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184 lines
5.9 KiB
C
184 lines
5.9 KiB
C
/*
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* This file has the header for AyStar
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* AyStar is a fast pathfinding routine and is used for things like
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* AI_pathfinding and Train_pathfinding.
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* For more information about AyStar (A* Algorithm), you can look at
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* http://en.wikipedia.org/wiki/A-star_search_algorithm
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*/
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#ifndef AYSTAR_H
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#define AYSTAR_H
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#include "queue.h"
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//#define AYSTAR_DEBUG
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enum {
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AYSTAR_FOUND_END_NODE,
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AYSTAR_EMPTY_OPENLIST,
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AYSTAR_STILL_BUSY,
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AYSTAR_NO_PATH,
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AYSTAR_LIMIT_REACHED,
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AYSTAR_DONE
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};
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enum{
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AYSTAR_INVALID_NODE = -1,
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};
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typedef struct AyStarNode AyStarNode;
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struct AyStarNode {
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TileIndex tile;
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uint direction;
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uint user_data[2];
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};
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// The resulting path has nodes looking like this.
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typedef struct PathNode PathNode;
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struct PathNode {
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AyStarNode node;
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// The parent of this item
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PathNode *parent;
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};
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// For internal use only
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// We do not save the h-value, because it is only needed to calculate the f-value.
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// h-value should _always_ be the distance left to the end-tile.
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typedef struct OpenListNode OpenListNode;
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struct OpenListNode {
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int g;
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PathNode path;
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};
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typedef struct AyStar AyStar;
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/*
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* This function is called to check if the end-tile is found
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* return values can be:
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* AYSTAR_FOUND_END_NODE : indicates this is the end tile
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* AYSTAR_DONE : indicates this is not the end tile (or direction was wrong)
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*/
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/*
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* The 2nd parameter should be OpenListNode, and NOT AyStarNode. AyStarNode is
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* part of OpenListNode and so it could be accessed without any problems.
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* The good part about OpenListNode is, and how AIs use it, that you can
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* access the parent of the current node, and so check if you, for example
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* don't try to enter the file tile with a 90-degree curve. So please, leave
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* this an OpenListNode, it works just fine -- TrueLight
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*/
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typedef int32 AyStar_EndNodeCheck(AyStar *aystar, OpenListNode *current);
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/*
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* This function is called to calculate the G-value for AyStar Algorithm.
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* return values can be:
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* AYSTAR_INVALID_NODE : indicates an item is not valid (e.g.: unwalkable)
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* Any value >= 0 : the g-value for this tile
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*/
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typedef int32 AyStar_CalculateG(AyStar *aystar, AyStarNode *current, OpenListNode *parent);
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/*
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* This function is called to calculate the H-value for AyStar Algorithm.
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* Mostly, this must result the distance (Manhattan way) between the
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* current point and the end point
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* return values can be:
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* Any value >= 0 : the h-value for this tile
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*/
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typedef int32 AyStar_CalculateH(AyStar *aystar, AyStarNode *current, OpenListNode *parent);
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/*
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* This function request the tiles around the current tile and put them in tiles_around
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* tiles_around is never resetted, so if you are not using directions, just leave it alone.
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* Warning: never add more tiles_around than memory allocated for it.
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*/
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typedef void AyStar_GetNeighbours(AyStar *aystar, OpenListNode *current);
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/*
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* If the End Node is found, this function is called.
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* It can do, for example, calculate the route and put that in an array
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*/
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typedef void AyStar_FoundEndNode(AyStar *aystar, OpenListNode *current);
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/*
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* Is called when aystar ends it pathfinding, but before cleanup.
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*/
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typedef void AyStar_BeforeExit(AyStar *aystar);
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// For internal use, see aystar.c
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typedef void AyStar_AddStartNode(AyStar *aystar, AyStarNode* start_node, uint g);
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typedef int AyStar_Main(AyStar *aystar);
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typedef int AyStar_Loop(AyStar *aystar);
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typedef int AyStar_CheckTile(AyStar *aystar, AyStarNode *current, OpenListNode *parent);
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typedef void AyStar_Free(AyStar *aystar);
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typedef void AyStar_Clear(AyStar *aystar);
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struct AyStar {
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/* These fields should be filled before initting the AyStar, but not changed
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* afterwards (except for user_data and user_path)! (free and init again to change them) */
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/* These should point to the application specific routines that do the
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* actual work */
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AyStar_CalculateG* CalculateG;
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AyStar_CalculateH* CalculateH;
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AyStar_GetNeighbours* GetNeighbours;
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AyStar_EndNodeCheck* EndNodeCheck;
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AyStar_FoundEndNode* FoundEndNode;
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AyStar_BeforeExit* BeforeExit;
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/* These are completely untouched by AyStar, they can be accesed by
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* the application specific routines to input and output data.
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* user_path should typically contain data about the resulting path
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* afterwards, user_target should typically contain information about
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* what where looking for, and user_data can contain just about
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* everything */
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void *user_path;
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void *user_target;
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uint user_data[10];
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/* How many loops are there called before AyStarMain_Main gives
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* control back to the caller. 0 = until done */
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byte loops_per_tick;
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/* If the g-value goes over this number, it stops searching
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* 0 = infinite */
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uint max_path_cost;
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/* The maximum amount of nodes that will be expanded, 0 = infinite */
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uint max_search_nodes;
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/* These should be filled with the neighbours of a tile by
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* GetNeighbours */
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AyStarNode neighbours[12];
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byte num_neighbours;
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/* These will contain the methods for manipulating the AyStar. Only
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* main() should be called externally */
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AyStar_AddStartNode* addstart;
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AyStar_Main* main;
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AyStar_Loop* loop;
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AyStar_Free* free;
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AyStar_Clear* clear;
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AyStar_CheckTile* checktile;
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/* These will contain the open and closed lists */
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/* The actual closed list */
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Hash ClosedListHash;
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/* The open queue */
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Queue OpenListQueue;
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/* An extra hash to speed up the process of looking up an element in
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* the open list */
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Hash OpenListHash;
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};
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void AyStarMain_AddStartNode(AyStar *aystar, AyStarNode *start_node, uint g);
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int AyStarMain_Main(AyStar *aystar);
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int AyStarMain_Loop(AyStar *aystar);
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int AyStarMain_CheckTile(AyStar *aystar, AyStarNode *current, OpenListNode *parent);
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void AyStarMain_Free(AyStar *aystar);
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void AyStarMain_Clear(AyStar *aystar);
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/* Initialize an AyStar. You should fill all appropriate fields before
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* callling init_AyStar (see the declaration of AyStar for which fields are
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* internal */
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void init_AyStar(AyStar* aystar, Hash_HashProc hash, uint num_buckets);
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#endif
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