Use bound parameters for pathfinding functions operating on entities

Source/controls/plrctrls.cpp

@@ -91,7 +91,7 @@ int GetDistance(Point destination, int maxDistance)
 	}
 
 	int8_t walkpath[MAX_PATH_LENGTH];
-	int steps = FindPath(PosOkPlayer, MyPlayerId, Players[MyPlayerId].position.future.x, Players[MyPlayerId].position.future.y, destination.x, destination.y, walkpath);
+	int steps = FindPath(std::bind(PosOkPlayer, MyPlayerId, std::placeholders::_1), Players[MyPlayerId].position.future.x, Players[MyPlayerId].position.future.y, destination.x, destination.y, walkpath);
 	if (steps > maxDistance)
 		return 0;
 

Source/monster.cpp

@@ -2140,7 +2140,7 @@ bool AiPlanWalk(int i)
 	assert((DWORD)i < MAXMONSTERS);
 	auto &monster = Monsters[i];
 
-	if (FindPath(MonsterIsTileAccessible, i, monster.position.tile.x, monster.position.tile.y, monster.enemyPosition.x, monster.enemyPosition.y, path) == 0) {
+	if (FindPath(std::bind(MonsterIsTileAccessible, i, std::placeholders::_1), monster.position.tile.x, monster.position.tile.y, monster.enemyPosition.x, monster.enemyPosition.y, path) == 0) {
 		return false;
 	}
 
@@ -2207,7 +2207,7 @@ bool AiPlanPath(int i)
 	}
 
 	bool clear = LineClear(
-	    std::bind(MonsterIsTileAvalible, i, std::placeholders::_1),
+	    std::bind(MonsterIsTileAvailable, i, std::placeholders::_1),
 	    monster.position.tile,
 	    monster.enemyPosition);
 	if (!clear || (monster._pathcount >= 5 && monster._pathcount < 8)) {

Source/path.cpp

@@ -61,7 +61,7 @@ int8_t path_directions[9] = { 5, 1, 6, 2, 0, 3, 8, 4, 7 };
  * check that each step is a valid position. Store the step directions (see
  * path_directions) in path, which must have room for 24 steps
  */
-int FindPath(bool (*posOk)(int, Point), int posOkArg, int sx, int sy, int dx, int dy, int8_t path[MAX_PATH_LENGTH])
+int FindPath(const std::function<bool(Point)> &posOk, int sx, int sy, int dx, int dy, int8_t path[MAX_PATH_LENGTH])
 {
 	// clear all nodes, create root nodes for the visited/frontier linked lists
 	gdwCurNodes = 0;
@@ -97,7 +97,7 @@ int FindPath(bool (*posOk)(int, Point), int posOkArg, int sx, int sy, int dx, in
 			return 0;
 		}
 		// ran out of nodes, abort!
-		if (!path_get_path(posOk, posOkArg, nextNode, dx, dy))
+		if (!path_get_path(posOk, nextNode, dx, dy))
 			return 0;
 	}
 	// frontier is empty, no path!
@@ -187,11 +187,11 @@ bool path_solid_pieces(PATHNODE *pPath, int dx, int dy)
  *
  * @return false if we ran out of preallocated nodes to use, else true
  */
-bool path_get_path(bool (*posOk)(int, Point), int posOkArg, PATHNODE *pPath, int x, int y)
+bool path_get_path(const std::function<bool(Point)> &posOk, PATHNODE *pPath, int x, int y)
 {
 	for (auto dir : PathDirs) {
 		Point tile = pPath->position + dir;
-		bool ok = posOk(posOkArg, tile);
+		bool ok = posOk(tile);
 		if ((ok && path_solid_pieces(pPath, tile.x, tile.y)) || (!ok && tile == Point { x, y })) {
 			if (!path_parent_path(pPath, tile.x, tile.y, x, y))
 				return false;

Source/path.h

@@ -5,6 +5,8 @@
  */
 #pragma once
 
+#include <functional>
+
 #include <SDL.h>
 
 #include "engine/direction.hpp"
@@ -24,11 +26,11 @@ struct PATHNODE {
 	struct PATHNODE *NextNode;
 };
 
-int FindPath(bool (*PosOk)(int, Point), int PosOkArg, int sx, int sy, int dx, int dy, int8_t path[MAX_PATH_LENGTH]);
+int FindPath(const std::function<bool(Point)> &posOk, int sx, int sy, int dx, int dy, int8_t path[MAX_PATH_LENGTH]);
 int path_get_h_cost(int sx, int sy, int dx, int dy);
 PATHNODE *GetNextPath();
 bool path_solid_pieces(PATHNODE *pPath, int dx, int dy);
-bool path_get_path(bool (*PosOk)(int, Point), int PosOkArg, PATHNODE *pPath, int x, int y);
+bool path_get_path(const std::function<bool(Point)> &posOk, PATHNODE *pPath, int x, int y);
 bool path_parent_path(PATHNODE *pPath, int dx, int dy, int sx, int sy);
 PATHNODE *path_get_node1(int dx, int dy);
 PATHNODE *path_get_node2(int dx, int dy);

Source/player.cpp

@@ -3489,6 +3489,15 @@ void ClrPlrPath(PlayerStruct &player)
 	memset(player.walkpath, WALK_NONE, sizeof(player.walkpath));
 }
 
+/**
+ * @brief Determines if the target position is clear for the given player to stand on.
+ *
+ * This requires an ID instead of a PlayerStruct& to compare with the dPlayer lookup table values.
+ *
+ * @param pnum ID of the player.
+ * @param position Dungeon tile coordinates.
+ * @return False if something (other than the player themselves) is blocking the tile.
+ */
 bool PosOkPlayer(int pnum, Point position)
 {
 	if (position.x < 0 || position.x >= MAXDUNX || position.y < 0 || position.y >= MAXDUNY)
@@ -3550,7 +3559,7 @@ void MakePlrPath(int pnum, Point targetPosition, bool endspace)
 		return;
 	}
 
-	int path = FindPath(PosOkPlayer, pnum, player.position.future.x, player.position.future.y, targetPosition.x, targetPosition.y, player.walkpath);
+	int path = FindPath(std::bind(PosOkPlayer, pnum, std::placeholders::_1), player.position.future.x, player.position.future.y, targetPosition.x, targetPosition.y, player.walkpath);
 	if (path == 0) {
 		return;
 	}