Animal Feeding and Hunger (#634)

changes:

rscadd: "Added hunger and feeding system for simple animals, this includes cats, dogs, mice, lizards, chickens, cows, etc"
rscadd: "Animals can now actually consume food instead of nibbling them eternally."
rscadd: "Animals can now be hand-fed by using food on them."
rscadd: "Animals will move more slowly when starving. Examining an animal will show if its hungry."
Basically added a very simple metabolising system for animals, and fixed up various eating/feeding functions. They only metabolise food, any other reagents are just removed and ignored for now, since most chemicals were designed for carbon mobs and often aren't valid

code/modules/mob/living/simple_animal/friendly/mouse.dm

@@ -30,6 +30,7 @@
 	universal_understand = 1
 	mob_size = 1
 	holder_type = /obj/item/weapon/holder/mouse
+	digest_factor = 0.05
 
 /mob/living/simple_animal/mouse/Life()
 	..()
@@ -75,6 +76,8 @@
 		holder_type = /obj/item/weapon/holder/mouse/white
 
 
+
+
 /mob/living/simple_animal/mouse/attack_hand(mob/living/carbon/human/M as mob)
 	if (src.stat == DEAD)//If the mouse is dead, we don't pet it, we just pickup the corpse on click
 		get_scooped(M)

code/modules/mob/living/simple_animal/simple_animal.dm

@@ -66,9 +66,29 @@
 	var/supernatural = 0
 	var/purge = 0
 
+	var/max_nutrition = 75
+	var/nutrition_step = 0.2 //nutrition lost per tick and per step, calculated from mob_size, 0.4 is a fallback
+	var/bite_factor = 0.4
+	var/digest_factor = 0.2 //A multiplier on how quickly reagents are digested
+
 /mob/living/simple_animal/New()
 	..()
 	verbs -= /mob/verb/observe
+	if (mob_size)
+		nutrition_step = mob_size * 0.05
+		bite_factor = mob_size * 0.3
+		max_nutrition *= 1 + (nutrition_step*3)//Max nutrition scales faster than costs, so bigger creatures eat less often
+		reagents = new/datum/reagents(5*mob_size, src)
+	else
+		reagents = new/datum/reagents(20, src)
+	nutrition = max_nutrition
+
+/mob/living/simple_animal/Move(NewLoc, direct)
+	. = ..()
+	if(.)
+		if(src.nutrition && src.stat != DEAD)
+			src.nutrition -= nutrition_step
+
 
 /mob/living/simple_animal/Login()
 	if(src && src.client)
@@ -78,6 +98,15 @@
 /mob/living/simple_animal/updatehealth()
 	return
 
+/mob/living/simple_animal/examine(mob/user)
+	..()
+	if (!nutrition)
+		user << "<span class='danger'>It looks starving!</span>"
+	else if (nutrition < max_nutrition *0.5)
+		user << "<span class='notice'>It looks hungry.</span>"
+	else if ((reagents.total_volume > 0 && nutrition > max_nutrition *0.75) || nutrition > max_nutrition *0.9)
+		user << "It looks full and contented."
+
 /mob/living/simple_animal/Life()
 	..()
 
@@ -104,7 +133,7 @@
 	handle_paralysed()
 	update_canmove()
 	handle_supernatural()
-
+	process_food()
 	//Movement
 	if(!client && !stop_automated_movement && wander && !anchored)
 		if(isturf(src.loc) && !resting && !buckled && canmove)		//This is so it only moves if it's not inside a closet, gentics machine, etc.
@@ -210,6 +239,40 @@
 	if(purge)
 		purge -= 1
 
+
+
+//Simple reagent processing for simple animals
+//This allows animals to digest food, and only food
+//Most drugs, poisons etc, are designed to work on carbons and affect many values a simple animal doesnt have
+/mob/living/simple_animal/proc/process_food()
+
+	if (nutrition)
+		nutrition -= nutrition_step//Bigger animals get hungry faster
+		nutrition = max(0,min(nutrition, max_nutrition))//clamp the value
+	else
+		if (prob(3))
+			src << "You feel hungry..."
+
+
+	if (!reagents || !reagents.total_volume)
+		return
+
+	for(var/datum/reagent/current in reagents.reagent_list)
+		var/removed = min(current.metabolism*digest_factor, current.volume)
+		if (istype(current, /datum/reagent/nutriment))//If its food, it feeds us
+			var/datum/reagent/nutriment/N = current
+			nutrition += removed*N.nutriment_factor
+		current.remove_self(removed)//If its not food, it just does nothing. no fancy effects
+
+/mob/living/simple_animal/proc/can_eat()
+	if (nutrition > max_nutrition * 0.9)
+		return 0//full
+
+	else if (nutrition > max_nutrition * 0.8)
+		return 1//content
+
+	else return 2//hungry
+
 /mob/living/simple_animal/gib()
 	..(icon_gib,1)
 
@@ -284,7 +347,10 @@
 							M.show_message("<span class='notice'>[user] applies the [MED] on [src].</span>")
 		else
 			user << "<span class='notice'>\The [src] is dead, medical items won't bring \him back to life.</span>"
-	if(meat_type && (stat == DEAD))	//if the animal has a meat, and if it is dead.
+	else if(istype(O, /obj/item/weapon/reagent_containers))
+		..()
+
+	else if(meat_type && (stat == DEAD))	//if the animal has a meat, and if it is dead.
 		if(istype(O, /obj/item/weapon/material/knife) || istype(O, /obj/item/weapon/material/knife/butch))
 			harvest(user)
 	else
@@ -320,6 +386,9 @@
 			tally = 1
 		tally *= purge
 
+	if (!nutrition)
+		tally += 4
+
 	return tally+config.animal_delay
 
 /mob/living/simple_animal/Stat()