astar_path.h

/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program 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, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#ifndef NUVIE_PATHFINDER_ASTAR_PATH_H
#define NUVIE_PATHFINDER_ASTAR_PATH_H

#include "ultima/nuvie/core/map.h"
#include "ultima/nuvie/pathfinder/path.h"

namespace Ultima {
namespace Nuvie {

typedef struct astar_node_s {
    MapCoord loc; // location
    uint32 to_start; // costs from this node to start and to goal
    uint32 to_goal;
    uint32 score; // node score
    uint32 len; // number of nodes before this one, regardless of score
    struct astar_node_s *parent;
    astar_node_s() : loc(0, 0, 0), to_start(0), to_goal(0), score(0), len(0),
        parent(nullptr) { }
} astar_node;
/* Provides A* search and cost methods for PathFinder and subclasses.
 */class AStarPath: public Path {
protected:
    Std::list<astar_node *> open_nodes, closed_nodes; // nodes seen
    astar_node *final_node; // last node in path search, used by create_path()
    /* Forms a usable path from results of a search. */
    void create_path();
    /* Search routine. */
    bool search_node_neighbors(astar_node *nnode, const MapCoord &goal, const uint32 max_score);
    bool compare_neighbors(astar_node *nnode, astar_node *neighbor,
                           sint32 nnode_to_neighbor, astar_node *in_open,
                           astar_node *in_closed);
    bool score_to_neighbor(sint8 dir, astar_node *nnode, astar_node *neighbor,
                           sint32 &nnode_to_neighbor);
public:
    AStarPath();
    ~AStarPath() override { }
    bool path_search(const MapCoord &start, const MapCoord &goal) override;
    uint32 path_cost_est(const MapCoord &s, const MapCoord &g) override  {
        return Path::path_cost_est(s, g);
    }
    uint32 get_max_score(uint32 cost) override {
        return Path::get_max_score(cost);
    }
    uint32 path_cost_est(const astar_node &n1, const astar_node &n2) {
        return Path::path_cost_est(n1.loc, n2.loc);
    }
    sint32 step_cost(const MapCoord &c1, const MapCoord &c2) override;
protected:
    /* FIXME: These node functions can be replaced with a priority_queue and a list. */
    astar_node *find_open_node(astar_node *ncmp);
    void push_open_node(astar_node *node);
    astar_node *pop_open_node();
    astar_node *find_closed_node(astar_node *ncmp);
    void remove_closed_node(astar_node *ncmp);
    void delete_nodes();
};

} // End of namespace Nuvie
} // End of namespace Ultima

#endif