aircraft_cmd.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 "aircraft.h"
#include "landscape.h"
#include "news_func.h"
#include "newgrf_engine.h"
#include "newgrf_sound.h"
#include "spritecache.h"
#include "strings_func.h"
#include "command_func.h"
#include "window_func.h"
#include "date_func.h"
#include "vehicle_func.h"
#include "sound_func.h"
#include "cheat_type.h"
#include "company_base.h"
#include "ai/ai.hpp"
#include "game/game.hpp"
#include "company_func.h"
#include "effectvehicle_func.h"
#include "station_base.h"
#include "engine_base.h"
#include "core/random_func.hpp"
#include "core/backup_type.hpp"
#include "zoom_func.h"
#include "disaster_vehicle.h"
#include "newgrf_airporttiles.h"
#include "framerate_type.h"
#include "aircraft_cmd.h"
#include "vehicle_cmd.h"
 
#include "table/strings.h"
 
#include "safeguards.h"
 
void Aircraft::UpdateDeltaXY()
{
  this->x_offs = -1;
  this->y_offs = -1;
  this->x_extent = 2;
  this->y_extent = 2;
 
  switch (this->subtype) {
    default: NOT_REACHED();
 
    case AIR_AIRCRAFT:
    case AIR_HELICOPTER:
      switch (this->state) {
        default: break;
        case ENDTAKEOFF:
        case LANDING:
        case HELILANDING:
        case FLYING:
          this->x_extent = 24;
          this->y_extent = 24;
          break;
      }
      this->z_extent = 5;
      break;
 
    case AIR_SHADOW:
      this->z_extent = 1;
      this->x_offs = 0;
      this->y_offs = 0;
      break;
 
    case AIR_ROTOR:
      this->z_extent = 1;
      break;
  }
}
 
static bool AirportMove(Aircraft *v, const AirportFTAClass *apc);
static bool AirportSetBlocks(Aircraft *v, const AirportFTA *current_pos, const AirportFTAClass *apc);
static bool AirportHasBlock(Aircraft *v, const AirportFTA *current_pos, const AirportFTAClass *apc);
static bool AirportFindFreeTerminal(Aircraft *v, const AirportFTAClass *apc);
static bool AirportFindFreeHelipad(Aircraft *v, const AirportFTAClass *apc);
static void CrashAirplane(Aircraft *v);
 
static const SpriteID _aircraft_sprite[] = {
  0x0EB5, 0x0EBD, 0x0EC5, 0x0ECD,
  0x0ED5, 0x0EDD, 0x0E9D, 0x0EA5,
  0x0EAD, 0x0EE5, 0x0F05, 0x0F0D,
  0x0F15, 0x0F1D, 0x0F25, 0x0F2D,
  0x0EED, 0x0EF5, 0x0EFD, 0x0F35,
  0x0E9D, 0x0EA5, 0x0EAD, 0x0EB5,
  0x0EBD, 0x0EC5
};
 
template <>
bool IsValidImageIndex<VEH_AIRCRAFT>(uint8 image_index)
{
  return image_index < lengthof(_aircraft_sprite);
}
 
enum HelicopterRotorStates {
  HRS_ROTOR_STOPPED,
  HRS_ROTOR_MOVING_1,
  HRS_ROTOR_MOVING_2,
  HRS_ROTOR_MOVING_3,
};
 
static StationID FindNearestHangar(const Aircraft *v)
{
  uint best = 0;
  StationID index = INVALID_STATION;
  TileIndex vtile = TileVirtXY(v->x_pos, v->y_pos);
  const AircraftVehicleInfo *avi = AircraftVehInfo(v->engine_type);
  uint max_range = v->acache.cached_max_range_sqr;
 
  /* Determine destinations where it's coming from and where it's heading to */
  const Station *last_dest = nullptr;
  const Station *next_dest = nullptr;
  if (max_range != 0) {
    if (v->current_order.IsType(OT_GOTO_STATION) ||
        (v->current_order.IsType(OT_GOTO_DEPOT) && v->current_order.GetDepotActionType() != ODATFB_NEAREST_DEPOT)) {
      last_dest = Station::GetIfValid(v->last_station_visited);
      next_dest = Station::GetIfValid(v->current_order.GetDestination());
    } else {
      last_dest = GetTargetAirportIfValid(v);
      next_dest = Station::GetIfValid(v->GetNextStoppingStation().value);
    }
  }
 
  for (const Station *st : Station::Iterate()) {
    if (st->owner != v->owner || !(st->facilities & FACIL_AIRPORT) || !st->airport.HasHangar()) continue;
 
    const AirportFTAClass *afc = st->airport.GetFTA();
 
    /* don't crash the plane if we know it can't land at the airport */
    if ((afc->flags & AirportFTAClass::SHORT_STRIP) && (avi->subtype & AIR_FAST) && !_cheats.no_jetcrash.value) continue;
 
    /* the plane won't land at any helicopter station */
    if (!(afc->flags & AirportFTAClass::AIRPLANES) && (avi->subtype & AIR_CTOL)) continue;
 
    /* Check if our last and next destinations can be reached from the depot airport. */
    if (max_range != 0) {
      uint last_dist = (last_dest != nullptr && last_dest->airport.tile != INVALID_TILE) ? DistanceSquare(st->airport.tile, last_dest->airport.tile) : 0;
      uint next_dist = (next_dest != nullptr && next_dest->airport.tile != INVALID_TILE) ? DistanceSquare(st->airport.tile, next_dest->airport.tile) : 0;
      if (last_dist > max_range || next_dist > max_range) continue;
    }
 
    /* v->tile can't be used here, when aircraft is flying v->tile is set to 0 */
    uint distance = DistanceSquare(vtile, st->airport.tile);
    if (distance < best || index == INVALID_STATION) {
      best = distance;
      index = st->index;
    }
  }
  return index;
}
 
void Aircraft::GetImage(Direction direction, EngineImageType image_type, VehicleSpriteSeq *result) const
{
  uint8 spritenum = this->spritenum;
 
  if (is_custom_sprite(spritenum)) {
    GetCustomVehicleSprite(this, direction, image_type, result);
    if (result->IsValid()) return;
 
    spritenum = this->GetEngine()->original_image_index;
  }
 
  assert(IsValidImageIndex<VEH_AIRCRAFT>(spritenum));
  result->Set(direction + _aircraft_sprite[spritenum]);
}
 
void GetRotorImage(const Aircraft *v, EngineImageType image_type, VehicleSpriteSeq *result)
{
  assert(v->subtype == AIR_HELICOPTER);
 
  const Aircraft *w = v->Next()->Next();
  if (is_custom_sprite(v->spritenum)) {
    GetCustomRotorSprite(v, image_type, result);
    if (result->IsValid()) return;
  }
 
  /* Return standard rotor sprites if there are no custom sprites for this helicopter */
  result->Set(SPR_ROTOR_STOPPED + w->state);
}
 
static void GetAircraftIcon(EngineID engine, EngineImageType image_type, VehicleSpriteSeq *result)
{
  const Engine *e = Engine::Get(engine);
  uint8 spritenum = e->u.air.image_index;
 
  if (is_custom_sprite(spritenum)) {
    GetCustomVehicleIcon(engine, DIR_W, image_type, result);
    if (result->IsValid()) return;
 
    spritenum = e->original_image_index;
  }
 
  assert(IsValidImageIndex<VEH_AIRCRAFT>(spritenum));
  result->Set(DIR_W + _aircraft_sprite[spritenum]);
}
 
void DrawAircraftEngine(int left, int right, int preferred_x, int y, EngineID engine, PaletteID pal, EngineImageType image_type)
{
  VehicleSpriteSeq seq;
  GetAircraftIcon(engine, image_type, &seq);
 
  Rect rect;
  seq.GetBounds(&rect);
  preferred_x = Clamp(preferred_x,
      left - UnScaleGUI(rect.left),
      right - UnScaleGUI(rect.right));
 
  seq.Draw(preferred_x, y, pal, pal == PALETTE_CRASH);
 
  if (!(AircraftVehInfo(engine)->subtype & AIR_CTOL)) {
    VehicleSpriteSeq rotor_seq;
    GetCustomRotorIcon(engine, image_type, &rotor_seq);
    if (!rotor_seq.IsValid()) rotor_seq.Set(SPR_ROTOR_STOPPED);
    rotor_seq.Draw(preferred_x, y - ScaleSpriteTrad(5), PAL_NONE, false);
  }
}
 
void GetAircraftSpriteSize(EngineID engine, uint &width, uint &height, int &xoffs, int &yoffs, EngineImageType image_type)
{
  VehicleSpriteSeq seq;
  GetAircraftIcon(engine, image_type, &seq);
 
  Rect rect;
  seq.GetBounds(&rect);
 
  width  = UnScaleGUI(rect.Width());
  height = UnScaleGUI(rect.Height());
  xoffs  = UnScaleGUI(rect.left);
  yoffs  = UnScaleGUI(rect.top);
}
 
CommandCost CmdBuildAircraft(DoCommandFlag flags, TileIndex tile, const Engine *e, Vehicle **ret)
{
  const AircraftVehicleInfo *avi = &e->u.air;
  const Station *st = Station::GetByTile(tile);
 
  /* Prevent building aircraft types at places which can't handle them */
  if (!CanVehicleUseStation(e->index, st)) return CMD_ERROR;
 
