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#include "stdafx.h"

     2

#include "ttd.h"

     3

#include "map.h"

     4

#include "command.h"

     5

#include "ai.h"

     6

     7

#define TEST_STATION_NO_DIR 0xFF

     8

     9

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

    10

// TODO: make it train compatible

    13

    Player *p = DEREF_PLAYER(_current_player);

    14

    if (dir == TEST_STATION_NO_DIR) {

    15

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

    16

        //  should be fixed!!!

    17

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

    18

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

    19

            if (res != CMD_ERROR)

    20

            	return true;

    21

        }

    22

        return false;

    23

    } else {

    24

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

    25

        if (res == CMD_ERROR)

    26

        	return false;

    27

    }

    28

    return true;

    29

}

    30

    31

    32

static bool IsRoad(TileIndex tile)

    33

{

    34

	return

    35

		// MP_STREET, but not a road depot?

    36

		(IsTileType(tile, MP_STREET) && !(_map5[tile] & 0x20)) ||

    37

		(IsTileType(tile, MP_TUNNELBRIDGE) && (

    38

			// road tunnel?

    39

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

    40

			// road bridge?

    41

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

    42

		));

    43

}

    44

    45

    46

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

    47

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

    48

    49

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

    52

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

    53

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

    54

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

    55

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

    56

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

    57

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

    58

    			return AYSTAR_FOUND_END_NODE;

    59

    60

	return AYSTAR_DONE;

    61

}

    62

    63

// Calculates the hash

    64

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

    67

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

    68

}

    69

    70

// Clear the memory of all the things

    73

	AyStarMain_Free(aystar);

    74

	free(aystar);

    75

}

    76

    77

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

    78

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

    79

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

    80

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

    81

    82

// This creates the AiPathFinder

    83

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

    84

	PathNode start_node;

    85

	uint x,y;

    86

	// Create AyStar

    87

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

    88

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

    89

	// Set the function pointers

    90

	result->CalculateG = AyStar_AiPathFinder_CalculateG;

    91

	result->CalculateH = AyStar_AiPathFinder_CalculateH;

    92

	result->EndNodeCheck = AyStar_AiPathFinder_EndNodeCheck;

    93

	result->FoundEndNode = AyStar_AiPathFinder_FoundEndNode;

    94

	result->GetNeighbours = AyStar_AiPathFinder_GetNeighbours;

    95

    96

	result->free = AyStar_AiPathFinder_Free;

    97

    98

	// Set some information

    99

	result->loops_per_tick = AI_PATHFINDER_LOOPS_PER_TICK;

   100

	result->max_path_cost = 0;

   101

	result->max_search_nodes = AI_PATHFINDER_MAX_SEARCH_NODES;

   102

   103

	// Set the user_data to the PathFinderInfo

   104

	result->user_target = PathFinderInfo;

   105

   106

	// Set the start node

   107

	start_node.parent = NULL;

   108

	start_node.node.direction = 0;

   109

	start_node.node.user_data[0] = 0;

   110

   111

	// Now we add all the starting tiles

   112

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

   113

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

   114

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

   115

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

   116

		}

   117

	}

   118

   119

	return result;

   120

}

   121

   122

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

   123

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

   124

	PathNode start_node;

   125

	uint x,y;

   126

   127

	aystar->clear(aystar);

   128

   129

	// Set the user_data to the PathFinderInfo

   130

	aystar->user_target = PathFinderInfo;

   131

   132

	// Set the start node

   133

	start_node.parent = NULL;

   134

	start_node.node.direction = 0;

   135

	start_node.node.user_data[0] = 0;

   136

	start_node.node.tile = PathFinderInfo->start_tile_tl;

   137

   138

	// Now we add all the starting tiles

   139

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

   140

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

   141

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

   142

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

   143

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

   144

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

   145

		}

   146

	}

   147

}

   148

   149

// The h-value, simple calculation

   150

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

   151

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

   152

	int r, r2;

