NVO no longer can be used with binoculars/optics (#5983)

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# About the pull request
Original NVG wouldn't allow you to use them with binos, but when Morrow
introduced helmet optics, for some reason he didn't carry over the
limitation. I don't know if it was intended or simply was an oversight.
Sadly my revert to NVGs
(#4807) didn't go through, but
I still believe that I was right about points I brought up in the PR, so
I am going to address them bit by bit now.

# Explain why it's good for the game
Using nightvision with anything that increases your field of view gives
an unreasonable advantage which should be limited only to specs and SGs.

# Testing Photographs and Procedure
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functioning successfully, ideally including edge cases. -->

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<details>
I did test it
</details>


# Changelog

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:cl: ihatethisengine
balance: night vision optics no longer can be used with binoculars.
/:cl:

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---------

Co-authored-by: Drathek <[email protected]>

code/game/objects/items/devices/helmet_visors.dm

@@ -238,6 +238,7 @@
 		on_light = new(attached_helmet)
 		on_light.set_light_on(TRUE)
 	START_PROCESSING(SSobj, src)
+	RegisterSignal(user, COMSIG_MOB_CHANGE_VIEW, PROC_REF(change_view))
 
 /obj/item/device/helmet_visor/night_vision/deactivate_visor(obj/item/clothing/head/helmet/marine/attached_helmet, mob/living/carbon/human/user)
 	user.remove_client_color_matrix("nvg_visor", 1 SECONDS)
@@ -247,6 +248,7 @@
 	if(visor_glows)
 		qdel(on_light)
 	UnregisterSignal(user, COMSIG_HUMAN_POST_UPDATE_SIGHT)
+	UnregisterSignal(user, COMSIG_MOB_CHANGE_VIEW)
 
 	user.update_sight()
 	STOP_PROCESSING(SSobj, src)
@@ -271,6 +273,10 @@
 	if(!.)
 		return
 
+	if(user.client.view > 7)
+		to_chat(user, SPAN_WARNING("You cannot use [src] while using optics."))
+		return FALSE
+
 	if(!NVG_VISOR_USAGE(FALSE))
 		to_chat(user, SPAN_NOTICE("Your [src] is out of power! You'll need to recharge it."))
 		return FALSE
@@ -290,6 +296,21 @@
 	user.lighting_alpha = lighting_alpha
 	user.sync_lighting_plane_alpha()
 
+/obj/item/device/helmet_visor/night_vision/proc/change_view(mob/user, new_size)
+	SIGNAL_HANDLER
+	if(new_size > 7) // cannot use binos with NVO
+		var/obj/item/clothing/head/helmet/marine/attached_helmet = loc
+		if(!istype(attached_helmet))
+			return
+		deactivate_visor(attached_helmet, user)
+		to_chat(user, SPAN_NOTICE("You deactivate [src] on [attached_helmet]."))
+		playsound_client(user.client, toggle_off_sound, null, 75)
+		attached_helmet.active_visor = null
+		attached_helmet.update_icon()
+		var/datum/action/item_action/cycle_helmet_huds/cycle_action = locate() in attached_helmet.actions
+		if(cycle_action)
+			cycle_action.set_default_overlay()
+
 #undef NVG_VISOR_USAGE
 
 /atom/movable/nvg_light

code/modules/clothing/head/helmet.dm

@@ -676,6 +676,7 @@ GLOBAL_LIST_INIT(allowed_helmet_items, list(
 	var/list/total_visors = built_in_visors + inserted_visors
 
 	if(!length(total_visors))
+		to_chat(user, SPAN_WARNING("There are no visors to swap to."))
 		return FALSE
 
 	if(active_visor)
@@ -692,6 +693,11 @@ GLOBAL_LIST_INIT(allowed_helmet_items, list(
 						skipped_hud = TRUE
 						continue
 
+					if(!next_visor.can_toggle(user))
+						iterator++
+						skipped_hud = TRUE
+						continue
+
 					active_visor = next_visor
 					toggle_visor(user, visor_to_deactivate, silent = TRUE) // disables the old visor
 					toggle_visor(user)
@@ -703,15 +709,19 @@ GLOBAL_LIST_INIT(allowed_helmet_items, list(
 			iterator++
 
 	for(var/obj/item/device/helmet_visor/new_visor in total_visors)
-
 		if(!isnull(GLOB.huds[new_visor.hud_type]?.hudusers[user]))
 			continue
 
+		if(!new_visor.can_toggle(user))
+			continue
+
 		active_visor = new_visor
 		toggle_visor(user)
 		return active_visor
 
+	to_chat(user, SPAN_WARNING("There are no visors to swap to currently."))
 	return FALSE
+
 /datum/action/item_action/cycle_helmet_huds/New(Target, obj/item/holder)
 	. = ..()
 	name = "Cycle helmet HUD"