  /* Make sure all aircraft end up in the first tile of the hangar. */
  tile = st->airport.GetHangarTile(st->airport.GetHangarNum(tile));
 
  if (flags & DC_EXEC) {
    Aircraft *v = new Aircraft(); // aircraft
    Aircraft *u = new Aircraft(); // shadow
    *ret = v;
 
    v->direction = DIR_SE;
 
    v->owner = u->owner = _current_company;
 
    v->tile = tile;
 
    uint x = TileX(tile) * TILE_SIZE + 5;
    uint y = TileY(tile) * TILE_SIZE + 3;
 
    v->x_pos = u->x_pos = x;
    v->y_pos = u->y_pos = y;
 
    u->z_pos = GetSlopePixelZ(x, y);
    v->z_pos = u->z_pos + 1;
 
    v->vehstatus = VS_HIDDEN | VS_STOPPED | VS_DEFPAL;
    u->vehstatus = VS_HIDDEN | VS_UNCLICKABLE | VS_SHADOW;
 
    v->spritenum = avi->image_index;
 
    v->cargo_cap = avi->passenger_capacity;
    v->refit_cap = 0;
    u->cargo_cap = avi->mail_capacity;
    u->refit_cap = 0;
 
    v->cargo_type = e->GetDefaultCargoType();
    u->cargo_type = CT_MAIL;
 
    v->name.clear();
    v->last_station_visited = INVALID_STATION;
    v->last_loading_station = INVALID_STATION;
 
    v->acceleration = avi->acceleration;
    v->engine_type = e->index;
    u->engine_type = e->index;
 
    v->subtype = (avi->subtype & AIR_CTOL ? AIR_AIRCRAFT : AIR_HELICOPTER);
    v->UpdateDeltaXY();
 
    u->subtype = AIR_SHADOW;
    u->UpdateDeltaXY();
 
    v->reliability = e->reliability;
    v->reliability_spd_dec = e->reliability_spd_dec;
    v->max_age = e->GetLifeLengthInDays();
 
    v->pos = GetVehiclePosOnBuild(tile);
 
    v->state = HANGAR;
    v->previous_pos = v->pos;
    v->targetairport = GetStationIndex(tile);
    v->SetNext(u);
 
    v->SetServiceInterval(Company::Get(_current_company)->settings.vehicle.servint_aircraft);
 
    v->date_of_last_service = _date;
    v->build_year = u->build_year = _cur_year;
 
    v->sprite_cache.sprite_seq.Set(SPR_IMG_QUERY);
    u->sprite_cache.sprite_seq.Set(SPR_IMG_QUERY);
 
    v->random_bits = VehicleRandomBits();
    u->random_bits = VehicleRandomBits();
 
    v->vehicle_flags = 0;
    if (e->flags & ENGINE_EXCLUSIVE_PREVIEW) SetBit(v->vehicle_flags, VF_BUILT_AS_PROTOTYPE);
    v->SetServiceIntervalIsPercent(Company::Get(_current_company)->settings.vehicle.servint_ispercent);
 
    v->InvalidateNewGRFCacheOfChain();
 
    v->cargo_cap = e->DetermineCapacity(v, &u->cargo_cap);
 
    v->InvalidateNewGRFCacheOfChain();
 
    UpdateAircraftCache(v, true);
 
    v->UpdatePosition();
    u->UpdatePosition();
 
    /* Aircraft with 3 vehicles (chopper)? */
    if (v->subtype == AIR_HELICOPTER) {
      Aircraft *w = new Aircraft();
      w->engine_type = e->index;
      w->direction = DIR_N;
      w->owner = _current_company;
      w->x_pos = v->x_pos;
      w->y_pos = v->y_pos;
      w->z_pos = v->z_pos + ROTOR_Z_OFFSET;
      w->vehstatus = VS_HIDDEN | VS_UNCLICKABLE;
      w->spritenum = 0xFF;
      w->subtype = AIR_ROTOR;
      w->sprite_cache.sprite_seq.Set(SPR_ROTOR_STOPPED);
      w->random_bits = VehicleRandomBits();
      /* Use rotor's air.state to store the rotor animation frame */
      w->state = HRS_ROTOR_STOPPED;
      w->UpdateDeltaXY();
 
      u->SetNext(w);
      w->UpdatePosition();
    }
  }
 
  return CommandCost();
}
 
 
bool Aircraft::FindClosestDepot(TileIndex *location, DestinationID *destination, bool *reverse)
{
  const Station *st = GetTargetAirportIfValid(this);
  /* If the station is not a valid airport or if it has no hangars */
  if (st == nullptr || !CanVehicleUseStation(this, st) || !st->airport.HasHangar()) {
    /* the aircraft has to search for a hangar on its own */
    StationID station = FindNearestHangar(this);
 
    if (station == INVALID_STATION) return false;
 
    st = Station::Get(station);
  }
 
  if (location    != nullptr) *location    = st->xy;
  if (destination != nullptr) *destination = st->index;
 
  return true;
}
 
static void CheckIfAircraftNeedsService(Aircraft *v)
{
  if (Company::Get(v->owner)->settings.vehicle.servint_aircraft == 0 || !v->NeedsAutomaticServicing()) return;
  if (v->IsChainInDepot()) {
    VehicleServiceInDepot(v);
    return;
  }
 
  /* When we're parsing conditional orders and the like
   * we don't want to consider going to a depot too. */
  if (!v->current_order.IsType(OT_GOTO_DEPOT) && !v->current_order.IsType(OT_GOTO_STATION)) return;
 
  const Station *st = Station::Get(v->current_order.GetDestination());
 
  assert(st != nullptr);
 
  /* only goto depot if the target airport has a depot */
  if (st->airport.HasHangar() && CanVehicleUseStation(v, st)) {
    v->current_order.MakeGoToDepot(st->index, ODTFB_SERVICE);
    SetWindowWidgetDirty(WC_VEHICLE_VIEW, v->index, WID_VV_START_STOP);
  } else if (v->current_order.IsType(OT_GOTO_DEPOT)) {
    v->current_order.MakeDummy();
    SetWindowWidgetDirty(WC_VEHICLE_VIEW, v->index, WID_VV_START_STOP);
  }
}
 
Money Aircraft::GetRunningCost() const
{
  const Engine *e = this->GetEngine();
  uint cost_factor = GetVehicleProperty(this, PROP_AIRCRAFT_RUNNING_COST_FACTOR, e->u.air.running_cost);
  return GetPrice(PR_RUNNING_AIRCRAFT, cost_factor, e->GetGRF());
}
 
void Aircraft::OnNewDay()
{
  if (!this->IsNormalAircraft()) return;
 
  if ((++this->day_counter & 7) == 0) DecreaseVehicleValue(this);
 
  CheckOrders(this);
 
  CheckVehicleBreakdown(this);
  AgeVehicle(this);
  CheckIfAircraftNeedsService(this);
 
  if (this->running_ticks == 0) return;
 
  CommandCost cost(EXPENSES_AIRCRAFT_RUN, this->GetRunningCost() * this->running_ticks / (DAYS_IN_YEAR * DAY_TICKS));
 
  this->profit_this_year -= cost.GetCost();
  this->running_ticks = 0;
 
  SubtractMoneyFromCompanyFract(this->owner, cost);
 
  SetWindowDirty(WC_VEHICLE_DETAILS, this->index);
  SetWindowClassesDirty(WC_AIRCRAFT_LIST);
}
 
static void HelicopterTickHandler(Aircraft *v)
{
  Aircraft *u = v->Next()->Next();
 
  if (u->vehstatus & VS_HIDDEN) return;
 
  /* if true, helicopter rotors do not rotate. This should only be the case if a helicopter is
   * loading/unloading at a terminal or stopped */
  if (v->current_order.IsType(OT_LOADING) || (v->vehstatus & VS_STOPPED)) {
    if (u->cur_speed != 0) {
      u->cur_speed++;
      if (u->cur_speed >= 0x80 && u->state == HRS_ROTOR_MOVING_3) {
        u->cur_speed = 0;
      }
    }
  } else {
    if (u->cur_speed == 0) {
      u->cur_speed = 0x70;
    }
    if (u->cur_speed >= 0x50) {
      u->cur_speed--;
    }
  }
 
  int tick = ++u->tick_counter;
  int spd = u->cur_speed >> 4;
 
  VehicleSpriteSeq seq;
  if (spd == 0) {
    u->state = HRS_ROTOR_STOPPED;
    GetRotorImage(v, EIT_ON_MAP, &seq);
    if (u->sprite_cache.sprite_seq == seq) return;
  } else if (tick >= spd) {
    u->tick_counter = 0;
    u->state++;
    if (u->state > HRS_ROTOR_MOVING_3) u->state = HRS_ROTOR_MOVING_1;
    GetRotorImage(v, EIT_ON_MAP, &seq);
  } else {
    return;
  }
 
  u->sprite_cache.sprite_seq = seq;
 
  u->UpdatePositionAndViewport();
}
 
void SetAircraftPosition(Aircraft *v, int x, int y, int z)
{
  v->x_pos = x;
  v->y_pos = y;
  v->z_pos = z;
 
  v->UpdatePosition();
  v->UpdateViewport(true, false);
  if (v->subtype == AIR_HELICOPTER) {
    GetRotorImage(v, EIT_ON_MAP, &v->Next()->Next()->sprite_cache.sprite_seq);
  }
 
  Aircraft *u = v->Next();
 
  int safe_x = Clamp(x, 0, MapMaxX() * TILE_SIZE);
  int safe_y = Clamp(y - 1, 0, MapMaxY() * TILE_SIZE);
  u->x_pos = x;
  u->y_pos = y - ((v->z_pos - GetSlopePixelZ(safe_x, safe_y)) >> 3);
 
  safe_y = Clamp(u->y_pos, 0, MapMaxY() * TILE_SIZE);
  u->z_pos = GetSlopePixelZ(safe_x, safe_y);
  u->sprite_cache.sprite_seq.CopyWithoutPalette(v->sprite_cache.sprite_seq); // the shadow is never coloured
 
  u->UpdatePositionAndViewport();
 
  u = u->Next();
  if (u != nullptr) {
    u->x_pos = x;
    u->y_pos = y;
    u->z_pos = z + ROTOR_Z_OFFSET;
 
    u->UpdatePositionAndViewport();
  }
}
 
void HandleAircraftEnterHangar(Aircraft *v)
{
  v->subspeed = 0;
  v->progress = 0;
 
