Convert ZAS "Airflow" into a subsystem plus fixes

* Port of the "Airflow" portions of Yonaguni/EuropaStation#618
* The "airflow" part of ZAS used to be handled by a sleep'd loop.   This has the potential to bunch up and lag.  Switching to a StonedMC managed subsystem improves it.
* Fixed to ensure that zshadow mobs cannot be blown around by the wind no matter how fierce.
* Added a message to mobs informing them when their boots save them from being wind-thwapped.
* Check w_class on non-item objects if they have it defined (might as well since var/w_class is on /obj)
* Tiny optimization of c_airblock

code/ZAS/Airflow.dm

@@ -26,15 +26,17 @@ mob/living/simple_animal/slime/airflow_stun()
 	return
 
 mob/living/carbon/human/airflow_stun()
-	if(shoes)
-		if(shoes.item_flags & NOSLIP) return 0
+	if(shoes && (shoes.item_flags & NOSLIP))
+		to_chat(src, "<span class='notice'>Air suddenly rushes past you!</span>")
+		return 0
 	..()
 
 atom/movable/proc/check_airflow_movable(n)
+	if(!simulated) return 0
 
 	if(anchored && !ismob(src)) return 0
 
-	if(!istype(src,/obj/item) && n < vsc.airflow_dense_pressure) return 0
+	if(!isobj(src) && n < vsc.airflow_dense_pressure) return 0
 
 	return 1
 
@@ -50,15 +52,20 @@ mob/living/silicon/check_airflow_movable()
 	return 0
 
 
-obj/item/check_airflow_movable(n)
-	. = ..()
+obj/check_airflow_movable(n)
+	if (!(. = ..()))
+		return 0
+	if(isnull(w_class))
+		if(n < vsc.airflow_dense_pressure) return 0 //most non-item objs don't have a w_class yet
 	switch(w_class)
-		if(2)
+		if(ITEMSIZE_TINY,ITEMSIZE_SMALL)
 			if(n < vsc.airflow_lightest_pressure) return 0
-		if(3)
+		if(ITEMSIZE_NORMAL)
 			if(n < vsc.airflow_light_pressure) return 0
-		if(4,5)
+		if(ITEMSIZE_LARGE,ITEMSIZE_HUGE)
 			if(n < vsc.airflow_medium_pressure) return 0
+		else
+			if(n < vsc.airflow_dense_pressure) return 0
 
 /atom/movable/var/tmp/turf/airflow_dest
 /atom/movable/var/tmp/airflow_speed = 0
@@ -78,116 +85,6 @@ obj/item/check_airflow_movable(n)
 		return 0
 	return 1
 
-/atom/movable/proc/GotoAirflowDest(n)
-	if(!airflow_dest) return
-	if(airflow_speed < 0) return
-	if(last_airflow > world.time - vsc.airflow_delay) return
-	if(airflow_speed)
-		airflow_speed = n/max(get_dist(src,airflow_dest),1)
-		return
-	if(airflow_dest == loc)
-		step_away(src,loc)
-	if(!src.AirflowCanMove(n))
-		return
-	if(ismob(src))
-		src << "<span class='danger'>You are sucked away by airflow!</span>"
-	last_airflow = world.time
-	var/airflow_falloff = 9 - sqrt((x - airflow_dest.x) ** 2 + (y - airflow_dest.y) ** 2)
-	if(airflow_falloff < 1)
-		airflow_dest = null
-		return
-	airflow_speed = min(max(n * (9/airflow_falloff),1),9)
-	var
-		xo = airflow_dest.x - src.x
-		yo = airflow_dest.y - src.y
-		od = 0
-	airflow_dest = null
-	if(!density)
-		density = 1
-		od = 1
-	while(airflow_speed > 0)
-		if(airflow_speed <= 0) break
-		airflow_speed = min(airflow_speed,15)
-		airflow_speed -= vsc.airflow_speed_decay
-		if(airflow_speed > 7)
-			if(airflow_time++ >= airflow_speed - 7)
-				if(od)
-					density = 0
-				sleep(1 * tick_multiplier)
-		else
-			if(od)
-				density = 0
-			sleep(max(1,10-(airflow_speed+3)) * tick_multiplier)
-		if(od)
-			density = 1
-		if ((!( src.airflow_dest ) || src.loc == src.airflow_dest))
-			src.airflow_dest = locate(min(max(src.x + xo, 1), world.maxx), min(max(src.y + yo, 1), world.maxy), src.z)
-		if ((src.x == 1 || src.x == world.maxx || src.y == 1 || src.y == world.maxy))
-			break
-		if(!istype(loc, /turf))
-			break
-		step_towards(src, src.airflow_dest)
-		var/mob/M = src
-		if(istype(M) && M.client)
-			M.setMoveCooldown(vsc.airflow_mob_slowdown)
-	airflow_dest = null
-	airflow_speed = 0
-	airflow_time = 0
-	if(od)
-		density = 0
-
-
-/atom/movable/proc/RepelAirflowDest(n)
-	if(!airflow_dest) return
-	if(airflow_speed < 0) return
-	if(last_airflow > world.time - vsc.airflow_delay) return
-	if(airflow_speed)
-		airflow_speed = n/max(get_dist(src,airflow_dest),1)
-		return
-	if(airflow_dest == loc)
-		step_away(src,loc)
-	if(!src.AirflowCanMove(n))
-		return
-	if(ismob(src))
-		src << "<span clas='danger'>You are pushed away by airflow!</span>"
-	last_airflow = world.time
-	var/airflow_falloff = 9 - sqrt((x - airflow_dest.x) ** 2 + (y - airflow_dest.y) ** 2)
-	if(airflow_falloff < 1)
-		airflow_dest = null
-		return
-	airflow_speed = min(max(n * (9/airflow_falloff),1),9)
-	var
-		xo = -(airflow_dest.x - src.x)
-		yo = -(airflow_dest.y - src.y)
-		od = 0
-	airflow_dest = null
-	if(!density)
-		density = 1
-		od = 1
-	while(airflow_speed > 0)
-		if(airflow_speed <= 0) return
-		airflow_speed = min(airflow_speed,15)
-		airflow_speed -= vsc.airflow_speed_decay
-		if(airflow_speed > 7)
-			if(airflow_time++ >= airflow_speed - 7)
-				sleep(1 * tick_multiplier)
-		else
-			sleep(max(1,10-(airflow_speed+3)) * tick_multiplier)
-		if ((!( src.airflow_dest ) || src.loc == src.airflow_dest))
-			src.airflow_dest = locate(min(max(src.x + xo, 1), world.maxx), min(max(src.y + yo, 1), world.maxy), src.z)
-		if ((src.x == 1 || src.x == world.maxx || src.y == 1 || src.y == world.maxy))
-			return
-		if(!istype(loc, /turf))
-			return
-		step_towards(src, src.airflow_dest)
-		if(ismob(src) && src:client)
-			src:client:move_delay = world.time + vsc.airflow_mob_slowdown
-	airflow_dest = null
-	airflow_speed = 0
-	airflow_time = 0
-	if(od)
-		density = 0
-
 /atom/movable/Bump(atom/A)
 	if(airflow_speed > 0 && airflow_dest)
 		airflow_hit(A)

code/ZAS/Atom.dm

@@ -76,7 +76,8 @@ turf/c_airblock(turf/other)
 			return AIR_BLOCKED
 
 	var/result = 0
-	for(var/atom/movable/M in contents)
+	for(var/mm in contents)
+		var/atom/movable/M = mm
 		result |= M.c_airblock(other)
 		if(result == BLOCKED) return BLOCKED
 	return result