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/* $Id$ */

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#include "../../stdafx.h"

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#include "../../openttd.h"

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#include "../../bridge_map.h"

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#include "../../debug.h"

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#include "../../functions.h"

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#include "../../map.h"

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#include "../../tile.h"

    10

#include "../../command.h"

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#include "trolly.h"

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#include "../../depot.h"

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#include "../../tunnel_map.h"

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#include "../../bridge.h"

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#include "../ai.h"

    16

    17

#define TEST_STATION_NO_DIR 0xFF

    18

    19

// Tests if a station can be build on the given spot

    20

// TODO: make it train compatible

    21

static bool TestCanBuildStationHere(TileIndex tile, byte dir)

    22

{

    23

	Player *p = GetPlayer(_current_player);

    24

    25

	if (dir == TEST_STATION_NO_DIR) {

    27

		// TODO: currently we only allow spots that can be access from al 4 directions...

    28

		//  should be fixed!!!

    29

		for (dir = 0; dir < 4; dir++) {

    30

			ret = AiNew_Build_Station(p, p->ainew.tbt, tile, 1, 1, dir, DC_QUERY_COST);

    32

		}

    33

		return false;

    34

	}

    35

    36

	// return true if command succeeded, so the inverse of CmdFailed()

    38

}

    39

    40

    41

static bool IsRoad(TileIndex tile)

    42

{

    43

	return

    44

		// MP_STREET, but not a road depot?

    45

		(IsTileType(tile, MP_STREET) && !IsTileDepotType(tile, TRANSPORT_ROAD)) ||

    46

		(IsTileType(tile, MP_TUNNELBRIDGE) && (

    47

			(IsTunnel(tile) && GetTunnelTransportType(tile) == TRANSPORT_ROAD) ||

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			(IsBridge(tile) && GetBridgeTransportType(tile) == TRANSPORT_ROAD)

    49

		));

    50

}

    51

    52

    53

// Checks if a tile 'a' is between the tiles 'b' and 'c'

    54

#define TILES_BETWEEN(a, b, c) (TileX(a) >= TileX(b) && TileX(a) <= TileX(c) && TileY(a) >= TileY(b) && TileY(a) <= TileY(c))

    55

    56

    57

// Check if the current tile is in our end-area

    58

static int32 AyStar_AiPathFinder_EndNodeCheck(AyStar *aystar, OpenListNode *current)

    59

{

    60

	const Ai_PathFinderInfo* PathFinderInfo = (Ai_PathFinderInfo*)aystar->user_target;

    61

    62

	// It is not allowed to have a station on the end of a bridge or tunnel ;)

    63

	if (current->path.node.user_data[0] != 0) return AYSTAR_DONE;

    64

	if (TILES_BETWEEN(current->path.node.tile, PathFinderInfo->end_tile_tl, PathFinderInfo->end_tile_br))

    65

		if (IsTileType(current->path.node.tile, MP_CLEAR) || IsTileType(current->path.node.tile, MP_TREES))

    66

			if (current->path.parent == NULL || TestCanBuildStationHere(current->path.node.tile, AiNew_GetDirection(current->path.parent->node.tile, current->path.node.tile)))

    67

				return AYSTAR_FOUND_END_NODE;

    68

    69

	return AYSTAR_DONE;

    70

}

    71

    72

    73

// Calculates the hash

    74

//   Currently it is a 10 bit hash, so the hash array has a max depth of 6 bits (so 64)

    75

static uint AiPathFinder_Hash(uint key1, uint key2)

    76

{

    77

	return (TileX(key1) & 0x1F) + ((TileY(key1) & 0x1F) << 5);

    78

}

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    80

    81

// Clear the memory of all the things

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static void AyStar_AiPathFinder_Free(AyStar *aystar)

    83

{

    84

	AyStarMain_Free(aystar);

    85

	delete aystar;

    86

}

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    88

    89

static int32 AyStar_AiPathFinder_CalculateG(AyStar *aystar, AyStarNode *current, OpenListNode *parent);

    90

static int32 AyStar_AiPathFinder_CalculateH(AyStar *aystar, AyStarNode *current, OpenListNode *parent);

    91

static void AyStar_AiPathFinder_FoundEndNode(AyStar *aystar, OpenListNode *current);

    92

static void AyStar_AiPathFinder_GetNeighbours(AyStar *aystar, OpenListNode *current);

    93

    94

    95

// This creates the AiPathFinder

    96

AyStar *new_AyStar_AiPathFinder(int max_tiles_around, Ai_PathFinderInfo *PathFinderInfo)