  Aircraft *u = v->Next();
  u->vehstatus |= VS_HIDDEN;
  u = u->Next();
  if (u != nullptr) {
    u->vehstatus |= VS_HIDDEN;
    u->cur_speed = 0;
  }
 
  SetAircraftPosition(v, v->x_pos, v->y_pos, v->z_pos);
}
 
static void PlayAircraftSound(const Vehicle *v)
{
  if (!PlayVehicleSound(v, VSE_START)) {
    SndPlayVehicleFx(AircraftVehInfo(v->engine_type)->sfx, v);
  }
}
 
 
void UpdateAircraftCache(Aircraft *v, bool update_range)
{
  uint max_speed = GetVehicleProperty(v, PROP_AIRCRAFT_SPEED, 0);
  if (max_speed != 0) {
    /* Convert from original units to km-ish/h */
    max_speed = (max_speed * 128) / 10;
 
    v->vcache.cached_max_speed = max_speed;
  } else {
    /* Use the default max speed of the vehicle. */
    v->vcache.cached_max_speed = AircraftVehInfo(v->engine_type)->max_speed;
  }
 
  /* Update cargo aging period. */
  v->vcache.cached_cargo_age_period = GetVehicleProperty(v, PROP_AIRCRAFT_CARGO_AGE_PERIOD, EngInfo(v->engine_type)->cargo_age_period);
  Aircraft *u = v->Next(); // Shadow for mail
  u->vcache.cached_cargo_age_period = GetVehicleProperty(u, PROP_AIRCRAFT_CARGO_AGE_PERIOD, EngInfo(u->engine_type)->cargo_age_period);
 
  /* Update aircraft range. */
  if (update_range) {
    v->acache.cached_max_range = GetVehicleProperty(v, PROP_AIRCRAFT_RANGE, AircraftVehInfo(v->engine_type)->max_range);
    /* Squared it now so we don't have to do it later all the time. */
    v->acache.cached_max_range_sqr = v->acache.cached_max_range * v->acache.cached_max_range;
  }
}
 
 
enum AircraftSpeedLimits {
  SPEED_LIMIT_TAXI     =     50,  
  SPEED_LIMIT_APPROACH =    230,  
  SPEED_LIMIT_BROKEN   =    320,  
  SPEED_LIMIT_HOLD     =    425,  
  SPEED_LIMIT_NONE     = 0xFFFF,  
};
 
static int UpdateAircraftSpeed(Aircraft *v, uint speed_limit = SPEED_LIMIT_NONE, bool hard_limit = true)
{
  uint spd = v->acceleration * 77;
  byte t;
 
  /* Adjust speed limits by plane speed factor to prevent taxiing
   * and take-off speeds being too low. */
  speed_limit *= _settings_game.vehicle.plane_speed;
 
  /* adjust speed for broken vehicles */
  if (v->vehstatus & VS_AIRCRAFT_BROKEN) {
    if (SPEED_LIMIT_BROKEN < speed_limit) hard_limit = false;
    speed_limit = std::min<uint>(speed_limit, SPEED_LIMIT_BROKEN);
  }
 
  if (v->vcache.cached_max_speed < speed_limit) {
    if (v->cur_speed < speed_limit) hard_limit = false;
    speed_limit = v->vcache.cached_max_speed;
  }
 
  v->subspeed = (t = v->subspeed) + (byte)spd;
 
  /* Aircraft's current speed is used twice so that very fast planes are
   * forced to slow down rapidly in the short distance needed. The magic
   * value 16384 was determined to give similar results to the old speed/48
   * method at slower speeds. This also results in less reduction at slow
   * speeds to that aircraft do not get to taxi speed straight after
   * touchdown. */
  if (!hard_limit && v->cur_speed > speed_limit) {
    speed_limit = v->cur_speed - std::max(1, ((v->cur_speed * v->cur_speed) / 16384) / _settings_game.vehicle.plane_speed);
  }
 
  spd = std::min(v->cur_speed + (spd >> 8) + (v->subspeed < t), speed_limit);
 
  /* updates statusbar only if speed have changed to save CPU time */
  if (spd != v->cur_speed) {
    v->cur_speed = spd;
    SetWindowWidgetDirty(WC_VEHICLE_VIEW, v->index, WID_VV_START_STOP);
  }
 
  /* Adjust distance moved by plane speed setting */
  if (_settings_game.vehicle.plane_speed > 1) spd /= _settings_game.vehicle.plane_speed;
 
  /* Convert direction-independent speed into direction-dependent speed. (old movement method) */
  spd = v->GetOldAdvanceSpeed(spd);
 
  spd += v->progress;
  v->progress = (byte)spd;
  return spd >> 8;
}
 
int GetTileHeightBelowAircraft(const Vehicle *v)
{
  int safe_x = Clamp(v->x_pos, 0, MapMaxX() * TILE_SIZE);
  int safe_y = Clamp(v->y_pos, 0, MapMaxY() * TILE_SIZE);
  return TileHeight(TileVirtXY(safe_x, safe_y)) * TILE_HEIGHT;
}
 
void GetAircraftFlightLevelBounds(const Vehicle *v, int *min_level, int *max_level)
{
  int base_altitude = GetTileHeightBelowAircraft(v);
  if (v->type == VEH_AIRCRAFT && Aircraft::From(v)->subtype == AIR_HELICOPTER) {
    base_altitude += HELICOPTER_HOLD_MAX_FLYING_ALTITUDE - PLANE_HOLD_MAX_FLYING_ALTITUDE;
  }
 
  /* Make sure eastbound and westbound planes do not "crash" into each
   * other by providing them with vertical separation
   */
  switch (v->direction) {
    case DIR_N:
    case DIR_NE:
    case DIR_E:
    case DIR_SE:
      base_altitude += 10;
      break;
 
    default: break;
  }
 
  /* Make faster planes fly higher so that they can overtake slower ones */
  base_altitude += std::min(20 * (v->vcache.cached_max_speed / 200) - 90, 0);
 
  if (min_level != nullptr) *min_level = base_altitude + AIRCRAFT_MIN_FLYING_ALTITUDE;
  if (max_level != nullptr) *max_level = base_altitude + AIRCRAFT_MAX_FLYING_ALTITUDE;
}
 
int GetAircraftHoldMaxAltitude(const Aircraft *v)
{
  int tile_height = GetTileHeightBelowAircraft(v);
 
  return tile_height + ((v->subtype == AIR_HELICOPTER) ? HELICOPTER_HOLD_MAX_FLYING_ALTITUDE : PLANE_HOLD_MAX_FLYING_ALTITUDE);
}
 
template <class T>
int GetAircraftFlightLevel(T *v, bool takeoff)
{
  /* Aircraft is in flight. We want to enforce it being somewhere
   * between the minimum and the maximum allowed altitude. */
  int aircraft_min_altitude;
  int aircraft_max_altitude;
  GetAircraftFlightLevelBounds(v, &aircraft_min_altitude, &aircraft_max_altitude);
  int aircraft_middle_altitude = (aircraft_min_altitude + aircraft_max_altitude) / 2;
 
  /* If those assumptions would be violated, aircraft would behave fairly strange. */
  assert(aircraft_min_altitude < aircraft_middle_altitude);
  assert(aircraft_middle_altitude < aircraft_max_altitude);
 
  int z = v->z_pos;
  if (z < aircraft_min_altitude ||
      (HasBit(v->flags, VAF_IN_MIN_HEIGHT_CORRECTION) && z < aircraft_middle_altitude)) {
    /* Ascend. And don't fly into that mountain right ahead.
     * And avoid our aircraft become a stairclimber, so if we start
     * correcting altitude, then we stop correction not too early. */
    SetBit(v->flags, VAF_IN_MIN_HEIGHT_CORRECTION);
    z += takeoff ? 2 : 1;
  } else if (!takeoff && (z > aircraft_max_altitude ||
      (HasBit(v->flags, VAF_IN_MAX_HEIGHT_CORRECTION) && z > aircraft_middle_altitude))) {
    /* Descend lower. You are an aircraft, not an space ship.
     * And again, don't stop correcting altitude too early. */
    SetBit(v->flags, VAF_IN_MAX_HEIGHT_CORRECTION);
    z--;
  } else if (HasBit(v->flags, VAF_IN_MIN_HEIGHT_CORRECTION) && z >= aircraft_middle_altitude) {
    /* Now, we have corrected altitude enough. */
    ClrBit(v->flags, VAF_IN_MIN_HEIGHT_CORRECTION);
  } else if (HasBit(v->flags, VAF_IN_MAX_HEIGHT_CORRECTION) && z <= aircraft_middle_altitude) {
    /* Now, we have corrected altitude enough. */
    ClrBit(v->flags, VAF_IN_MAX_HEIGHT_CORRECTION);
  }
 
  return z;
}
 
template int GetAircraftFlightLevel(DisasterVehicle *v, bool takeoff);
template int GetAircraftFlightLevel(Aircraft *v, bool takeoff);
 
static byte AircraftGetEntryPoint(const Aircraft *v, const AirportFTAClass *apc, Direction rotation)
{
  assert(v != nullptr);
  assert(apc != nullptr);
 
  /* In the case the station doesn't exit anymore, set target tile 0.
   * It doesn't hurt much, aircraft will go to next order, nearest hangar
   * or it will simply crash in next tick */
  TileIndex tile = 0;
 
  const Station *st = Station::GetIfValid(v->targetairport);
  if (st != nullptr) {
    /* Make sure we don't go to INVALID_TILE if the airport has been removed. */
    tile = (st->airport.tile != INVALID_TILE) ? st->airport.tile : st->xy;
  }
 
  int delta_x = v->x_pos - TileX(tile) * TILE_SIZE;
  int delta_y = v->y_pos - TileY(tile) * TILE_SIZE;
 
