Stuff Goon People Talked about wanting

code/__DEFINES/path.dm

@@ -3,3 +3,23 @@
 #define CANASTARPASS_DENSITY 0
 /// If this is set, we bypass density checks and always call the proc
 #define CANASTARPASS_ALWAYS_PROC 1
+
+/**
+ * A helper macro to see if it's possible to step from the first turf into the second one, minding things like door access and directional windows.
+ * If you really want to optimize things, optimize this, cuz this gets called a lot.
+ * We do early next.density check despite it being already checked in LinkBlockedWithAccess for short-circuit performance
+ */
+#define CAN_STEP(cur_turf, next, simulated_only, pass_info, avoid) (next && !next.density && !(simulated_only && SSpathfinder.space_type_cache[next.type]) && !cur_turf.LinkBlockedWithAccess(next, pass_info) && (next != avoid))
+
+#define DIAGONAL_DO_NOTHING NONE
+#define DIAGONAL_REMOVE_ALL 1
+#define DIAGONAL_REMOVE_CLUNKY 2
+
+// Set of delays for path_map reuse
+// The longer you go, the higher the risk of invalid paths
+#define MAP_REUSE_INSTANT (0)
+#define MAP_REUSE_SNAPPY (0.5 SECONDS)
+#define MAP_REUSE_FAST (2 SECONDS)
+#define MAP_REUSE_SLOW (20 SECONDS)
+// Longest delay, so any maps older then this will be discarded from the subsystem cache
+#define MAP_REUSE_SLOWEST (60 SECONDS)

code/__HELPERS/paths/jps.dm

@@ -0,0 +1,306 @@
+/**
+ * This file contains the stuff you need for using JPS (Jump Point Search) pathing, an alternative to A* that skips
+ * over large numbers of uninteresting tiles resulting in much quicker pathfinding solutions. Mind that diagonals
+ * cost the same as cardinal moves currently, so paths may look a bit strange, but should still be optimal.
+ */
+
+/// A helper macro for JPS, for telling when a node has forced neighbors that need expanding
+/// Only usable in the context of the jps datum because of the datum vars it relies on
+#define STEP_NOT_HERE_BUT_THERE(cur_turf, dirA, dirB) ((!CAN_STEP(cur_turf, get_step(cur_turf, dirA), simulated_only, pass_info, avoid) && CAN_STEP(cur_turf, get_step(cur_turf, dirB), simulated_only, pass_info, avoid)))
+
+/// The JPS Node datum represents a turf that we find interesting enough to add to the open list and possibly search for new tiles from
+/datum/jps_node
+	/// The turf associated with this node
+	var/turf/tile
+	/// The node we just came from
+	var/datum/jps_node/previous_node
+	/// The A* node weight (f_value = number_of_tiles + heuristic)
+	var/f_value
+	/// The A* node heuristic (a rough estimate of how far we are from the goal)
+	var/heuristic
+	/// How many steps it's taken to get here from the start (currently pulling double duty as steps taken & cost to get here, since all moves incl diagonals cost 1 rn)
+	var/number_tiles
+	/// How many steps it took to get here from the last node
+	var/jumps
+	/// Nodes store the endgoal so they can process their heuristic without a reference to the pathfind datum
+	var/turf/node_goal
+
+/datum/jps_node/New(turf/our_tile, datum/jps_node/incoming_previous_node, jumps_taken, turf/incoming_goal)
+	tile = our_tile
+	jumps = jumps_taken
+	if(incoming_goal) // if we have the goal argument, this must be the first/starting node
+		node_goal = incoming_goal
+	else if(incoming_previous_node) // if we have the parent, this is from a direct lateral/diagonal scan, we can fill it all out now
+		previous_node = incoming_previous_node
+		number_tiles = previous_node.number_tiles + jumps
+		node_goal = previous_node.node_goal
+		heuristic = get_dist(tile, node_goal)
+		f_value = number_tiles + heuristic
+	// otherwise, no parent node means this is from a subscan lateral scan, so we just need the tile for now until we call [datum/jps/proc/update_parent] on it
+
+/datum/jps_node/Destroy(force, ...)
