Shielding Auras (#8760)

Ports Baystation12/Baystation12#19992 and Baystation12/Baystation12#27266.

    Added a personal shield device to the traitor tools uplink.
    Added a radiant shielding aura spell to Battlemage and Cleric.
    Added an exosuit shield drone to the mechfab.

This works, but I'm not entirely happy with the sprites. The personal shield has no on-mob shimmer, it uses a mindbatterer grenade as an icon sprite. The wizard radiant spell uses a pretty big and janky sprite as an on-mob, and the exosuit's shield sprite doesn't follow the dir the mech faces, but that one I can maybe fix on my own. If anyone knows about that last one, lemme know, Bay had code for it that we do not.

code/modules/mob/living/carbon/human/update_icons.dm

@@ -149,6 +149,11 @@ There are several things that need to be remembered:
 		if(species.has_floating_eyes)
 			ovr += species.get_eyes(src)
 
+		for(var/aura in auras)
+			var/obj/aura/A = aura
+			var/icon/aura_overlay = icon(A.icon, icon_state = A.icon_state)
+			ovr += aura_overlay
+
 		add_overlay(ovr)
 
 	if (lying_prev != lying || size_multiplier != 1)

code/modules/mob/living/life.dm

@@ -25,6 +25,8 @@
 		//Random events (vomiting etc)
 		handle_random_events()
 
+		aura_check(AURA_TYPE_LIFE)
+
 		. = 1
 
 	//Handle temperature/pressure differences between body and environment

code/modules/mob/living/living.dm

@@ -906,3 +906,25 @@ default behaviour is:
 		Paralyse(rand(8,16))
 		make_jittery(rand(150,200))
 		adjustHalLoss(rand(50,60))
+
+/mob/living/update_icons()
+	for(var/aura in auras)
+		var/obj/aura/A = aura
+		var/icon/aura_overlay = icon(A.icon, icon_state = A.icon_state)
+		add_overlay(aura_overlay)
+
+/mob/living/proc/add_aura(var/obj/aura/aura)
+	LAZYDISTINCTADD(auras, aura)
+	update_icons()
+	return TRUE
+
+/mob/living/proc/remove_aura(var/obj/aura/aura)
+	LAZYREMOVE(auras, aura)
+	update_icons()
+	return TRUE
+
+/mob/living/Destroy()
+	if(auras)
+		for(var/a in auras)
+			remove_aura(a)
+	return ..()

code/modules/mob/living/living_defense.dm

@@ -100,6 +100,28 @@
 	P.on_hit(src, absorb, def_zone)
 	return absorb
 
+/mob/living/proc/aura_check(var/type)
+	if(!auras)
+		return TRUE
+	. = TRUE
+	var/list/newargs = args - args[1]
+	for(var/a in auras)
+		var/obj/aura/aura = a
+		var/result = 0
+		switch(type)
+			if(AURA_TYPE_WEAPON)
+				result = aura.attackby(arglist(newargs))
+			if(AURA_TYPE_BULLET)
+				result = aura.bullet_act(arglist(newargs))
+			if(AURA_TYPE_THROWN)
+				result = aura.hitby(arglist(newargs))
+			if(AURA_TYPE_LIFE)
+				result = aura.life_tick()
+		if(result & AURA_FALSE)
+			. = FALSE
+		if(result & AURA_CANCEL)
+			break
+
 //For visuals, blood splatters and so on.
 /mob/living/proc/bullet_impact_visuals(var/obj/item/projectile/P, var/def_zone, var/damage)
 	var/list/impact_sounds = LAZYACCESS(P.impact_sounds, get_bullet_impact_effect_type(def_zone))
@@ -170,6 +192,8 @@
 
 //this proc handles being hit by a thrown atom
 /mob/living/hitby(atom/movable/AM as mob|obj,var/speed = THROWFORCE_SPEED_DIVISOR)//Standardization and logging -Sieve
+	if(!aura_check(AURA_TYPE_THROWN, AM, speed))
+		return
 	if(istype(AM,/obj/))
 		var/obj/O = AM
 		var/dtype = O.damtype

code/modules/mob/living/living_defines.dm

@@ -69,4 +69,5 @@
 	var/burn_mod = 1
 	var/brute_mod = 1
 
-	var/limb_breaking = FALSE // used to limit people from queuing up limb-breaks
+	var/limb_breaking = FALSE // used to limit people from queuing up limb-breaks
+	var/list/obj/aura/auras //Basically a catch-all aura/force-field thing.