MODules don't create visual overlays when their required part isn't deployed (#87452)

## About The Pull Request
#86825 allowed MODsuits to only have a few of their parts deployed but
didn't change MODule overlay code, resulting in modules like welding
visor showing up even if you only have your gloves active.

## Why It's Good For The Game

Glitchy visuals begone.

## Changelog
🆑
fix: MODules don't create visual overlays when their required part isn't
deployed
/🆑

---------

Co-authored-by: Fikou <23585223+Fikou@users.noreply.github.com>
Co-authored-by: LemonInTheDark <58055496+LemonInTheDark@users.noreply.github.com>

code/modules/mod/mod_activation.dm

@@ -226,7 +226,8 @@
 		part.heat_protection = NONE
 		part.cold_protection = NONE
 		part.alternate_worn_layer = part_datum.unsealed_layer
-	wearer.update_clothing(part.slot_flags)
+	generate_suit_mask()
+	wearer.update_clothing(part.slot_flags | slot_flags)
 	wearer.update_obscured_slots(part.visor_flags_inv)
 	if((part.clothing_flags & (MASKINTERNALS|HEADINTERNALS)) && wearer.invalid_internals())
 		wearer.cutoff_internals()
@@ -263,8 +264,9 @@
 				continue
 			module.on_suit_deactivation()
 	update_speed()
-	update_appearance(UPDATE_ICON_STATE)
 	update_charge_alert()
+	update_appearance(UPDATE_ICON_STATE)
+	generate_suit_mask()
 	wearer.update_clothing(slot_flags)
 
 /// Quickly deploys all the suit parts and if successful, seals them and turns on the suit. Intended mostly for outfits.

code/modules/mod/mod_control.dm

@@ -475,6 +475,30 @@
 	wearer.update_spacesuit_hud_icon("0")
 	wearer = null
 
+/obj/item/mod/control/proc/get_sealed_slots(list/parts)
+	var/covered_slots = NONE
+	for(var/obj/item/part as anything in parts)
+		if(!get_part_datum(part).sealed)
+			parts -= part
+			continue
+		covered_slots |= part.slot_flags
+	return covered_slots
+
+/obj/item/mod/control/proc/generate_suit_mask()
+	var/list/parts = get_parts(all = TRUE)
+	var/covered_slots = get_sealed_slots(parts)
+	if(GLOB.mod_masks[skin])
+		if(GLOB.mod_masks[skin]["[covered_slots]"])
+			return GLOB.mod_masks[skin]["[covered_slots]"]
+	else
+		GLOB.mod_masks[skin] = list()
+	var/icon/slot_mask = icon('icons/blanks/32x32.dmi', "nothing")
+	for(var/obj/item/part as anything in parts)
+		slot_mask.Blend(icon(part.worn_icon, part.icon_state), ICON_OVERLAY)
+	slot_mask.Blend("#fff", ICON_ADD)
+	GLOB.mod_masks[skin]["[covered_slots]"] = slot_mask
+	return GLOB.mod_masks[skin]["[covered_slots]"]
+
 /obj/item/mod/control/proc/clean_up()
 	if(QDELING(src))
 		unset_wearer()

code/modules/mod/modules/_module.dm

@@ -45,6 +45,8 @@
 	var/allow_flags = NONE
 	/// A list of slots required in the suit to work. Formatted like list(x|y, z, ...) where either x or y are required and z is required.
 	var/list/required_slots = list()
+	/// If TRUE worn overlay will be masked with the suit, preventing any bits from poking out of its controur
+	var/mask_worn_overlay = FALSE
 	/// Timer for the cooldown
 	COOLDOWN_DECLARE(cooldown_timer)
 
@@ -335,23 +337,47 @@
 /// Generates an icon to be used for the suit's worn overlays
 /obj/item/mod/module/proc/generate_worn_overlay(mutable_appearance/standing)
 	. = list()
-	if(!mod.active)
+	if(!mod.active || !has_required_parts(mod.mod_parts, need_extended = TRUE))
 		return
-	var/used_overlay
-	if(overlay_state_use && !COOLDOWN_FINISHED(src, cooldown_timer))
-		used_overlay = overlay_state_use
-	else if(overlay_state_active && active)
-		used_overlay = overlay_state_active
-	else if(overlay_state_inactive)
-		used_overlay = overlay_state_inactive
+	var/used_overlay = get_current_overlay_state()
+	if (!used_overlay)
+		return
+	var/mutable_appearance/module_icon
+	if(mask_worn_overlay)
+		module_icon = mutable_appearance(get_module_icon_cache(used_overlay), layer = standing.layer + 0.1)
 	else
-		return
-	var/mutable_appearance/module_icon = mutable_appearance(overlay_icon_file, used_overlay, layer = standing.layer + 0.1)
+		module_icon = mutable_appearance(overlay_icon_file, used_overlay, layer = standing.layer + 0.1)
 	if(!use_mod_colors)
 		module_icon.appearance_flags |= RESET_COLOR
+
 	. += module_icon
 	SEND_SIGNAL(src, COMSIG_MODULE_GENERATE_WORN_OVERLAY, ., standing)
 