+	previous_node = null
+	return ..()
+
+/datum/jps_node/proc/update_parent(datum/jps_node/new_parent)
+	previous_node = new_parent
+	node_goal = previous_node.node_goal
+	jumps = get_dist(tile, previous_node.tile)
+	number_tiles = previous_node.number_tiles + jumps
+	heuristic = get_dist(tile, node_goal)
+	f_value = number_tiles + heuristic
+
+/// TODO: Macro this to reduce proc overhead
+/proc/HeapPathWeightCompare(datum/jps_node/a, datum/jps_node/b)
+	return b.f_value - a.f_value
+
+/datum/pathfind/jps
+	/// The movable we are pathing
+	var/atom/movable/caller
+	/// The turf we're trying to path to (note that this won't track a moving target)
+	var/turf/end
+	/// The open list/stack we pop nodes out from (TODO: make this a normal list and macro-ize the heap operations to reduce proc overhead)
+	var/datum/heap/open
+	/// The list we compile at the end if successful to pass back
+	var/list/path
+	///An assoc list that serves as the closed list. Key is the turf, points to true if we've seen it before
+	var/list/found_turfs
+
+	/// How far away we have to get to the end target before we can call it quits
+	var/mintargetdist = 0
+	/// If we should delete the first step in the path or not. Used often because it is just the starting tile
+	var/skip_first = FALSE
+	///Defines how we handle diagonal moves. See __DEFINES/path.dm
+	var/diagonal_handling = DIAGONAL_REMOVE_CLUNKY
+
+/datum/pathfind/jps/proc/setup(atom/movable/caller, list/access, max_distance, simulated_only, avoid, list/datum/callback/on_finish, atom/goal, mintargetdist, skip_first, diagonal_handling)
+	src.caller = caller
+	src.pass_info = new(caller, access)
+	src.max_distance = max_distance
+	src.simulated_only = simulated_only
+	src.avoid = avoid
+	src.on_finish = on_finish
+	src.mintargetdist = mintargetdist
+	src.skip_first = skip_first
+	src.diagonal_handling = diagonal_handling
+	end = get_turf(goal)
+	open = new /datum/heap(/proc/HeapPathWeightCompare)
+	found_turfs = list()
+
+/datum/pathfind/jps/Destroy(force)
+	. = ..()
+	caller = null
+	end = null
+	open = null
+
+/datum/pathfind/jps/start()
+	start = start || get_turf(caller)
+	. = ..()
+	if(!.)
+		return .
+
+	if(!get_turf(end))
+		stack_trace("Invalid JPS destination")
+		return FALSE
+	if(start.z != end.z || start == end ) //no pathfinding between z levels
+		return FALSE
+	if(max_distance && (max_distance < get_dist(start, end))) //if start turf is farther than max_distance from end turf, no need to do anything
+		return FALSE
+
+	var/datum/jps_node/current_processed_node = new (start, -1, 0, end)
+	open.insert(current_processed_node)
+	found_turfs[start] = TRUE // i'm sure this is fine
+	return TRUE
+
+/datum/pathfind/jps/search_step()
+	. = ..()
+	if(!.)
+		return .
+	if(QDELETED(caller))
+		return FALSE
+
+	while(!open.is_empty() && !path)
+		var/datum/jps_node/current_processed_node = open.pop() //get the lower f_value turf in the open list
+		if(max_distance && (current_processed_node.number_tiles > max_distance))//if too many steps, don't process that path
+			continue
+
+		var/turf/current_turf = current_processed_node.tile
+		for(var/scan_direction in list(EAST, WEST, NORTH, SOUTH))
+			lateral_scan_spec(current_turf, scan_direction, current_processed_node)
+
+		for(var/scan_direction in list(NORTHEAST, SOUTHEAST, NORTHWEST, SOUTHWEST))
+			diag_scan_spec(current_turf, scan_direction, current_processed_node)
+
+		// Stable, we'll just be back later
+		if(TICK_CHECK)
+			return TRUE
+	return TRUE
+
+/datum/pathfind/jps/finished()
+	//we're done! turn our reversed path (end to start) into a path (start to end)
+	found_turfs = null
+	QDEL_NULL(open)
+
+	var/list/path = src.path || list()
+	path = reverseList(path)
+	switch(diagonal_handling)
+		if(DIAGONAL_REMOVE_CLUNKY)
+			path = remove_clunky_diagonals(path, pass_info, simulated_only, avoid)
+		if(DIAGONAL_REMOVE_ALL)
+			path = remove_diagonals(path, pass_info, simulated_only, avoid)
+	if(skip_first && length(path) > 0)
+		path.Cut(1,2)
+	hand_back(path)
+	return ..()
+
+/// Called when we've hit the goal with the node that represents the last tile, then sets the path var to that path so it can be returned by [datum/pathfind/proc/search]
+/datum/pathfind/jps/proc/unwind_path(datum/jps_node/unwind_node)
+	path = new()
+	var/turf/iter_turf = unwind_node.tile
+	path.Add(iter_turf)
+
+	while(unwind_node.previous_node)
+		var/dir_goal = get_dir(iter_turf, unwind_node.previous_node.tile)
+		for(var/i in 1 to unwind_node.jumps)
+			iter_turf = get_step(iter_turf,dir_goal)
+			path.Add(iter_turf)
+		unwind_node = unwind_node.previous_node
+
+/**
+ * For performing lateral scans from a given starting turf.
