Add Dijkstra A* and A* without prefetching pathfind algorithms

doc/lua_api.txt

@@ -1186,6 +1186,20 @@ methods:
   ^ Return world-specific perlin noise (int(worldseed)+seeddiff)
 - clear_objects()
   ^ clear all objects in the environments
+- line_of_sight(pos1,pos2,stepsize) ->true/false
+  ^ checkif there is a direct line of sight between pos1 and pos2
+  ^ pos1 First position
+  ^ pos2 Second position
+  ^ stepsize smaller gives more accurate results but requires more computing
+             time. Default is 1.
+-find_path(pos1,pos2,searchdistance,max_jump,max_drop,algorithm) -> table containing path
+  ^ returns a table of 3d points representing a path from pos1 to pos2 or nil
+  ^ pos1: start position
+  ^ pos2: end position
+  ^ searchdistance: number of blocks to search in each direction
+  ^ max_jump: maximum height difference to consider walkable
+  ^ max_drop: maximum height difference to consider droppable
+  ^ algorithm: A*_noprefetch(default), A*, Dijkstra
 - spawn_tree (pos, {treedef})
   ^ spawns L-System tree at given pos with definition in treedef table
 treedef={

src/CMakeLists.txt

@@ -264,6 +264,7 @@ set(common_SRCS
 	clientserver.cpp
 	staticobject.cpp
 	serverlist.cpp
+	pathfinder.cpp
 	util/serialize.cpp
 	util/directiontables.cpp
 	util/numeric.cpp

src/environment.cpp

@@ -364,6 +364,29 @@ ServerMap & ServerEnvironment::getServerMap()
 	return *m_map;
 }
 
+bool ServerEnvironment::line_of_sight(v3f pos1, v3f pos2, float stepsize)
+{
+	float distance = pos1.getDistanceFrom(pos2);
+
+	//calculate normalized direction vector
+	v3f normalized_vector = v3f((pos2.X - pos1.X)/distance,
+								(pos2.Y - pos1.Y)/distance,
+								(pos2.Z - pos1.Z)/distance);
+
+	//find out if there's a node on path between pos1 and pos2
+	for (float i = 1; i < distance; i += stepsize) {
+		v3s16 pos = floatToInt(v3f(normalized_vector.X * i,
+				normalized_vector.Y * i,
+				normalized_vector.Z * i) +pos1,BS);
+
+		MapNode n = getMap().getNodeNoEx(pos);
+
+		if(n.param0 != CONTENT_AIR) {
+			return false;
+		}
+	}
+	return true;
+}
 
 void ServerEnvironment::serializePlayers(const std::string &savedir)
 {

src/environment.h

@@ -298,6 +298,9 @@ public:
 	// This makes stuff happen
 	void step(f32 dtime);
 	
+	//check if there's a line of sight between two positions
+	bool line_of_sight(v3f pos1, v3f pos2, float stepsize=1.0);
+
 private:
 
