02 : 0x00) |
              0x01;
        }
        case VEH_ROAD: {
          RoadTramType rtt = GetRoadTramType(RoadVehicle::From(v)->roadtype);
          RoadType param_type = GetRoadTypeTranslation(rtt, parameter, object->ro.grffile);
          if (param_type == INVALID_ROADTYPE) return 0x00;
          RoadType tile_type = GetRoadType(v->tile, rtt);
          if (tile_type == param_type) return 0x0F;
          return (HasPowerOnRoad(param_type, tile_type) ? 0x06 : 0x00) |
              0x01;
        }
        default: return 0x00;
      }
 
    case 0x64: { // Count consist's badge ID occurrence
      if (v->type != VEH_TRAIN) return GetBadgeVariableResult(*object->ro.grffile, v->GetEngine()->badges, parameter);
 
      /* Look up badge index. */
      if (parameter >= std::size(object->ro.grffile->badge_list)) return UINT_MAX;
      BadgeID index = object->ro.grffile->badge_list[parameter];
 
      /* Count number of vehicles that contain this badge index. */
      uint count = 0;
      for (; v != nullptr; v = v->Next()) {
        const auto &badges = v->GetEngine()->badges;
        if (std::ranges::find(badges, index) != std::end(badges)) count++;
      }
 
      return count;
    }
 
    case 0x7A: return GetBadgeVariableResult(*object->ro.grffile, v->GetEngine()->badges, parameter);
 
    case 0xFE:
    case 0xFF: {
      uint16_t modflags = 0;
 
      if (v->type == VEH_TRAIN) {
        const Train *t = Train::From(v);
        bool is_powered_wagon = HasBit(t->flags, VRF_POWEREDWAGON);
        const Train *u = is_powered_wagon ? t->First() : t; // for powered wagons the engine defines the type of engine (i.e. railtype)
        RailType railtype = GetRailType(v->tile);
        bool powered = t->IsEngine() || is_powered_wagon;
        bool has_power = HasPowerOnRail(u->railtype, railtype);
 
        if (powered && has_power) SetBit(modflags, 5);
        if (powered && !has_power) SetBit(modflags, 6);
        if (HasBit(t->flags, VRF_TOGGLE_REVERSE)) SetBit(modflags, 8);
      }
      if (v->vehicle_flags.Test(VehicleFlag::CargoUnloading)) SetBit(modflags, 1);
      if (v->vehicle_flags.Test(VehicleFlag::BuiltAsPrototype)) SetBit(modflags, 10);
 
      return variable == 0xFE ? modflags : GB(modflags, 8, 8);
    }
  }
 
  /*
   * General vehicle properties
   *
   * Some parts of the TTD Vehicle structure are omitted for various reasons
   * (see http://marcin.ttdpatch.net/sv1codec/TTD-locations.html#_VehicleArray)
   */
  switch (variable - 0x80) {
    case 0x00: return v->type + 0x10;
    case 0x01: return MapOldSubType(v);
    case 0x02: break; // not implemented
    case 0x03: break; // not implemented
    case 0x04: return v->index.base();
    case 0x05: return GB(v->index.base(), 8, 8);
    case 0x06: break; // not implemented
    case 0x07: break; // not implemented
    case 0x08: break; // not implemented
    case 0x09: break; // not implemented
    case 0x0A: return v->current_order.MapOldOrder();
    case 0x0B: return v->current_order.GetDestination().value;
    case 0x0C: return v->GetNumOrders();
    case 0x0D: return v->cur_real_order_index;
    case 0x0E: break; // not implemented
    case 0x0F: break; // not implemented
    case 0x10:
    case 0x11: {
      uint ticks;
      if (v->current_order.IsType(OT_LOADING)) {
        ticks = v->load_unload_ticks;
      } else {
        switch (v->type) {
          case VEH_TRAIN:    ticks = Train::From(v)->wait_counter; break;
          case VEH_AIRCRAFT: ticks = Aircraft::From(v)->turn_counter; break;
          default:           ticks = 0; break;
        }
      }
      return (variable - 0x80) == 0x10 ? ticks : GB(ticks, 8, 8);
    }
    case 0x12: return ClampTo<uint16_t>(v->date_of_last_service_newgrf - CalendarTime::DAYS_TILL_ORIGINAL_BASE_YEAR);
    case 0x13: return GB(ClampTo<uint16_t>(v->date_of_last_service_newgrf - CalendarTime::DAYS_TILL_ORIGINAL_BASE_YEAR), 8, 8);
    case 0x14: return v->GetServiceInterval();
    case 0x15: return GB(v->GetServiceInterval(), 8, 8);
    case 0x16: return v->last_station_visited.base();
    case 0x17: return v->tick_counter;
    case 0x18:
    case 0x19: {
      uint max_speed;
      switch (v->type) {
        case VEH_AIRCRAFT:
          max_speed = Aircraft::From(v)->GetSpeedOldUnits(); // Convert to old units.
          break;
 