  DiagDirection dir;
  if (abs(delta_y) < abs(delta_x)) {
    /* We are northeast or southwest of the airport */
    dir = delta_x < 0 ? DIAGDIR_NE : DIAGDIR_SW;
  } else {
    /* We are northwest or southeast of the airport */
    dir = delta_y < 0 ? DIAGDIR_NW : DIAGDIR_SE;
  }
  dir = ChangeDiagDir(dir, DiagDirDifference(DIAGDIR_NE, DirToDiagDir(rotation)));
  return apc->entry_points[dir];
}
 
 
static void MaybeCrashAirplane(Aircraft *v);
 
static bool AircraftController(Aircraft *v)
{
  /* nullptr if station is invalid */
  const Station *st = Station::GetIfValid(v->targetairport);
  /* INVALID_TILE if there is no station */
  TileIndex tile = INVALID_TILE;
  Direction rotation = DIR_N;
  uint size_x = 1, size_y = 1;
  if (st != nullptr) {
    if (st->airport.tile != INVALID_TILE) {
      tile = st->airport.tile;
      rotation = st->airport.rotation;
      size_x = st->airport.w;
      size_y = st->airport.h;
    } else {
      tile = st->xy;
    }
  }
  /* DUMMY if there is no station or no airport */
  const AirportFTAClass *afc = tile == INVALID_TILE ? GetAirport(AT_DUMMY) : st->airport.GetFTA();
 
  /* prevent going to INVALID_TILE if airport is deleted. */
  if (st == nullptr || st->airport.tile == INVALID_TILE) {
    /* Jump into our "holding pattern" state machine if possible */
    if (v->pos >= afc->nofelements) {
      v->pos = v->previous_pos = AircraftGetEntryPoint(v, afc, DIR_N);
    } else if (v->targetairport != v->current_order.GetDestination()) {
      /* If not possible, just get out of here fast */
      v->state = FLYING;
      UpdateAircraftCache(v);
      AircraftNextAirportPos_and_Order(v);
      /* get aircraft back on running altitude */
      SetAircraftPosition(v, v->x_pos, v->y_pos, GetAircraftFlightLevel(v));
      return false;
    }
  }
 
  /*  get airport moving data */
  const AirportMovingData amd = RotateAirportMovingData(afc->MovingData(v->pos), rotation, size_x, size_y);
 
  int x = TileX(tile) * TILE_SIZE;
  int y = TileY(tile) * TILE_SIZE;
 
  /* Helicopter raise */
  if (amd.flag & AMED_HELI_RAISE) {
    Aircraft *u = v->Next()->Next();
 
    /* Make sure the rotors don't rotate too fast */
    if (u->cur_speed > 32) {
      v->cur_speed = 0;
      if (--u->cur_speed == 32) {
        if (!PlayVehicleSound(v, VSE_START)) {
          SoundID sfx = AircraftVehInfo(v->engine_type)->sfx;
          /* For compatibility with old NewGRF we ignore the sfx property, unless a NewGRF-defined sound is used.
           * The baseset has only one helicopter sound, so this only limits using plane or cow sounds. */
          if (sfx < ORIGINAL_SAMPLE_COUNT) sfx = SND_18_TAKEOFF_HELICOPTER;
          SndPlayVehicleFx(sfx, v);
        }
      }
    } else {
      u->cur_speed = 32;
      int count = UpdateAircraftSpeed(v);
      if (count > 0) {
        v->tile = 0;
 
        int z_dest;
        GetAircraftFlightLevelBounds(v, &z_dest, nullptr);
 
        /* Reached altitude? */
        if (v->z_pos >= z_dest) {
          v->cur_speed = 0;
          return true;
        }
        SetAircraftPosition(v, v->x_pos, v->y_pos, std::min(v->z_pos + count, z_dest));
      }
    }
    return false;
  }
 
  /* Helicopter landing. */
  if (amd.flag & AMED_HELI_LOWER) {
    SetBit(v->flags, VAF_HELI_DIRECT_DESCENT);
 
    if (st == nullptr) {
      /* FIXME - AircraftController -> if station no longer exists, do not land
       * helicopter will circle until sign disappears, then go to next order
       * what to do when it is the only order left, right now it just stays in 1 place */
      v->state = FLYING;
      UpdateAircraftCache(v);
      AircraftNextAirportPos_and_Order(v);
      return false;
    }
 
    /* Vehicle is now at the airport.
     * Helicopter has arrived at the target landing pad, so the current position is also where it should land.
     * Except for Oilrigs which are special due to being a 1x1 station, and helicopters land outside it. */
    if (st->airport.type != AT_OILRIG) {
      x = v->x_pos;
      y = v->y_pos;
      tile = TileVirtXY(x, y);
    }
    v->tile = tile;
 
    /* Find altitude of landing position. */
    int z = GetSlopePixelZ(x, y) + 1 + afc->delta_z;
 
    if (z == v->z_pos) {
      Vehicle *u = v->Next()->Next();
 
      /*  Increase speed of rotors. When speed is 80, we've landed. */
      if (u->cur_speed >= 80) {
        ClrBit(v->flags, VAF_HELI_DIRECT_DESCENT);
        return true;
      }
      u->cur_speed += 4;
    } else {
      int count = UpdateAircraftSpeed(v);
      if (count > 0) {
        if (v->z_pos > z) {
          SetAircraftPosition(v, v->x_pos, v->y_pos, std::max(v->z_pos - count, z));
        } else {
          SetAircraftPosition(v, v->x_pos, v->y_pos, std::min(v->z_pos + count, z));
        }
      }
    }
    return false;
  }
 
  /* Get distance from destination pos to current pos. */
  uint dist = abs(x + amd.x - v->x_pos) +  abs(y + amd.y - v->y_pos);
 
  /* Need exact position? */
  if (!(amd.flag & AMED_EXACTPOS) && dist <= (amd.flag & AMED_SLOWTURN ? 8U : 4U)) return true;
 
  /* At final pos? */
  if (dist == 0) {
    /* Change direction smoothly to final direction. */
    DirDiff dirdiff = DirDifference(amd.direction, v->direction);
    /* if distance is 0, and plane points in right direction, no point in calling
     * UpdateAircraftSpeed(). So do it only afterwards */
    if (dirdiff == DIRDIFF_SAME) {
      v->cur_speed = 0;
      return true;
    }
 
    if (!UpdateAircraftSpeed(v, SPEED_LIMIT_TAXI)) return false;
 
    v->direction = ChangeDir(v->direction, dirdiff > DIRDIFF_REVERSE ? DIRDIFF_45LEFT : DIRDIFF_45RIGHT);
    v->cur_speed >>= 1;
 
    SetAircraftPosition(v, v->x_pos, v->y_pos, v->z_pos);
    return false;
  }
 
  if (amd.flag & AMED_BRAKE && v->cur_speed > SPEED_LIMIT_TAXI * _settings_game.vehicle.plane_speed) {
    MaybeCrashAirplane(v);
    if ((v->vehstatus & VS_CRASHED) != 0) return false;
  }
 
  uint speed_limit = SPEED_LIMIT_TAXI;
  bool hard_limit = true;
 
  if (amd.flag & AMED_NOSPDCLAMP)   speed_limit = SPEED_LIMIT_NONE;
  if (amd.flag & AMED_HOLD)       { speed_limit = SPEED_LIMIT_HOLD;     hard_limit = false; }
  if (amd.flag & AMED_LAND)       { speed_limit = SPEED_LIMIT_APPROACH; hard_limit = false; }
  if (amd.flag & AMED_BRAKE)      { speed_limit = SPEED_LIMIT_TAXI;     hard_limit = false; }
 
  int count = UpdateAircraftSpeed(v, speed_limit, hard_limit);
  if (count == 0) return false;
 
  /* If the plane will be a few subpixels away from the destination after
   * this movement loop, start nudging it towards the exact position for
   * the whole loop. Otherwise, heavily depending on the speed of the plane,
   * it is possible we totally overshoot the target, causing the plane to
   * make a loop, and trying again, and again, and again .. */
  bool nudge_towards_target = static_cast<uint>(count) + 3 > dist;
 
  if (v->turn_counter != 0) v->turn_counter--;
 
  do {
 
    GetNewVehiclePosResult gp;
 
    if (nudge_towards_target || (amd.flag & AMED_LAND)) {
      /* move vehicle one pixel towards target */
      gp.x = (v->x_pos != (x + amd.x)) ?
          v->x_pos + ((x + amd.x > v->x_pos) ? 1 : -1) :
          v->x_pos;
      gp.y = (v->y_pos != (y + amd.y)) ?
          v->y_pos + ((y + amd.y > v->y_pos) ? 1 : -1) :
          v->y_pos;
 
      /* Oilrigs must keep v->tile as st->airport.tile, since the landing pad is in a non-airport tile */
      gp.new_tile = (st->airport.type == AT_OILRIG) ? st->airport.tile : TileVirtXY(gp.x, gp.y);
 
    } else {
 
      /* Turn. Do it slowly if in the air. */
      Direction newdir = GetDirectionTowards(v, x + amd.x, y + amd.y);
      if (newdir != v->direction) {
        if (amd.flag & AMED_SLOWTURN && v->number_consecutive_turns < 8 && v->subtype == AIR_AIRCRAFT) {
          if (v->turn_counter == 0 || newdir == v->last_direction) {
            if (newdir == v->last_direction) {
              v->number_consecutive_turns = 0;
            } else {
              v->number_consecutive_turns++;
            }
            v->turn_counter = 2 * _settings_game.vehicle.plane_speed;
            v->last_direction = v->direction;
            v->direction = newdir;
          }
 
          /* Move vehicle. */
          gp = GetNewVehiclePos(v);
        } else {
          v->cur_speed >>= 1;
          v->direction = newdir;
 