 	/*

src/pathfinder.h

@@ -0,0 +1,345 @@
+/*
+Minetest
+Copyright (C) 2013 sapier, sapier at gmx dot net
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#ifndef PATHFINDER_H_
+#define PATHFINDER_H_
+
+/******************************************************************************/
+/* Includes                                                                   */
+/******************************************************************************/
+#include <vector>
+
+#include "server.h"
+#include "irr_v3d.h"
+
+
+/******************************************************************************/
+/* Typedefs and macros                                                        */
+/******************************************************************************/
+
+//#define PATHFINDER_DEBUG
+
+typedef enum {
+	DIR_XP,
+	DIR_XM,
+	DIR_ZP,
+	DIR_ZM
+} path_directions;
+
+/** List of supported algorithms */
+typedef enum {
+	DIJKSTRA,           /**< Dijkstra shortest path algorithm             */
+	A_PLAIN,            /**< A* algorithm using heuristics to find a path */
+	A_PLAIN_NP          /**< A* algorithm without prefetching of map data */
+} algorithm;
+
+/******************************************************************************/
+/* declarations                                                               */
+/******************************************************************************/
+
+/** c wrapper function to use from scriptapi */
+std::vector<v3s16> get_Path(ServerEnvironment* env,
+							v3s16 source,
+							v3s16 destination,
+							unsigned int searchdistance,
+							unsigned int max_jump,
+							unsigned int max_drop,
+							algorithm algo);
+
+/** representation of cost in specific direction */
+class path_cost {
+public:
+
+	/** default constructor */
+	path_cost();
+
+	/** copy constructor */
+	path_cost(const path_cost& b);
+
+	/** assignment operator */
+	path_cost& operator= (const path_cost& b);
+
+	bool valid;              /**< movement is possible         */
+	int  value;              /**< cost of movement             */
+	int  direction;          /**< y-direction of movement      */
+	bool updated;            /**< this cost has ben calculated */
+
+};
+
+
+/** representation of a mapnode to be used for pathfinding */
+class path_gridnode {
+
+public:
+	/** default constructor */
+	path_gridnode();
+
+	/** copy constructor */
+	path_gridnode(const path_gridnode& b);
+
+	/**
+	 * assignment operator
+	 * @param b node to copy
+	 */
+	path_gridnode& operator= (const path_gridnode& b);
+
+	/**
+	 * read cost in a specific direction
+	 * @param dir direction of cost to fetch
+	 */
+	path_cost get_cost(v3s16 dir);
+
+	/**
+	 * set cost value for movement
+	 * @param dir direction to set cost for
+	 * @cost cost to set
+	 */
+	void      set_cost(v3s16 dir,path_cost cost);
+
+	bool      valid;               /**< node is on surface                    */
+	bool      target;              /**< node is target position               */
+	bool      source;              /**< node is stating position              */
+	int       totalcost;           /**< cost to move here from starting point */
+	v3s16     sourcedir;           /**< origin of movement for current cost   */
+	int       surfaces;            /**< number of surfaces with same x,z value*/
+	v3s16     pos;                 /**< real position of node                 */
+	path_cost directions[4];       /**< cost in different directions          */
+
+	/* debug values */
+	bool      is_element;          /**< node is element of path detected      */
+	char      type;                /**< type of node                          */
+};
+
+/** class doing pathfinding */
+class pathfinder {
+
+public:
+	/**
+	 * default constructor
+	 */
+	pathfinder();
+
+	/**
+	 * path evaluation function
+	 * @param env environment to look for path
+	 * @param source origin of path
+	 * @param destination end position of path
+	 * @param searchdistance maximum number of nodes to look in each direction
+	 * @param max_jump maximum number of blocks a path may jump up
+	 * @param max_drop maximum number of blocks a path may drop
+	 * @param algo algorithm to use for finding a path
+	 */
+	std::vector<v3s16> get_Path(ServerEnvironment* env,
+			v3s16 source,
+			v3s16 destination,
+			unsigned int searchdistance,
+			unsigned int max_jump,
+			unsigned int max_drop,
+			algorithm algo);
+
+private:
+	/** data struct for storing internal information */
+	struct limits {
+		struct limit {
+			int min;
+			int max;
+		};
+
+		limit X;
+		limit Y;
+		limit Z;
+	};
+
+	/* helper functions */
+
+	/**
+	 * transform index pos to mappos
+	 * @param ipos a index position
+	 * @return map position
+	 */
+	v3s16          getRealPos(v3s16 ipos);
+
+	/**
