adds a visible line when using iv drips / bloodpacks

code/game/machinery/iv_drip.dm

@@ -8,6 +8,7 @@
 	var/mob/living/carbon/attached = null
 	var/mode = 1 // 1 is injecting, 0 is taking blood.
 	var/obj/item/reagent_container/beaker = null
+	var/datum/beam/current_beam = null
 
 /obj/structure/machinery/iv_drip/update_icon()
 	if(src.attached)
@@ -35,6 +36,26 @@
 			filling.color = mix_color_from_reagents(reagents.reagent_list)
 			overlays += filling
 
+/obj/structure/machinery/iv_drip/proc/update_beam(ignore = FALSE)
+	var/beam_icon = "iv_tube"
+	if(mode)
+		if(beaker)
+			beam_icon = (beaker.reagents.total_volume == 0) ? "iv_tube" : "iv_tube_blood"
+		if(current_beam && current_beam.icon_state != beam_icon || ignore)
+			delete_beam()
+			current_beam = attached.beam(src, beam_icon)
+	else
+		if(beaker)
+			beam_icon = (attached.blood_volume == 0) ? "iv_tube" : "iv_tube_blood"
+		if(current_beam && current_beam.icon_state != beam_icon || ignore)
+			delete_beam()
+			current_beam = src.beam(attached, beam_icon)
+
+/obj/structure/machinery/iv_drip/proc/delete_beam()
+	if(current_beam)
+		qdel(current_beam)
+		current_beam = null
+
 /obj/structure/machinery/iv_drip/MouseDrop(over_object, src_location, over_location)
 	..()
 
@@ -48,6 +69,7 @@
 			"You detach \the [src] from \the [attached].")
 			attached.active_transfusions -= src
 			attached = null
+			delete_beam()
 			update_icon()
 			stop_processing()
 			return
@@ -57,6 +79,7 @@
 			"You attach \the [src] to \the [over_object].")
 			attached = over_object
 			attached.active_transfusions += src
+			update_beam(ignore = TRUE)
 			update_icon()
 			start_processing()
 
@@ -81,6 +104,7 @@
 			log_admin("[key_name(user)] put a [beaker] into [src], containing [reagentnames] at ([src.loc.x],[src.loc.y],[src.loc.z]).")
 
 			to_chat(user, "You attach \the [W] to \the [src].")
+			update_beam()
 			update_icon()
 		return
 	else
@@ -97,6 +121,7 @@
 				attached.emote("scream")
 			attached.active_transfusions -= src
 			attached = null
+			delete_beam()
 			update_icon()
 			stop_processing()
 			return
@@ -110,6 +135,7 @@
 					// speed up transfer on blood packs
 					transfer_amount = 4
 				attached.inject_blood(beaker, transfer_amount)
+				update_beam()
 				update_icon()
 
 		// Take blood
@@ -135,12 +161,14 @@
 				visible_message("\The [src] beeps loudly.")
 
 			T.take_blood(beaker,amount)
+			update_beam()
 			update_icon()
 
 /obj/structure/machinery/iv_drip/attack_hand(mob/user as mob)
 	if(src.beaker)
 		src.beaker.forceMove(get_turf(src))
 		src.beaker = null
+		update_beam()
 		update_icon()
 	else
 		return ..()
@@ -159,6 +187,7 @@
 
 	mode = !mode
 	to_chat(usr, "The IV drip is now [mode ? "injecting" : "taking blood"].")
+	update_beam(ignore = TRUE)
 
 /obj/structure/machinery/iv_drip/get_examine_text(mob/user)
 	. = ..()

code/game/objects/items/reagent_containers/blood_pack.dm

@@ -13,7 +13,9 @@
 
 	var/mode = BLOOD_BAG_INJECTING
 	var/mob/living/carbon/human/connected_to
+	var/mob/living/carbon/human/connected_from
 	var/blood_type = null
+	var/datum/beam/current_beam = null
 
 /obj/item/reagent_container/blood/Initialize()
 	. = ..()
@@ -32,6 +34,24 @@
 		if(10 to 50) icon_state = "half"
 		if(51 to INFINITY) icon_state = "full"
 
+/obj/item/reagent_container/blood/proc/update_beam(ignore = FALSE)
+	var/beam_icon = "iv_tube"
+	if(mode)
+		beam_icon = (reagents.total_volume == 0) ? "iv_tube" : "iv_tube_blood"
+		if(current_beam && current_beam.icon_state != beam_icon || ignore)
+			delete_beam()
+			current_beam = connected_to.beam(connected_from, beam_icon)
+	else
+		beam_icon = (connected_to.blood_volume == 0) ? "iv_tube" : "iv_tube_blood"
+		if(current_beam && current_beam.icon_state != beam_icon || ignore)
+			delete_beam()
+			current_beam = connected_from.beam(connected_to, beam_icon)
+
+/obj/item/reagent_container/blood/proc/delete_beam()
+	if(current_beam)
+		qdel(current_beam)
+		current_beam = null
+
 /obj/item/reagent_container/blood/attack(mob/attacked_mob, mob/user)
 	. = ..()
 
@@ -45,6 +65,8 @@
 			"You detach [src] from [connected_to].")
 		connected_to.active_transfusions -= src
 		connected_to = null
+		connected_from = null
+		delete_beam()
 		return
 
 	if(!skillcheck(user, SKILL_SURGERY, SKILL_SURGERY_NOVICE))
@@ -60,10 +82,12 @@
 
 	if(istype(attacked_mob, /mob/living/carbon/human))
 		connected_to = attacked_mob
+		connected_from = user
 		connected_to.active_transfusions += src
 		START_PROCESSING(SSobj, src)
 		user.visible_message("[user] attaches \the [src] to [connected_to].", \
 			"You attach \the [src] to [connected_to].")
+		update_beam(ignore = TRUE)
 
 /obj/item/reagent_container/blood/process()
 	//if we're not connected to anything stop doing stuff
@@ -91,6 +115,7 @@
 		if(volume > 0)
 			var/transfer_amount = REAGENTS_METABOLISM * 30
 			connected_to.inject_blood(src, transfer_amount)
+			update_beam()
 			return
 
 	// Take blood
@@ -105,6 +130,11 @@
 		return
 
 	connected_to.take_blood(src, amount)
+	update_beam()
+
+/obj/item/reagent_container/blood/dropped()
+	..()
+	bad_disconnect()
 
 ///Used to standardize effects of a blood bag disconnecting improperly
 /obj/item/reagent_container/blood/proc/bad_disconnect()
@@ -117,6 +147,8 @@
 		connected_to.emote("scream")
 	connected_to.active_transfusions -= src
 	connected_to = null
+	connected_from = null
+	delete_beam()
 
 /obj/item/reagent_container/blood/verb/toggle_mode()
 	set category = "Object"
@@ -131,6 +163,7 @@
 
 	mode = !mode
 	to_chat(usr, "The blood bag is now [mode ? "giving blood" : "taking blood"].")
+	update_beam(ignore = TRUE)
 
 
 /obj/item/reagent_container/blood/APlus