        default:
          max_speed = v->vcache.cached_max_speed;
          break;
      }
      return (variable - 0x80) == 0x18 ? max_speed : GB(max_speed, 8, 8);
    }
    case 0x1A: return v->x_pos;
    case 0x1B: return GB(v->x_pos, 8, 8);
    case 0x1C: return v->y_pos;
    case 0x1D: return GB(v->y_pos, 8, 8);
    case 0x1E: return v->z_pos;
    case 0x1F: return object->rotor_in_gui ? DIR_W : v->direction; // for rotors the spriteset contains animation frames, so NewGRF need a different way to tell the helicopter orientation.
    case 0x20: break; // not implemented
    case 0x21: break; // not implemented
    case 0x22: break; // not implemented
    case 0x23: break; // not implemented
    case 0x24: break; // not implemented
    case 0x25: break; // not implemented
    case 0x26: break; // not implemented
    case 0x27: break; // not implemented
    case 0x28: return 0; // cur_image is a potential desyncer due to Action1 in static NewGRFs.
    case 0x29: return 0; // cur_image is a potential desyncer due to Action1 in static NewGRFs.
    case 0x2A: break; // not implemented
    case 0x2B: break; // not implemented
    case 0x2C: break; // not implemented
    case 0x2D: break; // not implemented
    case 0x2E: break; // not implemented
    case 0x2F: break; // not implemented
    case 0x30: break; // not implemented
    case 0x31: break; // not implemented
    case 0x32: return v->vehstatus.base();
    case 0x33: return 0; // non-existent high byte of vehstatus
    case 0x34: return v->type == VEH_AIRCRAFT ? (v->cur_speed * 10) / 128 : v->cur_speed;
    case 0x35: return GB(v->type == VEH_AIRCRAFT ? (v->cur_speed * 10) / 128 : v->cur_speed, 8, 8);
    case 0x36: return v->subspeed;
    case 0x37: return v->acceleration;
    case 0x38: break; // not implemented
    case 0x39: return v->cargo_type;
    case 0x3A: return v->cargo_cap;
    case 0x3B: return GB(v->cargo_cap, 8, 8);
    case 0x3C: return ClampTo<uint16_t>(v->cargo.StoredCount());
    case 0x3D: return GB(ClampTo<uint16_t>(v->cargo.StoredCount()), 8, 8);
    case 0x3E: return v->cargo.GetFirstStation().base();
    case 0x3F: return ClampTo<uint8_t>(v->cargo.PeriodsInTransit());
    case 0x40: return ClampTo<uint16_t>(v->age);
    case 0x41: return GB(ClampTo<uint16_t>(v->age), 8, 8);
    case 0x42: return ClampTo<uint16_t>(v->max_age);
    case 0x43: return GB(ClampTo<uint16_t>(v->max_age), 8, 8);
    case 0x44: return (Clamp(v->build_year, CalendarTime::ORIGINAL_BASE_YEAR, CalendarTime::ORIGINAL_MAX_YEAR) - CalendarTime::ORIGINAL_BASE_YEAR).base();
    case 0x45: return v->unitnumber;
    case 0x46: return v->GetEngine()->grf_prop.local_id;
    case 0x47: return GB(v->GetEngine()->grf_prop.local_id, 8, 8);
    case 0x48:
      if (v->type != VEH_TRAIN || v->spritenum != 0xFD) return v->spritenum;
      return HasBit(Train::From(v)->flags, VRF_REVERSE_DIRECTION) ? 0xFE : 0xFD;
 