   153

	if (PathFinderInfo->end_direction != AI_PATHFINDER_NO_DIRECTION) {

   154

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

   155

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

   156

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

   157

	} else {

   158

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

   159

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

   160

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

   161

	}

   162

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

   163

	if (r2 < r) r = r2;

   164

	return r * AI_PATHFINDER_H_MULTIPLER;

   165

}

   166

   167

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

   168

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

   169

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

   170

	uint i = 0;

   171

	PathNode *parent = &current->path;

   172

   173

	do {

   174

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

   175

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

   176

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

   177

			// We ran out of space for the PathFinder

   178

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

   179

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

   180

			return;

   181

		}

   182

		parent = parent->parent;

   183

	} while (parent != NULL);

   184

	PathFinderInfo->route_length = i;

   185

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

   186

}

   187

   188

// What tiles are around us.

   189

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

   190

		uint i;

   191

		int r;

   192

		int dir;

   193

   194

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

   195

   196

    aystar->num_neighbours = 0;

   197

   198

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

   199

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

   200

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

   201

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

   202

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

   203

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

   204

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

   205

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

   206

   207

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

   208

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

   209

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

   210

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

   211

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

   212

   					// This problem only is valid for tunnels:

   213

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

   214

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

   215

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

   216

       				}

   217

       			}

   218

       		}

   219

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

   220

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

   221

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

   222

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

   223

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

   224

       			}

   225

       		}

   226

   227

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

   228

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

   229

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

   230

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

   231

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

   232

       		}

   233

       		dir = 0;

   234

   235

       		// First, check if we have a parent

   236

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

   237

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

   238

       			if (PathFinderInfo->start_direction != AI_PATHFINDER_NO_DIRECTION) {

   239

		       		// We do need a direction?

   240

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

   241

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

   242

		       			continue;

   243

		       	}

   244

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

   245

       			if (PathFinderInfo->rail_or_road) {

   246

       				// Rail check

   247

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

   248

       				r = DoCommandByTile(current->path.node.tile, 0, dir, DC_AUTO | DC_NO_WATER, CMD_BUILD_SINGLE_RAIL);

   249

       				if (r == CMD_ERROR) continue;

   250

#ifdef AI_PATHFINDER_NO_90DEGREES_TURN

   251

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

   252

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

   253

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

   254

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

   255

       						continue;

   256

       					}

   257

       				}

   258

#endif

   259

       			} else {

   260

       				// Road check

   261

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

   262

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

   263

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

   264

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

   265

       						dir = 0;

   266

       					} else {

   267

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

   268

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

   269

	       						// We do miss some pieces :(

   270

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

   271

	       					} else {

   272

	       						dir = 0;

   273

    	   					}

   274

    	   				}

   275

       				}

   276

       				// Only destruct things if it is MP_CLEAR of MP_TREES

   277

       				if (dir != 0) {

   278

       					r = DoCommandByTile(current->path.node.tile, dir, 0, DC_AUTO | DC_NO_WATER, CMD_BUILD_ROAD);

   279

       					if (r == CMD_ERROR) continue;

   280

       				}

   281

       			}

   282

   283

       		}

   284

   285

			// The tile can be connected

   286

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

   287

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

   288

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

   289

       	}

   290

    }

   291

   292

    // Next step, check for bridges and tunnels

   293

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

   294

   295

        TileInfo ti;

   296

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

   297

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

   298

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

   299

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

   300

    	TileIndex new_tile = tile;

   301

   302

    	FindLandscapeHeightByTile(&ti, tile);

   303

   304

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

   305

   		//  And if there is a road or rail blocking

   306

   		if (ti.tileh != 0 ||

   307

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

   308

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

   309

   310

    		for (;;) {

   311

    			new_tile += TileOffsByDir(dir);

   312

   313

    	    	// Precheck, is the length allowed?

   314

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

   315

   316

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

   317

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

   318

   319

    	    	// Try building the bridge..

   320

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

   321

	    	   	if (r == CMD_ERROR) continue;

   322

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

   323

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

   324

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

   325

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

   326

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

   327

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

   328

			}

   329

    	}

   330

   331

    	// Next, check for tunnels!

