1

/* $Id$ */

     2

     3

/** @file pathfind.cpp */

     4

     5

#include "stdafx.h"

     6

#include "openttd.h"

     7

#include "bridge_map.h"

     8

#include "station_map.h"

     9

#include "depot.h"

    10

#include "tile_cmd.h"

    11

#include "landscape.h"

    12

#include "pathfind.h"

    13

#include "rail_type.h"

    14

#include "debug.h"

    15

#include "tunnel_map.h"

    16

#include "settings_type.h"

    17

#include "depot.h"

    18

#include "tunnelbridge_map.h"

    19

#include "core/random_func.hpp"

    20

#include "tunnelbridge.h"

    21

    22

/* remember which tiles we have already visited so we don't visit them again. */

    23

static bool TPFSetTileBit(TrackPathFinder *tpf, TileIndex tile, int dir)

    24

{

    25

	uint hash, val, offs;

    26

	TrackPathFinderLink *link, *new_link;

    27

	uint bits = 1 << dir;

    28

    29

	if (tpf->disable_tile_hash)

    30

		return true;

    31

    32

	hash = PATHFIND_HASH_TILE(tile);

    33

    34

	val = tpf->hash_head[hash];

    35

    36

	if (val == 0) {

    37

		/* unused hash entry, set the appropriate bit in it and return true

    38

		 * to indicate that a bit was set. */

    39

		tpf->hash_head[hash] = bits;

    40

		tpf->hash_tile[hash] = tile;

    41

		return true;

    42

	} else if (!(val & 0x8000)) {

    43

		/* single tile */

    44

    45

		if (tile == tpf->hash_tile[hash]) {

    46

			/* found another bit for the same tile,

    47

			 * check if this bit is already set, if so, return false */

    48

			if (val & bits)

    49

				return false;

    50

    51

			/* otherwise set the bit and return true to indicate that the bit

    52

			 * was set */

    53

			tpf->hash_head[hash] = val | bits;

    54

			return true;

    55

		} else {

    56

			/* two tiles with the same hash, need to make a link */

    57

    58

			/* allocate a link. if out of links, handle this by returning

    59

			 * that a tile was already visisted. */

    60

			if (tpf->num_links_left == 0) {

    61

				return false;

    62

			}

    63

			tpf->num_links_left--;

    64

			link = tpf->new_link++;

    65

    66

			/* move the data that was previously in the hash_??? variables

    67

			 * to the link struct, and let the hash variables point to the link */

    68

			link->tile = tpf->hash_tile[hash];

    69

			tpf->hash_tile[hash] = PATHFIND_GET_LINK_OFFS(tpf, link);

    70

    71

			link->flags = tpf->hash_head[hash];

    72

			tpf->hash_head[hash] = 0xFFFF; // multi link

    73

    74

			link->next = 0xFFFF;

    75

		}

    76

	} else {

    77

		/* a linked list of many tiles,

    78

		 * find the one corresponding to the tile, if it exists.

    79

		 * otherwise make a new link */

    80

    81

		offs = tpf->hash_tile[hash];

    82

		do {

    83

			link = PATHFIND_GET_LINK_PTR(tpf, offs);

    84

			if (tile == link->tile) {

    85

				/* found the tile in the link list,

    86

				 * check if the bit was alrady set, if so return false to indicate that the

    87

				 * bit was already set */

    88

				if (link->flags & bits)

    89

					return false;

    90

				link->flags |= bits;

    91

				return true;

    92

			}

    93

		} while ((offs=link->next) != 0xFFFF);

    94

	}

    95

    96

	/* get here if we need to add a new link to link,

    97

	 * first, allocate a new link, in the same way as before */

    98

	if (tpf->num_links_left == 0) {

    99

			return false;

   100

	}

   101

	tpf->num_links_left--;

   102

	new_link = tpf->new_link++;

   103

   104

	/* then fill the link with the new info, and establish a ptr from the old

   105

	 * link to the new one */

   106

	new_link->tile = tile;

   107

	new_link->flags = bits;

   108

	new_link->next = 0xFFFF;

   109

   110

	link->next = PATHFIND_GET_LINK_OFFS(tpf, new_link);

   111

	return true;

   112

}

   113

   114

static const byte _bits_mask[4] = {

   115

	0x19,

   116

	0x16,

   117

	0x25,

   118

	0x2A,

   119

};