          /* When leaving a terminal an aircraft often goes to a position
           * directly in front of it. If it would move while turning it
           * would need an two extra turns to end up at the correct position.
           * To make it easier just disallow all moving while turning as
           * long as an aircraft is on the ground. */
          gp.x = v->x_pos;
          gp.y = v->y_pos;
          gp.new_tile = gp.old_tile = v->tile;
        }
      } else {
        v->number_consecutive_turns = 0;
        /* Move vehicle. */
        gp = GetNewVehiclePos(v);
      }
    }
 
    v->tile = gp.new_tile;
    /* If vehicle is in the air, use tile coordinate 0. */
    if (amd.flag & (AMED_TAKEOFF | AMED_SLOWTURN | AMED_LAND)) v->tile = 0;
 
    /* Adjust Z for land or takeoff? */
    int z = v->z_pos;
 
    if (amd.flag & AMED_TAKEOFF) {
      z = GetAircraftFlightLevel(v, true);
    } else if (amd.flag & AMED_HOLD) {
      /* Let the plane drop from normal flight altitude to holding pattern altitude */
      if (z > GetAircraftHoldMaxAltitude(v)) z--;
    } else if ((amd.flag & AMED_SLOWTURN) && (amd.flag & AMED_NOSPDCLAMP)) {
      z = GetAircraftFlightLevel(v);
    }
 
    /* NewGRF airports (like a rotated intercontinental from OpenGFX+Airports) can be non-rectangular
     * and their primary (north-most) tile does not have to be part of the airport.
     * As such, the height of the primary tile can be different from the rest of the airport.
     * Given we are landing/breaking, and as such are not a helicopter, we know that there has to be a hangar.
     * We also know that the airport itself has to be completely flat (otherwise it is not a valid airport).
     * Therefore, use the height of this hangar to calculate our z-value. */
    int airport_z = v->z_pos;
    if ((amd.flag & (AMED_LAND | AMED_BRAKE)) && st != nullptr) {
      assert(st->airport.HasHangar());
      TileIndex hangar_tile = st->airport.GetHangarTile(0);
      airport_z = GetTileMaxPixelZ(hangar_tile) + 1; // To avoid clashing with the shadow
    }
 
    if (amd.flag & AMED_LAND) {
      if (st->airport.tile == INVALID_TILE) {
        /* Airport has been removed, abort the landing procedure */
        v->state = FLYING;
        UpdateAircraftCache(v);
        AircraftNextAirportPos_and_Order(v);
        /* get aircraft back on running altitude */
        SetAircraftPosition(v, gp.x, gp.y, GetAircraftFlightLevel(v));
        continue;
      }
 
      /* We're not flying below our destination, right? */
      assert(airport_z <= z);
      int t = std::max(1U, dist - 4);
      int delta = z - airport_z;
 
      /* Only start lowering when we're sufficiently close for a 1:1 glide */
      if (delta >= t) {
        z -= CeilDiv(z - airport_z, t);
      }
      if (z < airport_z) z = airport_z;
    }
 
    /* We've landed. Decrease speed when we're reaching end of runway. */
    if (amd.flag & AMED_BRAKE) {
 
      if (z > airport_z) {
        z--;
      } else if (z < airport_z) {
        z++;
      }
 
    }
 
    SetAircraftPosition(v, gp.x, gp.y, z);
  } while (--count != 0);
  return false;
}
 
static bool HandleCrashedAircraft(Aircraft *v)
{
  v->crashed_counter += 3;
 
  Station *st = GetTargetAirportIfValid(v);
 
  /* make aircraft crash down to the ground */
  if (v->crashed_counter < 500 && st == nullptr && ((v->crashed_counter % 3) == 0) ) {
    int z = GetSlopePixelZ(Clamp(v->x_pos, 0, MapMaxX() * TILE_SIZE), Clamp(v->y_pos, 0, MapMaxY() * TILE_SIZE));
    v->z_pos -= 1;
    if (v->z_pos == z) {
      v->crashed_counter = 500;
      v->z_pos++;
    }
  }
 
  if (v->crashed_counter < 650) {
    uint32 r;
    if (Chance16R(1, 32, r)) {
      static const DirDiff delta[] = {
        DIRDIFF_45LEFT, DIRDIFF_SAME, DIRDIFF_SAME, DIRDIFF_45RIGHT
      };
 
      v->direction = ChangeDir(v->direction, delta[GB(r, 16, 2)]);
      SetAircraftPosition(v, v->x_pos, v->y_pos, v->z_pos);
      r = Random();
      CreateEffectVehicleRel(v,
        GB(r, 0, 4) - 4,
        GB(r, 4, 4) - 4,
        GB(r, 8, 4),
        EV_EXPLOSION_SMALL);
    }
  } else if (v->crashed_counter >= 10000) {
    /*  remove rubble of crashed airplane */
 
    /* clear runway-in on all airports, set by crashing plane
     * small airports use AIRPORT_BUSY, city airports use RUNWAY_IN_OUT_block, etc.
     * but they all share the same number */
    if (st != nullptr) {
      CLRBITS(st->airport.flags, RUNWAY_IN_block);
      CLRBITS(st->airport.flags, RUNWAY_IN_OUT_block); // commuter airport
      CLRBITS(st->airport.flags, RUNWAY_IN2_block);    // intercontinental
    }
 
    delete v;
 
    return false;
  }
 
  return true;
}
 
 
static void HandleAircraftSmoke(Aircraft *v, bool mode)
{
  static const struct {
    int8 x;
    int8 y;
  } smoke_pos[] = {
    {  5,  5 },
    {  6,  0 },
    {  5, -5 },
    {  0, -6 },
    { -5, -5 },
    { -6,  0 },
    { -5,  5 },
    {  0,  6 }
  };
 
  if (!(v->vehstatus & VS_AIRCRAFT_BROKEN)) return;
 
  /* Stop smoking when landed */
  if (v->cur_speed < 10) {
    v->vehstatus &= ~VS_AIRCRAFT_BROKEN;
    v->breakdown_ctr = 0;
    return;
  }
 
  /* Spawn effect et most once per Tick, i.e. !mode */
  if (!mode && (v->tick_counter & 0x0F) == 0) {
    CreateEffectVehicleRel(v,
      smoke_pos[v->direction].x,
      smoke_pos[v->direction].y,
      2,
      EV_BREAKDOWN_SMOKE_AIRCRAFT
    );
  }
}
 
void HandleMissingAircraftOrders(Aircraft *v)
{
  /*
   * We do not have an order. This can be divided into two cases:
   * 1) we are heading to an invalid station. In this case we must
   *    find another airport to go to. If there is nowhere to go,
   *    we will destroy the aircraft as it otherwise will enter
   *    the holding pattern for the first airport, which can cause
   *    the plane to go into an undefined state when building an
   *    airport with the same StationID.
   * 2) we are (still) heading to a (still) valid airport, then we
   *    can continue going there. This can happen when you are
   *    changing the aircraft's orders while in-flight or in for
   *    example a depot. However, when we have a current order to
   *    go to a depot, we have to keep that order so the aircraft
   *    actually stops.
   */
  const Station *st = GetTargetAirportIfValid(v);
  if (st == nullptr) {
    Backup<CompanyID> cur_company(_current_company, v->owner, FILE_LINE);
    CommandCost ret = Command<CMD_SEND_VEHICLE_TO_DEPOT>::Do(DC_EXEC, v->index, DepotCommand::None, {});
    cur_company.Restore();
 
    if (ret.Failed()) CrashAirplane(v);
  } else if (!v->current_order.IsType(OT_GOTO_DEPOT)) {
    v->current_order.Free();
  }
}
 
 
TileIndex Aircraft::GetOrderStationLocation(StationID station)
{
  /* Orders are changed in flight, ensure going to the right station. */
  if (this->state == FLYING) {
    AircraftNextAirportPos_and_Order(this);
  }
 
  /* Aircraft do not use dest-tile */
  return 0;
}
 
void Aircraft::MarkDirty()
{
  this->colourmap = PAL_NONE;
  this->UpdateViewport(true, false);
  if (this->subtype == AIR_HELICOPTER) {
    GetRotorImage(this, EIT_ON_MAP, &this->Next()->Next()->sprite_cache.sprite_seq);
  }
}
 
 
uint Aircraft::Crash(bool flooded)
{
  uint pass = Vehicle::Crash(flooded) + 2; // pilots
  this->crashed_counter = flooded ? 9000 : 0; // max 10000, disappear pretty fast when flooded
 
  return pass;
}
 
static void CrashAirplane(Aircraft *v)
{
  CreateEffectVehicleRel(v, 4, 4, 8, EV_EXPLOSION_LARGE);
 
  uint pass = v->Crash();
  SetDParam(0, pass);
 
  v->cargo.Truncate();
  v->Next()->cargo.Truncate();
  const Station *st = GetTargetAirportIfValid(v);
  StringID newsitem;
  TileIndex vt;
  if (st == nullptr) {
    newsitem = STR_NEWS_PLANE_CRASH_OUT_OF_FUEL;
    vt = TileVirtXY(v->x_pos, v->y_pos);
  } else {
    SetDParam(1, st->index);
    newsitem = STR_NEWS_AIRCRAFT_CRASH;
    vt = v->tile;
  }
 
  AI::NewEvent(v->owner, new ScriptEventVehicleCrashed(v->index, vt, st == nullptr ? ScriptEventVehicleCrashed::CRASH_AIRCRAFT_NO_AIRPORT : ScriptEventVehicleCrashed::CRASH_PLANE_LANDING));
  Game::NewEvent(new ScriptEventVehicleCrashed(v->index, vt, st == nullptr ? ScriptEventVehicleCrashed::CRASH_AIRCRAFT_NO_AIRPORT : ScriptEventVehicleCrashed::CRASH_PLANE_LANDING));
 
  NewsType newstype = NT_ACCIDENT;
  if (v->owner != _local_company) {
    newstype = NT_ACCIDENT_OTHER;
  }
 
  AddTileNewsItem(newsitem, newstype, vt, nullptr, st != nullptr ? st->index : INVALID_STATION);
 