   332

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

   333

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

   334

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

   335

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

   336

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

   337

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

   338

    		// Now simply check if a tunnel can be build

   339

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

   340

    		FindLandscapeHeightByTile(&ti, _build_tunnel_endtile);

   341

    		if (r != CMD_ERROR && (ti.tileh == 3 || ti.tileh == 6 || ti.tileh == 9 || ti.tileh == 12)) {

   342

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

   343

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

   344

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

   345

    		}

   346

    	}

   347

  	}

   348

}

   349

   350

extern uint GetRailFoundation(uint tileh, uint bits);

   351

extern uint GetRoadFoundation(uint tileh, uint bits);

   352

extern uint GetBridgeFoundation(uint tileh, byte direction);

   353

enum {

   354

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

   355

};

   356

   357

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

   358

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

   359

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

   360

	int r, res = 0;

   361

	TileInfo ti, parent_ti;

   362

   363

	// Gather some information about the tile..

   364

	FindLandscapeHeightByTile(&ti, current->tile);

   365

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

   366

   367

	// Check if we hit the end-tile

   368

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

   369

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

   370

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

   371

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

   372

			return AYSTAR_INVALID_NODE;

   373

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

   374

		return 0;

   375

	}

   376

   377

	// Give everything a small penalty

   378

	res += AI_PATHFINDER_PENALTY;

   379

   380

	if (!PathFinderInfo->rail_or_road) {

   381

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

   382

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

   383

		if (IsRoad(current->tile)) {

   384

			res -= AI_PATHFINDER_ROAD_ALREADY_EXISTS_BONUS;

   385

		}

   386

	}

   387

   388

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

   389

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

   390

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

   391

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

   392

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

   393

			if (PathFinderInfo->rail_or_road) {

   394

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

   395

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

   396

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

   397

					res += AI_PATHFINDER_TILE_GOES_UP_PENALTY;

   398

				}

   399

			} else {

   400

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

   401

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

   402

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

   403

						res += AI_PATHFINDER_TILE_GOES_UP_PENALTY;

   404

				}

   405

			}

   406

		}

   407

	}

   408

   409

	// Are we part of a tunnel?

   410

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

   411

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

   412

		// Ironicly, we are using BridgeCode here ;)

   413

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

   414

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

   415

	}

   416

   417

	// Are we part of a bridge?

   418

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

   419

		// That means for every length a penalty

   420

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

   421

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

   422

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

   423

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

   424

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

   425

				res += AI_PATHFINDER_BRIDGE_GOES_UP_PENALTY;

   426

		}

   427

		// Second for the end point

   428

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

   429

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

   430

				res += AI_PATHFINDER_BRIDGE_GOES_UP_PENALTY;

   431

		}

   432

		if (parent_ti.tileh == 0)

   433

			res += AI_PATHFINDER_BRIDGE_GOES_UP_PENALTY;

   434

		if (ti.tileh == 0)

   435

			res += AI_PATHFINDER_BRIDGE_GOES_UP_PENALTY;

   436

	}

   437

   438

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

   439

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

   440

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

   441

	if (!PathFinderInfo->rail_or_road) {

   442

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

   443

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

   444

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

   445

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

   446

				res += AI_PATHFINDER_DIRECTION_CHANGE_ON_EXISTING_ROAD_PENALTY;

   447

			else

   448

				res += AI_PATHFINDER_DIRECTION_CHANGE_PENALTY;

   449

		}

   450

	} else {

   451

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

   452

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

   453

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

   454

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

   455

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

   456

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

   457

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

   458

   459

			// First see if they are different

   460

			if (dir1 != dir2) {

   461

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

   462

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

   463

					// It is not, so we changed of direction

   464

					res += AI_PATHFINDER_DIRECTION_CHANGE_PENALTY;

   465

				}

   466

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

   467

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

   468

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

   469

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

   470

						res += AI_PATHFINDER_CURVE_PENALTY;

   471

					}

   472

				}

   473

			}

   474

		}

   475

	}

   476

   477

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

   478

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

   479

   480

	// Return our value

   481

	return res;

   482

}