frosch
99 lines
3.6 KiB
C++
99 lines
3.6 KiB
C++
/*
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* This file is part of OpenTTD.
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* OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
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* OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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* See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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* @file aystar.h
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* This file has the header for %AyStar.
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* %AyStar is a fast path finding routine and is used for things like AI path finding and Train path finding.
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* For more information about AyStar (A* Algorithm), you can look at
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* <A HREF='http://en.wikipedia.org/wiki/A-star_search_algorithm'>http://en.wikipedia.org/wiki/A-star_search_algorithm</A>.
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*/
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#ifndef AYSTAR_H
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#define AYSTAR_H
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#include "yapf/nodelist.hpp"
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#include "yapf/yapf_node.hpp"
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static const int AYSTAR_DEF_MAX_SEARCH_NODES = 10000; ///< Reference limit for #AyStar::max_search_nodes
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/** Return status of #AyStar methods. */
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enum class AyStarStatus : uint8_t {
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FoundEndNode, ///< An end node was found.
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EmptyOpenList, ///< All items are tested, and no path has been found.
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StillBusy, ///< Some checking was done, but no path found yet, and there are still items left to try.
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NoPath, ///< No path to the goal was found.
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LimitReached, ///< The AYSTAR_DEF_MAX_SEARCH_NODES limit has been reached, aborting search.
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Done, ///< Not an end-tile, or wrong direction.
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};
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static const int AYSTAR_INVALID_NODE = -1; ///< Item is not valid (for example, not walkable).
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using AyStarNode = CYapfNodeKeyTrackDir;
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struct PathNode : CYapfNodeT<AyStarNode, PathNode> {
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};
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/**
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* %AyStar search algorithm struct.
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*/
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class AyStar {
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protected:
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/**
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* Calculate the G-value for the %AyStar algorithm.
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* @return G value of the node:
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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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virtual int32_t CalculateG(const AyStarNode ¤t, const PathNode &parent) const = 0;
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/**
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* Calculate the H-value for the %AyStar algorithm.
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* Mostly, this must return the distance (Manhattan way) between the current point and the end point.
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* @return The h-value for this tile (any value >= 0)
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*/
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virtual int32_t CalculateH(const AyStarNode ¤t, const PathNode &parent) const = 0;
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/**
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* This function requests the tiles around the current tile.
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* #neighbours is never reset, so if you are not using directions, just leave it alone.
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*/
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virtual void GetNeighbours(const PathNode ¤t, std::vector<AyStarNode> &neighours) const = 0;
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/**
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* Check whether the end-tile is found.
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* @param current Node to exam.
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* @return Status of the node:
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* - #AyStarStatus::FoundEndNode : indicates this is the end tile
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* - #AyStarStatus::Done : indicates this is not the end tile (or direction was wrong)
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*/
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virtual AyStarStatus EndNodeCheck(const PathNode ¤t) const = 0;
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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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virtual void FoundEndNode(const PathNode ¤t) = 0;
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void AddStartNode(AyStarNode *start_node, int g);
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AyStarStatus Main();
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public:
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virtual ~AyStar() = default;
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private:
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NodeList<PathNode, 8, 10> nodes;
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mutable std::vector<AyStarNode> neighbours;
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AyStarStatus Loop();
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void OpenListAdd(PathNode *parent, const AyStarNode *node, int f, int g);
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void CheckTile(AyStarNode *current, PathNode *parent);
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};
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#endif /* AYSTAR_H */
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