    97

{

    98

	PathNode start_node;

    99

	uint x;

   100

	uint y;

   101

	// Create AyStar

   102

	AyStar *result = new AyStar();

   103

	init_AyStar(result, AiPathFinder_Hash, 1 << 10);

   104

	// Set the function pointers

   105

	result->CalculateG = AyStar_AiPathFinder_CalculateG;

   106

	result->CalculateH = AyStar_AiPathFinder_CalculateH;

   107

	result->EndNodeCheck = AyStar_AiPathFinder_EndNodeCheck;

   108

	result->FoundEndNode = AyStar_AiPathFinder_FoundEndNode;

   109

	result->GetNeighbours = AyStar_AiPathFinder_GetNeighbours;

   110

   111

	result->free = AyStar_AiPathFinder_Free;

   112

   113

	// Set some information

   114

	result->loops_per_tick = AI_PATHFINDER_LOOPS_PER_TICK;

   115

	result->max_path_cost = 0;

   116

	result->max_search_nodes = AI_PATHFINDER_MAX_SEARCH_NODES;

   117

   118

	// Set the user_data to the PathFinderInfo

   119

	result->user_target = PathFinderInfo;

   120

   121

	// Set the start node

   122

	start_node.parent = NULL;

   123

	start_node.node.direction = 0;

   124

	start_node.node.user_data[0] = 0;

   125

   126

	// Now we add all the starting tiles

   127

	for (x = TileX(PathFinderInfo->start_tile_tl); x <= TileX(PathFinderInfo->start_tile_br); x++) {

   128

		for (y = TileY(PathFinderInfo->start_tile_tl); y <= TileY(PathFinderInfo->start_tile_br); y++) {

   129

			start_node.node.tile = TileXY(x, y);

   130

			result->addstart(result, &start_node.node, 0);

   131

		}

   132

	}

   133

   134

	return result;

   135

}

   136

   137

   138

// To reuse AyStar we sometimes have to clean all the memory

   139

void clean_AyStar_AiPathFinder(AyStar *aystar, Ai_PathFinderInfo *PathFinderInfo)

   140

{

   141

	PathNode start_node;

   142

	uint x;

   143

	uint y;

   144

   145

	aystar->clear(aystar);

   146

   147

	// Set the user_data to the PathFinderInfo

   148

	aystar->user_target = PathFinderInfo;

   149

   150

	// Set the start node

   151

	start_node.parent = NULL;

   152

	start_node.node.direction = 0;

   153

	start_node.node.user_data[0] = 0;

   154

	start_node.node.tile = PathFinderInfo->start_tile_tl;

   155

   156

	// Now we add all the starting tiles

   157

	for (x = TileX(PathFinderInfo->start_tile_tl); x <= TileX(PathFinderInfo->start_tile_br); x++) {

   158

		for (y = TileY(PathFinderInfo->start_tile_tl); y <= TileY(PathFinderInfo->start_tile_br); y++) {

   159

			TileIndex tile = TileXY(x, y);

   160

   161

			if (!IsTileType(tile, MP_CLEAR) && !IsTileType(tile, MP_TREES)) continue;

   162

			if (!TestCanBuildStationHere(tile, TEST_STATION_NO_DIR)) continue;

   163

			start_node.node.tile = tile;

   164

			aystar->addstart(aystar, &start_node.node, 0);

   165

		}

   166

	}

   167

}

   168

   169

   170

// The h-value, simple calculation

   171

static int32 AyStar_AiPathFinder_CalculateH(AyStar *aystar, AyStarNode *current, OpenListNode *parent)

   172

{

   173

	const Ai_PathFinderInfo* PathFinderInfo = (Ai_PathFinderInfo*)aystar->user_target;

   174

	int r, r2;

   175

   176

	if (PathFinderInfo->end_direction != AI_PATHFINDER_NO_DIRECTION) {

   177

		// The station is pointing to a direction, add a tile towards that direction, so the H-value is more accurate

   178

		r = DistanceManhattan(current->tile, PathFinderInfo->end_tile_tl + TileOffsByDiagDir(PathFinderInfo->end_direction));

   179

		r2 = DistanceManhattan(current->tile, PathFinderInfo->end_tile_br + TileOffsByDiagDir(PathFinderInfo->end_direction));

   180

	} else {

   181

		// No direction, so just get the fastest route to the station

   182

		r = DistanceManhattan(current->tile, PathFinderInfo->end_tile_tl);

   183

		r2 = DistanceManhattan(current->tile, PathFinderInfo->end_tile_br);

   184

	}

   185

	// See if the bottomright is faster than the topleft..

