Prometheans can now change hair transparency separate from body transparency. (#5832)

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## About The Pull Request

Title.
Hair transparency is now configurable from an opacity of 100-255 for
prometheans.
However, body transparency is still a toggle. This is because apparently
the transparent body is an actual _sprite_ rather than just changing the
transparency of the sprite, and I don't want to bother changing that
right now. Maybe in a later PR I will.

## Why It's Good For The Game

Customization good.

## Changelog

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🆑
qol: Prommies can now change their hair transparency separate from body
transparency.
/🆑

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code/modules/mob/living/carbon/human/update_icons.dm

@@ -445,8 +445,7 @@ GLOBAL_LIST_EMPTY(damage_icon_parts)
 		apply_layer(HAIR_LAYER)
 		return
 
-	if(head_organ.transparent)
-		face_standing += rgb(,,,120)
+	face_standing += rgb(,,,head_organ.hair_opacity)
 
 	overlays_standing[HAIR_LAYER] = image(face_standing, layer = BODY_LAYER+HAIR_LAYER)
 	apply_layer(HAIR_LAYER)

code/modules/organs/external/species/slime.dm

@@ -67,3 +67,4 @@
 	encased = 0
 	spread_dam = 1
 	transparent = 1
+	hair_opacity = 160

code/modules/organs/external/subtypes/standard.dm

@@ -258,6 +258,7 @@
 	damage_force = 3
 	throw_force = 7
 
+	var/hair_opacity = 255
 	var/can_intake_reagents = TRUE
 	var/eyes_over_markings = FALSE
 	var/eye_icon = "eyes_s"

code/modules/species/promethean/promethean.dm

@@ -117,7 +117,8 @@ var/datum/species/shapeshifter/promethean/prometheans
 	inherent_verbs = list(
 		/mob/living/proc/eat_trash,
 		/mob/living/proc/set_size,
-		/mob/living/carbon/human/proc/promethean_select_opaqueness,
+		/mob/living/carbon/human/proc/promethean_toggle_body_transparency,
+		/mob/living/carbon/human/proc/promethean_set_hair_transparency,
 		/mob/living/carbon/human/proc/prommie_blobform,
 		/mob/living/carbon/human/proc/regenerate,
 		/mob/living/carbon/human/proc/shapeshifter_select_colour,

code/modules/species/species_shapeshift.dm

@@ -509,9 +509,9 @@ var/list/wrapped_species_by_ref = list()
 
 	update_wing_showing()
 
-/mob/living/carbon/human/proc/promethean_select_opaqueness()
+/mob/living/carbon/human/proc/promethean_toggle_body_transparency()
 
-	set name = "Toggle Transparency"
+	set name = "Toggle Body Opacity" //Opacity is a shorter word than Transparency - the latter word cuts off on the verb button.
 	set category = "Abilities"
 
 	if(stat || world.time < last_special)
@@ -522,9 +522,27 @@ var/list/wrapped_species_by_ref = list()
 	for(var/limb in src.organs)
 		var/obj/item/organ/external/L = limb
 		L.transparent = !L.transparent
-	visible_message(SPAN_NOTICE("\The [src]'s interal composition seems to change."))
+	visible_message(SPAN_NOTICE("\The [src]'s internal composition seems to change."))
 	update_icons_body()
 
+/mob/living/carbon/human/proc/promethean_set_hair_transparency()
+
+	set name = "Set Hair Opacity"
+	set category = "Abilities"
+
+	if(stat || world.time < last_special)
+		return
+
+	last_special = world.time + 50
+
+	var/new_transparency = input("Pick a number between 100 and 255, 255 being no transparency.", "Change Transparency") as num|null
+	if(new_transparency)
+		new_transparency = clamp(new_transparency,100,255)
+		var/obj/item/organ/external/head/H = src.get_organ(BP_HEAD)
+		H.hair_opacity = new_transparency
+		visible_message(SPAN_NOTICE("\The [src]'s \"hair\" composition seems to change."))
+		update_hair()
+
 /datum/species/shapeshifter/handle_environment_special(mob/living/carbon/human/H)
 	// Heal remaining damage.
 	if(H.fire_stacks >= 0 && heal_rate > 0)