+	 * transform mappos to index pos
+	 * @param pos a real pos
+	 * @return index position
+	 */
+	v3s16          getIndexPos(v3s16 pos);
+
+	/**
+	 * get gridnode at a specific index position
+	 * @param ipos index position
+	 * @return gridnode for index
+	 */
+	path_gridnode& getIndexElement(v3s16 ipos);
+
+	/**
+	 * invert a 3d position
+	 * @param pos 3d position
+	 * @return pos *-1
+	 */
+	v3s16          invert(v3s16 pos);
+
+	/**
+	 * check if a index is within current search area
+	 * @param index position to validate
+	 * @return true/false
+	 */
+	bool           valid_index(v3s16 index);
+
+	/**
+	 * translate position to float position
+	 * @param pos integer position
+	 * @return float position
+	 */
+	v3f            tov3f(v3s16 pos);
+
+
+	/* algorithm functions */
+
+	/**
+	 * calculate 2d manahttan distance to target
+	 * @param pos position to calc distance
+	 * @return integer distance
+	 */
+	int           get_manhattandistance(v3s16 pos);
+
+	/**
+	 * get best direction based uppon heuristics
+	 * @param directions list of unchecked directions
+	 * @param g_pos mapnode to start from
+	 * @return direction to check
+	 */
+	v3s16         get_dir_heuristic(std::vector<v3s16>& directions,path_gridnode& g_pos);
+
+	/**
+	 * build internal data representation of search area
+	 * @return true/false if costmap creation was successfull
+	 */
+	bool          build_costmap();
+
+	/**
+	 * calculate cost of movement
+	 * @param pos real world position to start movement
+	 * @param dir direction to move to
+	 * @return cost information
+	 */
+	path_cost     calc_cost(v3s16 pos,v3s16 dir);
+
+	/**
+	 * recursive update whole search areas total cost information
+	 * @param ipos position to check next
+	 * @param srcdir positionc checked last time
+	 * @param total_cost cost of moving to ipos
+	 * @param level current recursion depth
+	 * @return true/false path to destination has been found
+	 */
+	bool          update_all_costs(v3s16 ipos,v3s16 srcdir,int total_cost,int level);
+
+	/**
+	 * recursive try to find a patrh to destionation
+	 * @param ipos position to check next
+	 * @param srcdir positionc checked last time
+	 * @param total_cost cost of moving to ipos
+	 * @param level current recursion depth
+	 * @return true/false path to destination has been found
+	 */
+	bool          update_cost_heuristic(v3s16 ipos,v3s16 srcdir,int current_cost,int level);
+
+	/**
+	 * recursive build a vector containing all nodes from source to destination
+	 * @param path vector to add nodes to
+	 * @param pos pos to check next
+	 * @param level recursion depth
+	 */
+	void          build_path(std::vector<v3s16>& path,v3s16 pos, int level);
+
+	/* variables */
+	int m_max_index_x;          /**< max index of search area in x direction  */
+	int m_max_index_y;          /**< max index of search area in y direction  */
+	int m_max_index_z;          /**< max index of search area in z direction  */
+
+
+	int m_searchdistance;       /**< max distance to search in each direction */
+	int m_maxdrop;              /**< maximum number of blocks a path may drop */
+	int m_maxjump;              /**< maximum number of blocks a path may jump */
+	int m_min_target_distance;  /**< current smalest path to target           */
+
+	bool m_prefetch;            /**< prefetch cost data                       */
+
+	v3s16 m_start;              /**< source position                          */
+	v3s16 m_destination;        /**< destination position                     */
+
+	limits m_limits;            /**< position limits in real map coordinates  */
+
+	/** 3d grid containing all map data already collected and analyzed */
+	std::vector<std::vector<std::vector<path_gridnode> > > m_data;
+
+	ServerEnvironment* m_env;   /**< minetest environment pointer             */
+
+#ifdef PATHFINDER_DEBUG
+
+	/**
+	 * print collected cost information
+	 */
+	void print_cost();
+
+	/**
+	 * print collected cost information in a specific direction
+	 * @param dir direction to print
+	 */
+	void print_cost(path_directions dir);
+
+	/**
+	 * print type of node as evaluated
+	 */
+	void print_type();
+
+	/**
+	 * print pathlenght for all nodes in search area
+	 */
+	void print_pathlen();
+
+	/**
+	 * print a path
+	 * @param path path to show
+	 */
+	void print_path(std::vector<v3s16> path);
+
+	/**
+	 * print y direction for all movements
+	 */
+	void print_ydir();
+
+	/**
+	 * print y direction for moving in a specific direction
+	 * @param dir direction to show data
+	 */
+	void print_ydir(path_directions dir);
+
+	/**
+	 * helper function to translate a direction to speaking text
+	 * @param dir direction to translate
+	 * @return textual name of direction
+	 */
+	std::string dir_to_name(path_directions dir);
+#endif
+};
+
+#endif /* PATHFINDER_H_ */