   186

	if (r2 < r) r = r2;

   187

	return r * AI_PATHFINDER_H_MULTIPLER;

   188

}

   189

   190

   191

// We found the end.. let's get the route back and put it in an array

   192

static void AyStar_AiPathFinder_FoundEndNode(AyStar *aystar, OpenListNode *current)

   193

{

   194

	Ai_PathFinderInfo *PathFinderInfo = (Ai_PathFinderInfo*)aystar->user_target;

   195

	uint i = 0;

   196

	PathNode *parent = &current->path;

   197

   198

	do {

   199

		PathFinderInfo->route_extra[i] = parent->node.user_data[0];

   200

		PathFinderInfo->route[i++] = parent->node.tile;

   201

		if (i > lengthof(PathFinderInfo->route)) {

   202

			// We ran out of space for the PathFinder

   203

			DEBUG(ai, 0, "No more space in pathfinder route[] array");

   204

			PathFinderInfo->route_length = -1; // -1 indicates out of space

   205

			return;

   206

		}

   207

		parent = parent->parent;

   208

	} while (parent != NULL);

   209

	PathFinderInfo->route_length = i;

   210

	DEBUG(ai, 1, "Found route of %d nodes long in %d nodes of searching", i, Hash_Size(&aystar->ClosedListHash));

   211

}

   212

   213

   214

// What tiles are around us.

   215

static void AyStar_AiPathFinder_GetNeighbours(AyStar *aystar, OpenListNode *current)

   216

{

   218

	int dir;

   219

   220

	Ai_PathFinderInfo *PathFinderInfo = (Ai_PathFinderInfo*)aystar->user_target;

   221

   222

	aystar->num_neighbours = 0;

   223

   224

	// Go through all surrounding tiles and check if they are within the limits

   225

	for (DiagDirection i = DIAGDIR_BEGIN; i < DIAGDIR_END; i++) {

   226

		TileIndex ctile = current->path.node.tile; // Current tile

   227

		TileIndex atile = ctile + TileOffsByDiagDir(i); // Adjacent tile

   228

   229

		if (TileX(atile) > 1 && TileX(atile) < MapMaxX() - 1 &&

   230

				TileY(atile) > 1 && TileY(atile) < MapMaxY() - 1) {

   231

			// We also directly test if the current tile can connect to this tile..

   232

			//  We do this simply by just building the tile!

   233

   234

			// If the next step is a bridge, we have to enter it the right way

   235

			if (!PathFinderInfo->rail_or_road && IsRoad(atile)) {

   236

				if (IsTileType(atile, MP_TUNNELBRIDGE)) {

   237

					if (IsTunnel(atile)) {

   238

						if (GetTunnelDirection(atile) != i) continue;

   239

					} else {

   240

						if (GetBridgeRampDirection(atile) != i) continue;

   241

					}

   242

				}

   243

			}

   244

   245

			if ((AI_PATHFINDER_FLAG_BRIDGE & current->path.node.user_data[0]) != 0 ||

   246

					(AI_PATHFINDER_FLAG_TUNNEL & current->path.node.user_data[0]) != 0) {

   247

				// We are a bridge/tunnel, how cool!!

   248

				//  This means we can only point forward.. get the direction from the user_data

   249

				if ((uint)i != (current->path.node.user_data[0] >> 8)) continue;

   250

			}

   251

			dir = 0;

   252

   253

			// First, check if we have a parent

   254

			if (current->path.parent == NULL && current->path.node.user_data[0] == 0) {

   255

				// If not, this means we are at the starting station

   256

				if (PathFinderInfo->start_direction != AI_PATHFINDER_NO_DIRECTION) {

   257

					// We do need a direction?