  ModifyStationRatingAround(vt, v->owner, -160, 30);
  if (_settings_client.sound.disaster) SndPlayVehicleFx(SND_12_EXPLOSION, v);
}
 
static void MaybeCrashAirplane(Aircraft *v)
{
 
  Station *st = Station::Get(v->targetairport);
 
  uint32 prob;
  if ((st->airport.GetFTA()->flags & AirportFTAClass::SHORT_STRIP) &&
      (AircraftVehInfo(v->engine_type)->subtype & AIR_FAST) &&
      !_cheats.no_jetcrash.value) {
    prob = 3276;
  } else {
    if (_settings_game.vehicle.plane_crashes == 0) return;
    prob = (0x4000 << _settings_game.vehicle.plane_crashes) / 1500;
  }
 
  if (GB(Random(), 0, 22) > prob) return;
 
  /* Crash the airplane. Remove all goods stored at the station. */
  for (CargoID i = 0; i < NUM_CARGO; i++) {
    st->goods[i].rating = 1;
    st->goods[i].cargo.Truncate();
  }
 
  CrashAirplane(v);
}
 
static void AircraftEntersTerminal(Aircraft *v)
{
  if (v->current_order.IsType(OT_GOTO_DEPOT)) return;
 
  Station *st = Station::Get(v->targetairport);
  v->last_station_visited = v->targetairport;
 
  /* Check if station was ever visited before */
  if (!(st->had_vehicle_of_type & HVOT_AIRCRAFT)) {
    st->had_vehicle_of_type |= HVOT_AIRCRAFT;
    SetDParam(0, st->index);
    /* show newsitem of celebrating citizens */
    AddVehicleNewsItem(
      STR_NEWS_FIRST_AIRCRAFT_ARRIVAL,
      (v->owner == _local_company) ? NT_ARRIVAL_COMPANY : NT_ARRIVAL_OTHER,
      v->index,
      st->index
    );
    AI::NewEvent(v->owner, new ScriptEventStationFirstVehicle(st->index, v->index));
    Game::NewEvent(new ScriptEventStationFirstVehicle(st->index, v->index));
  }
 
  v->BeginLoading();
}
 
static void AircraftLandAirplane(Aircraft *v)
{
  Station *st = Station::Get(v->targetairport);
 
  TileIndex vt = TileVirtXY(v->x_pos, v->y_pos);
 
  v->UpdateDeltaXY();
 
  AirportTileAnimationTrigger(st, vt, AAT_STATION_AIRPLANE_LAND);
 
  if (!PlayVehicleSound(v, VSE_TOUCHDOWN)) {
    SndPlayVehicleFx(SND_17_SKID_PLANE, v);
  }
}
 
 
void AircraftNextAirportPos_and_Order(Aircraft *v)
{
  if (v->current_order.IsType(OT_GOTO_STATION) || v->current_order.IsType(OT_GOTO_DEPOT)) {
    v->targetairport = v->current_order.GetDestination();
  }
 
  const Station *st = GetTargetAirportIfValid(v);
  const AirportFTAClass *apc = st == nullptr ? GetAirport(AT_DUMMY) : st->airport.GetFTA();
  Direction rotation = st == nullptr ? DIR_N : st->airport.rotation;
  v->pos = v->previous_pos = AircraftGetEntryPoint(v, apc, rotation);
}
 
void AircraftLeaveHangar(Aircraft *v, Direction exit_dir)
{
  v->cur_speed = 0;
  v->subspeed = 0;
  v->progress = 0;
  v->direction = exit_dir;
  v->vehstatus &= ~VS_HIDDEN;
  {
    Vehicle *u = v->Next();
    u->vehstatus &= ~VS_HIDDEN;
 
    /* Rotor blades */
    u = u->Next();
    if (u != nullptr) {
      u->vehstatus &= ~VS_HIDDEN;
      u->cur_speed = 80;
    }
  }
 
  VehicleServiceInDepot(v);
  SetAircraftPosition(v, v->x_pos, v->y_pos, v->z_pos);
  InvalidateWindowData(WC_VEHICLE_DEPOT, v->tile);
  SetWindowClassesDirty(WC_AIRCRAFT_LIST);
}
 
static void AircraftEventHandler_EnterTerminal(Aircraft *v, const AirportFTAClass *apc)
{
  AircraftEntersTerminal(v);
  v->state = apc->layout[v->pos].heading;
}
 
static void AircraftEventHandler_EnterHangar(Aircraft *v, const AirportFTAClass *apc)
{
  VehicleEnterDepot(v);
  v->state = apc->layout[v->pos].heading;
}
 
static void AircraftEventHandler_InHangar(Aircraft *v, const AirportFTAClass *apc)
{
  /* if we just arrived, execute EnterHangar first */
  if (v->previous_pos != v->pos) {
    AircraftEventHandler_EnterHangar(v, apc);
    return;
  }
 
  /* if we were sent to the depot, stay there */
  if (v->current_order.IsType(OT_GOTO_DEPOT) && (v->vehstatus & VS_STOPPED)) {
    v->current_order.Free();
    return;
  }
 
  if (!v->current_order.IsType(OT_GOTO_STATION) &&
      !v->current_order.IsType(OT_GOTO_DEPOT))
    return;
 
  /* We are leaving a hangar, but have to go to the exact same one; re-enter */
  if (v->current_order.IsType(OT_GOTO_DEPOT) && v->current_order.GetDestination() == v->targetairport) {
    VehicleEnterDepot(v);
    return;
  }
 
  /* if the block of the next position is busy, stay put */
  if (AirportHasBlock(v, &apc->layout[v->pos], apc)) return;
 
  /* We are already at the target airport, we need to find a terminal */
  if (v->current_order.GetDestination() == v->targetairport) {
    /* FindFreeTerminal:
     * 1. Find a free terminal, 2. Occupy it, 3. Set the vehicle's state to that terminal */
    if (v->subtype == AIR_HELICOPTER) {
      if (!AirportFindFreeHelipad(v, apc)) return; // helicopter
    } else {
      if (!AirportFindFreeTerminal(v, apc)) return; // airplane
    }
  } else { // Else prepare for launch.
    /* airplane goto state takeoff, helicopter to helitakeoff */
    v->state = (v->subtype == AIR_HELICOPTER) ? HELITAKEOFF : TAKEOFF;
  }
  const Station *st = Station::GetByTile(v->tile);
  AircraftLeaveHangar(v, st->airport.GetHangarExitDirection(v->tile));
  AirportMove(v, apc);
}
 
static void AircraftEventHandler_AtTerminal(Aircraft *v, const AirportFTAClass *apc)
{
  /* if we just arrived, execute EnterTerminal first */
  if (v->previous_pos != v->pos) {
    AircraftEventHandler_EnterTerminal(v, apc);
    /* on an airport with helipads, a helicopter will always land there
     * and get serviced at the same time - setting */
    if (_settings_game.order.serviceathelipad) {
      if (v->subtype == AIR_HELICOPTER && apc->num_helipads > 0) {
        /* an excerpt of ServiceAircraft, without the invisibility stuff */
        v->date_of_last_service = _date;
        v->breakdowns_since_last_service = 0;
        v->reliability = v->GetEngine()->reliability;
        SetWindowDirty(WC_VEHICLE_DETAILS, v->index);
      }
    }
    return;
  }
 
  if (v->current_order.IsType(OT_NOTHING)) return;
 
  /* if the block of the next position is busy, stay put */
  if (AirportHasBlock(v, &apc->layout[v->pos], apc)) return;
 
  /* airport-road is free. We either have to go to another airport, or to the hangar
   * ---> start moving */
 
  bool go_to_hangar = false;
  switch (v->current_order.GetType()) {
    case OT_GOTO_STATION: // ready to fly to another airport
      break;
    case OT_GOTO_DEPOT:   // visit hangar for servicing, sale, etc.
      go_to_hangar = v->current_order.GetDestination() == v->targetairport;
      break;
    case OT_CONDITIONAL:
      /* In case of a conditional order we just have to wait a tick
       * longer, so the conditional order can actually be processed;
       * we should not clear the order as that makes us go nowhere. */
      return;
    default:  // orders have been deleted (no orders), goto depot and don't bother us
      v->current_order.Free();
      go_to_hangar = Station::Get(v->targetairport)->airport.HasHangar();
  }
 
  if (go_to_hangar && Station::Get(v->targetairport)->airport.HasHangar()) {
    v->state = HANGAR;
  } else {
    /* airplane goto state takeoff, helicopter to helitakeoff */
    v->state = (v->subtype == AIR_HELICOPTER) ? HELITAKEOFF : TAKEOFF;
  }
  AirportMove(v, apc);
}
 
static void AircraftEventHandler_General(Aircraft *v, const AirportFTAClass *apc)
{
  error("OK, you shouldn't be here, check your Airport Scheme!");
}
 
static void AircraftEventHandler_TakeOff(Aircraft *v, const AirportFTAClass *apc)
{
  PlayAircraftSound(v); // play takeoffsound for airplanes
  v->state = STARTTAKEOFF;
}
 
static void AircraftEventHandler_StartTakeOff(Aircraft *v, const AirportFTAClass *apc)
{
  v->state = ENDTAKEOFF;
  v->UpdateDeltaXY();
}
 
static void AircraftEventHandler_EndTakeOff(Aircraft *v, const AirportFTAClass *apc)
{
  v->state = FLYING;
  /* get the next position to go to, differs per airport */
  AircraftNextAirportPos_and_Order(v);
}
 
static void AircraftEventHandler_HeliTakeOff(Aircraft *v, const AirportFTAClass *apc)
{
  v->state = FLYING;
  v->UpdateDeltaXY();
 
  /* get the next position to go to, differs per airport */
  AircraftNextAirportPos_and_Order(v);
 
  /* Send the helicopter to a hangar if needed for replacement */
  if (v->NeedsAutomaticServicing()) {
    Backup<CompanyID> cur_company(_current_company, v->owner, FILE_LINE);
    Command<CMD_SEND_VEHICLE_TO_DEPOT>::Do(DC_EXEC, v->index, DepotCommand::Service | DepotCommand::LocateHangar, {});
    cur_company.Restore();
  }
}
 
static void AircraftEventHandler_Flying(Aircraft *v, const AirportFTAClass *apc)
{
  Station *st = Station::Get(v->targetairport);
 
