yapf_ship.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 "../../ship.h"
#include "../../vehicle_func.h"
 
#include "yapf.hpp"
#include "yapf_node_ship.hpp"
#include "yapf_ship_regions.h"
#include "../water_regions.h"
 
#include "../../safeguards.h"
 
constexpr int NUMBER_OR_WATER_REGIONS_LOOKAHEAD = 4;
constexpr int MAX_SHIP_PF_NODES = (NUMBER_OR_WATER_REGIONS_LOOKAHEAD + 1) * WATER_REGION_NUMBER_OF_TILES * 4; // 4 possible exit dirs per tile.
 
constexpr int SHIP_LOST_PATH_LENGTH = 8; // The length of the (aimless) path assigned when a ship is lost.
 
template <class Types>
class CYapfDestinationTileWaterT
{
public:
  typedef typename Types::Tpf Tpf; 
  typedef typename Types::TrackFollower TrackFollower;
  typedef typename Types::NodeList::Item Node; 
  typedef typename Node::Key Key; 
 
protected:
  TileIndex dest_tile;
  TrackdirBits dest_trackdirs;
  StationID dest_station;
 
  bool has_intermediate_dest = false;
  TileIndex intermediate_dest_tile;
  WaterRegionPatchDesc intermediate_dest_region_patch;
 
public:
  void SetDestination(const Ship *v)
  {
    if (v->current_order.IsType(OT_GOTO_STATION)) {
      this->dest_station = v->current_order.GetDestination();
      this->dest_tile = CalcClosestStationTile(this->dest_station, v->tile, STATION_DOCK);
      this->dest_trackdirs = INVALID_TRACKDIR_BIT;
    } else {
      this->dest_station = INVALID_STATION;
      this->dest_tile = v->dest_tile;
      this->dest_trackdirs = TrackStatusToTrackdirBits(GetTileTrackStatus(v->dest_tile, TRANSPORT_WATER, 0));
    }
  }
 
  void SetIntermediateDestination(const WaterRegionPatchDesc &water_region_patch)
  {
    this->has_intermediate_dest = true;
    this->intermediate_dest_tile = GetWaterRegionCenterTile(water_region_patch);
    this->intermediate_dest_region_patch = water_region_patch;
  }
 
protected:
  inline Tpf& Yapf()
  {
    return *static_cast<Tpf*>(this);
  }
 
public:
  inline bool PfDetectDestination(Node &n)
  {
    return this->PfDetectDestinationTile(n.segment_last_tile, n.segment_last_td);
  }
 
  inline bool PfDetectDestinationTile(TileIndex tile, Trackdir trackdir)
  {
    if (this->has_intermediate_dest) {
      /* GetWaterRegionInfo is much faster than GetWaterRegionPatchInfo so we try that first. */
      if (GetWaterRegionInfo(tile) != this->intermediate_dest_region_patch) return false;
      return GetWaterRegionPatchInfo(tile) == this->intermediate_dest_region_patch;
    }
 
    if (this->dest_station != INVALID_STATION) return IsDockingTile(tile) && IsShipDestinationTile(tile, this->dest_station);
 
    return tile == this->dest_tile && ((this->dest_trackdirs & TrackdirToTrackdirBits(trackdir)) != TRACKDIR_BIT_NONE);
  }
 
  inline bool PfCalcEstimate(Node &n)
  {
    const TileIndex destination_tile = this->has_intermediate_dest ? this->intermediate_dest_tile : this->dest_tile;
 
    static const int dg_dir_to_x_offs[] = { -1, 0, 1, 0 };
    static const int dg_dir_to_y_offs[] = { 0, 1, 0, -1 };
    if (this->PfDetectDestination(n)) {
      n.estimate = n.cost;
      return true;
    }
 
    TileIndex tile = n.segment_last_tile;
    DiagDirection exitdir = TrackdirToExitdir(n.segment_last_td);
    int x1 = 2 * TileX(tile) + dg_dir_to_x_offs[(int)exitdir];
    int y1 = 2 * TileY(tile) + dg_dir_to_y_offs[(int)exitdir];
    int x2 = 2 * TileX(destination_tile);
    int y2 = 2 * TileY(destination_tile);
    int dx = abs(x1 - x2);
    int dy = abs(y1 - y2);
    int dmin = std::min(dx, dy);
    int dxy = abs(dx - dy);
    int d = dmin * YAPF_TILE_CORNER_LENGTH + (dxy - 1) * (YAPF_TILE_LENGTH / 2);
    n.estimate = n.cost + d;
    assert(n.estimate >= n.parent->estimate);
    return true;
  }
};
 
