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/* $Id$ */

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/** @file yapf_base.hpp */

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#ifndef  YAPF_BASE_HPP

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#define  YAPF_BASE_HPP

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#include "../debug.h"

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extern int _total_pf_time_us;

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/** CYapfBaseT - A-star type path finder base class.

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 *  Derive your own pathfinder from it. You must provide the following template argument:

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 *    Types      - used as collection of local types used in pathfinder

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 *

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 * Requirements for the Types struct:

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 *  ----------------------------------

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 *  The following types must be defined in the 'Types' argument:

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 *    - Types::Tpf - your pathfinder derived from CYapfBaseT

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 *    - Types::NodeList - open/closed node list (look at CNodeList_HashTableT)

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 *  NodeList needs to have defined local type Titem - defines the pathfinder node type.

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 *  Node needs to define local type Key - the node key in the collection ()

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 *

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 *  For node list you can use template class CNodeList_HashTableT, for which

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 *  you need to declare only your node type. Look at test_yapf.h for an example.

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 *

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 *

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 *  Requrements to your pathfinder class derived from CYapfBaseT:

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 *  -------------------------------------------------------------

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 *  Your pathfinder derived class needs to implement following methods:

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 *    FORCEINLINE void PfSetStartupNodes()

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 *    FORCEINLINE void PfFollowNode(Node& org)

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 *    FORCEINLINE bool PfCalcCost(Node& n)

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 *    FORCEINLINE bool PfCalcEstimate(Node& n)

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 *    FORCEINLINE bool PfDetectDestination(Node& n)

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 *

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 *  For more details about those methods, look at the end of CYapfBaseT

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 *  declaration. There are some examples. For another example look at

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 *  test_yapf.h (part or unittest project).

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 */

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template <class Types>

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class CYapfBaseT {

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public:

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	typedef typename Types::Tpf Tpf;           ///< the pathfinder class (derived from THIS class)

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	typedef typename Types::TrackFollower TrackFollower;

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	typedef typename Types::NodeList NodeList; ///< our node list

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	typedef typename NodeList::Titem Node;     ///< this will be our node type

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	typedef typename Node::Key Key;            ///< key to hash tables

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	NodeList             m_nodes;              ///< node list multi-container

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protected:

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	Node*                m_pBestDestNode;      ///< pointer to the destination node found at last round

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	Node*                m_pBestIntermediateNode; ///< here should be node closest to the destination if path not found

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	const YapfSettings  *m_settings;           ///< current settings (_patches.yapf)

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	int                  m_max_search_nodes;   ///< maximum number of nodes we are allowed to visit before we give up

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	const Vehicle*       m_veh;                ///< vehicle that we are trying to drive

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	int                  m_stats_cost_calcs;   ///< stats - how many node's costs were calculated

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	int                  m_stats_cache_hits;   ///< stats - how many node's costs were reused from cache

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public:

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	CPerformanceTimer    m_perf_cost;          ///< stats - total CPU time of this run

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	CPerformanceTimer    m_perf_slope_cost;    ///< stats - slope calculation CPU time

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	CPerformanceTimer    m_perf_ts_cost;       ///< stats - GetTrackStatus() CPU time

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	CPerformanceTimer    m_perf_other_cost;    ///< stats - other CPU time

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public:

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	int                  m_num_steps;          ///< this is there for debugging purposes (hope it doesn't hurt)

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public:

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	/// default constructor

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	FORCEINLINE CYapfBaseT()

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		: m_pBestDestNode(NULL)

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		, m_pBestIntermediateNode(NULL)

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		, m_settings(&_patches.yapf)

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		, m_max_search_nodes(PfGetSettings().max_search_nodes)

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		, m_veh(NULL)

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		, m_stats_cost_calcs(0)

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		, m_stats_cache_hits(0)

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		, m_num_steps(0)

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	{

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	}

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	/// default destructor

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	~CYapfBaseT() {}

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protected:

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	/// to access inherited path finder

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	FORCEINLINE Tpf& Yapf() {return *static_cast<Tpf*>(this);}

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public:

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	/// return current settings (can be custom - player based - but later)

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	FORCEINLINE const YapfSettings& PfGetSettings() const

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	{

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		return *m_settings;

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	}

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	/** Main pathfinder routine:

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	 *   - set startup node(s)

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	 *   - main loop that stops if:

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	 *      - the destination was found

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	 *      - or the open list is empty (no route to destination).