src/scriptapi_env.cpp

@@ -26,6 +26,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "content_sao.h"
 #include "script.h"
 #include "treegen.h"
+#include "pathfinder.h"
 #include "util/pointedthing.h"
 #include "scriptapi_types.h"
 #include "scriptapi_noise.h"
@@ -647,6 +648,69 @@ int EnvRef::l_clear_objects(lua_State *L)
 	return 0;
 }
 
+int EnvRef::l_line_of_sight(lua_State *L) {
+	float stepsize = 1.0;
+
+	//infostream<<"EnvRef::l_get_node()"<<std::endl;
+	EnvRef *o = checkobject(L, 1);
+	ServerEnvironment *env = o->m_env;
+	if(env == NULL) return 0;
+
+	// read position 1 from lua
+	v3f pos1 = checkFloatPos(L, 2);
+	// read position 2 from lua
+	v3f pos2 = checkFloatPos(L, 2);
+	//read step size from lua
+	if(lua_isnumber(L, 3))
+	stepsize = lua_tonumber(L, 3);
+
+	return (env->line_of_sight(pos1,pos2,stepsize));
+}
+
+int EnvRef::l_find_path(lua_State *L)
+{
+	EnvRef *o = checkobject(L, 1);
+	ServerEnvironment *env = o->m_env;
+
+	if(env == NULL) return 0;
+
+	v3s16 pos1                  = read_v3s16(L, 2);
+	v3s16 pos2                  = read_v3s16(L, 3);
+	unsigned int searchdistance = luaL_checkint(L, 4);
+	unsigned int max_jump       = luaL_checkint(L, 5);
+	unsigned int max_drop       = luaL_checkint(L, 6);
+	algorithm algo              = A_PLAIN_NP;
+	if(! lua_isnil(L, 7)) {
+		std::string algorithm       = luaL_checkstring(L,7);
+
+		if (algorithm == "A*")
+			algo = A_PLAIN;
+
+		if (algorithm == "Dijkstra")
+			algo = DIJKSTRA;
+	}
+
+	std::vector<v3s16> path =
+			get_Path(env,pos1,pos2,searchdistance,max_jump,max_drop,algo);
+
+	if (path.size() > 0)
+	{
+		lua_newtable(L);
+		int top = lua_gettop(L);
+		unsigned int index = 1;
+		for (std::vector<v3s16>::iterator i = path.begin(); i != path.end();i++)
+		{
+			lua_pushnumber(L,index);
+			push_v3s16(L, *i);
+			lua_settable(L, top);
+			index++;
+		}
+		return 1;
+	}
+
+	return 0;
+}
+
 int EnvRef::l_spawn_tree(lua_State *L)
 {
 	EnvRef *o = checkobject(L, 1);
@@ -780,6 +844,8 @@ const luaL_reg EnvRef::methods[] = {
 	luamethod(EnvRef, get_perlin_map),
 	luamethod(EnvRef, clear_objects),
 	luamethod(EnvRef, spawn_tree),
+	luamethod(EnvRef, line_of_sight),
+	luamethod(EnvRef, find_path),
 	{0,0}
 };
 

src/scriptapi_env.h

@@ -137,6 +137,12 @@ private:
 
 	static int l_spawn_tree(lua_State *L);
 
+
+	static int l_line_of_sight(lua_State *L);
+
+	//find a path between two positions
+	static int l_find_path(lua_State *L);
+
 public:
 	EnvRef(ServerEnvironment *env);