1

#include "stdafx.h"

     2

#include "ttd.h"

     3

#include "command.h"

     4

#include "ai.h"

     5

     6

#define TEST_STATION_NO_DIR 0xFF

     7

     8

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

     9

// TODO: make it train compatible

    10

bool TestCanBuildStationHere(uint tile, byte dir) {

    11

    Player *p = DEREF_PLAYER(_current_player);

    12

    if (dir == TEST_STATION_NO_DIR) {

    13

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

    14

        //  should be fixed!!!

    15

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

    16

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

    17

            if (res != CMD_ERROR)

    18

            	return true;

    19

        }

    20

        return false;

    21

    } else {

    22

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

    23

        if (res == CMD_ERROR)

    24

        	return false;

    25

    }

    26

    return true;

    27

}

    28

    29

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

    30

#define TILES_BETWEEN(a,b,c) (GET_TILE_X(a) >= GET_TILE_X(b) && GET_TILE_X(a) <= GET_TILE_X(c) && GET_TILE_Y(a) >= GET_TILE_Y(b) && GET_TILE_Y(a) <= GET_TILE_Y(c))

    31

    32

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

    33

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

    34

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

    35

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

    36

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

    37

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

    38

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

    39

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

    40

    			return AYSTAR_FOUND_END_NODE;

    41

    42

	return AYSTAR_DONE;

    43

}

    44

    45

// Calculates the hash

    46

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

    47

uint AiPathFinder_Hash(uint key1, uint key2) {

    48

	return (GET_TILE_X(key1) & 0x1F) + ((GET_TILE_Y(key1) & 0x1F) << 5);

    49

}

    50

    51

// Clear the memory of all the things

    52

void AyStar_AiPathFinder_Free(AyStar *aystar) {

    53

	AyStarMain_Free(aystar);

    54

	free(aystar);

    55

}

    56

    57

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

    58

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

    59

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

    60

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

    61

    62

// This creates the AiPathFinder

    63

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

    64

	PathNode start_node;

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	uint x,y;

    66

	// Create AyStar

    67

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

    68

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

    69

	// Set the function pointers

    70

	result->CalculateG = AyStar_AiPathFinder_CalculateG;

    71

	result->CalculateH = AyStar_AiPathFinder_CalculateH;

    72

	result->EndNodeCheck = AyStar_AiPathFinder_EndNodeCheck;

    73

	result->FoundEndNode = AyStar_AiPathFinder_FoundEndNode;

    74

	result->GetNeighbours = AyStar_AiPathFinder_GetNeighbours;

    75

    76

	result->free = AyStar_AiPathFinder_Free;

    77

    78

	// Set some information

    79

	result->loops_per_tick = AI_PATHFINDER_LOOPS_PER_TICK;

    80

	result->max_path_cost = 0;

    81

	result->max_search_nodes = AI_PATHFINDER_MAX_SEARCH_NODES;

    82

    83

	// Set the user_data to the PathFinderInfo

    84

	result->user_target = PathFinderInfo;

    85

    86

	// Set the start node

    87

	start_node.parent = NULL;

    88

	start_node.node.direction = 0;

    89

	start_node.node.user_data[0] = 0;

    90

    91

	// Now we add all the starting tiles

    92

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

    93

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

    94

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

    95

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

    96

		}

    97

	}

    98

    99

	return result;

   100

}

   101

   102

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

   103

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

   104

	PathNode start_node;

   105

	uint x,y;

   106

   107

	aystar->clear(aystar);

   108

   109

	// Set the user_data to the PathFinderInfo

   110

	aystar->user_target = PathFinderInfo;

   111

   112

	// Set the start node

   113

	start_node.parent = NULL;

   114

	start_node.node.direction = 0;

   115

	start_node.node.user_data[0] = 0;

   116

	start_node.node.tile = PathFinderInfo->start_tile_tl;

   117

   118

	// Now we add all the starting tiles

   119

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

   120

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

   121

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

   122

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

   123

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

   124

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

   125

		}

   126

	}

   127

}

   128

   129

// The h-value, simple calculation

   130

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

   131

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

   132

	int r, r2;

   133

	if (PathFinderInfo->end_direction != AI_PATHFINDER_NO_DIRECTION) {

   134

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

   135

		r = GetTileDist(current->tile, PathFinderInfo->end_tile_tl + _tiles_around[PathFinderInfo->end_direction]);