    case 0x49: return v->day_counter;
    case 0x4A: return v->breakdowns_since_last_service;
    case 0x4B: return v->breakdown_ctr;
    case 0x4C: return v->breakdown_delay;
    case 0x4D: return v->breakdown_chance;
    case 0x4E: return v->reliability;
    case 0x4F: return GB(v->reliability, 8, 8);
    case 0x50: return v->reliability_spd_dec;
    case 0x51: return GB(v->reliability_spd_dec, 8, 8);
    case 0x52: return ClampTo<int32_t>(v->GetDisplayProfitThisYear());
    case 0x53: return GB(ClampTo<int32_t>(v->GetDisplayProfitThisYear()),  8, 24);
    case 0x54: return GB(ClampTo<int32_t>(v->GetDisplayProfitThisYear()), 16, 16);
    case 0x55: return GB(ClampTo<int32_t>(v->GetDisplayProfitThisYear()), 24,  8);
    case 0x56: return ClampTo<int32_t>(v->GetDisplayProfitLastYear());
    case 0x57: return GB(ClampTo<int32_t>(v->GetDisplayProfitLastYear()),  8, 24);
    case 0x58: return GB(ClampTo<int32_t>(v->GetDisplayProfitLastYear()), 16, 16);
    case 0x59: return GB(ClampTo<int32_t>(v->GetDisplayProfitLastYear()), 24,  8);
    case 0x5A: return (v->Next() == nullptr ? VehicleID::Invalid() : v->Next()->index).base();
    case 0x5B: break; // not implemented
    case 0x5C: return ClampTo<int32_t>(v->value);
    case 0x5D: return GB(ClampTo<int32_t>(v->value),  8, 24);
    case 0x5E: return GB(ClampTo<int32_t>(v->value), 16, 16);
    case 0x5F: return GB(ClampTo<int32_t>(v->value), 24,  8);
    case 0x60: break; // not implemented
    case 0x61: break; // not implemented
    case 0x62: break; // vehicle specific, see below
    case 0x63: break; // not implemented
    case 0x64: break; // vehicle specific, see below
    case 0x65: break; // vehicle specific, see below
    case 0x66: break; // vehicle specific, see below
    case 0x67: break; // vehicle specific, see below
    case 0x68: break; // vehicle specific, see below
    case 0x69: break; // vehicle specific, see below
    case 0x6A: break; // not implemented
    case 0x6B: break; // not implemented
    case 0x6C: break; // not implemented
    case 0x6D: break; // not implemented
    case 0x6E: break; // not implemented
    case 0x6F: break; // not implemented
    case 0x70: break; // not implemented
    case 0x71: break; // not implemented
    case 0x72: return v->cargo_subtype;
    case 0x73: break; // vehicle specific, see below
    case 0x74: break; // vehicle specific, see below
    case 0x75: break; // vehicle specific, see below
    case 0x76: break; // vehicle specific, see below
    case 0x77: break; // vehicle specific, see below
    case 0x78: break; // not implemented
    case 0x79: break; // not implemented
    case 0x7A: return v->random_bits;
    case 0x7B: return v->waiting_triggers;
    case 0x7C: break; // vehicle specific, see below
    case 0x7D: break; // vehicle specific, see below
    case 0x7E: break; // not implemented
    case 0x7F: break; // vehicle specific, see below
  }
 