   120

   121

static const DiagDirection _tpf_new_direction[14] = {

   122

	DIAGDIR_NE, DIAGDIR_SE, DIAGDIR_NE, DIAGDIR_SE, DIAGDIR_SW, DIAGDIR_SE,

   123

	INVALID_DIAGDIR, INVALID_DIAGDIR,

   124

	DIAGDIR_SW, DIAGDIR_NW, DIAGDIR_NW, DIAGDIR_SW, DIAGDIR_NW, DIAGDIR_NE,

   125

};

   126

   127

static const DiagDirection _tpf_prev_direction[14] = {

   128

	DIAGDIR_NE, DIAGDIR_SE, DIAGDIR_SE, DIAGDIR_NE, DIAGDIR_SE, DIAGDIR_SW,

   129

	INVALID_DIAGDIR, INVALID_DIAGDIR,

   130

	DIAGDIR_SW, DIAGDIR_NW, DIAGDIR_SW, DIAGDIR_NW, DIAGDIR_NE, DIAGDIR_NW,

   131

};

   132

   133

   134

static const byte _otherdir_mask[4] = {

   135

	0x10,

   136

	0,

   137

	0x5,

   138

	0x2A,

   139

};

   140

   141

static void TPFMode2(TrackPathFinder* tpf, TileIndex tile, DiagDirection direction)

   142

{

   143

	uint bits;

   144

	RememberData rd;

   145

   146

	assert(tpf->tracktype == TRANSPORT_WATER);

   147

   148

	/* This addition will sometimes overflow by a single tile.

   149

	 * The use of TILE_MASK here makes sure that we still point at a valid

   150

	 * tile, and then this tile will be in the sentinel row/col, so GetTileTrackStatus will fail. */

   151

	tile = TILE_MASK(tile + TileOffsByDiagDir(direction));

   152

   153

	if (++tpf->rd.cur_length > 50)

   154

		return;

   155

   156

	bits = GetTileTrackStatus(tile, tpf->tracktype, tpf->sub_type);

   157

	bits = (byte)((bits | (bits >> 8)) & _bits_mask[direction]);

   158

	if (bits == 0)

   159

		return;

   160

   161

	assert(TileX(tile) != MapMaxX() && TileY(tile) != MapMaxY());

   162

   163

	uint i = 0;

   164

	/* only one direction */

   165

	if (KillFirstBit(bits) == 0) {

   166

		i = FindFirstBit(bits);

   167

		rd = tpf->rd;

   168

		goto continue_here;

   169

	}

   170

	/* several directions */

   171

	do {

   172

		i = FindFirstBit(bits);

   173

		rd = tpf->rd;

   174

   175

		/* Change direction 4 times only */

   176

		if ((byte)i != tpf->rd.pft_var6) {

   177

			if (++tpf->rd.depth > 4) {

   178

				tpf->rd = rd;

   179

				return;

   180

			}

   181

			tpf->rd.pft_var6 = (byte)i;

   182

		}

   183

   184

continue_here:

   185

		tpf->the_dir = (Trackdir)(i + (HasBit(_otherdir_mask[direction], i) ? 8 : 0));

   186

   187

		if (!tpf->enum_proc(tile, tpf->userdata, tpf->the_dir, tpf->rd.cur_length, NULL)) {

   188

			TPFMode2(tpf, tile, _tpf_new_direction[tpf->the_dir]);

   189

		}

   190

   191

		tpf->rd = rd;

   192

	} while (ClrBit(bits, i) != 0);

   193

   194

}

   195

   196

/**

   197

 * Checks if any vehicle can enter/leave tile in given diagdir

   198

 * Checks only for rail/road depots and road non-drivethrough stations

   199

 * @param tile tile to check

   200

 * @param side side of tile we are trying to leave/enter

   201

 * @param tracktype type of transport

   202

 * @pre tile has trackbit at that diagdir

   203

 * @return true iff vehicle can enter/leve the tile in given side

   204

 */

   205

static inline bool CanAccessTileInDir(TileIndex tile, DiagDirection side, TransportType tracktype)

   206

{

   207

	if (tracktype == TRANSPORT_RAIL) {

   208

		/* depot from wrong side */

   209

		if (IsTileDepotType(tile, TRANSPORT_RAIL) && GetRailDepotDirection(tile) != side) return false;