template <class Types>
class CYapfFollowShipT
{
public:
  typedef typename Types::Tpf Tpf; 
  typedef typename Types::TrackFollower TrackFollower;
  typedef typename Types::NodeList::Item Node; 
  typedef typename Node::Key Key; 
 
protected:
  inline Tpf &Yapf()
  {
    return *static_cast<Tpf*>(this);
  }
 
  std::vector<WaterRegionDesc> water_region_corridor;
 
public:
  inline void PfFollowNode(Node &old_node)
  {
    TrackFollower F(Yapf().GetVehicle());
    if (F.Follow(old_node.key.tile, old_node.key.td)) {
      if (this->water_region_corridor.empty()
          || std::ranges::find(this->water_region_corridor, GetWaterRegionInfo(F.new_tile)) != this->water_region_corridor.end()) {
        Yapf().AddMultipleNodes(&old_node, F);
      }
    }
  }
 
  inline void RestrictSearch(const std::vector<WaterRegionPatchDesc> &path)
  {
    this->water_region_corridor.clear();
    for (const WaterRegionPatchDesc &path_entry : path) this->water_region_corridor.push_back(path_entry);
  }
 
  inline char TransportTypeChar() const
  {
    return 'w';
  }
 
  static Trackdir GetRandomTrackdir(TrackdirBits trackdirs)
  {
    const int strip_amount = RandomRange(CountBits(trackdirs));
    for (int s = 0; s < strip_amount; ++s) RemoveFirstTrackdir(&trackdirs);
    return FindFirstTrackdir(trackdirs);
  }
 
  static std::pair<TileIndex, Trackdir> GetRandomFollowUpTileTrackdir(const Ship *v, TileIndex tile, Trackdir dir)
  {
    TrackFollower follower(v);
    if (follower.Follow(tile, dir)) {
      TrackdirBits dirs = follower.new_td_bits;
      const TrackdirBits dirs_without_90_degree = dirs & ~TrackdirCrossesTrackdirs(dir);
      if (dirs_without_90_degree != TRACKDIR_BIT_NONE) dirs = dirs_without_90_degree;
      return { follower.new_tile, GetRandomTrackdir(dirs) };
    }
    return { follower.new_tile, INVALID_TRACKDIR };
  }
 
  static Trackdir CreateRandomPath(const Ship *v, ShipPathCache &path_cache, int path_length)
  {
    std::pair<TileIndex, Trackdir> tile_dir = { v->tile, v->GetVehicleTrackdir()};
    for (int i = 0; i < path_length; ++i) {
      tile_dir = GetRandomFollowUpTileTrackdir(v, tile_dir.first, tile_dir.second);
      if (tile_dir.second == INVALID_TRACKDIR) break;
      path_cache.push_back(tile_dir.second);
    }
 
    if (path_cache.empty()) return INVALID_TRACKDIR;
 
    /* Reverse the path so we can take from the end. */
    std::reverse(std::begin(path_cache), std::end(path_cache));
 
    const Trackdir result = path_cache.back().trackdir;
    path_cache.pop_back();
    return result;
  }
 
  static Trackdir ChooseShipTrack(const Ship *v, TileIndex tile, TrackdirBits forward_dirs, TrackdirBits reverse_dirs,
    bool &path_found, ShipPathCache &path_cache, Trackdir &best_origin_dir)
  {
    const std::vector<WaterRegionPatchDesc> high_level_path = YapfShipFindWaterRegionPath(v, tile, NUMBER_OR_WATER_REGIONS_LOOKAHEAD + 1);
    if (high_level_path.empty()) {
      path_found = false;
      /* Make the ship move around aimlessly. This prevents repeated pathfinder calls and clearly indicates that the ship is lost. */
      return CreateRandomPath(v, path_cache, SHIP_LOST_PATH_LENGTH);
    }
 
    /* Try one time without restricting the search area, which generally results in better and more natural looking paths.
     * However the pathfinder can hit the node limit in certain situations such as long aqueducts or maze-like terrain.
     * If that happens we run the pathfinder again, but restricted only to the regions provided by the region pathfinder. */
    for (int attempt = 0; attempt < 2; ++attempt) {
      Tpf pf(MAX_SHIP_PF_NODES);
 
      /* Set origin and destination nodes */
      pf.SetOrigin(v->tile, forward_dirs | reverse_dirs);
      pf.SetDestination(v);
      const bool is_intermediate_destination = static_cast<int>(high_level_path.size()) >= NUMBER_OR_WATER_REGIONS_LOOKAHEAD + 1;
      if (is_intermediate_destination) pf.SetIntermediateDestination(high_level_path.back());
 
      /* Restrict the search area to prevent the low level pathfinder from expanding too many nodes. This can happen
       * when the terrain is very "maze-like" or when the high level path "teleports" via a very long aqueduct. */
      if (attempt > 0) pf.RestrictSearch(high_level_path);
 
      /* Find best path. */
      path_found = pf.FindPath(v);
      Node *node = pf.GetBestNode();
      if (attempt == 0 && !path_found) continue; // Try again with restricted search area.
 
