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#include "stdafx.h"

     2

#include "ttd.h"

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#include "debug.h"

     4

#include "map.h"

     5

#include "tile.h"

     6

#include "command.h"

     7

#include "ai.h"

     8

#include "depot.h"

     9

    10

#define TEST_STATION_NO_DIR 0xFF

    11

    12

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

    13

// TODO: make it train compatible

    14

static bool TestCanBuildStationHere(uint tile, byte dir)

    15

{

    31

}

    32

    33

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static bool IsRoad(TileIndex tile)

    35

{

    36

	return

    37

		// MP_STREET, but not a road depot?

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

    39

		(IsTileType(tile, MP_TUNNELBRIDGE) && (

    40

			// road tunnel?

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			((_map5[tile] & 0x80) == 0 && (_map5[tile] & 0x4) == 0x4) ||

    42

			// road bridge?

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			((_map5[tile] & 0x80) != 0 && (_map5[tile] & 0x2) == 0x2)

    44

		));

    45

}

    46

    47

    48

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

    49

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

    50

    51

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

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

    53

{

    54

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

    55

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

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

    57

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

    58

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

    59

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

    60

    			return AYSTAR_FOUND_END_NODE;

    61

    62

	return AYSTAR_DONE;

    63

}

    64

    65

// Calculates the hash

    66

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

    67

static uint AiPathFinder_Hash(uint key1, uint key2)

    68

{

    69

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

    70

}

    71

    72

// Clear the memory of all the things

    73

static void AyStar_AiPathFinder_Free(AyStar *aystar)

    74

{

    75

	AyStarMain_Free(aystar);

    76

	free(aystar);

    77

}

    78

    79

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

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

    81

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

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

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// This creates the AiPathFinder

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AyStar *new_AyStar_AiPathFinder(int max_tiles_around, Ai_PathFinderInfo *PathFinderInfo) {

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	PathNode start_node;

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	uint x,y;

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	// Create AyStar

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	AyStar *result = malloc(sizeof(AyStar));

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

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	// Set the function pointers

    92

	result->CalculateG = AyStar_AiPathFinder_CalculateG;

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	result->CalculateH = AyStar_AiPathFinder_CalculateH;

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	result->EndNodeCheck = AyStar_AiPathFinder_EndNodeCheck;

    95

	result->FoundEndNode = AyStar_AiPathFinder_FoundEndNode;

    96

	result->GetNeighbours = AyStar_AiPathFinder_GetNeighbours;

    97

    98

	result->free = AyStar_AiPathFinder_Free;

    99

   100

	// Set some information

   101

	result->loops_per_tick = AI_PATHFINDER_LOOPS_PER_TICK;

   102

	result->max_path_cost = 0;

   103

	result->max_search_nodes = AI_PATHFINDER_MAX_SEARCH_NODES;

   104

   105

	// Set the user_data to the PathFinderInfo

   106

	result->user_target = PathFinderInfo;

   107

   108

	// Set the start node

   109

	start_node.parent = NULL;

   110

	start_node.node.direction = 0;

   111

	start_node.node.user_data[0] = 0;

   112

   113

	// Now we add all the starting tiles

   114

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

   115

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

   116

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

   117

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

   118

		}

   119

	}

   120

   121

	return result;

   122

}

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   124

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

   125

void clean_AyStar_AiPathFinder(AyStar *aystar, Ai_PathFinderInfo *PathFinderInfo) {

   126

	PathNode start_node;

   127

	uint x,y;

   128

   129

	aystar->clear(aystar);

   130

   131

	// Set the user_data to the PathFinderInfo

   132

	aystar->user_target = PathFinderInfo;

   133

   134

	// Set the start node

   135

	start_node.parent = NULL;

   136

	start_node.node.direction = 0;

   137

	start_node.node.user_data[0] = 0;

   138

	start_node.node.tile = PathFinderInfo->start_tile_tl;