   136

		r2 = GetTileDist(current->tile, PathFinderInfo->end_tile_br + _tiles_around[PathFinderInfo->end_direction]);

   137

	} else {

   138

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

   139

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

   140

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

   141

	}

   142

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

   143

	if (r2 < r) r = r2;

   144

	return r * AI_PATHFINDER_H_MULTIPLER;

   145

}

   146

   147

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

   148

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

   149

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

   150

	int i = 0;

   151

	PathNode *parent = &current->path;

   152

   153

	do {

   154

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

   155

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

   156

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

   157

			// We ran out of space for the PathFinder

   158

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

   159

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

   160

			return;

   161

		}

   162

		parent = parent->parent;

   163

	} while (parent != NULL);

   164

	PathFinderInfo->route_length = i;

   165

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

   166

}

   167

   168

// What tiles are around us.

   169

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

   170

    int i, r, dir;

   171

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

   172

   173

    aystar->num_neighbours = 0;

   174

   175

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

   176

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

   177

   		if (GET_TILE_X(_tiles_around[i] + current->path.node.tile) > 1 && GET_TILE_X(_tiles_around[i] + current->path.node.tile) < TILE_X_MAX - 1 &&

   178

       		GET_TILE_Y(_tiles_around[i] + current->path.node.tile) > 1 && GET_TILE_Y(_tiles_around[i] + current->path.node.tile) < TILE_Y_MAX - 1) {

   179

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

   180

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

   181

   182

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

   183

       		if (!PathFinderInfo->rail_or_road && AI_PATHFINDER_IS_ROAD(current->path.node.tile + _tiles_around[i])) {

   184

       			if (IS_TILETYPE(current->path.node.tile + _tiles_around[i], MP_TUNNELBRIDGE)) {

   185

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

   186

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

   187

   					// This problem only is valid for tunnels:

   188

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

   189

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

   190

       					if ((i^2) != (_map5[current->path.node.tile + _tiles_around[i]] & 3)) continue;

   191

       				}

   192

       			}

   193

       		}

   194

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

   195

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

   196

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

   197

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

   198

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

   199

       			}

   200

       		}

   201

   202

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

   203

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

   204

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

   205

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

   206

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

   207

       		}

   208

       		dir = 0;

   209

   210

       		// First, check if we have a parent

   211

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

   212

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

   213

       			if (PathFinderInfo->start_direction != AI_PATHFINDER_NO_DIRECTION) {

   214

		       		// We do need a direction?

   215

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

   216

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

   217

		       			continue;

   218

		       	}

   219

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

   220

       			if (PathFinderInfo->rail_or_road) {

   221

       				// Rail check

   222

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

   223

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

   224

       				if (r == CMD_ERROR) continue;

   225

#ifdef AI_PATHFINDER_NO_90DEGREES_TURN

   226

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

   227

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

   228

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

   229

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

   230

       						continue;

   231

       					}

   232

       				}

   233

#endif

   234

       			} else {

   235

       				// Road check

   236

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

   237

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

   238

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

   239

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

   240

       						dir = 0;

   241

       					} else {

   242

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

   243

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

   244

	       						// We do miss some pieces :(

   245

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

   246

	       					} else {

   247

	       						dir = 0;

   248

    	   					}

   249

    	   				}

   250

       				}

   251

       				// Only destruct things if it is MP_CLEAR of MP_TREES

   252

       				if (dir != 0) {

   253

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

   254

       					if (r == CMD_ERROR) continue;

   255

       				}

   256

       			}

   257

   258

       		}

   259

   260

			// The tile can be connected

   261

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

   262

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

   263

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

   264

       	}

   265

    }

   266

   267

    // Next step, check for bridges and tunnels

   268

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

   269

   270

        TileInfo ti;

   271

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

   272

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

   273

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

   274

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

   275

    	TileIndex new_tile = tile;

   276

   277

    	FindLandscapeHeightByTile(&ti, tile);

   278

   279

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

   280

   		//  And if there is a road or rail blocking

   281

   		if (ti.tileh != 0 ||

   282

     		(PathFinderInfo->rail_or_road && IS_TILETYPE(tile + _tiles_around[dir], MP_STREET)) ||

   283

       		(!PathFinderInfo->rail_or_road && IS_TILETYPE(tile + _tiles_around[dir], MP_RAILWAY))) {

   284

   285

    		for (;;) {

   286

    			new_tile += _tiles_around[dir];

   287

   288

    	    	// Precheck, is the length allowed?