      /* Make the ship move around aimlessly. This prevents repeated pathfinder calls and clearly indicates that the ship is lost. */
      if (!path_found) return CreateRandomPath(v, path_cache, SHIP_LOST_PATH_LENGTH);
 
      /* Return only the path within the current water region if an intermediate destination was returned. If not, cache the entire path
       * to the final destination tile. The low-level pathfinder might actually prefer a different docking tile in a nearby region. Without
       * caching the full path the ship can get stuck in a loop. */
      const WaterRegionPatchDesc end_water_patch = GetWaterRegionPatchInfo(node->GetTile());
      assert(GetWaterRegionPatchInfo(tile) == high_level_path.front());
      const WaterRegionPatchDesc start_water_patch = high_level_path.front();
      while (node->parent) {
        const WaterRegionPatchDesc node_water_patch = GetWaterRegionPatchInfo(node->GetTile());
 
        const bool node_water_patch_on_high_level_path = std::ranges::find(high_level_path, node_water_patch) != high_level_path.end();
        const bool add_full_path = !is_intermediate_destination && node_water_patch != end_water_patch;
 
        /* The cached path must always lead to a region patch that's on the high level path.
         * This is what can happen when that's not the case https://github.com/OpenTTD/OpenTTD/issues/12176. */
        if (add_full_path || !node_water_patch_on_high_level_path || node_water_patch == start_water_patch) {
          path_cache.push_back(node->GetTrackdir());
        } else {
          path_cache.clear();
        }
        node = node->parent;
      }
      assert(node->GetTile() == v->tile);
 
      /* Return INVALID_TRACKDIR to trigger a ship reversal if that is the best option. */
      best_origin_dir = node->GetTrackdir();
      if ((TrackdirToTrackdirBits(best_origin_dir) & forward_dirs) == TRACKDIR_BIT_NONE) {
        path_cache.clear();
        return INVALID_TRACKDIR;
      }
 
      /* A empty path means we are already at the destination. The pathfinder shouldn't have been called at all.
       * Return a random reachable trackdir to hopefully nudge the ship out of this strange situation. */
      if (path_cache.empty()) return CreateRandomPath(v, path_cache, 1);
 
      /* Take out the last trackdir as the result. */
      const Trackdir result = path_cache.back().trackdir;
      path_cache.pop_back();
 
      /* Clear path cache when in final water region patch. This is to allow ships to spread over different docking tiles dynamically. */
      if (start_water_patch == end_water_patch) path_cache.clear();
 
      return result;
    }
 
    return INVALID_TRACKDIR;
  }
 
  static bool CheckShipReverse(const Ship *v, Trackdir *trackdir)
  {
    bool path_found = false;
    ShipPathCache dummy_cache;
    Trackdir best_origin_dir = INVALID_TRACKDIR;
 
    if (trackdir == nullptr) {
      /* The normal case, typically called when ships leave a dock. */
      const Trackdir reverse_dir = ReverseTrackdir(v->GetVehicleTrackdir());
      const TrackdirBits forward_dirs = TrackdirToTrackdirBits(v->GetVehicleTrackdir());
      const TrackdirBits reverse_dirs = TrackdirToTrackdirBits(reverse_dir);
      (void)ChooseShipTrack(v, v->tile, forward_dirs, reverse_dirs, path_found, dummy_cache, best_origin_dir);
      return path_found && best_origin_dir == reverse_dir;
    } else {
      /* This gets called when a ship suddenly can't move forward, e.g. due to terraforming. */
      const DiagDirection entry = ReverseDiagDir(VehicleExitDir(v->direction, v->state));
      const TrackdirBits reverse_dirs = DiagdirReachesTrackdirs(entry) & TrackStatusToTrackdirBits(GetTileTrackStatus(v->tile, TRANSPORT_WATER, 0, entry));
      (void)ChooseShipTrack(v, v->tile, TRACKDIR_BIT_NONE, reverse_dirs, path_found, dummy_cache, best_origin_dir);
      *trackdir = path_found && best_origin_dir != INVALID_TRACKDIR ? best_origin_dir : GetRandomTrackdir(reverse_dirs);
      return true;
    }
  }
};
 
template <class Types>
class CYapfCostShipT
{
public:
  typedef typename Types::Tpf Tpf; 
  typedef typename Types::TrackFollower TrackFollower;
  typedef typename Types::NodeList::Item Node; 
  typedef typename Node::Key Key; 
 