  /* Runway busy, not allowed to use this airstation or closed, circle. */
  if (CanVehicleUseStation(v, st) && (st->owner == OWNER_NONE || st->owner == v->owner) && !(st->airport.flags & AIRPORT_CLOSED_block)) {
    /* {32,FLYING,NOTHING_block,37}, {32,LANDING,N,33}, {32,HELILANDING,N,41},
     * if it is an airplane, look for LANDING, for helicopter HELILANDING
     * it is possible to choose from multiple landing runways, so loop until a free one is found */
    byte landingtype = (v->subtype == AIR_HELICOPTER) ? HELILANDING : LANDING;
    const AirportFTA *current = apc->layout[v->pos].next;
    while (current != nullptr) {
      if (current->heading == landingtype) {
        /* save speed before, since if AirportHasBlock is false, it resets them to 0
         * we don't want that for plane in air
         * hack for speed thingie */
        uint16 tcur_speed = v->cur_speed;
        uint16 tsubspeed = v->subspeed;
        if (!AirportHasBlock(v, current, apc)) {
          v->state = landingtype; // LANDING / HELILANDING
          if (v->state == HELILANDING) SetBit(v->flags, VAF_HELI_DIRECT_DESCENT);
          /* it's a bit dirty, but I need to set position to next position, otherwise
           * if there are multiple runways, plane won't know which one it took (because
           * they all have heading LANDING). And also occupy that block! */
          v->pos = current->next_position;
          SETBITS(st->airport.flags, apc->layout[v->pos].block);
          return;
        }
        v->cur_speed = tcur_speed;
        v->subspeed = tsubspeed;
      }
      current = current->next;
    }
  }
  v->state = FLYING;
  v->pos = apc->layout[v->pos].next_position;
}
 
static void AircraftEventHandler_Landing(Aircraft *v, const AirportFTAClass *apc)
{
  v->state = ENDLANDING;
  AircraftLandAirplane(v);  // maybe crash airplane
 
  /* check if the aircraft needs to be replaced or renewed and send it to a hangar if needed */
  if (v->NeedsAutomaticServicing()) {
    Backup<CompanyID> cur_company(_current_company, v->owner, FILE_LINE);
    Command<CMD_SEND_VEHICLE_TO_DEPOT>::Do(DC_EXEC, v->index, DepotCommand::Service, {});
    cur_company.Restore();
  }
}
 
static void AircraftEventHandler_HeliLanding(Aircraft *v, const AirportFTAClass *apc)
{
  v->state = HELIENDLANDING;
  v->UpdateDeltaXY();
}
 
static void AircraftEventHandler_EndLanding(Aircraft *v, const AirportFTAClass *apc)
{
  /* next block busy, don't do a thing, just wait */
  if (AirportHasBlock(v, &apc->layout[v->pos], apc)) return;
 
  /* if going to terminal (OT_GOTO_STATION) choose one
   * 1. in case all terminals are busy AirportFindFreeTerminal() returns false or
   * 2. not going for terminal (but depot, no order),
   * --> get out of the way to the hangar. */
  if (v->current_order.IsType(OT_GOTO_STATION)) {
    if (AirportFindFreeTerminal(v, apc)) return;
  }
  v->state = HANGAR;
 
}
 
static void AircraftEventHandler_HeliEndLanding(Aircraft *v, const AirportFTAClass *apc)
{
  /*  next block busy, don't do a thing, just wait */
  if (AirportHasBlock(v, &apc->layout[v->pos], apc)) return;
 
  /* if going to helipad (OT_GOTO_STATION) choose one. If airport doesn't have helipads, choose terminal
   * 1. in case all terminals/helipads are busy (AirportFindFreeHelipad() returns false) or
   * 2. not going for terminal (but depot, no order),
   * --> get out of the way to the hangar IF there are terminals on the airport.
   * --> else TAKEOFF
   * the reason behind this is that if an airport has a terminal, it also has a hangar. Airplanes
   * must go to a hangar. */
  if (v->current_order.IsType(OT_GOTO_STATION)) {
    if (AirportFindFreeHelipad(v, apc)) return;
  }
  v->state = Station::Get(v->targetairport)->airport.HasHangar() ? HANGAR : HELITAKEOFF;
}
 
typedef void AircraftStateHandler(Aircraft *v, const AirportFTAClass *apc);
static AircraftStateHandler * const _aircraft_state_handlers[] = {
  AircraftEventHandler_General,        // TO_ALL         =  0
  AircraftEventHandler_InHangar,       // HANGAR         =  1
  AircraftEventHandler_AtTerminal,     // TERM1          =  2
  AircraftEventHandler_AtTerminal,     // TERM2          =  3
  AircraftEventHandler_AtTerminal,     // TERM3          =  4
  AircraftEventHandler_AtTerminal,     // TERM4          =  5
  AircraftEventHandler_AtTerminal,     // TERM5          =  6
  AircraftEventHandler_AtTerminal,     // TERM6          =  7
  AircraftEventHandler_AtTerminal,     // HELIPAD1       =  8
  AircraftEventHandler_AtTerminal,     // HELIPAD2       =  9
  AircraftEventHandler_TakeOff,        // TAKEOFF        = 10
  AircraftEventHandler_StartTakeOff,   // STARTTAKEOFF   = 11
  AircraftEventHandler_EndTakeOff,     // ENDTAKEOFF     = 12
  AircraftEventHandler_HeliTakeOff,    // HELITAKEOFF    = 13
  AircraftEventHandler_Flying,         // FLYING         = 14
  AircraftEventHandler_Landing,        // LANDING        = 15
  AircraftEventHandler_EndLanding,     // ENDLANDING     = 16
  AircraftEventHandler_HeliLanding,    // HELILANDING    = 17
  AircraftEventHandler_HeliEndLanding, // HELIENDLANDING = 18
  AircraftEventHandler_AtTerminal,     // TERM7          = 19
  AircraftEventHandler_AtTerminal,     // TERM8          = 20
  AircraftEventHandler_AtTerminal,     // HELIPAD3       = 21
};
 
static void AirportClearBlock(const Aircraft *v, const AirportFTAClass *apc)
{
  /* we have left the previous block, and entered the new one. Free the previous block */
  if (apc->layout[v->previous_pos].block != apc->layout[v->pos].block) {
    Station *st = Station::Get(v->targetairport);
 
    CLRBITS(st->airport.flags, apc->layout[v->previous_pos].block);
  }
}
 
static void AirportGoToNextPosition(Aircraft *v)
{
  /* if aircraft is not in position, wait until it is */
  if (!AircraftController(v)) return;
 
  const AirportFTAClass *apc = Station::Get(v->targetairport)->airport.GetFTA();
 
  AirportClearBlock(v, apc);
  AirportMove(v, apc); // move aircraft to next position
}
 
/* gets pos from vehicle and next orders */
static bool AirportMove(Aircraft *v, const AirportFTAClass *apc)
{
  /* error handling */
  if (v->pos >= apc->nofelements) {
    Debug(misc, 0, "[Ap] position {} is not valid for current airport. Max position is {}", v->pos, apc->nofelements-1);
    assert(v->pos < apc->nofelements);
  }
 
  const AirportFTA *current = &apc->layout[v->pos];
  /* we have arrived in an important state (eg terminal, hangar, etc.) */
  if (current->heading == v->state) {
    byte prev_pos = v->pos; // location could be changed in state, so save it before-hand
    byte prev_state = v->state;
    _aircraft_state_handlers[v->state](v, apc);
    if (v->state != FLYING) v->previous_pos = prev_pos;
    if (v->state != prev_state || v->pos != prev_pos) UpdateAircraftCache(v);
    return true;
  }
 
  v->previous_pos = v->pos; // save previous location
 
  /* there is only one choice to move to */
  if (current->next == nullptr) {
    if (AirportSetBlocks(v, current, apc)) {
      v->pos = current->next_position;
      UpdateAircraftCache(v);
    } // move to next position
    return false;
  }
 
  /* there are more choices to choose from, choose the one that
   * matches our heading */
  do {
    if (v->state == current->heading || current->heading == TO_ALL) {
      if (AirportSetBlocks(v, current, apc)) {
        v->pos = current->next_position;
        UpdateAircraftCache(v);
      } // move to next position
      return false;
    }
    current = current->next;
  } while (current != nullptr);
 
  Debug(misc, 0, "[Ap] cannot move further on Airport! (pos {} state {}) for vehicle {}", v->pos, v->state, v->index);
  NOT_REACHED();
}
 
static bool AirportHasBlock(Aircraft *v, const AirportFTA *current_pos, const AirportFTAClass *apc)
{
  const AirportFTA *reference = &apc->layout[v->pos];
  const AirportFTA *next = &apc->layout[current_pos->next_position];
 
  /* same block, then of course we can move */
  if (apc->layout[current_pos->position].block != next->block) {
    const Station *st = Station::Get(v->targetairport);
    uint64 airport_flags = next->block;
 
    /* check additional possible extra blocks */
    if (current_pos != reference && current_pos->block != NOTHING_block) {
      airport_flags |= current_pos->block;
    }
 
    if (st->airport.flags & airport_flags) {
      v->cur_speed = 0;
      v->subspeed = 0;
      return true;
    }
  }
  return false;
}
 
static bool AirportSetBlocks(Aircraft *v, const AirportFTA *current_pos, const AirportFTAClass *apc)
{
  const AirportFTA *next = &apc->layout[current_pos->next_position];
  const AirportFTA *reference = &apc->layout[v->pos];
 