   258

					if (AiNew_GetDirection(ctile, atile) != PathFinderInfo->start_direction) {

   259

						// We are not pointing the right way, invalid tile

   260

						continue;

   261

					}

   262

				}

   263

			} else if (current->path.node.user_data[0] == 0) {

   264

				if (PathFinderInfo->rail_or_road) {

   265

					// Rail check

   266

					dir = AiNew_GetRailDirection(current->path.parent->node.tile, ctile, atile);

   267

					ret = AI_DoCommand(ctile, 0, dir, DC_AUTO | DC_NO_WATER, CMD_BUILD_SINGLE_RAIL);

   268

					if (CmdFailed(ret)) continue;

   269

#ifdef AI_PATHFINDER_NO_90DEGREES_TURN

   270

					if (current->path.parent->parent != NULL) {

   271

						// Check if we don't make a 90degree curve

   272

						int dir1 = AiNew_GetRailDirection(current->path.parent->parent->node.tile, current->path.parent->node.tile, ctile);

   273

						if (_illegal_curves[dir1] == dir || _illegal_curves[dir] == dir1) {

   274

							continue;

   275

						}

   276

					}

   277

#endif

   278

				} else {

   279

					// Road check

   280

					dir = AiNew_GetRoadDirection(current->path.parent->node.tile, ctile, atile);

   281

					if (IsRoad(ctile)) {

   282

						if (IsTileType(ctile, MP_TUNNELBRIDGE)) {

   283

							// We have a bridge, how nicely! We should mark it...

   284

							dir = 0;

   285

						} else {

   286

							// It already has road.. check if we miss any bits!

   287

							if ((GetAnyRoadBits(ctile, ROADTYPE_ROAD) & dir) != dir) {

   288

								// We do miss some pieces :(

   289

								dir &= ~GetAnyRoadBits(ctile, ROADTYPE_ROAD);

   290

							} else {

   291

								dir = 0;

   292

							}

   293

						}

   294

					}

   295

					// Only destruct things if it is MP_CLEAR of MP_TREES

   296

					if (dir != 0) {

   297

						ret = AI_DoCommand(ctile, dir, 0, DC_AUTO | DC_NO_WATER, CMD_BUILD_ROAD);

   298

						if (CmdFailed(ret)) continue;

   299

					}

   300

				}

   301

			}

   302

   303

			// The tile can be connected

   304

			aystar->neighbours[aystar->num_neighbours].tile = atile;

   305

			aystar->neighbours[aystar->num_neighbours].user_data[0] = 0;

   306

			aystar->neighbours[aystar->num_neighbours++].direction = 0;

   307

		}

   308

	}

   309

   310

	// Next step, check for bridges and tunnels

   311

	if (current->path.parent != NULL && current->path.node.user_data[0] == 0) {

   312

		// First we get the dir from this tile and his parent

   313

		DiagDirection dir = AiNew_GetDirection(current->path.parent->node.tile, current->path.node.tile);

   314

		// It means we can only walk with the track, so the bridge has to be in the same direction

   315

		TileIndex tile = current->path.node.tile;

   316

		TileIndex new_tile = tile;

   317

		Slope tileh = GetTileSlope(tile, NULL);

   318

   319

		// Bridges can only be build on land that is not flat

   320

		//  And if there is a road or rail blocking

   321

		if (tileh != SLOPE_FLAT ||

   322

				(PathFinderInfo->rail_or_road && IsTileType(tile + TileOffsByDiagDir(dir), MP_STREET)) ||

   323

				(!PathFinderInfo->rail_or_road && IsTileType(tile + TileOffsByDiagDir(dir), MP_RAILWAY))) {

   324

			for (;;) {

   325

				new_tile += TileOffsByDiagDir(dir);

   326

   327

				// Precheck, is the length allowed?

   328

				if (!CheckBridge_Stuff(0, GetBridgeLength(tile, new_tile))) break;

   329

   330

				// Check if we hit the station-tile.. we don't like that!

   331

				if (TILES_BETWEEN(new_tile, PathFinderInfo->end_tile_tl, PathFinderInfo->end_tile_br)) break;

   332

   333

				// Try building the bridge..

   334

				ret = AI_DoCommand(tile, new_tile, (0 << 8) + (MAX_BRIDGES / 2), DC_AUTO, CMD_BUILD_BRIDGE);

   335

				if (CmdFailed(ret)) continue;

   336

				// We can build a bridge here.. add him to the neighbours

   337

				aystar->neighbours[aystar->num_neighbours].tile = new_tile;

   338

				aystar->neighbours[aystar->num_neighbours].user_data[0] = AI_PATHFINDER_FLAG_BRIDGE + (dir << 8);

   339

				aystar->neighbours[aystar->num_neighbours++].direction = 0;

   340

				// We can only have 12 neighbours, and we need 1 left for tunnels

   341

				if (aystar->num_neighbours == 11) break;

   342

			}

   343

		}

   344

   345

		// Next, check for tunnels!

