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 "../../industry.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::Titem Node;        
  typedef typename Node::Key Key;                      
 
protected:
  TileIndex    m_destTile;
  TrackdirBits m_destTrackdirs;
  StationID    m_destStation;
 
  bool                 m_has_intermediate_dest = false;
  TileIndex            m_intermediate_dest_tile;
  WaterRegionPatchDesc m_intermediate_dest_region_patch;
 
public:
  void SetDestination(const Ship *v)
  {
    if (v->current_order.IsType(OT_GOTO_STATION)) {
      m_destStation = v->current_order.GetDestination();
      m_destTile = CalcClosestStationTile(m_destStation, v->tile, STATION_DOCK);
      m_destTrackdirs = INVALID_TRACKDIR_BIT;
    } else {
      m_destStation = INVALID_STATION;
      m_destTile = v->dest_tile;
      m_destTrackdirs = TrackStatusToTrackdirBits(GetTileTrackStatus(v->dest_tile, TRANSPORT_WATER, 0));
    }
  }
 
  void SetIntermediateDestination(const WaterRegionPatchDesc &water_region_patch)
  {
    m_has_intermediate_dest = true;
    m_intermediate_dest_tile = GetWaterRegionCenterTile(water_region_patch);
    m_intermediate_dest_region_patch = water_region_patch;
  }
 
protected:
  inline Tpf& Yapf()
  {
    return *static_cast<Tpf*>(this);
  }
 
public:
  inline bool PfDetectDestination(Node &n)
  {
    return PfDetectDestinationTile(n.m_segment_last_tile, n.m_segment_last_td);
  }
 
  inline bool PfDetectDestinationTile(TileIndex tile, Trackdir trackdir)
  {
    if (m_has_intermediate_dest) {
      /* GetWaterRegionInfo is much faster than GetWaterRegionPatchInfo so we try that first. */
      if (GetWaterRegionInfo(tile) != m_intermediate_dest_region_patch) return false;
      return GetWaterRegionPatchInfo(tile) == m_intermediate_dest_region_patch;
    }
 
    if (m_destStation != INVALID_STATION) return IsDockingTile(tile) && IsShipDestinationTile(tile, m_destStation);
 
    return tile == m_destTile && ((m_destTrackdirs & TrackdirToTrackdirBits(trackdir)) != TRACKDIR_BIT_NONE);
  }
 
  inline bool PfCalcEstimate(Node &n)
  {
    const TileIndex destination_tile = m_has_intermediate_dest ? m_intermediate_dest_tile : m_destTile;
 
    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 (PfDetectDestination(n)) {
      n.m_estimate = n.m_cost;
      return true;
    }
 
    TileIndex tile = n.m_segment_last_tile;
    DiagDirection exitdir = TrackdirToExitdir(n.m_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.m_estimate = n.m_cost + d;
    assert(n.m_estimate >= n.m_parent->m_estimate);
    return true;
  }
};
 
template <class Types>
class CYapfFollowShipT
{
public:
  typedef typename Types::Tpf Tpf;                     
  typedef typename Types::TrackFollower TrackFollower;
  typedef typename Types::NodeList::Titem Node;        
  typedef typename Node::Key Key;                      
 
protected:
  inline Tpf &Yapf()
  {
    return *static_cast<Tpf*>(this);
  }
 
  std::vector<WaterRegionDesc> m_water_region_corridor;
 
public:
  inline void PfFollowNode(Node &old_node)
  {
    TrackFollower F(Yapf().GetVehicle());
    if (F.Follow(old_node.m_key.m_tile, old_node.m_key.m_td)) {
      if (m_water_region_corridor.empty()
          || std::find(m_water_region_corridor.begin(), m_water_region_corridor.end(),
            GetWaterRegionInfo(F.m_new_tile)) != m_water_region_corridor.end()) {
        Yapf().AddMultipleNodes(&old_node, F);
      }
    }
  }
 
  inline void RestrictSearch(const std::vector<WaterRegionPatchDesc> &path)
  {
    m_water_region_corridor.clear();
    for (const WaterRegionPatchDesc &path_entry : path) m_water_region_corridor.push_back(path_entry);
  }
 
  inline char TransportTypeChar() const
  {
    return 'w';
  }
 
  static Trackdir CreateRandomPath(const Ship *v, TileIndex tile, Trackdir dir, ShipPathCache &path_cache, int path_length)
  {
    for (int i = 0; i < path_length; ++i) {
      TrackFollower F(v);
      if (F.Follow(tile, dir)) {
        tile = F.m_new_tile;
        TrackdirBits dirs = F.m_new_td_bits & ~TrackdirCrossesTrackdirs(dir);
        const int strip_amount = _random.Next(CountBits(dirs));
        for (int s = 0; s < strip_amount; ++s) RemoveFirstTrackdir(&dirs);
        dir = FindFirstTrackdir(dirs);
        if (dir == INVALID_TRACKDIR) break;
        path_cache.push_back(dir);
      }
    }
 
    if (path_cache.empty()) return INVALID_TRACKDIR;
 
    const Trackdir result = path_cache.front();
    path_cache.pop_front();
    return result;
  }
 
  static Trackdir ChooseShipTrack(const Ship *v, TileIndex tile, DiagDirection enterdir, TrackBits tracks, bool &path_found, ShipPathCache &path_cache)
  {
    /* Handle special case - when next tile is destination tile. */
    if (tile == v->dest_tile) {
      /* Convert tracks to trackdirs */
      TrackdirBits trackdirs = TrackBitsToTrackdirBits(tracks);
      /* Limit to trackdirs reachable from enterdir. */
      trackdirs &= DiagdirReachesTrackdirs(enterdir);
 