+ *
+ * These scans are called from both the main search loop, as well as subscans for diagonal scans, and they treat finding interesting turfs slightly differently.
+ * If we're doing a normal lateral scan, we already have a parent node supplied, so we just create the new node and immediately insert it into the heap, ezpz.
+ * If we're part of a subscan, we still need for the diagonal scan to generate a parent node, so we return a node datum with just the turf and let the diag scan
+ * proc handle transferring the values and inserting them into the heap.
+ *
+ * Arguments:
+ * * original_turf: What turf did we start this scan at?
+ * * heading: What direction are we going in? Obviously, should be cardinal
+ * * parent_node: Only given for normal lateral scans, if we don't have one, we're a diagonal subscan.
+*/
+/datum/pathfind/jps/proc/lateral_scan_spec(turf/original_turf, heading, datum/jps_node/parent_node)
+	var/steps_taken = 0
+
+	var/turf/current_turf = original_turf
+	var/turf/lag_turf = original_turf
+	var/datum/can_pass_info/pass_info = src.pass_info
+
+	while(TRUE)
+		if(path)
+			return
+		lag_turf = current_turf
+		current_turf = get_step(current_turf, heading)
+		steps_taken++
+		if(!CAN_STEP(lag_turf, current_turf, simulated_only, pass_info, avoid))
+			return
+
+		if(current_turf == end || (mintargetdist && (get_dist(current_turf, end) <= mintargetdist)))
+			var/datum/jps_node/final_node = new(current_turf, parent_node, steps_taken)
+			found_turfs[current_turf] = TRUE
+			if(parent_node) // if this is a direct lateral scan we can wrap up, if it's a subscan from a diag, we need to let the diag make their node first, then finish
+				unwind_path(final_node)
+			return final_node
+		else if(found_turfs[current_turf]) // already visited, essentially in the closed list
+			return
+		else
+			found_turfs[current_turf] = TRUE
+
+		if(parent_node && parent_node.number_tiles + steps_taken > max_distance)
+			return
+
+		var/interesting = FALSE // have we found a forced neighbor that would make us add this turf to the open list?
+
+		switch(heading)
+			if(NORTH)
+				if(STEP_NOT_HERE_BUT_THERE(current_turf, WEST, NORTHWEST) || STEP_NOT_HERE_BUT_THERE(current_turf, EAST, NORTHEAST))
+					interesting = TRUE
+			if(SOUTH)
+				if(STEP_NOT_HERE_BUT_THERE(current_turf, WEST, SOUTHWEST) || STEP_NOT_HERE_BUT_THERE(current_turf, EAST, SOUTHEAST))
+					interesting = TRUE
+			if(EAST)
+				if(STEP_NOT_HERE_BUT_THERE(current_turf, NORTH, NORTHEAST) || STEP_NOT_HERE_BUT_THERE(current_turf, SOUTH, SOUTHEAST))
+					interesting = TRUE
+			if(WEST)
+				if(STEP_NOT_HERE_BUT_THERE(current_turf, NORTH, NORTHWEST) || STEP_NOT_HERE_BUT_THERE(current_turf, SOUTH, SOUTHWEST))
+					interesting = TRUE
+
+		if(interesting)
+			var/datum/jps_node/newnode = new(current_turf, parent_node, steps_taken)
+			if(parent_node) // if we're a diagonal subscan, we'll handle adding ourselves to the heap in the diag
+				open.insert(newnode)
+			return newnode
+
+/**
+ * For performing diagonal scans from a given starting turf.
