Ling Fixes + Various other fixes

code/modules/mob/_modifiers/changeling.dm

@@ -0,0 +1,93 @@
+/datum/modifier/changeling
+	name = "changeling"
+	desc = "Changeling modifier."
+
+	var/required_chems = 1	// Default is to require at least 1 chem unit. This does not consume it.
+
+	var/chem_maintenance = 1	// How many chems are expended per cycle, if we are consuming chems.
+
+	var/max_genetic_damage = 100
+
+	var/max_stat = 0
+
+	var/use_chems = FALSE	// Do we have an upkeep cost on chems?
+
+	var/exterior_modifier = FALSE	// Should we be checking the origin mob for chems?
+
+/datum/modifier/changeling/check_if_valid()
+	var/mob/living/L = null
+	if(exterior_modifier)
+		if(origin)
+			L = origin.resolve()
+		else
+			expire()
+			return
+
+	if((!exterior_modifier && !holder.changeling_power(required_chems, 0, max_genetic_damage, max_stat)) || (exterior_modifier && L && !L.changeling_power(required_chems, 0, max_genetic_damage, max_stat)))
+		expire()
+	else
+		..()
+
+/datum/modifier/changeling/tick()
+	..()
+
+	if(use_chems)
+		var/mob/living/L = null
+
+		if(exterior_modifier)
+			L = origin.resolve()
+
+		else
+			L = holder
+
+		L.mind.changeling.chem_charges = between(0, L.mind.changeling.chem_charges - chem_maintenance, L.mind.changeling.chem_storage)
+
+/datum/modifier/changeling/thermal_sight
+	name = "Thermal Adaptation"
+	desc = "Our eyes are capable of seeing into the infrared spectrum to accurately identify prey through walls."
+	vision_flags = SEE_MOBS
+
+	on_expired_text = "<span class='alien'>Your sight returns to what it once was.</span>"
+	stacks = MODIFIER_STACK_EXTEND
+
+/datum/modifier/changeling/thermal_sight/check_if_valid()
+	var/mob/living/L = null
+
+	if(exterior_modifier)
+		L = origin.resolve()
+
+	else
+		L = holder
+
+	if(!L)
+		expire()
+		return
+
+	var/datum/changeling/changeling = L.changeling_power(0,0,100,CONSCIOUS)
+
+	if(!changeling)
+		expire()
+		return
+
+	if(!changeling.thermal_sight)
+		expire()
+		return
+
+	..()
+
+/datum/modifier/changeling/thermal_sight/expire()
+	var/mob/living/L = null
+
+	if(exterior_modifier)
+		L = origin.resolve()
+
+	else
+		L = holder
+
+	if(L)
+		var/datum/changeling/changeling = L.changeling_power(0,0,100,CONSCIOUS)
+
+		if(changeling)
+			changeling.thermal_sight = FALSE
+
+	..()

code/modules/mob/_modifiers/modifiers.dm

@@ -51,6 +51,8 @@
 	var/emp_modifier					// Added to the EMP strength, which is an inverse scale from 1 to 4, with 1 being the strongest EMP. 5 is a nullification.
 	var/explosion_modifier				// Added to the bomb strength, which is an inverse scale from 1 to 3, with 1 being gibstrength. 4 is a nullification.
 
+	var/vision_flags					// Vision flags to add to the mob. SEE_MOB, SEE_OBJ, etc.
+
 /datum/modifier/New(var/new_holder, var/new_origin)
 	holder = new_holder
 	if(new_origin)