   210

	} else if (tracktype == TRANSPORT_ROAD) {

   211

		/* depot from wrong side */

   212

		if (IsTileDepotType(tile, TRANSPORT_ROAD) && GetRoadDepotDirection(tile) != side) return false;

   213

		/* non-driverthrough road station from wrong side */

   214

		if (IsStandardRoadStopTile(tile) && GetRoadStopDir(tile) != side) return false;

   215

	}

   216

   217

	return true;

   218

}

   219

   220

static const uint16 _tpfmode1_and[4] = { 0x1009, 0x16, 0x520, 0x2A00 };

   221

   222

static void TPFMode1(TrackPathFinder* tpf, TileIndex tile, DiagDirection direction)

   223

{

   224

	const TileIndex tile_org = tile;

   225

   226

	if (IsTileType(tile, MP_TUNNELBRIDGE)) {

   227

		/* wrong track type */

   228

		if (GetTunnelBridgeTransportType(tile) != tpf->tracktype) return;

   229

   230

		DiagDirection dir = GetTunnelBridgeDirection(tile);

   231

		/* entering tunnel / bridge? */

   232

		if (dir == direction) {

   233

			TileIndex endtile = GetOtherTunnelBridgeEnd(tile);

   234

   235

			tpf->rd.cur_length += GetTunnelBridgeLength(tile, endtile) + 1;

   236

   237

			TPFSetTileBit(tpf, tile, 14);

   238

			TPFSetTileBit(tpf, endtile, 14);

   239

   240

			tile = endtile;

   241

		} else {

   242

			/* leaving tunnel / bridge? */

   243

			if (ReverseDiagDir(dir) != direction) return;

   244

		}

   245

	} else {

   246

		/* can we leave tile in this dir? */

   247

		if (!CanAccessTileInDir(tile, direction, tpf->tracktype)) return;

   248

	}

   249

   250

	tile += TileOffsByDiagDir(direction);

   251

   252

	/* can we enter tile in this dir? */

   253

	if (!CanAccessTileInDir(tile, ReverseDiagDir(direction), tpf->tracktype)) return;

   254

   255

	/* Check if the new tile is a tunnel or bridge head and that the direction

   256

	 * and transport type match */

   257

	if (IsTileType(tile, MP_TUNNELBRIDGE)) {

   258

		if (GetTunnelBridgeDirection(tile) != direction ||

   259

				GetTunnelBridgeTransportType(tile) != tpf->tracktype) {

   260

			return;

   261

		}

   262

	}

   263

   264

	uint32 bits = GetTileTrackStatus(tile, tpf->tracktype, tpf->sub_type);

   265

   266

	/* Check in case of rail if the owner is the same */

   267

	if (tpf->tracktype == TRANSPORT_RAIL) {

   268

		if (bits != 0 && GetTileTrackStatus(tile_org, TRANSPORT_RAIL, 0) != 0) {

   269

			if (GetTileOwner(tile_org) != GetTileOwner(tile)) return;

   270

		}

   271

	}

   272

   273

	tpf->rd.cur_length++;

   274

   275

	if ((byte)bits != tpf->var2) {

   276

		bits &= _tpfmode1_and[direction];

   277

		bits |= bits >> 8;

   278

	}

   279

	bits &= 0xBF;

   280

   281

	if (bits != 0) {

   282

		if (!tpf->disable_tile_hash || (tpf->rd.cur_length <= 64 && (KillFirstBit(bits) == 0 || ++tpf->rd.depth <= 7))) {

   283

			do {

   284

				int i = FIND_FIRST_BIT(bits);

   285

				bits = KillFirstBit(bits);

   286

   287

				tpf->the_dir = (Trackdir)((_otherdir_mask[direction] & (byte)(1 << i)) ? (i + 8) : i);

   288

				RememberData rd = tpf->rd;

   289

   290

				if (TPFSetTileBit(tpf, tile, tpf->the_dir) &&

   291

						!tpf->enum_proc(tile, tpf->userdata, tpf->the_dir, tpf->rd.cur_length, &tpf->rd.pft_var6) ) {

   292

					TPFMode1(tpf, tile, _tpf_new_direction[tpf->the_dir]);

   293

				}

   294

				tpf->rd = rd;

   295

			} while (bits != 0);

   296

		}

   297

	}

   298

}

   299

   300

void FollowTrack(TileIndex tile, uint16 flags, uint sub_type, DiagDirection direction, TPFEnumProc *enum_proc, TPFAfterProc *after_proc, void *data)