  /* Vehicle specific properties */
  switch (v->type) {
    case VEH_TRAIN: {
      Train *t = Train::From(v);
      switch (variable - 0x80) {
        case 0x62: return t->track;
        case 0x66: return t->railtype;
        case 0x73: return 0x80 + VEHICLE_LENGTH - t->gcache.cached_veh_length;
        case 0x74: return t->gcache.cached_power;
        case 0x75: return GB(t->gcache.cached_power,  8, 24);
        case 0x76: return GB(t->gcache.cached_power, 16, 16);
        case 0x77: return GB(t->gcache.cached_power, 24,  8);
        case 0x7C: return t->First()->index.base();
        case 0x7D: return GB(t->First()->index.base(), 8, 8);
        case 0x7F: return 0; // Used for vehicle reversing hack in TTDP
      }
      break;
    }
 
    case VEH_ROAD: {
      RoadVehicle *rv = RoadVehicle::From(v);
      switch (variable - 0x80) {
        case 0x62: return rv->state;
        case 0x64: return rv->blocked_ctr;
        case 0x65: return GB(rv->blocked_ctr, 8, 8);
        case 0x66: return rv->overtaking;
        case 0x67: return rv->overtaking_ctr;
        case 0x68: return rv->crashed_ctr;
        case 0x69: return GB(rv->crashed_ctr, 8, 8);
      }
      break;
    }
 
    case VEH_SHIP: {
      Ship *s = Ship::From(v);
      switch (variable - 0x80) {
        case 0x62: return s->state;
      }
      break;
    }
 
    case VEH_AIRCRAFT: {
      Aircraft *a = Aircraft::From(v);
      switch (variable - 0x80) {
        case 0x62: return MapAircraftMovementState(a);  // Current movement state
        case 0x63: return a->targetairport.base();      // Airport to which the action refers
        case 0x66: return MapAircraftMovementAction(a); // Current movement action
      }
      break;
    }
 
    default: break;
  }
 
  Debug(grf, 1, "Unhandled vehicle variable 0x{:X}, type 0x{:X}", variable, (uint)v->type);
 
  available = false;
  return UINT_MAX;
}
 
/* virtual */ uint32_t VehicleScopeResolver::GetVariable(uint8_t variable, [[maybe_unused]] uint32_t parameter, bool &available) const
{
  if (this->v == nullptr) {
    /* Vehicle does not exist, so we're in a purchase list */
    switch (variable) {
      case 0x43: return GetCompanyInfo(_current_company, LiveryHelper(this->self_type, nullptr)); // Owner information
      case 0x46: return 0;               // Motion counter
      case 0x47: { // Vehicle cargo info
        const Engine *e = Engine::Get(this->self_type);
        CargoType cargo_type = e->GetDefaultCargoType();
        if (IsValidCargoType(cargo_type)) {
          const CargoSpec *cs = CargoSpec::Get(cargo_type);
          return (cs->classes.base() << 16) | (cs->weight << 8) | this->ro.grffile->cargo_map[cargo_type];
        } else {
          return 0x000000FF;
        }
      }
      case 0x48: return Engine::Get(this->self_type)->flags.base(); // Vehicle Type Info
      case 0x49: return TimerGameCalendar::year.base(); // 'Long' format build year
      case 0x4B: return TimerGameCalendar::date.base(); // Long date of last service
 
      case 0x7A: return GetBadgeVariableResult(*this->ro.grffile, Engine::Get(this->self_type)->badges, parameter);
 
      case 0x92: return ClampTo<uint16_t>(TimerGameCalendar::date - CalendarTime::DAYS_TILL_ORIGINAL_BASE_YEAR); // Date of last service
      case 0x93: return GB(ClampTo<uint16_t>(TimerGameCalendar::date - CalendarTime::DAYS_TILL_ORIGINAL_BASE_YEAR), 8, 8);
      case 0xC4: return (Clamp(TimerGameCalendar::year, CalendarTime::ORIGINAL_BASE_YEAR, CalendarTime::ORIGINAL_MAX_YEAR) - CalendarTime::ORIGINAL_BASE_YEAR).base(); // Build year
      case 0xC6: return Engine::Get(this->self_type)->grf_prop.local_id;
      case 0xC7: return GB(Engine::Get(this->self_type)->grf_prop.local_id, 8, 8);
      case 0xDA: return VehicleID::Invalid().base(); // Next vehicle
      case 0xF2: return 0; // Cargo subtype
    }
 
    available = false;
    return UINT_MAX;
  }
 
  return VehicleGetVariable(const_cast<Vehicle*>(this->v), this, variable, parameter, available);
}
 