   346

		// Tunnels can only be built on slopes corresponding to the direction

   347

		//  For now, we check both sides for this tile.. terraforming gives fuzzy result

   348

		if ((dir == DIAGDIR_NE && tileh == SLOPE_NE) ||

   349

				(dir == DIAGDIR_SE && tileh == SLOPE_SE) ||

   350

				(dir == DIAGDIR_SW && tileh == SLOPE_SW) ||

   351

				(dir == DIAGDIR_NW && tileh == SLOPE_NW)) {

   352

			// Now simply check if a tunnel can be build

   353

			ret = AI_DoCommand(tile, (PathFinderInfo->rail_or_road?0:0x200), 0, DC_AUTO, CMD_BUILD_TUNNEL);

   354

			tileh = GetTileSlope(_build_tunnel_endtile, NULL);

   356

				aystar->neighbours[aystar->num_neighbours].tile = _build_tunnel_endtile;

   357

				aystar->neighbours[aystar->num_neighbours].user_data[0] = AI_PATHFINDER_FLAG_TUNNEL + (dir << 8);

   358

				aystar->neighbours[aystar->num_neighbours++].direction = 0;

   359

			}

   360

		}

   361

	}

   362

}

   363

   364

   365

extern uint GetRailFoundation(Slope tileh, TrackBits bits); // XXX function declaration in .c

   366

extern uint GetRoadFoundation(Slope tileh, RoadBits bits); // XXX function declaration in .c

   367

extern uint GetBridgeFoundation(Slope tileh, Axis); // XXX function declaration in .c

   368

enum BridgeFoundation {

   369

	BRIDGE_NO_FOUNDATION = 1 << 0 | 1 << 3 | 1 << 6 | 1 << 9 | 1 << 12,

   370

};

   371

   372

// The most important function: it calculates the g-value

   373

static int32 AyStar_AiPathFinder_CalculateG(AyStar *aystar, AyStarNode *current, OpenListNode *parent)

   374

{

   375

	Ai_PathFinderInfo *PathFinderInfo = (Ai_PathFinderInfo*)aystar->user_target;

   376

	int r, res = 0;

   377

	Slope tileh = GetTileSlope(current->tile, NULL);

   378

	Slope parent_tileh = GetTileSlope(parent->path.node.tile, NULL);

   379

   380

	// Check if we hit the end-tile

   381

	if (TILES_BETWEEN(current->tile, PathFinderInfo->end_tile_tl, PathFinderInfo->end_tile_br)) {

   382

		// We are at the end-tile, check if we had a direction or something...

   383

		if (PathFinderInfo->end_direction != AI_PATHFINDER_NO_DIRECTION && AiNew_GetDirection(current->tile, parent->path.node.tile) != PathFinderInfo->end_direction) {

   384

			// We are not pointing the right way, invalid tile

   385

			return AYSTAR_INVALID_NODE;

   386

		}

   387

		// If it was valid, drop out.. we don't build on the endtile

   388

		return 0;

   389

	}

   390

   391

	// Give everything a small penalty

   392

	res += AI_PATHFINDER_PENALTY;

   393

   394

	if (!PathFinderInfo->rail_or_road) {

   395

		// Road has the lovely advantage it can use other road... check if

   396

		//  the current tile is road, and if so, give a good bonus

   397

		if (IsRoad(current->tile)) {

   398

			res -= AI_PATHFINDER_ROAD_ALREADY_EXISTS_BONUS;

   399

		}

   400

	}

   401

   402

	// We should give a penalty when the tile is going up or down.. this is one way to do so!

   403

	//  Too bad we have to count it from the parent.. but that is not so bad.

   404

	// We also dislike long routes on slopes, since they do not look too realistic

   405

	//  when there is a flat land all around, they are more expensive to build, and

   406

	//  especially they essentially block the ability to connect or cross the road

   407

	//  from one side.

   408

	if (parent_tileh != SLOPE_FLAT && parent->path.parent != NULL) {

   409

		// Skip if the tile was from a bridge or tunnel

   410

		if (parent->path.node.user_data[0] == 0 && current->user_data[0] == 0) {

   411

			if (PathFinderInfo->rail_or_road) {

   412

				r = GetRailFoundation(parent_tileh, (TrackBits)(1 << AiNew_GetRailDirection(parent->path.parent->node.tile, parent->path.node.tile, current->tile)));

   413

				// Maybe is BRIDGE_NO_FOUNDATION a bit strange here, but it contains just the right information..