  /* if the next position is in another block, check it and wait until it is free */
  if ((apc->layout[current_pos->position].block & next->block) != next->block) {
    uint64 airport_flags = next->block;
    /* search for all all elements in the list with the same state, and blocks != N
     * this means more blocks should be checked/set */
    const AirportFTA *current = current_pos;
    if (current == reference) current = current->next;
    while (current != nullptr) {
      if (current->heading == current_pos->heading && current->block != 0) {
        airport_flags |= current->block;
        break;
      }
      current = current->next;
    }
 
    /* if the block to be checked is in the next position, then exclude that from
     * checking, because it has been set by the airplane before */
    if (current_pos->block == next->block) airport_flags ^= next->block;
 
    Station *st = Station::Get(v->targetairport);
    if (st->airport.flags & airport_flags) {
      v->cur_speed = 0;
      v->subspeed = 0;
      return false;
    }
 
    if (next->block != NOTHING_block) {
      SETBITS(st->airport.flags, airport_flags); // occupy next block
    }
  }
  return true;
}
 
struct MovementTerminalMapping {
  AirportMovementStates state; 
  uint64 airport_flag;         
};
 
static const MovementTerminalMapping _airport_terminal_mapping[] = {
  {TERM1, TERM1_block},
  {TERM2, TERM2_block},
  {TERM3, TERM3_block},
  {TERM4, TERM4_block},
  {TERM5, TERM5_block},
  {TERM6, TERM6_block},
  {TERM7, TERM7_block},
  {TERM8, TERM8_block},
  {HELIPAD1, HELIPAD1_block},
  {HELIPAD2, HELIPAD2_block},
  {HELIPAD3, HELIPAD3_block},
};
 
static bool FreeTerminal(Aircraft *v, byte i, byte last_terminal)
{
  assert(last_terminal <= lengthof(_airport_terminal_mapping));
  Station *st = Station::Get(v->targetairport);
  for (; i < last_terminal; i++) {
    if ((st->airport.flags & _airport_terminal_mapping[i].airport_flag) == 0) {
      /* TERMINAL# HELIPAD# */
      v->state = _airport_terminal_mapping[i].state; // start moving to that terminal/helipad
      SETBITS(st->airport.flags, _airport_terminal_mapping[i].airport_flag); // occupy terminal/helipad
      return true;
    }
  }
  return false;
}
 
static uint GetNumTerminals(const AirportFTAClass *apc)
{
  uint num = 0;
 
  for (uint i = apc->terminals[0]; i > 0; i--) num += apc->terminals[i];
 
  return num;
}
 
static bool AirportFindFreeTerminal(Aircraft *v, const AirportFTAClass *apc)
{
  /* example of more terminalgroups
   * {0,HANGAR,NOTHING_block,1}, {0,TERMGROUP,TERM_GROUP1_block,0}, {0,TERMGROUP,TERM_GROUP2_ENTER_block,1}, {0,0,N,1},
   * Heading TERMGROUP denotes a group. We see 2 groups here:
   * 1. group 0 -- TERM_GROUP1_block (check block)
   * 2. group 1 -- TERM_GROUP2_ENTER_block (check block)
   * First in line is checked first, group 0. If the block (TERM_GROUP1_block) is free, it
   * looks at the corresponding terminals of that group. If no free ones are found, other
   * possible groups are checked (in this case group 1, since that is after group 0). If that
   * fails, then attempt fails and plane waits
   */
  if (apc->terminals[0] > 1) {
    const Station *st = Station::Get(v->targetairport);
    const AirportFTA *temp = apc->layout[v->pos].next;
 
    while (temp != nullptr) {
      if (temp->heading == TERMGROUP) {
        if (!(st->airport.flags & temp->block)) {
          /* read which group do we want to go to?
           * (the first free group) */
          uint target_group = temp->next_position + 1;
 
          /* at what terminal does the group start?
           * that means, sum up all terminals of
           * groups with lower number */
          uint group_start = 0;
          for (uint i = 1; i < target_group; i++) {
            group_start += apc->terminals[i];
          }
 
          uint group_end = group_start + apc->terminals[target_group];
          if (FreeTerminal(v, group_start, group_end)) return true;
        }
      } else {
        /* once the heading isn't 255, we've exhausted the possible blocks.
         * So we cannot move */
        return false;
      }
      temp = temp->next;
    }
  }
 
  /* if there is only 1 terminalgroup, all terminals are checked (starting from 0 to max) */
  return FreeTerminal(v, 0, GetNumTerminals(apc));
}
 
static bool AirportFindFreeHelipad(Aircraft *v, const AirportFTAClass *apc)
{
  /* if an airport doesn't have helipads, use terminals */
  if (apc->num_helipads == 0) return AirportFindFreeTerminal(v, apc);
 
  /* only 1 helicoptergroup, check all helipads
   * The blocks for helipads start after the last terminal (MAX_TERMINALS) */
  return FreeTerminal(v, MAX_TERMINALS, apc->num_helipads + MAX_TERMINALS);
}
 
static void AircraftHandleDestTooFar(Aircraft *v, bool too_far)
{
  if (too_far) {
    if (!HasBit(v->flags, VAF_DEST_TOO_FAR)) {
      SetBit(v->flags, VAF_DEST_TOO_FAR);
      SetWindowWidgetDirty(WC_VEHICLE_VIEW, v->index, WID_VV_START_STOP);
      AI::NewEvent(v->owner, new ScriptEventAircraftDestTooFar(v->index));
      if (v->owner == _local_company) {
        /* Post a news message. */
        SetDParam(0, v->index);
        AddVehicleAdviceNewsItem(STR_NEWS_AIRCRAFT_DEST_TOO_FAR, v->index);
      }
    }
    return;
  }
 
  if (HasBit(v->flags, VAF_DEST_TOO_FAR)) {
    /* Not too far anymore, clear flag and message. */
    ClrBit(v->flags, VAF_DEST_TOO_FAR);
    SetWindowWidgetDirty(WC_VEHICLE_VIEW, v->index, WID_VV_START_STOP);
    DeleteVehicleNews(v->index, STR_NEWS_AIRCRAFT_DEST_TOO_FAR);
  }
}
 
static bool AircraftEventHandler(Aircraft *v, int loop)
{
  if (v->vehstatus & VS_CRASHED) {
    return HandleCrashedAircraft(v);
  }
 
  if (v->vehstatus & VS_STOPPED) return true;
 
  v->HandleBreakdown();
 
  HandleAircraftSmoke(v, loop != 0);
  ProcessOrders(v);
  v->HandleLoading(loop != 0);
 
  if (v->current_order.IsType(OT_LOADING) || v->current_order.IsType(OT_LEAVESTATION)) return true;
 
  if (v->state >= ENDTAKEOFF && v->state <= HELIENDLANDING) {
    /* If we are flying, unconditionally clear the 'dest too far' state. */
    AircraftHandleDestTooFar(v, false);
  } else if (v->acache.cached_max_range_sqr != 0) {
    /* Check the distance to the next destination. This code works because the target
     * airport is only updated after take off and not on the ground. */
    Station *cur_st = Station::GetIfValid(v->targetairport);
    Station *next_st = v->current_order.IsType(OT_GOTO_STATION) || v->current_order.IsType(OT_GOTO_DEPOT) ? Station::GetIfValid(v->current_order.GetDestination()) : nullptr;
 
    if (cur_st != nullptr && cur_st->airport.tile != INVALID_TILE && next_st != nullptr && next_st->airport.tile != INVALID_TILE) {
      uint dist = DistanceSquare(cur_st->airport.tile, next_st->airport.tile);
      AircraftHandleDestTooFar(v, dist > v->acache.cached_max_range_sqr);
    }
  }
 
  if (!HasBit(v->flags, VAF_DEST_TOO_FAR)) AirportGoToNextPosition(v);
 
  return true;
}
 
bool Aircraft::Tick()
{
  if (!this->IsNormalAircraft()) return true;
 
  PerformanceAccumulator framerate(PFE_GL_AIRCRAFT);
 
  this->tick_counter++;
 
  if (!(this->vehstatus & VS_STOPPED)) this->running_ticks++;
 
  if (this->subtype == AIR_HELICOPTER) HelicopterTickHandler(this);
 
  this->current_order_time++;
 
  for (uint i = 0; i != 2; i++) {
    /* stop if the aircraft was deleted */
    if (!AircraftEventHandler(this, i)) return false;
  }
 
  return true;
}
 
 
Station *GetTargetAirportIfValid(const Aircraft *v)
{
  assert(v->type == VEH_AIRCRAFT);
 
  Station *st = Station::GetIfValid(v->targetairport);
  if (st == nullptr) return nullptr;
 
  return st->airport.tile == INVALID_TILE ? nullptr : st;
}
 
void UpdateAirplanesOnNewStation(const Station *st)
{
  /* only 1 station is updated per function call, so it is enough to get entry_point once */
  const AirportFTAClass *ap = st->airport.GetFTA();
  Direction rotation = st->airport.tile == INVALID_TILE ? DIR_N : st->airport.rotation;
 
  for (Aircraft *v : Aircraft::Iterate()) {
    if (!v->IsNormalAircraft() || v->targetairport != st->index) continue;
    assert(v->state == FLYING);
 
    Order *o = &v->current_order;
    /* The aircraft is heading to a hangar, but the new station doesn't have one,
     * or the aircraft can't land on the new station. Cancel current order. */
    if (o->IsType(OT_GOTO_DEPOT) && !(o->GetDepotOrderType() & ODTFB_PART_OF_ORDERS) && o->GetDestination() == st->index &&
        (!st->airport.HasHangar() || !CanVehicleUseStation(v, st))) {
      o->MakeDummy();
      SetWindowWidgetDirty(WC_VEHICLE_VIEW, v->index, WID_VV_START_STOP);
    }
    v->pos = v->previous_pos = AircraftGetEntryPoint(v, ap, rotation);
    UpdateAircraftCache(v);
  }
 
  /* Heliports don't have a hangar. Invalidate all go to hangar orders from all aircraft. */
  if (!st->airport.HasHangar()) RemoveOrderFromAllVehicles(OT_GOTO_DEPOT, st->index, true);
}