 
/* virtual */ const SpriteGroup *VehicleResolverObject::ResolveReal(const RealSpriteGroup *group) const
{
  const Vehicle *v = this->self_scope.v;
 
  if (v == nullptr) {
    if (!group->loading.empty()) return group->loading[0];
    if (!group->loaded.empty())  return group->loaded[0];
    return nullptr;
  }
 
  const Order &order = v->First()->current_order;
  bool not_loading = (order.GetUnloadType() & OUFB_NO_UNLOAD) && (order.GetLoadType() & OLFB_NO_LOAD);
  bool in_motion = !order.IsType(OT_LOADING) || not_loading;
 
  uint totalsets = in_motion ? (uint)group->loaded.size() : (uint)group->loading.size();
 
  if (totalsets == 0) return nullptr;
 
  uint set = (v->cargo.StoredCount() * totalsets) / std::max<uint16_t>(1u, v->cargo_cap);
  set = std::min(set, totalsets - 1);
 
  return in_motion ? group->loaded[set] : group->loading[set];
}
 
GrfSpecFeature VehicleResolverObject::GetFeature() const
{
  switch (Engine::Get(this->self_scope.self_type)->type) {
    case VEH_TRAIN: return GSF_TRAINS;
    case VEH_ROAD: return GSF_ROADVEHICLES;
    case VEH_SHIP: return GSF_SHIPS;
    case VEH_AIRCRAFT: return GSF_AIRCRAFT;
    default: return GSF_INVALID;
  }
}
 
uint32_t VehicleResolverObject::GetDebugID() const
{
  return Engine::Get(this->self_scope.self_type)->grf_prop.local_id;
}
 
static const GRFFile *GetEngineGrfFile(EngineID engine_type)
{
  const Engine *e = Engine::Get(engine_type);
  return (e != nullptr) ? e->GetGRF() : nullptr;
}
 
VehicleResolverObject::VehicleResolverObject(EngineID engine_type, const Vehicle *v, WagonOverride wagon_override, bool rotor_in_gui,
    CallbackID callback, uint32_t callback_param1, uint32_t callback_param2)
  : ResolverObject(GetEngineGrfFile(engine_type), callback, callback_param1, callback_param2),
  self_scope(*this, engine_type, v, rotor_in_gui),
  parent_scope(*this, engine_type, ((v != nullptr) ? v->First() : v), rotor_in_gui),
  relative_scope(*this, engine_type, v, rotor_in_gui),
  cached_relative_count(0)
{
  if (wagon_override == WO_SELF) {
    this->root_spritegroup = GetWagonOverrideSpriteSet(engine_type, SpriteGroupCargo::SG_DEFAULT, engine_type);
  } else {
    if (wagon_override != WO_NONE && v != nullptr && v->IsGroundVehicle()) {
      assert(v->engine_type == engine_type); // overrides make little sense with fake scopes
 
      /* For trains we always use cached value, except for callbacks because the override spriteset
       * to use may be different than the one cached. It happens for callback 0x15 (refit engine),
       * as v->cargo_type is temporary changed to the new type */
      if (wagon_override == WO_CACHED && v->type == VEH_TRAIN) {
        this->root_spritegroup = Train::From(v)->tcache.cached_override;
      } else {
        this->root_spritegroup = GetWagonOverrideSpriteSet(v->engine_type, v->cargo_type, v->GetGroundVehicleCache()->first_engine);
      }
    }
 
    if (this->root_spritegroup == nullptr) {
      const Engine *e = Engine::Get(engine_type);
      CargoType cargo = v != nullptr ? v->cargo_type : SpriteGroupCargo::SG_PURCHASE;
      this->root_spritegroup = e->grf_prop.GetSpriteGroup(cargo);
      if (this->root_spritegroup == nullptr) this->root_spritegroup = e->grf_prop.GetSpriteGroup(SpriteGroupCargo::SG_DEFAULT);
    }
  }
}
 