   414

				if (r >= 15 || (r == 0 && HASBIT(BRIDGE_NO_FOUNDATION, tileh))) {

   415

					res += AI_PATHFINDER_TILE_GOES_UP_PENALTY;

   416

				} else {

   417

					res += AI_PATHFINDER_FOUNDATION_PENALTY;

   418

				}

   419

			} else {

   420

				if (!IsRoad(parent->path.node.tile) || !IsTileType(parent->path.node.tile, MP_TUNNELBRIDGE)) {

   421

					r = GetRoadFoundation(parent_tileh, (RoadBits)AiNew_GetRoadDirection(parent->path.parent->node.tile, parent->path.node.tile, current->tile));

   422

					if (r >= 15 || r == 0) {

   423

						res += AI_PATHFINDER_TILE_GOES_UP_PENALTY;

   424

					} else {

   425

						res += AI_PATHFINDER_FOUNDATION_PENALTY;

   426

					}

   427

				}

   428

			}

   429

		}

   430

	}

   431

   432

	// Are we part of a tunnel?

   433

	if ((AI_PATHFINDER_FLAG_TUNNEL & current->user_data[0]) != 0) {

   434

		// Tunnels are very expensive when build on long routes..

   435

		// Ironicly, we are using BridgeCode here ;)

   436

		r = AI_PATHFINDER_TUNNEL_PENALTY * GetBridgeLength(current->tile, parent->path.node.tile);

   437

		res += r + (r >> 8);

   438

	}

   439

   440

	// Are we part of a bridge?

   441

	if ((AI_PATHFINDER_FLAG_BRIDGE & current->user_data[0]) != 0) {

   442

		// That means for every length a penalty

   443

		res += AI_PATHFINDER_BRIDGE_PENALTY * GetBridgeLength(current->tile, parent->path.node.tile);

   444

		// Check if we are going up or down, first for the starting point

   445

		// In user_data[0] is at the 8th bit the direction

   446

		if (!HASBIT(BRIDGE_NO_FOUNDATION, parent_tileh)) {

   447

			if (GetBridgeFoundation(parent_tileh, (Axis)((current->user_data[0] >> 8) & 1)) < 15) {

   448

				res += AI_PATHFINDER_BRIDGE_GOES_UP_PENALTY;

   449

			}

   450

		}

   451

		// Second for the end point

   452

		if (!HASBIT(BRIDGE_NO_FOUNDATION, tileh)) {

   453

			if (GetBridgeFoundation(tileh, (Axis)((current->user_data[0] >> 8) & 1)) < 15) {

   454

				res += AI_PATHFINDER_BRIDGE_GOES_UP_PENALTY;

   455

			}

   456

		}

   457

		if (parent_tileh == SLOPE_FLAT) res += AI_PATHFINDER_BRIDGE_GOES_UP_PENALTY;

   458

		if (tileh == SLOPE_FLAT) res += AI_PATHFINDER_BRIDGE_GOES_UP_PENALTY;

   459

	}

   460

   461

	//  To prevent the AI from taking the fastest way in tiles, but not the fastest way

   462

	//    in speed, we have to give a good penalty to direction changing

   463

	//  This way, we get almost the fastest way in tiles, and a very good speed on the track

   464

	if (!PathFinderInfo->rail_or_road) {

   465

		if (parent->path.parent != NULL &&

   466

				AiNew_GetDirection(current->tile, parent->path.node.tile) != AiNew_GetDirection(parent->path.node.tile, parent->path.parent->node.tile)) {

   467

			// When road exists, we don't like turning, but its free, so don't be to piggy about it

   468

			if (IsRoad(parent->path.node.tile)) {

   469

				res += AI_PATHFINDER_DIRECTION_CHANGE_ON_EXISTING_ROAD_PENALTY;

   470

			} else {

   471

				res += AI_PATHFINDER_DIRECTION_CHANGE_PENALTY;

   472

			}

   473

		}

   474

	} else {

   475

		// For rail we have 1 exeption: diagonal rail..

   476

		// So we fetch 2 raildirection. That of the current one, and of the one before that

   477

		if (parent->path.parent != NULL && parent->path.parent->parent != NULL) {

   478

			int dir1 = AiNew_GetRailDirection(parent->path.parent->node.tile, parent->path.node.tile, current->tile);

   479

			int dir2 = AiNew_GetRailDirection(parent->path.parent->parent->node.tile, parent->path.parent->node.tile, parent->path.node.tile);

   480

			// First, see if we are on diagonal path, that is better than straight path

   481

			if (dir1 > 1) res -= AI_PATHFINDER_DIAGONAL_BONUS;