(svn r85) -Add: initial commit of new AI (enable in Patch menu)

-Add: generalised A* Algorithm
-Add: generalised queues (Fifo, Stack, InsSort, BinaryHeap)

1 files changed, 457 insertions, 0 deletions

diff --git a/ai_pathfinder.c b/ai_pathfinder.c
new file mode 100644
index 000000000..148ce1116
--- /dev/null
+++ b/ai_pathfinder.c
@@ -0,0 +1,457 @@
+#include "stdafx.h"

+#include "ttd.h"

+#include "command.h"

+#include "ai.h"

+

+#define TEST_STATION_NO_DIR 0xFF

+

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

+// TODO: make it train compatible

+bool TestCanBuildStationHere(uint tile, byte dir) {

+    Player *p = DEREF_PLAYER(_current_player);

+    if (dir == TEST_STATION_NO_DIR) {

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

+        //  should be fixed!!!

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

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

+            if (res != CMD_ERROR)

+            	return true;

+        }

+        return false;

+    } else {

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

+        if (res == CMD_ERROR)

+        	return false;

+    }

+    return true;

+}

+

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

+#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))

+

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

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

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

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

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

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

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

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

+    			return AYSTAR_FOUND_END_NODE;

+		

+	return AYSTAR_DONE;

+}

+

+// Calculates the hash

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

+uint AiPathFinder_Hash(uint key1, uint key2) {

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

+}

+

+// Clear the memory of all the things

+void AyStar_AiPathFinder_Free(AyStar *aystar) {

+	AyStarMain_Free(aystar);

+	free(aystar);

+}

+

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

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

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

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

+

+// This creates the AiPathFinder

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

+	PathNode start_node;

+	uint x,y;

+	// Create AyStar

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

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

+	// Set the function pointers

+	result->CalculateG = AyStar_AiPathFinder_CalculateG;

+	result->CalculateH = AyStar_AiPathFinder_CalculateH;

+	result->EndNodeCheck = AyStar_AiPathFinder_EndNodeCheck;

+	result->FoundEndNode = AyStar_AiPathFinder_FoundEndNode;

+	result->GetNeighbours = AyStar_AiPathFinder_GetNeighbours;

+

+	result->free = AyStar_AiPathFinder_Free;

+

+	// Set some information

+	result->loops_per_tick = AI_PATHFINDER_LOOPS_PER_TICK;

+	result->max_path_cost = 0;

+	result->max_search_nodes = AI_PATHFINDER_MAX_SEARCH_NODES;

+

+	// Set the user_data to the PathFinderInfo

+	result->user_target = PathFinderInfo;

+

+	// Set the start node

+	start_node.parent = NULL;

+	start_node.node.direction = 0;

+	start_node.node.user_data[0] = 0;

+

+	// Now we add all the starting tiles

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

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

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

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

+		}

+	}

+

+	return result;

+}

+

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

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

+	PathNode start_node;

+	uint x,y;

+	

+	aystar->clear(aystar);

+

+	// Set the user_data to the PathFinderInfo

+	aystar->user_target = PathFinderInfo;

+

+	// Set the start node

+	start_node.parent = NULL;

+	start_node.node.direction = 0;

+	start_node.node.user_data[0] = 0;

+	start_node.node.tile = PathFinderInfo->start_tile_tl;

+

+	// Now we add all the starting tiles

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

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

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

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

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

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

+		}

+	}

+}

+

+// The h-value, simple calculation

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

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

+	int r, r2;

+	if (PathFinderInfo->end_direction != AI_PATHFINDER_NO_DIRECTION) {

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

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

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

+	} else {

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

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

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

+	}

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

+	if (r2 < r) r = r2;

+	return r * AI_PATHFINDER_H_MULTIPLER;

+}

+

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

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

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

+	int i = 0;

+	PathNode *parent = &current->path;

+	

+	do {

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

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

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

+			// We ran out of space for the PathFinder

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

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

+			return;

+		}

+		parent = parent->parent;

+	} while (parent != NULL);

+	PathFinderInfo->route_length = i;

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

+}

+

+// What tiles are around us.

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

+    int i, r, dir;

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

+    

+    aystar->num_neighbours = 0;

+    

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

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

+   		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 &&

+       		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) {

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

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

+       		

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

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

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

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

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

+   					// This problem only is valid for tunnels:

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

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

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

+       				}

+       			}

+       		}

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

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

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

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

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

+       			}

+       		}

+       		

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

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

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

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

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

+       		}

+       		dir = 0;

+       		

+       		// First, check if we have a parent

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

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

+       			if (PathFinderInfo->start_direction != AI_PATHFINDER_NO_DIRECTION) {

+		       		// We do need a direction?

