Merge pull request #12680 from FartMaster69420/stack-stacking

Stack Stacking

code/game/objects/items/stacks/stack_vr.dm

@@ -0,0 +1,20 @@
+// Porting stack dragging/auto stacking from TG.
+
+/obj/item/stack/proc/merge(obj/item/stack/S) //Merge src into S, as much as possible
+	if(uses_charge || S.uses_charge) // This should realistically never happen, but in case it does lets avoid breaking things.
+		return
+
+	var/transfer = get_amount()
+	transfer = min(transfer, S.max_amount - S.amount)
+	if(pulledby)
+		pulledby.start_pulling(S)
+	transfer_fingerprints_to(S)
+	if(blood_DNA)
+		S.blood_DNA |= blood_DNA
+	use(transfer)
+	S.add(transfer)
+
+/obj/item/stack/Crossed(var/atom/movable/AM)
+	if(AM != src && istype(AM, src.type) && !AM.throwing)
+		merge(AM)
+	return ..()