 
 
void GetCustomEngineSprite(EngineID engine, const Vehicle *v, Direction direction, EngineImageType image_type, VehicleSpriteSeq *result)
{
  VehicleResolverObject object(engine, v, VehicleResolverObject::WO_CACHED, false, CBID_NO_CALLBACK);
  result->Clear();
 
  bool sprite_stack = EngInfo(engine)->misc_flags.Test(EngineMiscFlag::SpriteStack);
  uint max_stack = sprite_stack ? static_cast<uint>(std::size(result->seq)) : 1;
  for (uint stack = 0; stack < max_stack; ++stack) {
    object.ResetState();
    object.callback_param1 = image_type | (stack << 8);
    const SpriteGroup *group = object.Resolve();
    uint32_t reg100 = sprite_stack ? GetRegister(0x100) : 0;
    if (group != nullptr && group->GetNumResults() != 0) {
      result->seq[result->count].sprite = group->GetResult() + (direction % group->GetNumResults());
      result->seq[result->count].pal    = GB(reg100, 0, 16); // zero means default recolouring
      result->count++;
    }
    if (!HasBit(reg100, 31)) break;
  }
}
 
 
void GetRotorOverrideSprite(EngineID engine, const struct Aircraft *v, EngineImageType image_type, VehicleSpriteSeq *result)
{
  const Engine *e = Engine::Get(engine);
 
  /* Only valid for helicopters */
  assert(e->type == VEH_AIRCRAFT);
  assert(!(e->u.air.subtype & AIR_CTOL));
 
  /* We differ from TTDPatch by resolving the sprite using the primary vehicle 'v', and not using the rotor vehicle 'v->Next()->Next()'.
   * TTDPatch copies some variables between the vehicles each time, to somehow synchronize the rotor vehicle with the primary vehicle.
   * We use 'rotor_in_gui' to replicate when the variables differ.
   * But some other variables like 'rotor state' and 'rotor speed' are not available in OpenTTD, while they are in TTDPatch. */
  bool rotor_in_gui = image_type != EIT_ON_MAP;
  VehicleResolverObject object(engine, v, VehicleResolverObject::WO_SELF, rotor_in_gui, CBID_NO_CALLBACK);
  result->Clear();
  uint rotor_pos = v == nullptr || rotor_in_gui ? 0 : v->Next()->Next()->state;
 
  bool sprite_stack = e->info.misc_flags.Test(EngineMiscFlag::SpriteStack);
  uint max_stack = sprite_stack ? static_cast<uint>(std::size(result->seq)) : 1;
  for (uint stack = 0; stack < max_stack; ++stack) {
    object.ResetState();
    object.callback_param1 = image_type | (stack << 8);
    const SpriteGroup *group = object.Resolve();
    uint32_t reg100 = sprite_stack ? GetRegister(0x100) : 0;
    if (group != nullptr && group->GetNumResults() != 0) {
      result->seq[result->count].sprite = group->GetResult() + (rotor_pos % group->GetNumResults());
      result->seq[result->count].pal    = GB(reg100, 0, 16); // zero means default recolouring
      result->count++;
    }
    if (!HasBit(reg100, 31)) break;
  }
}
 
 
bool UsesWagonOverride(const Vehicle *v)
{
  assert(v->type == VEH_TRAIN);
  return Train::From(v)->tcache.cached_override != nullptr;
}
 
uint16_t GetVehicleCallback(CallbackID callback, uint32_t param1, uint32_t param2, EngineID engine, const Vehicle *v)
{
  VehicleResolverObject object(engine, v, VehicleResolverObject::WO_UNCACHED, false, callback, param1, param2);
  return object.ResolveCallback();
}
 
uint16_t GetVehicleCallbackParent(CallbackID callback, uint32_t param1, uint32_t param2, EngineID engine, const Vehicle *v, const Vehicle *parent)
{
  VehicleResolverObject object(engine, v, VehicleResolverObject::WO_NONE, false, callback, param1, param2);
  object.parent_scope.SetVehicle(parent);
  return object.ResolveCallback();
}
 