      /* use vehicle's current direction if that's possible, otherwise use first usable one. */
      Trackdir veh_dir = v->GetVehicleTrackdir();
      return (HasTrackdir(trackdirs, veh_dir)) ? veh_dir : (Trackdir)FindFirstBit(trackdirs);
    }
 
    /* Move back to the old tile/trackdir (where ship is coming from). */
    TileIndex src_tile = TileAddByDiagDir(tile, ReverseDiagDir(enterdir));
    Trackdir trackdir = v->GetVehicleTrackdir();
    assert(IsValidTrackdir(trackdir));
 
    /* Convert origin trackdir to TrackdirBits. */
    TrackdirBits trackdirs = TrackdirToTrackdirBits(trackdir);
 
    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, src_tile, trackdir, 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(src_tile, trackdirs);
      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.
      if (!path_found || !node) return INVALID_TRACKDIR;
 
      /* 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());
      const WaterRegionPatchDesc start_water_patch = GetWaterRegionPatchInfo(tile);
      while (node->m_parent) {
        const WaterRegionPatchDesc node_water_patch = GetWaterRegionPatchInfo(node->GetTile());
        if (node_water_patch == start_water_patch || (!is_intermediate_destination && node_water_patch != end_water_patch)) {
          path_cache.push_front(node->GetTrackdir());
        }
        node = node->m_parent;
      }
      assert(!path_cache.empty());
 
      /* Take out the last trackdir as the result. */
      const Trackdir result = path_cache.front();
      path_cache.pop_front();
 
      /* 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, TileIndex tile, Trackdir td1, Trackdir td2, Trackdir *trackdir)
  {
    const std::vector<WaterRegionPatchDesc> high_level_path = YapfShipFindWaterRegionPath(v, tile, NUMBER_OR_WATER_REGIONS_LOOKAHEAD + 1);
    if (high_level_path.empty()) {
      if (trackdir) *trackdir = INVALID_TRACKDIR;
      return false;
    }
 
    /* Create pathfinder instance. */
    Tpf pf(MAX_SHIP_PF_NODES);
    /* Set origin and destination nodes. */
    if (trackdir == nullptr) {
      pf.SetOrigin(tile, TrackdirToTrackdirBits(td1) | TrackdirToTrackdirBits(td2));
    } else {
      DiagDirection entry = ReverseDiagDir(VehicleExitDir(v->direction, v->state));
      TrackdirBits rtds = DiagdirReachesTrackdirs(entry) & TrackStatusToTrackdirBits(GetTileTrackStatus(tile, TRANSPORT_WATER, 0, entry));
      pf.SetOrigin(tile, rtds);
    }
    pf.SetDestination(v);
    if (high_level_path.size() > 1) pf.SetIntermediateDestination(high_level_path.back());
    pf.RestrictSearch(high_level_path);
 
    /* Find best path. */
    if (!pf.FindPath(v)) return false;
 
    Node *pNode = pf.GetBestNode();
    if (pNode == nullptr) return false;
 
    /* Path was found, walk through the path back to the origin. */
    while (pNode->m_parent != nullptr) {
      pNode = pNode->m_parent;
    }
 
    Trackdir best_trackdir = pNode->GetTrackdir();
    if (trackdir != nullptr) {
      *trackdir = best_trackdir;
    } else {
      assert(best_trackdir == td1 || best_trackdir == td2);
    }
    return best_trackdir != td1;
  }
};
 
template <class Types>
class CYapfCostShipT
{
public:
  typedef typename Types::Tpf Tpf;              
  typedef typename Types::TrackFollower TrackFollower;
  typedef typename Types::NodeList::Titem 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 += CurveCost(n.m_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->m_tiles_skipped;
 
    /* Ocean/canal speed penalty. */
    const ShipVehicleInfo *svi = ShipVehInfo(Yapf().GetVehicle()->engine_type);
    byte 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->m_tiles_skipped) * speed_frac / (256 - speed_frac);
 
    /* Apply it. */
    n.m_cost = n.m_parent->m_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) { m_max_search_nodes = max_nodes; }
};
 
Track YapfShipChooseTrack(const Ship *v, TileIndex tile, DiagDirection enterdir, TrackBits tracks, bool &path_found, ShipPathCache &path_cache)
{
  Trackdir td_ret = CYapfShip::ChooseShipTrack(v, tile, enterdir, tracks, path_found, path_cache);
  return (td_ret != INVALID_TRACKDIR) ? TrackdirToTrack(td_ret) : INVALID_TRACK;
}
 
bool YapfShipCheckReverse(const Ship *v, Trackdir *trackdir)
{
  Trackdir td = v->GetVehicleTrackdir();
  Trackdir td_rev = ReverseTrackdir(td);
  TileIndex tile = v->tile;
  return CYapfShip::CheckShipReverse(v, tile, td, td_rev, trackdir);
}