Adds Rocket Backblast (#55681)

This PR adds the backblast element, which when attached to a gun, creates giant plumes of fire when said gun is fired. The PM9 rocket launcher that nuke ops can buy kinda sucks and even a direct hit with the standard rockets loaded isn't enough to guarantee a one-hit crit on a direct hit against an armored opponent, which sucks for how much you pay for it. In that vein, I've also buffed the standard rockets a bit, they now do 50 brute up from 30 on a direct hit, and they create flames on their explosion.

Also makes a tweak to /proc/get_turf_in_angle(), since tile coordinates start at 1,1 instead of 0,0 that proc is now clamped to min 1,1 rather than 0,0

code/modules/projectiles/ammunition/caseless/rocket.dm

@@ -12,6 +12,11 @@
 	icon_state = "84mm-hedp"
 	projectile_type = /obj/projectile/bullet/a84mm
 
+/obj/item/ammo_casing/caseless/rocket/weak
+	name = "\improper PM-9HE Low-Yield"
+	desc = "An 84mm High Explosive rocket. This one isn't quite as devastating."
+	projectile_type = /obj/projectile/bullet/a84mm_weak
+
 /obj/item/ammo_casing/caseless/a75
 	desc = "A .75 bullet casing."
 	caliber = "75"

code/modules/projectiles/gun.dm

@@ -322,6 +322,8 @@
 	if(user)
 		SEND_SIGNAL(user, COMSIG_MOB_FIRED_GUN, user, target, params, zone_override)
 
+	SEND_SIGNAL(src, COMSIG_GUN_FIRED, user, target, params, zone_override)
+
 	add_fingerprint(user)
 
 	if(semicd)

code/modules/projectiles/guns/ballistic/launchers.dm

@@ -44,7 +44,8 @@
 
 /obj/item/gun/ballistic/rocketlauncher
 	name = "\improper PML-9"
-	desc = "A reusable rocket propelled grenade launcher. The words \"NT this way\" and an arrow have been written near the barrel."
+	desc = "A reusable rocket propelled grenade launcher. The words \"NT this way\" and an arrow have been written near the barrel. \
+	A sticker near the cheek rest reads, \"ENSURE AREA BEHIND IS CLEAR BEFORE FIRING\""
 	icon_state = "rocketlauncher"
 	inhand_icon_state = "rocketlauncher"
 	mag_type = /obj/item/ammo_box/magazine/internal/rocketlauncher
@@ -61,10 +62,22 @@
 	cartridge_wording = "rocket"
 	empty_indicator = TRUE
 	tac_reloads = FALSE
+	/// Do we shit flames behind us when we fire?
+	var/backblast = TRUE
+
+/obj/item/gun/ballistic/rocketlauncher/Initialize()
+	. = ..()
+	if(backblast)
+		AddElement(/datum/element/backblast)
 
 /obj/item/gun/ballistic/rocketlauncher/unrestricted
 	pin = /obj/item/firing_pin
 
+/obj/item/gun/ballistic/rocketlauncher/nobackblast
+	name = "flameless PML-11"
+	desc = "A reusable rocket propelled grenade launcher. This one has been fitted with a special coolant loop to avoid embarassing teamkill 'accidents' from backblast."
+	backblast = FALSE
+
 /obj/item/gun/ballistic/rocketlauncher/afterattack()
 	. = ..()
 	magazine.get_round(FALSE) //Hack to clear the mag after it's fired