   301

{

   302

	TrackPathFinder tpf;

   303

   304

	assert(direction < 4);

   305

   306

	/* initialize path finder variables */

   307

	tpf.userdata = data;

   308

	tpf.enum_proc = enum_proc;

   309

	tpf.new_link = tpf.links;

   310

	tpf.num_links_left = lengthof(tpf.links);

   311

   312

	tpf.rd.cur_length = 0;

   313

	tpf.rd.depth = 0;

   314

	tpf.rd.pft_var6 = 0;

   315

   316

	tpf.var2 = HasBit(flags, 15) ? 0x43 : 0xFF; // 0x8000

   317

   318

	tpf.disable_tile_hash = HasBit(flags, 12);  // 0x1000

   319

   320

   321

	tpf.tracktype = (TransportType)(flags & 0xFF);

   322

	tpf.sub_type = sub_type;

   323

   324

	if (HasBit(flags, 11)) {

   325

		tpf.rd.pft_var6 = 0xFF;

   326

		tpf.enum_proc(tile, data, INVALID_TRACKDIR, 0, 0);

   327

		TPFMode2(&tpf, tile, direction);

   328

	} else {

   329

		/* clear the hash_heads */

   330

		memset(tpf.hash_head, 0, sizeof(tpf.hash_head));

   331

		TPFMode1(&tpf, tile, direction);

   332

	}

   333

   334

	if (after_proc != NULL)

   335

		after_proc(&tpf);

   336

}

   337

   338

struct StackedItem {

   339

	TileIndex tile;

   340

	uint16 cur_length; ///< This is the current length to this tile.

   341

	uint16 priority;   ///< This is the current length + estimated length to the goal.

   342

	TrackdirByte track;

   343

	byte depth;

   344

	byte state;

   345

	byte first_track;

   346

};

   347

   348

static const Trackdir _new_trackdir[6][4] = {

   349

{TRACKDIR_X_NE,    INVALID_TRACKDIR, TRACKDIR_X_SW,    INVALID_TRACKDIR,},

   350

{INVALID_TRACKDIR, TRACKDIR_Y_SE,    INVALID_TRACKDIR, TRACKDIR_Y_NW,},

   351

{INVALID_TRACKDIR, TRACKDIR_UPPER_E, TRACKDIR_UPPER_W, INVALID_TRACKDIR,},

   352

{TRACKDIR_LOWER_E, INVALID_TRACKDIR, INVALID_TRACKDIR, TRACKDIR_LOWER_W,},

   353

{TRACKDIR_LEFT_N,  TRACKDIR_LEFT_S,  INVALID_TRACKDIR, INVALID_TRACKDIR,},

   354

{INVALID_TRACKDIR, INVALID_TRACKDIR, TRACKDIR_RIGHT_S, TRACKDIR_RIGHT_N,},

   355

};

   356

   357

struct HashLink {

   358

	TileIndex tile;

   359

	uint16 typelength;

   360

	uint16 next;

   361

};

   362

   363

struct NewTrackPathFinder {

   364

	NTPEnumProc *enum_proc;

   365

	void *userdata;

   366

	TileIndex dest;

   367

   368

	TransportType tracktype;

   369

	RailTypes railtypes;

   370

	uint maxlength;

   371

   372

	HashLink *new_link;

   373

	uint num_links_left;

   374

   375

	uint nstack;

   376

	StackedItem stack[256];     ///< priority queue of stacked items

   377

   378

	uint16 hash_head[0x400];    ///< hash heads. 0 means unused. 0xFFFC = length, 0x3 = dir

   379

	TileIndex hash_tile[0x400]; ///< tiles. or links.

   380

   381

	HashLink links[0x400];      ///< hash links

   382

   383

};

   384

#define NTP_GET_LINK_OFFS(tpf, link) ((byte*)(link) - (byte*)tpf->links)

   385

#define NTP_GET_LINK_PTR(tpf, link_offs) (HashLink*)((byte*)tpf->links + (link_offs))

   386

   387

#define ARR(i) tpf->stack[(i)-1]

   388

   389

/** called after a new element was added in the queue at the last index.

