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/* $Id$ */

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/** @file npf.h */

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#ifndef NPF_H

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#define NPF_H

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#include "aystar.h"

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#include "station.h"

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/* mowing grass */

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enum {

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	NPF_HASH_BITS = 12, ///< The size of the hash used in pathfinding. Just changing this value should be sufficient to change the hash size. Should be an even value.

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	/* Do no change below values */

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	NPF_HASH_SIZE = 1 << NPF_HASH_BITS,

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	NPF_HASH_HALFBITS = NPF_HASH_BITS / 2,

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	NPF_HASH_HALFMASK = (1 << NPF_HASH_HALFBITS) - 1

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};

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/* For new pathfinding. Define here so it is globally available without having

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 * to include npf.h */

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enum {

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	NPF_TILE_LENGTH = 100

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};

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enum {

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	/** This penalty is the equivalent of "inifite", which means that paths that

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	 * get this penalty will be chosen, but only if there is no other route

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	 * without it. Be careful with not applying this penalty to often, or the

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	 * total path cost might overflow..

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	 * For now, this is just a Very Big Penalty, we might actually implement

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	 * this in a nicer way :-)

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	 */

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	NPF_INFINITE_PENALTY = 1000 * NPF_TILE_LENGTH

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};

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/* Meant to be stored in AyStar.targetdata */

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struct NPFFindStationOrTileData {

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	TileIndex dest_coords;   ///< An indication of where the station is, for heuristic purposes, or the target tile

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	StationID station_index; ///< station index we're heading for, or INVALID_STATION when we're heading for a tile

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};

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/* Indices into AyStar.userdata[] */

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enum {

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	NPF_TYPE = 0,  ///< Contains a TransportTypes value

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	NPF_SUB_TYPE,  ///< Contains the sub transport type

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	NPF_OWNER,     ///< Contains an Owner value

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	NPF_RAILTYPES, ///< Contains a bitmask the compatible RailTypes of the engine when NPF_TYPE == TRANSPORT_RAIL. Unused otherwise.

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};

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/* Indices into AyStarNode.userdata[] */

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enum {

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	NPF_TRACKDIR_CHOICE = 0, ///< The trackdir chosen to get here

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	NPF_NODE_FLAGS,

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};

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/* Flags for AyStarNode.userdata[NPF_NODE_FLAGS]. Use NPFGetBit() and NPFGetBit() to use them. */

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enum NPFNodeFlag {

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	NPF_FLAG_SEEN_SIGNAL,     ///< Used to mark that a signal was seen on the way, for rail only

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	NPF_FLAG_REVERSE,         ///< Used to mark that this node was reached from the second start node, if applicable

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	NPF_FLAG_LAST_SIGNAL_RED, ///< Used to mark that the last signal on this path was red

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};

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/* Meant to be stored in AyStar.userpath */

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struct NPFFoundTargetData {

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	uint best_bird_dist;    ///< The best heuristic found. Is 0 if the target was found

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	uint best_path_dist;    ///< The shortest path. Is (uint)-1 if no path is found

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	Trackdir best_trackdir; ///< The trackdir that leads to the shortest path/closest birds dist

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	AyStarNode node;        ///< The node within the target the search led us to

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};

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/* These functions below are _not_ re-entrant, in favor of speed! */

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/* Will search from the given tile and direction, for a route to the given

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 * station for the given transport type. See the declaration of

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 * NPFFoundTargetData above for the meaning of the result. */

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/* Will search as above, but with two start nodes, the second being the

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 * reverse. Look at the NPF_FLAG_REVERSE flag in the result node to see which

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 * direction was taken (NPFGetBit(result.node, NPF_FLAG_REVERSE)) */

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/* Will search a route to the closest depot. */

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/* Search using breadth first. Good for little track choice and inaccurate

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 * heuristic, such as railway/road.*/

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/* Same as above but with two start nodes, the second being the reverse. Call

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 * NPFGetBit(result.node, NPF_FLAG_REVERSE) to see from which node the path

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 * orginated. All pathfs from the second node will have the given

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 * reverse_penalty applied (NPF_TILE_LENGTH is the equivalent of one full

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 * tile).

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 */

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/* Search by trying each depot in order of Manhattan Distance. Good for lots

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 * of choices and accurate heuristics, such as water. */

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void NPFFillWithOrderData(NPFFindStationOrTileData* fstd, Vehicle* v);

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/*

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 * Functions to manipulate the various NPF related flags on an AyStarNode.

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 */

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/**

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 * Returns the current value of the given flag on the given AyStarNode.

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 */

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static inline bool NPFGetFlag(const AyStarNode* node, NPFNodeFlag flag)

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{

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	return HasBit(node->user_data[NPF_NODE_FLAGS], flag);

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}

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/**

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 * Sets the given flag on the given AyStarNode to the given value.

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 */

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static inline void NPFSetFlag(AyStarNode* node, NPFNodeFlag flag, bool value)

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{

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	if (value)

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		SetBit(node->user_data[NPF_NODE_FLAGS], flag);

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	else

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		ClrBit(node->user_data[NPF_NODE_FLAGS], flag);

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}

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#endif /* NPF_H */