Adds a lfwb-inspired orbiting pixel + flashing outline animation to the sprint and combat buttons (toggleable via prefs) (#11623)

* Adds a flashing effect to the sprint and combat mode toggles (toggleable via prefs)

* Adds the ability to change the color of the hud toggle flash as well

modular_citadel/code/_onclick/hud/screen_objects.dm

@@ -12,6 +12,7 @@
 	name = "toggle combat mode"
 	icon = 'modular_citadel/icons/ui/screen_midnight.dmi'
 	icon_state = "combat_off"
+	var/mutable_appearance/flashy
 
 /obj/screen/combattoggle/Click()
 	if(iscarbon(usr))
@@ -29,6 +30,19 @@
 	else
 		icon_state = "combat_off"
 
+/obj/screen/combattoggle/update_overlays()
+	. = ..()
+	var/mob/living/carbon/user = hud?.mymob
+	if(!istype(user) || !user.client)
+		return
+
+	if((user.combat_flags & COMBAT_FLAG_COMBAT_ACTIVE) && user.client.prefs.hud_toggle_flash)
+		if(!flashy)
+			flashy = mutable_appearance('icons/mob/screen_gen.dmi', "togglefull_flash")
+		if(flashy.color != user.client.prefs.hud_toggle_color)
+			flashy.color = user.client.prefs.hud_toggle_color
+		. += flashy //TODO - beg lummox jr for the ability to force mutable appearances or images to be created rendering from their first frame of animation rather than being based entirely around the client's frame count
+
 /obj/screen/voretoggle
 	name = "toggle vore mode"
 	icon = 'modular_citadel/icons/ui/screen_midnight.dmi'

modular_citadel/code/_onclick/hud/sprint.dm

@@ -6,6 +6,7 @@
 	icon = 'modular_citadel/icons/ui/screen_midnight.dmi'
 	icon_state = "act_sprint"
 	layer = ABOVE_HUD_LAYER - 0.1
+	var/mutable_appearance/flashy
 
 /obj/screen/sprintbutton/Click()
 	if(ishuman(usr))
@@ -23,6 +24,19 @@
 	else
 		icon_state = "act_sprint"
 
+/obj/screen/sprintbutton/update_overlays()
+	. = ..()
+	var/mob/living/carbon/user = hud?.mymob
+	if(!istype(user) || !user.client)
+		return
+
+	if((user.combat_flags & COMBAT_FLAG_SPRINT_ACTIVE) && user.client.prefs.hud_toggle_flash)
+		if(!flashy)
+			flashy = mutable_appearance('icons/mob/screen_gen.dmi', "togglehalf_flash")
+		if(flashy.color != user.client.prefs.hud_toggle_color)
+			flashy.color = user.client.prefs.hud_toggle_color
+		. += flashy
+
 //Sprint buffer onscreen code.
 /datum/hud/var/obj/screen/sprint_buffer/sprint_buffer