 
/* Callback 36 handlers */
int GetVehicleProperty(const Vehicle *v, PropertyID property, int orig_value, bool is_signed)
{
  return GetEngineProperty(v->engine_type, property, orig_value, v, is_signed);
}
 
 
int GetEngineProperty(EngineID engine, PropertyID property, int orig_value, const Vehicle *v, bool is_signed)
{
  uint16_t callback = GetVehicleCallback(CBID_VEHICLE_MODIFY_PROPERTY, property, 0, engine, v);
  if (callback != CALLBACK_FAILED) {
    if (is_signed) {
      /* Sign extend 15 bit integer */
      return static_cast<int16_t>(callback << 1) / 2;
    } else {
      return callback;
    }
  }
 
  return orig_value;
}
 
bool TestVehicleBuildProbability(Vehicle *v, EngineID engine, BuildProbabilityType type)
{
  uint16_t p = GetVehicleCallback(CBID_VEHICLE_BUILD_PROBABILITY, to_underlying(type), 0, engine, v);
  if (p == CALLBACK_FAILED) return false;
 
  const uint16_t PROBABILITY_RANGE = 100;
  return p + RandomRange(PROBABILITY_RANGE) >= PROBABILITY_RANGE;
}
 
static void DoTriggerVehicle(Vehicle *v, VehicleTrigger trigger, uint16_t base_random_bits, bool first)
{
  /* We can't trigger a non-existent vehicle... */
  assert(v != nullptr);
 
  VehicleResolverObject object(v->engine_type, v, VehicleResolverObject::WO_CACHED, false, CBID_RANDOM_TRIGGER);
  object.waiting_triggers = v->waiting_triggers | trigger;
  v->waiting_triggers = object.waiting_triggers; // store now for var 5F
 
  const SpriteGroup *group = object.Resolve();
  if (group == nullptr) return;
 
  /* Store remaining triggers. */
  v->waiting_triggers = object.GetRemainingTriggers();
 
  /* Rerandomise bits. Scopes other than SELF are invalid for rerandomisation. For bug-to-bug-compatibility with TTDP we ignore the scope. */
  uint16_t new_random_bits = Random();
  uint32_t reseed = object.GetReseedSum();
  v->random_bits &= ~reseed;
  v->random_bits |= (first ? new_random_bits : base_random_bits) & reseed;
 
  switch (trigger) {
    case VEHICLE_TRIGGER_NEW_CARGO:
      /* All vehicles in chain get ANY_NEW_CARGO trigger now.
       * So we call it for the first one and they will recurse.
       * Indexing part of vehicle random bits needs to be
       * same for all triggered vehicles in the chain (to get
       * all the random-cargo wagons carry the same cargo,
       * i.e.), so we give them all the NEW_CARGO triggered
       * vehicle's portion of random bits. */
      assert(first);
      DoTriggerVehicle(v->First(), VEHICLE_TRIGGER_ANY_NEW_CARGO, new_random_bits, false);
      break;
 
    case VEHICLE_TRIGGER_DEPOT:
      /* We now trigger the next vehicle in chain recursively.
       * The random bits portions may be different for each
       * vehicle in chain. */
      if (v->Next() != nullptr) DoTriggerVehicle(v->Next(), trigger, 0, true);
      break;
 
    case VEHICLE_TRIGGER_EMPTY:
      /* We now trigger the next vehicle in chain
       * recursively.  The random bits portions must be same
       * for each vehicle in chain, so we give them all
       * first chained vehicle's portion of random bits. */
      if (v->Next() != nullptr) DoTriggerVehicle(v->Next(), trigger, first ? new_random_bits : base_random_bits, false);
      break;
 
    case VEHICLE_TRIGGER_ANY_NEW_CARGO:
      /* Now pass the trigger recursively to the next vehicle
       * in chain. */
      assert(!first);
      if (v->Next() != nullptr) DoTriggerVehicle(v->Next(), VEHICLE_TRIGGER_ANY_NEW_CARGO, base_random_bits, false);
      break;
 
    case VEHICLE_TRIGGER_CALLBACK_32:
      /* Do not do any recursion */
      break;
  }
}
 
void TriggerVehicle(Vehicle *v, VehicleTrigger trigger)
{
  if (trigger == VEHICLE_TRIGGER_DEPOT) {
    /* store that the vehicle entered a depot this tick */
    VehicleEnteredDepotThisTick(v);
  }
 
  v->InvalidateNewGRFCacheOfChain();
  DoTriggerVehicle(v, trigger, 0, true);
  v->InvalidateNewGRFCacheOfChain();
}
 