+ *
+ * Unlike lateral scans, these only are called from the main search loop, so we don't need to worry about returning anything,
+ * though we do need to handle the return values of our lateral subscans of course.
+ *
+ * Arguments:
+ * * original_turf: What turf did we start this scan at?
+ * * heading: What direction are we going in? Obviously, should be diagonal
+ * * parent_node: We should always have a parent node for diagonals
+*/
+/datum/pathfind/jps/proc/diag_scan_spec(turf/original_turf, heading, datum/jps_node/parent_node)
+	var/steps_taken = 0
+	var/turf/current_turf = original_turf
+	var/turf/lag_turf = original_turf
+	var/datum/can_pass_info/pass_info = src.pass_info
+
+	while(TRUE)
+		if(path)
+			return
+		lag_turf = current_turf
+		current_turf = get_step(current_turf, heading)
+		steps_taken++
+		if(!CAN_STEP(lag_turf, current_turf, simulated_only, pass_info, avoid))
+			return
+
+		if(current_turf == end || (mintargetdist && (get_dist(current_turf, end) <= mintargetdist)))
+			var/datum/jps_node/final_node = new(current_turf, parent_node, steps_taken)
+			found_turfs[current_turf] = TRUE
+			unwind_path(final_node)
+			return
+		else if(found_turfs[current_turf]) // already visited, essentially in the closed list
+			return
+		else
+			found_turfs[current_turf] = TRUE
+
+		if(parent_node.number_tiles + steps_taken > max_distance)
+			return
+
+		var/interesting = FALSE // have we found a forced neighbor that would make us add this turf to the open list?
+		var/datum/jps_node/possible_child_node // otherwise, did one of our lateral subscans turn up something?
+
+		switch(heading)
+			if(NORTHWEST)
+				if(STEP_NOT_HERE_BUT_THERE(current_turf, EAST, NORTHEAST) || STEP_NOT_HERE_BUT_THERE(current_turf, SOUTH, SOUTHWEST))
+					interesting = TRUE
+				else
+					possible_child_node = (lateral_scan_spec(current_turf, WEST) || lateral_scan_spec(current_turf, NORTH))
+			if(NORTHEAST)
+				if(STEP_NOT_HERE_BUT_THERE(current_turf, WEST, NORTHWEST) || STEP_NOT_HERE_BUT_THERE(current_turf, SOUTH, SOUTHEAST))
+					interesting = TRUE
+				else
+					possible_child_node = (lateral_scan_spec(current_turf, EAST) || lateral_scan_spec(current_turf, NORTH))
+			if(SOUTHWEST)
+				if(STEP_NOT_HERE_BUT_THERE(current_turf, EAST, SOUTHEAST) || STEP_NOT_HERE_BUT_THERE(current_turf, NORTH, NORTHWEST))
+					interesting = TRUE
+				else
+					possible_child_node = (lateral_scan_spec(current_turf, SOUTH) || lateral_scan_spec(current_turf, WEST))
+			if(SOUTHEAST)
+				if(STEP_NOT_HERE_BUT_THERE(current_turf, WEST, SOUTHWEST) || STEP_NOT_HERE_BUT_THERE(current_turf, NORTH, NORTHEAST))
+					interesting = TRUE
+				else
+					possible_child_node = (lateral_scan_spec(current_turf, SOUTH) || lateral_scan_spec(current_turf, EAST))
+
+		if(interesting || possible_child_node)
+			var/datum/jps_node/newnode = new(current_turf, parent_node, steps_taken)
+			open.insert(newnode)
+			if(possible_child_node)
+				possible_child_node.update_parent(newnode)
+				open.insert(possible_child_node)
+				if(possible_child_node.tile == end || (mintargetdist && (get_dist(possible_child_node.tile, end) <= mintargetdist)))
+					unwind_path(possible_child_node)
+			return