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	 *      - or the maximum amount of loops reached - m_max_search_nodes (default = 10000)

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	 * @return true if the path was found */

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	inline bool FindPath(const Vehicle *v)

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	{

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		m_veh = v;

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#ifndef NO_DEBUG_MESSAGES

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		CPerformanceTimer perf;

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		perf.Start();

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#endif /* !NO_DEBUG_MESSAGES */

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		Yapf().PfSetStartupNodes();

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		while (true) {

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			m_num_steps++;

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			Node *n = m_nodes.GetBestOpenNode();

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			if (n == NULL)

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				break;

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			// if the best open node was worse than the best path found, we can finish

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			if (m_pBestDestNode != NULL && m_pBestDestNode->GetCost() < n->GetCostEstimate())

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				break;

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			Yapf().PfFollowNode(*n);

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			if (m_max_search_nodes == 0 || m_nodes.ClosedCount() < m_max_search_nodes) {

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				m_nodes.PopOpenNode(n->GetKey());

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				m_nodes.InsertClosedNode(*n);

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			} else {

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				m_pBestDestNode = m_pBestIntermediateNode;

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				break;

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			}

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		}

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		bool bDestFound = (m_pBestDestNode != NULL) && (m_pBestDestNode != m_pBestIntermediateNode);

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#ifndef NO_DEBUG_MESSAGES

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		perf.Stop();

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		if (_debug_yapf_level >= 3) {

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			int t = perf.Get(1000000);

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			_total_pf_time_us += t;

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			UnitID veh_idx = (m_veh != NULL) ? m_veh->unitnumber : 0;

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			char ttc = Yapf().TransportTypeChar();

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			float cache_hit_ratio = (m_stats_cache_hits == 0) ? 0.0f : ((float)m_stats_cache_hits / (float)(m_stats_cache_hits + m_stats_cost_calcs) * 100.0f);

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			int cost = bDestFound ? m_pBestDestNode->m_cost : -1;

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			int dist = bDestFound ? m_pBestDestNode->m_estimate - m_pBestDestNode->m_cost : -1;

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			DEBUG(yapf, 3, "[YAPF%c]%c%4d- %d us - %d rounds - %d open - %d closed - CHR %4.1f%% - c%d(sc%d, ts%d, o%d) -- ",

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			  ttc, bDestFound ? '-' : '!', veh_idx, t, m_num_steps, m_nodes.OpenCount(), m_nodes.ClosedCount(),

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			  cache_hit_ratio, cost, dist, m_perf_cost.Get(1000000), m_perf_slope_cost.Get(1000000),

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			  m_perf_ts_cost.Get(1000000), m_perf_other_cost.Get(1000000)

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			);

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		}

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#endif /* !NO_DEBUG_MESSAGES */

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		return bDestFound;

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	}

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	/** If path was found return the best node that has reached the destination. Otherwise

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	 *  return the best visited node (which was nearest to the destination).

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	 */

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	FORCEINLINE Node* GetBestNode()

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	{

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		return (m_pBestDestNode != NULL) ? m_pBestDestNode : m_pBestIntermediateNode;

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	}

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	/** Calls NodeList::CreateNewNode() - allocates new node that can be filled and used

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	 *  as argument for AddStartupNode() or AddNewNode()

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	 */

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	FORCEINLINE Node& CreateNewNode()

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	{

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		Node& node = *m_nodes.CreateNewNode();

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		return node;

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	}

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	/** Add new node (created by CreateNewNode and filled with data) into open list */

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	FORCEINLINE void AddStartupNode(Node& n)

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	{

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		Yapf().PfNodeCacheFetch(n);

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		// insert the new node only if it is not there

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		if (m_nodes.FindOpenNode(n.m_key) == NULL) {

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			m_nodes.InsertOpenNode(n);

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		} else {

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			// if we are here, it means that node is already there - how it is possible?

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			//   probably the train is in the position that both its ends point to the same tile/exit-dir

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			//   very unlikely, but it happened

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		}

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	}

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	/** add multiple nodes - direct children of the given node */

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	FORCEINLINE void AddMultipleNodes(Node* parent, const TrackFollower &tf)

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	{

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		bool is_choice = (KillFirstBit(tf.m_new_td_bits) != TRACKDIR_BIT_NONE);

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		for (TrackdirBits rtds = tf.m_new_td_bits; rtds != TRACKDIR_BIT_NONE; rtds = KillFirstBit(rtds)) {

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			Trackdir td = (Trackdir)FindFirstBit2x64(rtds);

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			Node& n = Yapf().CreateNewNode();

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			n.Set(parent, tf.m_new_tile, td, is_choice);

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			Yapf().AddNewNode(n, tf);

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		}

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	}

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	/** AddNewNode() - called by Tderived::PfFollowNode() for each child node.