/* Functions for changing the order of vehicle purchase lists */
 
struct ListOrderChange {
  EngineID engine; 
  uint16_t target; 
 
  ListOrderChange(EngineID engine, uint16_t target) : engine(engine), target(target) {}
};
 
static std::vector<ListOrderChange> _list_order_changes;
 
void AlterVehicleListOrder(EngineID engine, uint16_t target)
{
  /* Add the list order change to a queue */
  _list_order_changes.emplace_back(engine, target);
}
 
static bool EnginePreSort(const EngineID &a, const EngineID &b)
{
  const Engine &engine_a = *Engine::Get(a);
  const Engine &engine_b = *Engine::Get(b);
 
  /* 1. Sort by engine type */
  if (engine_a.type != engine_b.type) return static_cast<int>(engine_a.type) < static_cast<int>(engine_b.type);
 
  /* 2. Sort by scope-GRFID */
  if (engine_a.grf_prop.grfid != engine_b.grf_prop.grfid) return engine_a.grf_prop.grfid < engine_b.grf_prop.grfid;
 
  /* 3. Sort by local ID */
  return static_cast<int>(engine_a.grf_prop.local_id) < static_cast<int>(engine_b.grf_prop.local_id);
}
 
void CommitVehicleListOrderChanges()
{
  /* Build a list of EngineIDs. EngineIDs are sequential from 0 up to the number of pool items with no gaps. */
  std::vector<EngineID> ordering(Engine::GetNumItems());
  std::iota(std::begin(ordering), std::end(ordering), EngineID::Begin());
 
  /* Pre-sort engines by scope-grfid and local index */
  std::ranges::sort(ordering, EnginePreSort);
 
  /* Apply Insertion-Sort operations */
  for (const ListOrderChange &loc : _list_order_changes) {
    EngineID source = loc.engine;
 
    Engine *engine_source = Engine::Get(source);
    if (engine_source->grf_prop.local_id == loc.target) continue;
 
    EngineID target = _engine_mngr.GetID(engine_source->type, loc.target, engine_source->grf_prop.grfid);
    if (target == EngineID::Invalid()) continue;
 
    auto it_source = std::ranges::find(ordering, source);
    auto it_target = std::ranges::find(ordering, target);
 
    assert(it_source != std::end(ordering) && it_target != std::end(ordering));
    assert(it_source != it_target);
 
    /* Move just this item to before the target. */
    Slide(it_source, std::next(it_source), it_target);
  }
 
  /* Store final sort-order */
  for (uint16_t index = 0; const EngineID &eid : ordering) {
    Engine::Get(eid)->list_position = index;
    ++index;
  }
 
  /* Clear out the queue */
  _list_order_changes.clear();
  _list_order_changes.shrink_to_fit();
}
 
void FillNewGRFVehicleCache(const Vehicle *v)
{
  VehicleResolverObject ro(v->engine_type, v, VehicleResolverObject::WO_NONE);
 
  /* These variables we have to check; these are the ones with a cache. */
  static const int cache_entries[][2] = {
    { 0x40, NCVV_POSITION_CONSIST_LENGTH },
    { 0x41, NCVV_POSITION_SAME_ID_LENGTH },
    { 0x42, NCVV_CONSIST_CARGO_INFORMATION },
    { 0x43, NCVV_COMPANY_INFORMATION },
    { 0x4D, NCVV_POSITION_IN_VEHICLE },
  };
  static_assert(NCVV_END == lengthof(cache_entries));
 
  /* Resolve all the variables, so their caches are set. */
  for (const auto &cache_entry : cache_entries) {
    /* Only resolve when the cache isn't valid. */
    if (HasBit(v->grf_cache.cache_valid, cache_entry[1])) continue;
    bool stub;
    ro.GetScope(VSG_SCOPE_SELF)->GetVariable(cache_entry[0], 0, stub);
  }
 
  /* Make sure really all bits are set. */
  assert(v->grf_cache.cache_valid == (1 << NCVV_END) - 1);
}