   139

   140

	// Now we add all the starting tiles

   141

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

   142

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

   143

			if (!(IsTileType(TILE_XY(x,y), MP_CLEAR) || IsTileType(TILE_XY(x,y), MP_TREES))) continue;

   144

			if (!TestCanBuildStationHere(TILE_XY(x,y),TEST_STATION_NO_DIR)) continue;

   145

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

   146

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

   147

		}

   148

	}

   149

}

   150

   151

// The h-value, simple calculation

   152

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

   153

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

   154

	int r, r2;

   155

	if (PathFinderInfo->end_direction != AI_PATHFINDER_NO_DIRECTION) {

   156

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

   157

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

   158

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

   159

	} else {

   160

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

   161

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

   162

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

   163

	}

   164

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

   165

	if (r2 < r) r = r2;

   166

	return r * AI_PATHFINDER_H_MULTIPLER;

   167

}

   168

   169

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

   170

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

   171

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

   172

	uint i = 0;

   173

	PathNode *parent = &current->path;

   174

   175

	do {

   176

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

   177

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

   178

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

   179

			// We ran out of space for the PathFinder

   180

			DEBUG(ai,0)("[AiPathFinder] Ran out of spacein the route[] array!!!");

   181

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

   182

			return;

   183

		}

   184

		parent = parent->parent;

   185

	} while (parent != NULL);

   186

	PathFinderInfo->route_length = i;

   187

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

   188

}

   189

   190

// What tiles are around us.

   191

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

   192

		uint i;

   194

		int dir;

   195

   196

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

   197

   198

    aystar->num_neighbours = 0;

   199

   200

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

   201

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

   202

   		if (TileX(TileOffsByDir(i) + current->path.node.tile) > 1 &&

   203

					TileX(TileOffsByDir(i) + current->path.node.tile) < MapMaxX() - 1 &&

   204

       		TileY(TileOffsByDir(i) + current->path.node.tile) > 1 &&

   205

					TileY(TileOffsByDir(i) + current->path.node.tile) < MapMaxY() - 1) {

   206

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

   207

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

   208

   209

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

   210

       		if (!PathFinderInfo->rail_or_road && IsRoad(current->path.node.tile + TileOffsByDir(i))) {

   211

       			if (IsTileType(current->path.node.tile + TileOffsByDir(i), MP_TUNNELBRIDGE)) {

   212

       				// An existing bridge... let's test the direction ;)

   213

       				if ((_map5[current->path.node.tile + TileOffsByDir(i)] & 1U) != (i & 1)) continue;

   214

   					// This problem only is valid for tunnels:

   215

       				// When the last tile was not yet a tunnel, check if we enter from the right side..

   216

       				if ((_map5[current->path.node.tile + TileOffsByDir(i)] & 0x80) == 0) {

   217

       					if (i != (_map5[current->path.node.tile + TileOffsByDir(i)] & 3U)) continue;

   218

       				}

   219

       			}

   220

       		}

   221

       		// But also if we are on a bridge, we can only move a certain direction

   222

       		if (!PathFinderInfo->rail_or_road && IsRoad(current->path.node.tile)) {

   223

       			if (IsTileType(current->path.node.tile, MP_TUNNELBRIDGE)) {

   224

       				// An existing bridge/tunnel... let's test the direction ;)

   225

       				if ((_map5[current->path.node.tile] & 1U) != (i & 1)) continue;

   226

       			}

   227

       		}

   228

   229

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

   230

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

   231

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

   232

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

   233

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

   234

       		}

   235

       		dir = 0;

   236

   237

       		// First, check if we have a parent

   238

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

   239

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

   240

       			if (PathFinderInfo->start_direction != AI_PATHFINDER_NO_DIRECTION) {

   241

		       		// We do need a direction?