  Tpf &Yapf()
  {
    return *static_cast<Tpf*>(this);
  }
 
public:
  inline int CurveCost(Trackdir td1, Trackdir td2)
  {
    assert(IsValidTrackdir(td1));
    assert(IsValidTrackdir(td2));
 
    if (HasTrackdir(TrackdirCrossesTrackdirs(td1), td2)) {
      /* 90-deg curve penalty. */
      return Yapf().PfGetSettings().ship_curve90_penalty;
    } else if (td2 != NextTrackdir(td1)) {
      /* 45-deg curve penalty. */
      return Yapf().PfGetSettings().ship_curve45_penalty;
    }
    return 0;
  }
 
  static Vehicle *CountShipProc(Vehicle *v, void *data)
  {
    uint *count = (uint*)data;
    /* Ignore other vehicles (aircraft) and ships inside depot. */
    if (v->type == VEH_SHIP && (v->vehstatus & VS_HIDDEN) == 0) (*count)++;
 
    return nullptr;
  }
 
  inline bool PfCalcCost(Node &n, const TrackFollower *tf)
  {
    /* Base tile cost depending on distance. */
    int c = IsDiagonalTrackdir(n.GetTrackdir()) ? YAPF_TILE_LENGTH : YAPF_TILE_CORNER_LENGTH;
    /* Additional penalty for curves. */
    c += this->CurveCost(n.parent->GetTrackdir(), n.GetTrackdir());
 
    if (IsDockingTile(n.GetTile())) {
      /* Check docking tile for occupancy. */
      uint count = 0;
      HasVehicleOnPos(n.GetTile(), &count, &CountShipProc);
      c += count * 3 * YAPF_TILE_LENGTH;
    }
 
    /* Skipped tile cost for aqueducts. */
    c += YAPF_TILE_LENGTH * tf->tiles_skipped;
 
    /* Ocean/canal speed penalty. */
    const ShipVehicleInfo *svi = ShipVehInfo(Yapf().GetVehicle()->engine_type);
    uint8_t speed_frac = (GetEffectiveWaterClass(n.GetTile()) == WATER_CLASS_SEA) ? svi->ocean_speed_frac : svi->canal_speed_frac;
    if (speed_frac > 0) c += YAPF_TILE_LENGTH * (1 + tf->tiles_skipped) * speed_frac / (256 - speed_frac);
 
    /* Apply it. */
    n.cost = n.parent->cost + c;
    return true;
  }
};
 
template <class Tpf_, class Ttrack_follower, class Tnode_list>
struct CYapfShip_TypesT
{
  typedef CYapfShip_TypesT<Tpf_, Ttrack_follower, Tnode_list>  Types;         
  typedef Tpf_                                                 Tpf;           
  typedef Ttrack_follower                                      TrackFollower; 
  typedef Tnode_list                                           NodeList;
  typedef Ship                                                 VehicleType;
 
  typedef CYapfBaseT<Types>                 PfBase;        
  typedef CYapfFollowShipT<Types>           PfFollow;      
  typedef CYapfOriginTileT<Types>           PfOrigin;      
  typedef CYapfDestinationTileWaterT<Types> PfDestination; 
  typedef CYapfSegmentCostCacheNoneT<Types> PfCache;       
  typedef CYapfCostShipT<Types>             PfCost;        
};
 
struct CYapfShip : CYapfT<CYapfShip_TypesT<CYapfShip, CFollowTrackWater, CShipNodeListExitDir > >
{
  explicit CYapfShip(int max_nodes) { this->max_search_nodes = max_nodes; }
};
 
Track YapfShipChooseTrack(const Ship *v, TileIndex tile, bool &path_found, ShipPathCache &path_cache)
{
  Trackdir best_origin_dir = INVALID_TRACKDIR;
  const TrackdirBits origin_dirs = TrackdirToTrackdirBits(v->GetVehicleTrackdir());
  const Trackdir td_ret = CYapfShip::ChooseShipTrack(v, tile, origin_dirs, TRACKDIR_BIT_NONE, path_found, path_cache, best_origin_dir);
  return (td_ret != INVALID_TRACKDIR) ? TrackdirToTrack(td_ret) : INVALID_TRACK;
}
 
bool YapfShipCheckReverse(const Ship *v, Trackdir *trackdir)
{
  return CYapfShip::CheckShipReverse(v, trackdir);
}