code/modules/projectiles/projectile/bullets/_incendiary.dm

@@ -15,3 +15,58 @@
 	if(location)
 		new /obj/effect/hotspot(location)
 		location.hotspot_expose(700, 50, 1)
+
+/// Used in [the backblast element][/datum/element/backblast]
+/obj/projectile/bullet/incendiary/backblast
+	damage = 15
+	range = 10 // actually overwritten in the backblast element
+	alpha = 0
+	pass_flags = PASSTABLE | PASSMOB
+	sharpness = SHARP_NONE
+	shrapnel_type = null
+	embedding = null
+	ricochet_chance = 10000
+	ricochets_max = 4
+	ricochet_incidence_leeway = 0
+	suppressed = SUPPRESSED_VERY
+	damage_type = BURN
+	flag = BOMB
+	speed = 1.2
+	wound_bonus = 30
+	bare_wound_bonus = 30
+	wound_falloff_tile = -4
+	fire_stacks = 3
+
+	/// Lazy attempt at knockback, any items this plume hits will be knocked back this far. Decrements with each tile passed.
+	var/knockback_range = 7
+	/// A lazylist of all the items we've already knocked back, so we don't do it again
+	var/list/launched_items
+
+/// we only try to knock back the first 6 items per tile
+#define BACKBLAST_MAX_ITEM_KNOCKBACK	6
+
+/obj/projectile/bullet/incendiary/backblast/Move()
+	. = ..()
+	if(knockback_range <= 0)
+		return
+	knockback_range--
+	var/turf/current_turf = get_turf(src)
+	var/turf/throw_at_turf = get_turf_in_angle(Angle, current_turf, 7)
+	var/thrown_items = 0
+
+	for(var/iter in current_turf.contents)
+		if(thrown_items > BACKBLAST_MAX_ITEM_KNOCKBACK)
+			break
+		if(isitem(iter))
+			var/obj/item/iter_item = iter
+			if(iter_item.anchored || LAZYFIND(launched_items, iter_item) || iter_item.throwing)
+				continue
+			thrown_items++
+			iter_item.throw_at(throw_at_turf, knockback_range, knockback_range)
+			LAZYADD(launched_items, iter_item)
+		else if(isliving(iter))
+			var/mob/living/incineratee = iter
+			incineratee.take_bodypart_damage(0, damage, wound_bonus=wound_bonus, bare_wound_bonus=bare_wound_bonus)
+			incineratee.adjust_fire_stacks(fire_stacks)
+
+#undef BACKBLAST_MAX_ITEM_KNOCKBACK

code/modules/projectiles/projectile/special/rocket.dm

@@ -10,6 +10,7 @@
 	explosion(target, -1, 0, 2)
 	return BULLET_ACT_HIT
 
+/// PM9 HEDP rocket
 /obj/projectile/bullet/a84mm
 	name ="\improper HEDP rocket"
 	desc = "USE A WEEL GUN"
@@ -33,11 +34,12 @@
 		S.take_overall_damage(anti_armour_damage*0.75, anti_armour_damage*0.25)
 	return BULLET_ACT_HIT
 
+/// PM9 standard rocket
 /obj/projectile/bullet/a84mm_he
 	name ="\improper HE missile"
 	desc = "Boom."
 	icon_state = "missile"
-	damage = 30
+	damage = 50
 	ricochets_max = 0 //it's a MISSILE
 	embedding = null
 	shrapnel_type = null
@@ -45,11 +47,30 @@
 /obj/projectile/bullet/a84mm_he/on_hit(atom/target, blocked=0)
 	..()
 	if(!isliving(target)) //if the target isn't alive, so is a wall or something
-		explosion(target, 0, 1, 2, 4)
+		explosion(target, 0, 1, 2, 4, flame_range = 3)
 	else
-		explosion(target, 0, 0, 2, 4)
+		explosion(target, 0, 0, 2, 4, flame_range = 3)
 	return BULLET_ACT_HIT
 
+/// PM9 weak rocket
+/obj/projectile/bullet/a84mm_weak
+	name ="low-yield HE missile"
+	desc = "Boom, but less so."
+	icon_state = "missile"
+	damage = 30
+	ricochets_max = 0 //it's a MISSILE
+	embedding = null
+	shrapnel_type = null
+
+/obj/projectile/bullet/a84mm_weak/on_hit(atom/target, blocked=0)
+	..()
+	if(!isliving(target)) //if the target isn't alive, so is a wall or something
+		explosion(target, 0, 1, 2, 4, flame_range = 3)
+	else
+		explosion(target, 0, 0, 2, 4, flame_range = 3)
+	return BULLET_ACT_HIT
+
+/// Mech BRM-6 missile
 /obj/projectile/bullet/a84mm_br
 	name ="\improper HE missile"
 	desc = "Boom."