   242

		       		if (AiNew_GetDirection(current->path.node.tile, current->path.node.tile + TileOffsByDir(i)) != PathFinderInfo->start_direction)

   243

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

   244

		       			continue;

   245

		       	}

   246

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

   247

       			if (PathFinderInfo->rail_or_road) {

   248

       				// Rail check

   249

       				dir = AiNew_GetRailDirection(current->path.parent->node.tile, current->path.node.tile, current->path.node.tile + TileOffsByDir(i));

   252

#ifdef AI_PATHFINDER_NO_90DEGREES_TURN

   253

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

   254

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

   255

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

   256

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

   257

       						continue;

   258

       					}

   259

       				}

   260

#endif

   261

       			} else {

   262

       				// Road check

   263

       				dir = AiNew_GetRoadDirection(current->path.parent->node.tile, current->path.node.tile, current->path.node.tile + TileOffsByDir(i));

   264

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

   265

       					if (IsTileType(current->path.node.tile, MP_TUNNELBRIDGE)) {

   266

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

   267

       						dir = 0;

   268

       					} else {

   269

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

   270

	       					if ((_map5[current->path.node.tile] & dir) != dir) {

   271

	       						// We do miss some pieces :(

   272

	       						dir &= ~_map5[current->path.node.tile];

   273

	       					} else {

   274

	       						dir = 0;

   275

    	   					}

   276

    	   				}

   277

       				}

   278

       				// Only destruct things if it is MP_CLEAR of MP_TREES

   279

       				if (dir != 0) {

   282

       				}

   283

       			}

   284

   285

       		}

   286

   287

			// The tile can be connected

   288

   			aystar->neighbours[aystar->num_neighbours].tile = TileOffsByDir(i) + current->path.node.tile;

   289

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

   290

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

   291

       	}

   292

    }

   293

   294

    // Next step, check for bridges and tunnels

   295

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

   296

   297

        TileInfo ti;

   298

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

   299

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

   300

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

   301

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

   302

    	TileIndex new_tile = tile;

   303

   304

    	FindLandscapeHeightByTile(&ti, tile);

   305

   306

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

   307

   		//  And if there is a road or rail blocking

   308

   		if (ti.tileh != 0 ||

   309

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

   310

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

   311

   312

    		for (;;) {

   313

    			new_tile += TileOffsByDir(dir);

   314

   315

    	    	// Precheck, is the length allowed?

   316

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

   317

   318

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

   319

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

   320

   321

    	    	// Try building the bridge..

   324

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

   325

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

   326

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

   327

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

   328

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

   329

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

   330

			}

   331

    	}

   332

   333

    	// Next, check for tunnels!

   334

    	// Tunnels can only be build with tileh of 3, 6, 9 or 12, depending on the direction

   335

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

   336

    	if ((dir == 0 && ti.tileh == 12) ||

   337

    		(dir == 1 && ti.tileh == 6) ||

   338

    		(dir == 2 && ti.tileh == 3) ||

   339

    		(dir == 3 && ti.tileh == 9)) {

   340

    		// Now simply check if a tunnel can be build

   342

    		FindLandscapeHeightByTile(&ti, _build_tunnel_endtile);

   344

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

   345

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

   346

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

   347

    		}

   348

    	}

   349

  	}

   350

}

   351

   352

extern uint GetRailFoundation(uint tileh, uint bits);

   353

extern uint GetRoadFoundation(uint tileh, uint bits);

   354

extern uint GetBridgeFoundation(uint tileh, byte direction);

   355

enum {

   356

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

   357

};

   358

   359

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

   360

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

   361

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

   362

	int r, res = 0;

   363

	TileInfo ti, parent_ti;

   364

   365

	// Gather some information about the tile..

   366

	FindLandscapeHeightByTile(&ti, current->tile);

   367

	FindLandscapeHeightByTile(&parent_ti, parent->path.node.tile);

   368

   369

	// Check if we hit the end-tile

   370

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

   371

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

   372

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

   373

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

   374

			return AYSTAR_INVALID_NODE;

   375

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

   376

		return 0;

   377

	}

   378

   379

	// Give everything a small penalty

   380

	res += AI_PATHFINDER_PENALTY;

   381

   382

	if (!PathFinderInfo->rail_or_road) {

   383

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

   384

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

   385

		if (IsRoad(current->tile)) {

   386

			res -= AI_PATHFINDER_ROAD_ALREADY_EXISTS_BONUS;

   387

		}

   388

	}

   389

   390

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

   391

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

   392

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

   393

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

   394

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

   395

	//  from one side.