   289

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

   290

   291

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

   292

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

   293

   294

    	    	// Try building the bridge..

   295

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

   296

	    	   	if (r == CMD_ERROR) continue;

   297

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

   298

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

   299

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

   300

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

   301

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

   302

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

   303

			}

   304

    	}

   305

   306

    	// Next, check for tunnels!

   307

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

   308

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

   309

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

   310

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

   311

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

   312

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

   313

    		// Now simply check if a tunnel can be build

   314

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

   315

    		FindLandscapeHeightByTile(&ti, _build_tunnel_endtile);

   316

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

   317

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

   318

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

   319

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

   320

    		}

   321

    	}

   322

  	}

   323

}

   324

   325

extern uint GetRailFoundation(uint tileh, uint bits);

   326

extern uint GetRoadFoundation(uint tileh, uint bits);

   327

extern uint GetBridgeFoundation(uint tileh, byte direction);

   328

enum {

   329

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

   330

};

   331

   332

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

   333

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

   334

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

   335

	int r, res = 0;

   336

	TileInfo ti, parent_ti;

   337

   338

	// Gather some information about the tile..

   339

	FindLandscapeHeightByTile(&ti, current->tile);

   340

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

   341

   342

	// Check if we hit the end-tile

   343

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

   344

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

   345

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

   346

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

   347

			return AYSTAR_INVALID_NODE;

   348

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

   349

		return 0;

   350

	}

   351

   352

	// Give everything a small penalty

   353

	res += AI_PATHFINDER_PENALTY;

   354

   355

	if (!PathFinderInfo->rail_or_road) {

   356

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

   357

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

   358

		if (AI_PATHFINDER_IS_ROAD(current->tile)) {

   359

			res -= AI_PATHFINDER_ROAD_ALREADY_EXISTS_BONUS;

   360

		}

   361

	}

   362

   363

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

   364

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

   365

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

   366

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

   367

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

   368

			if (PathFinderInfo->rail_or_road) {

   369

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

   370

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

   371

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

   372

					res += AI_PATHFINDER_TILE_GOES_UP_PENALTY;

   373

				}

   374

			} else {

   375

				if (!(AI_PATHFINDER_IS_ROAD(parent->path.node.tile) && IS_TILETYPE(parent->path.node.tile, MP_TUNNELBRIDGE))) {

   376

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

   377

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

   378

						res += AI_PATHFINDER_TILE_GOES_UP_PENALTY;

   379

				}

   380

			}

   381

		}

   382

	}

   383

   384

	// Are we part of a tunnel?

   385

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

   386

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

   387

		// Ironicly, we are using BridgeCode here ;)

   388

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

   389

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

   390

	}

   391

   392

	// Are we part of a bridge?

   393

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

   394

		// That means for every length a penalty

   395

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

   396

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

   397

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

   398

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

   399

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

   400

				res += AI_PATHFINDER_BRIDGE_GOES_UP_PENALTY;

   401

		}

   402

		// Second for the end point

   403

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

   404

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

   405

				res += AI_PATHFINDER_BRIDGE_GOES_UP_PENALTY;

   406

		}

   407

		if (parent_ti.tileh == 0)

   408

			res += AI_PATHFINDER_BRIDGE_GOES_UP_PENALTY;

   409

		if (ti.tileh == 0)

   410

			res += AI_PATHFINDER_BRIDGE_GOES_UP_PENALTY;

   411

	}

   412

   413

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

   414

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

   415

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

   416

	if (!PathFinderInfo->rail_or_road) {

   417

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

   418

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

   419

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

   420

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

   421

				res += AI_PATHFINDER_DIRECTION_CHANGE_ON_EXISTING_ROAD_PENALTY;

   422

			else

   423

				res += AI_PATHFINDER_DIRECTION_CHANGE_PENALTY;

   424

		}

   425

	} else {

   426

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

   427

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

   428

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

   429

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

   430

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

   431

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

   432

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

   433

   434

			// First see if they are different

   435

			if (dir1 != dir2) {

   436

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

   437

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

   438

					// It is not, so we changed of direction

   439

					res += AI_PATHFINDER_DIRECTION_CHANGE_PENALTY;

   440

				}

   441

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

   442

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

   443

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

   444

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

   445

						res += AI_PATHFINDER_CURVE_PENALTY;

   446

					}

   447

				}

   448

			}

   449

		}

   450

	}

   451

   452

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

   453

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

   454

   455

	// Return our value

   456

	return res;

   457

}