   390

 * move it down to the proper position */

   391

static inline void HeapifyUp(NewTrackPathFinder *tpf)

   392

{

   393

	StackedItem si;

   394

	int i = ++tpf->nstack;

   395

   396

	while (i != 1 && ARR(i).priority < ARR(i>>1).priority) {

   397

		/* the child element is larger than the parent item.

   398

		 * swap the child item and the parent item. */

   399

		si = ARR(i); ARR(i) = ARR(i >> 1); ARR(i >> 1) = si;

   400

		i >>= 1;

   401

	}

   402

}

   403

   404

/** called after the element 0 was eaten. fill it with a new element */

   405

static inline void HeapifyDown(NewTrackPathFinder *tpf)

   406

{

   407

	StackedItem si;

   408

	int i = 1, j;

   409

	int n;

   410

   411

	assert(tpf->nstack > 0);

   412

	n = --tpf->nstack;

   413

   414

	if (n == 0) return; // heap is empty so nothing to do?

   415

   416

	/* copy the last item to index 0. we use it as base for heapify. */

   417

	ARR(1) = ARR(n + 1);

   418

   419

	while ((j = i * 2) <= n) {

   420

		/* figure out which is smaller of the children. */

   421

		if (j != n && ARR(j).priority > ARR(j + 1).priority)

   422

			j++; // right item is smaller

   423

   424

		assert(i <= n && j <= n);

   425

		if (ARR(i).priority <= ARR(j).priority)

   426

			break; // base elem smaller than smallest, done!

   427

   428

		/* swap parent with the child */

   429

		si = ARR(i); ARR(i) = ARR(j); ARR(j) = si;

   430

		i = j;

   431

	}

   432

}

   433

   434

/** mark a tile as visited and store the length of the path.

   435

 * if we already had a better path to this tile, return false.

   436

 * otherwise return true. */

   437

static bool NtpVisit(NewTrackPathFinder* tpf, TileIndex tile, DiagDirection dir, uint length)

   438

{

   439

	uint hash,head;

   440

	HashLink *link, *new_link;

   441

   442

	assert(length < 16384-1);

   443

   444

	hash = PATHFIND_HASH_TILE(tile);

   445

   446

	/* never visited before? */

   447

	if ((head=tpf->hash_head[hash]) == 0) {

   448

		tpf->hash_tile[hash] = tile;

   449

		tpf->hash_head[hash] = dir | (length << 2);

   450

		return true;

   451

	}

   452

   453

	if (head != 0xffff) {

   454

		if (tile == tpf->hash_tile[hash] && (head & 0x3) == (uint)dir) {

   455

   456

			/* longer length */

   457

			if (length >= (head >> 2)) return false;

   458

   459

			tpf->hash_head[hash] = dir | (length << 2);

   460

			return true;

   461

		}

   462

		/* two tiles with the same hash, need to make a link

   463

		 * allocate a link. if out of links, handle this by returning

   464

		 * that a tile was already visisted. */

   465

		if (tpf->num_links_left == 0) {

   466

			DEBUG(ntp, 1, "No links left");

   467

			return false;

   468

		}

   469

   470

		tpf->num_links_left--;

   471

		link = tpf->new_link++;

   472

   473

		/* move the data that was previously in the hash_??? variables

   474

		 * to the link struct, and let the hash variables point to the link */

   475

		link->tile = tpf->hash_tile[hash];

   476

		tpf->hash_tile[hash] = NTP_GET_LINK_OFFS(tpf, link);

   477

   478

		link->typelength = tpf->hash_head[hash];

   479

		tpf->hash_head[hash] = 0xFFFF; // multi link

   480

		link->next = 0xFFFF;

   481

	} else {

   482

		/* a linked list of many tiles,

   483

		 * find the one corresponding to the tile, if it exists.

   484

		 * otherwise make a new link */

   485

   486

		uint offs = tpf->hash_tile[hash];

   487

		do {

   488

			link = NTP_GET_LINK_PTR(tpf, offs);

   489

			if (tile == link->tile && (link->typelength & 0x3U) == (uint)dir) {

   490

				if (length >= (uint)(link->typelength >> 2)) return false;

   491

				link->typelength = dir | (length << 2);

   492

				return true;

   493

			}

   494

		} while ((offs = link->next) != 0xFFFF);

   495

	}

   496

   497

	/* get here if we need to add a new link to link,

   498

	 * first, allocate a new link, in the same way as before */

   499

	if (tpf->num_links_left == 0) {