   396

	if (parent_ti.tileh != 0 && parent->path.parent != NULL) {

   397

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

   398

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

   399

			if (PathFinderInfo->rail_or_road) {

   400

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

   401

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

   402

				if (r >= 15 || (r == 0 && (BRIDGE_NO_FOUNDATION & (1 << ti.tileh)))) {

   403

					res += AI_PATHFINDER_TILE_GOES_UP_PENALTY;

   404

				} else {

   405

					res += AI_PATHFINDER_FOUNDATION_PENALTY;

   406

				}

   407

			} else {

   408

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

   409

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

   410

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

   411

						res += AI_PATHFINDER_TILE_GOES_UP_PENALTY;

   412

					else

   413

						res += AI_PATHFINDER_FOUNDATION_PENALTY;

   414

				}

   415

			}

   416

		}

   417

	}

   418

   419

	// Are we part of a tunnel?

   420

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

   421

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

   422

		// Ironicly, we are using BridgeCode here ;)

   423

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

   424

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

   425

	}

   426

   427

	// Are we part of a bridge?

   428

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

   429

		// That means for every length a penalty

   430

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

   431

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

   432

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

   433

		if (!(BRIDGE_NO_FOUNDATION & (1 << parent_ti.tileh))) {

   434

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

   435

				res += AI_PATHFINDER_BRIDGE_GOES_UP_PENALTY;

   436

		}

   437

		// Second for the end point

   438

		if (!(BRIDGE_NO_FOUNDATION & (1 << ti.tileh))) {

   439

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

   440

				res += AI_PATHFINDER_BRIDGE_GOES_UP_PENALTY;

   441

		}

   442

		if (parent_ti.tileh == 0)

   443

			res += AI_PATHFINDER_BRIDGE_GOES_UP_PENALTY;

   444

		if (ti.tileh == 0)

   445

			res += AI_PATHFINDER_BRIDGE_GOES_UP_PENALTY;

   446

	}

   447

   448

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

   449

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

   450

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

   451

	if (!PathFinderInfo->rail_or_road) {

   452

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

   453

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

   454

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

   455

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

   456

				res += AI_PATHFINDER_DIRECTION_CHANGE_ON_EXISTING_ROAD_PENALTY;

   457

			else

   458

				res += AI_PATHFINDER_DIRECTION_CHANGE_PENALTY;

   459

		}

   460

	} else {

   461

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

   462

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

   463

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

   464

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

   465

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

   466

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

   467

			if (dir1 > 1) { res -= AI_PATHFINDER_DIAGONAL_BONUS; }

   468

   469

			// First see if they are different

   470

			if (dir1 != dir2) {

   471

				// dir 2 and 3 are 1 diagonal track, and 4 and 5.

   472

				if (!(((dir1 == 2 || dir1 == 3) && (dir2 == 2 || dir2 == 3)) || ((dir1 == 4 || dir1 == 5) && (dir2 == 4 || dir2 == 5)))) {

   473

					// It is not, so we changed of direction

   474

					res += AI_PATHFINDER_DIRECTION_CHANGE_PENALTY;

   475

				}

   476

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

   477

					int dir3 = AiNew_GetRailDirection(parent->path.parent->parent->parent->node.tile, parent->path.parent->parent->node.tile, parent->path.parent->node.tile);

   478

					// Check if we changed 3 tiles of direction in 3 tiles.. bad!!!

   479

					if ((dir1 == 0 || dir1 == 1) && dir2 > 1 && (dir3 == 0 || dir3 == 1)) {

   480

						res += AI_PATHFINDER_CURVE_PENALTY;

   481

					}

   482

				}

   483

			}

   484

		}

   485

	}

   486

   487

	// Res should never be below zero.. if so, make it zero!

   488

	if (res < 0) { res = 0; }