Improved spider web AI (#76637)

## About The Pull Request

The AI I coded for spiders deciding where to make webs when they aren't
otherwise occupied would do so by finding the _closest_ valid tile,
which seemed like a good idea at the time. The problem with that is that
the "closest" algorithm we use has a predictable search pattern which
meant that spiders would always predictably make a diagonal line of webs
pointing South West, which looked very silly.
I've rewritten how they pick targets to introduce some randomness, which
causes them to properly spread out and make a nicer-looking structure:
which serves purely to annoy spacemen who need to pass through this
area.


![image](https://github.com/tgstation/tgstation/assets/7483112/cb01828f-7653-4010-a4f5-2abc6e10b630)

I'll be honest I mostly did this while bored waiting for other PRs which
I require for my other branch to get merged.

## Why It's Good For The Game

This probably only annoyed me to be quite honest and if you left one
alone for long enough it would fill enough space that you couldn't tell
anyway, but it does look nicer now.

## Changelog

🆑
add: AI-controlled spiders will make more web-shaped webs.
/🆑

code/__DEFINES/traits.dm

@@ -354,6 +354,8 @@ Remember to update _globalvars/traits.dm if you're adding/removing/renaming trai
 #define TRAIT_WEB_WEAVER "web_weaver"
 /// Can navigate the web without getting stuck
 #define TRAIT_WEB_SURFER "web_surfer"
+/// A web is being spun on this turf presently
+#define TRAIT_SPINNING_WEB_TURF "spinning_web_turf"
 #define TRAIT_ABDUCTOR_TRAINING "abductor-training"
 #define TRAIT_ABDUCTOR_SCIENTIST_TRAINING "abductor-scientist-training"
 #define TRAIT_SURGEON "surgeon"

code/modules/mob/living/basic/space_fauna/spider/giant_spider/giant_spider_subtrees.dm

@@ -27,22 +27,31 @@
 		finish_action(controller, succeeded = TRUE)
 		return
 
-	var/list/potential_turfs = list()
-	for(var/turf/turf_in_view in oview(scan_range, our_turf))
+	var/list/turfs_by_range = list()
+	for (var/i in 1 to scan_range)
+		turfs_by_range["[i]"] = list()
+	for (var/turf/turf_in_view in oview(scan_range, our_turf))
 		if (!is_valid_web_turf(turf_in_view))
 			continue
-		potential_turfs += turf_in_view
+		turfs_by_range["[get_dist(our_turf, turf_in_view)]"] += turf_in_view
 
-	if (!length(potential_turfs))
+	var/list/final_turfs
+	for (var/list/turf_list as anything in turfs_by_range)
+		if (length(turfs_by_range[turf_list]))
+			final_turfs = turfs_by_range[turf_list]
+			break
+	if (!length(final_turfs))
 		finish_action(controller, succeeded = FALSE)
 		return
 
-	controller.set_blackboard_key(target_key, get_closest_atom(/turf/, potential_turfs, our_turf))
+	controller.set_blackboard_key(target_key, pick(final_turfs))
 	finish_action(controller, succeeded = TRUE)
 
 /datum/ai_behavior/find_unwebbed_turf/proc/is_valid_web_turf(turf/target_turf, mob/living/spider)
 	if (locate(/obj/structure/spider/stickyweb) in target_turf)
 		return FALSE
+	if (HAS_TRAIT(target_turf, TRAIT_SPINNING_WEB_TURF))
+		return FALSE
 	return !target_turf.is_blocked_turf(source_atom = spider)
 
 /// Run the spin web behaviour if we have an ability to use for it

code/modules/mob/living/basic/space_fauna/spider/spider_abilities/web.dm

@@ -34,6 +34,10 @@
 		if (feedback)
 			owner.balloon_alert(owner, "invalid location!")
 		return FALSE
+	if(HAS_TRAIT(owner.loc, TRAIT_SPINNING_WEB_TURF))
+		if (feedback)
+			owner.balloon_alert(owner, "already being webbed!")
+		return FALSE
 	if(obstructed_by_other_web())
 		if (feedback)
 			owner.balloon_alert(owner, "already webbed!")
@@ -52,11 +56,12 @@
 		owner.balloon_alert_to_viewers("sealing web...")
 	else
 		owner.balloon_alert_to_viewers("spinning web...")
-
+	ADD_TRAIT(spider_turf, TRAIT_SPINNING_WEB_TURF, REF(src))
 	if(do_after(owner, webbing_time, target = spider_turf, interaction_key = DOAFTER_SOURCE_SPIDER) && owner.loc == spider_turf)
 		plant_web(spider_turf, web)
 	else
 		owner?.balloon_alert(owner, "interrupted!") // Null check because we might have been interrupted via being disintegrated
+	REMOVE_TRAIT(spider_turf, TRAIT_SPINNING_WEB_TURF, REF(src))
 	build_all_button_icons()
 
 /// Creates a web in the current turf