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	 *  Nodes are evaluated here and added into open list */

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	void AddNewNode(Node &n, const TrackFollower &tf)

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	{

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		// evaluate the node

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		bool bCached = Yapf().PfNodeCacheFetch(n);

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		if (!bCached) {

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			m_stats_cost_calcs++;

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		} else {

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			m_stats_cache_hits++;

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		}

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		bool bValid = Yapf().PfCalcCost(n, &tf);

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		if (bCached) {

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			Yapf().PfNodeCacheFlush(n);

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		}

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		if (bValid) bValid = Yapf().PfCalcEstimate(n);

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		// have the cost or estimate callbacks marked this node as invalid?

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		if (!bValid) return;

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		// detect the destination

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		bool bDestination = Yapf().PfDetectDestination(n);

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		if (bDestination) {

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			if (m_pBestDestNode == NULL || n < *m_pBestDestNode) {

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				m_pBestDestNode = &n;

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			}

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			m_nodes.FoundBestNode(n);

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			return;

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		}

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		if (m_max_search_nodes > 0 && (m_pBestIntermediateNode == NULL || (m_pBestIntermediateNode->GetCostEstimate() - m_pBestIntermediateNode->GetCost()) > (n.GetCostEstimate() - n.GetCost()))) {

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			m_pBestIntermediateNode = &n;

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		}

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		// check new node against open list

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		Node* openNode = m_nodes.FindOpenNode(n.GetKey());

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		if (openNode != NULL) {

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			// another node exists with the same key in the open list

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			// is it better than new one?

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			if (n.GetCostEstimate() < openNode->GetCostEstimate()) {

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				// update the old node by value from new one

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				m_nodes.PopOpenNode(n.GetKey());

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				*openNode = n;

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				// add the updated old node back to open list

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				m_nodes.InsertOpenNode(*openNode);

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			}

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			return;

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		}

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		// check new node against closed list

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		Node* closedNode = m_nodes.FindClosedNode(n.GetKey());

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		if (closedNode != NULL) {

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			// another node exists with the same key in the closed list

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			// is it better than new one?

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			int node_est = n.GetCostEstimate();

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			int closed_est = closedNode->GetCostEstimate();

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			if (node_est < closed_est) {

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				// If this assert occurs, you have probably problem in

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				// your Tderived::PfCalcCost() or Tderived::PfCalcEstimate().

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				// The problem could be:

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				//  - PfCalcEstimate() gives too large numbers

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				//  - PfCalcCost() gives too small numbers

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				//  - You have used negative cost penalty in some cases (cost bonus)

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				assert(0);

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				return;

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			}

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			return;

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		}

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		// the new node is really new

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		// add it to the open list

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		m_nodes.InsertOpenNode(n);

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	}

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	const Vehicle* GetVehicle() const {return m_veh;}

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	void DumpBase(DumpTarget &dmp) const

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	{

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		dmp.WriteStructT("m_nodes", &m_nodes);

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		dmp.WriteLine("m_num_steps = %d", m_num_steps);

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	}

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	// methods that should be implemented at derived class Types::Tpf (derived from CYapfBaseT)

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#if 0

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	/** Example: PfSetStartupNodes() - set source (origin) nodes */

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	FORCEINLINE void PfSetStartupNodes()

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	{

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		// example:

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		Node& n1 = *base::m_nodes.CreateNewNode();

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		.

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		. // setup node members here

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		.

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		base::m_nodes.InsertOpenNode(n1);

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	}

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	/** Example: PfFollowNode() - set following (child) nodes of the given node */

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	FORCEINLINE void PfFollowNode(Node& org)

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	{

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		for (each follower of node org) {

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			Node& n = *base::m_nodes.CreateNewNode();

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			.

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			. // setup node members here

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			.

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			n.m_parent   = &org; // set node's parent to allow back tracking

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			AddNewNode(n);

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		}

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	}

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	/** Example: PfCalcCost() - set path cost from origin to the given node */

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	FORCEINLINE bool PfCalcCost(Node& n)

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	{

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		// evaluate last step cost

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		int cost = ...;

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		// set the node cost as sum of parent's cost and last step cost

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		n.m_cost = n.m_parent->m_cost + cost;

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		return true; // true if node is valid follower (i.e. no obstacle was found)

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	}

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	/** Example: PfCalcEstimate() - set path cost estimate from origin to the target through given node */

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	FORCEINLINE bool PfCalcEstimate(Node& n)

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	{

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		// evaluate the distance to our destination

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		int distance = ...;

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		// set estimate as sum of cost from origin + distance to the target

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		n.m_estimate = n.m_cost + distance;

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		return true; // true if node is valid (i.e. not too far away :)

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	}

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	/** Example: PfDetectDestination() - return true if the given node is our destination */

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	FORCEINLINE bool PfDetectDestination(Node& n)

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	{

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		bool bDest = (n.m_key.m_x == m_x2) && (n.m_key.m_y == m_y2);

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		return bDest;

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	}

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#endif

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};

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#endif /* YAPF_BASE_HPP */