+/obj/item/mod/module/proc/get_current_overlay_state()
+	if(overlay_state_use && !COOLDOWN_FINISHED(src, cooldown_timer))
+		return overlay_state_use
+	if(overlay_state_active && active)
+		return overlay_state_active
+	if(overlay_state_inactive)
+		return overlay_state_inactive
+	return null
+
+/obj/item/mod/module/proc/get_module_icon_cache(used_overlay)
+	var/covered_slots = mod.get_sealed_slots(mod.get_parts(all = TRUE))
+	if (GLOB.mod_module_overlays[mod.skin])
+		if (GLOB.mod_module_overlays[mod.skin]["[covered_slots]"])
+			if (GLOB.mod_module_overlays[mod.skin]["[covered_slots]"][used_overlay])
+				return GLOB.mod_module_overlays[mod.skin]["[covered_slots]"][used_overlay]
+		else
+			GLOB.mod_module_overlays[mod.skin]["[covered_slots]"] = list()
+	else
+		GLOB.mod_module_overlays[mod.skin] = list()
+		GLOB.mod_module_overlays[mod.skin]["[covered_slots]"] = list()
+	var/icon/mod_mask = icon(mod.generate_suit_mask())
+	mod_mask.Blend(icon(overlay_icon_file, used_overlay), ICON_MULTIPLY)
+	GLOB.mod_module_overlays[mod.skin]["[covered_slots]"][used_overlay] = mod_mask
+	return GLOB.mod_module_overlays[mod.skin]["[covered_slots]"][used_overlay]
+
 /// Updates the signal used by active modules to be activated
 /obj/item/mod/module/proc/update_signal(value)
 	switch(value)

code/modules/mod/modules/modules_antag.dm

@@ -16,6 +16,7 @@
 	overlay_state_inactive = "module_armorbooster_off"
 	overlay_state_active = "module_armorbooster_on"
 	use_mod_colors = TRUE
+	mask_worn_overlay = TRUE
 	/// Whether or not this module removes pressure protection.
 	var/remove_pressure_protection = TRUE
 	/// Speed added to the control unit.
@@ -213,6 +214,7 @@
 	removable = FALSE
 	incompatible_modules = list(/obj/item/mod/module/insignia)
 	overlay_state_inactive = "module_insignia"
+	mask_worn_overlay = TRUE
 
 /obj/item/mod/module/insignia/generate_worn_overlay(mutable_appearance/standing)
 	overlay_state_inactive = "[initial(overlay_state_inactive)]-[mod.skin]"
@@ -266,6 +268,7 @@
 
 //Bite of 87 Springlock - Equips faster, disguised as DNA lock.
 /obj/item/mod/module/springlock/bite_of_87
+	step_change = 0.1
 
 /obj/item/mod/module/springlock/bite_of_87/Initialize(mapload)
 	. = ..()
@@ -276,12 +279,6 @@
 	complexity = initial(the_dna_lock_behind_the_slaughter.complexity)
 	use_energy_cost = initial(the_dna_lock_behind_the_slaughter.use_energy_cost)
 
-/obj/item/mod/module/springlock/bite_of_87/on_install()
-	mod.activation_step_time *= 0.1
-
-/obj/item/mod/module/springlock/bite_of_87/on_uninstall(deleting = FALSE)
-	mod.activation_step_time *= 10
-
 /obj/item/mod/module/springlock/bite_of_87/on_suit_activation()
 	..()
 	if(check_holidays(APRIL_FOOLS) || prob(1))

code/modules/mod/modules/modules_maint.dm

@@ -14,12 +14,13 @@
 	var/static/list/gas_connections = list(
 		COMSIG_TURF_EXPOSE = PROC_REF(on_wearer_exposed_gas),
 	)
+	var/step_change = 0.5
 
 /obj/item/mod/module/springlock/on_install()
-	mod.activation_step_time *= 0.5
+	mod.activation_step_time *= step_change
 
 /obj/item/mod/module/springlock/on_uninstall(deleting = FALSE)
-	mod.activation_step_time *= 2
+	mod.activation_step_time /= step_change
 
 /obj/item/mod/module/springlock/on_suit_activation()
 	RegisterSignal(mod.wearer, COMSIG_ATOM_EXPOSE_REAGENTS, PROC_REF(on_wearer_exposed))