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

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

+		       			continue;

+		       	}

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

+       			if (PathFinderInfo->rail_or_road) {

+       				// Rail check

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

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

+       				if (r == CMD_ERROR) continue;

+#ifdef AI_PATHFINDER_NO_90DEGREES_TURN

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

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

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

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

+       						continue;

+       					}

+       				}

+#endif

+       			} else {

+       				// Road check

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

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

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

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

+       						dir = 0;

+       					} else {

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

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

+	       						// We do miss some pieces :(

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

+	       					} else {

+	       						dir = 0;

+    	   					}

+    	   				}

+       				}

+       				// Only destruct things if it is MP_CLEAR of MP_TREES

+       				if (dir != 0) {

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

+       					if (r == CMD_ERROR) continue;

+       				}

+       			}

+       			

+       		}

+       		

+			// The tile can be connected

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

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

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

+       	}

+    }

+    

+    // Next step, check for bridges and tunnels

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

+

+        TileInfo ti;

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

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

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

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

+    	TileIndex new_tile = tile;

+    	

+    	FindLandscapeHeightByTile(&ti, tile);

+    	

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

+   		//  And if there is a road or rail blocking

+   		if (ti.tileh != 0 ||

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

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

+

+    		for (;;) {

+    			new_tile += _tiles_around[dir];

+    	

+    	    	// Precheck, is the length allowed?

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

+    	    	

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

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

+

+    	    	// Try building the bridge..

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

+	    	   	if (r == CMD_ERROR) continue;

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

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

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

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

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

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

+			}

+    	}

+    	

+    	// Next, check for tunnels!

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

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

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

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

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

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

+    		// Now simply check if a tunnel can be build

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

+    		FindLandscapeHeightByTile(&ti, _build_tunnel_endtile);

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

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

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

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

+    		}

+    	}

+  	}

+}

+

+extern uint GetRailFoundation(uint tileh, uint bits);

+extern uint GetRoadFoundation(uint tileh, uint bits);

+extern uint GetBridgeFoundation(uint tileh, byte direction);

+enum {

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

+};

+

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

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

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

+	int r, res = 0;

+	TileInfo ti, parent_ti;

+	

+	// Gather some information about the tile..

+	FindLandscapeHeightByTile(&ti, current->tile);

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

+	

+	// Check if we hit the end-tile

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

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

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

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

+			return AYSTAR_INVALID_NODE;

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

+		return 0;

+	}

+	

+	// Give everything a small penalty

+	res += AI_PATHFINDER_PENALTY;

+

+	if (!PathFinderInfo->rail_or_road) {

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

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

+		if (AI_PATHFINDER_IS_ROAD(current->tile)) {

+			res -= AI_PATHFINDER_ROAD_ALREADY_EXISTS_BONUS;

+		}

+	}

+	

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

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

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

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

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

+			if (PathFinderInfo->rail_or_road) {

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

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

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

+					res += AI_PATHFINDER_TILE_GOES_UP_PENALTY;

+				}

+			} else {

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

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

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

+						res += AI_PATHFINDER_TILE_GOES_UP_PENALTY;

+				}

+			}

+		}

+	}

+	

+	// Are we part of a tunnel?

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

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

+		// Ironicly, we are using BridgeCode here ;)

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

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

+	}

+

+	// Are we part of a bridge?

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

+		// That means for every length a penalty

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

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

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

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

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

+				res += AI_PATHFINDER_BRIDGE_GOES_UP_PENALTY;

+		}

+		// Second for the end point

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

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

+				res += AI_PATHFINDER_BRIDGE_GOES_UP_PENALTY;

+		}

+		if (parent_ti.tileh == 0)

+			res += AI_PATHFINDER_BRIDGE_GOES_UP_PENALTY;

+		if (ti.tileh == 0)

+			res += AI_PATHFINDER_BRIDGE_GOES_UP_PENALTY;

+	}

+	

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

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

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

+	if (!PathFinderInfo->rail_or_road) {

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

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

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

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

+				res += AI_PATHFINDER_DIRECTION_CHANGE_ON_EXISTING_ROAD_PENALTY;

+			else

+				res += AI_PATHFINDER_DIRECTION_CHANGE_PENALTY;

+		}

+	} else {

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

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

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

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

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

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

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

+

+			// First see if they are different

+			if (dir1 != dir2) {

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

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

+					// It is not, so we changed of direction

+					res += AI_PATHFINDER_DIRECTION_CHANGE_PENALTY;

+				}

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

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

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

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

+						res += AI_PATHFINDER_CURVE_PENALTY;

+					}

+				}

+			}

+		}

+	}

+	

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

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

+

+	// Return our value

+	return res;

+}