mob-engine/init.lua

creatures = {}

-- Max number of mobs per mapblock
creatures.zombie_max = 3
creatures.ghost_max = 1
creatures.sheep_max = 4

creatures.ANIM_STAND = 1
creatures.ANIM_SIT = 2
creatures.ANIM_LAY = 3
creatures.ANIM_WALK  = 4
creatures.ANIM_EAT = 5
creatures.ANIM_RUN = 6

-- Drop items (when not killed by player) only if items get removed
creatures.drop_on_death = false
local remove_items = minetest.setting_get("remove_items")
local remove_items_2 = minetest.setting_get("item_entity_ttl")
if minetest.get_modpath("builtin_item") ~= nil and ((remove_items ~= nil and tonumber(remove_items) > 0) or
    (remove_items_2 ~= nil and tonumber(remove_items_2) > 0)) then
	creatures.drop_on_death = true
end

-- spawning controls (experimental)
creatures.spawned = {}
local spawn_day = 600
local tod = 0
local absolute_mob_max = 50

local function timer(tick)
	tod = tod + 1
	if tod > spawn_day then
		tod = 0
		creatures.spawned = nil
		creatures.spawned = {}
	end
	minetest.after(tick, timer, tick)
end

timer(1)


local tool_uses = {0, 30, 110, 150, 280, 300, 500, 1000}

-- helping functions

function creatures.spawn(pos, number, mob, limit, range, abs_max)
	if not pos or not number or not mob then return end
	if number < 1 then return end
	if limit == nil then limit = 1 end
	if range == nil then range = 10 end
	if abs_max == nil then abs_max = absolute_mob_max end
	local m_name = string.sub(mob,11)
	local spawned = creatures.spawned[m_name]
	if not spawned then spawned = 0 end
	local res,mobs,player_near = creatures.find_mates(pos, m_name, range)
	for i=1,number do
		local x = 1/math.random(1,3)
		local z = 1/math.random(1,3)
		local p = {x=pos.x+x,y=pos.y,z=pos.z+z}
		if mobs+i <= limit and spawned+i < abs_max then
			local obj = minetest.add_entity(p, mob)
			if obj then
				creatures.spawned[m_name] = spawned + 1
				minetest.log("action", "Spawned "..mob.." at ("..pos.x..","..pos.y..","..pos.z..")")
			end
		end
	end
end

function creatures.add_wear(player, def)
	if not minetest.setting_getbool("creative_mode") then
		local item = player:get_wielded_item()
		if def and def.damage_groups and def.damage_groups.fleshy then
			local uses = tool_uses[def.damage_groups.fleshy] or 0
			if uses > 0 then
				local wear = 65535/uses
				item:add_wear(wear)
				player:set_wielded_item(item)
			end
		end
	end
end

function creatures.drop(pos, items, dir)
	if dir == nil then
		dir = {x=1,y=1,z=1}
	end
	for _,item in ipairs(items) do
		for i=1,item.count do
			local x = 1/math.random(1,5)*dir.x--math.random(0, 6)/3 - 0.5*dir.x
			local z = 1/math.random(1,5)*dir.z--math.random(0, 6)/3 - 0.5*dir.z
			local p = {x=pos.x+x,y=pos.y,z=pos.z+z}
			local node = minetest.get_node_or_nil(p)
			if node == nil or not node.name or node.name ~= "air" then
				p = pos
			end
			local obj = minetest.add_item(p, {name=item.name})
		end
	end
end

function creatures.find_mates(pos, name, radius)
	local player_near = false
	local mobs = 0
	local res = false
	for  _,obj in ipairs(minetest.get_objects_inside_radius(pos, radius)) do
		if obj:is_player() then
			player_near = true 
		else
			local entity = obj:get_luaentity()
			if entity and entity.mob_name and entity.mob_name == name then
				mobs = mobs + 1
				res = true
			end
		end
	end

	return res,mobs,player_near
end

function creatures.compare_pos(pos1,pos2)
	if pos1.x == pos2.x and pos1.y == pos2.y and pos1.z == pos2.z then
		return true
	end
	return false
end

function creatures.attack(self, pos1, pos2, dist, range)
	if not self then return end
	if not pos1 or not pos2 then return end
	if minetest.line_of_sight(pos1,pos2) ~= true then
		return
	end
	if dist < range and self.attacking_timer > 0.6 then
		self.attacker:punch(self.object, 1.0,  {
				full_punch_interval=1.0,
				damage_groups = {fleshy=1}
		})
		self.attacking_timer = 0
	end
end

function creatures.jump(self, pos, jump_y, timer)
	if not self or not pos then return end
	if self.direction ~= nil then
		if self.jump_timer > timer then
			self.jump_timer = 0
			local p = {x=pos.x + self.direction.x,y=pos.y,z=pos.z + self.direction.z}-- pos
			local n = minetest.get_node_or_nil(p)
			p.y = p.y+1
			local n2 = minetest.get_node_or_nil(p)
			local def = nil
			local def2 = nil
			if n and n.name then
				def = minetest.registered_items[n.name]
			end
			if n2 and n2.name then
				def2 = minetest.registered_items[n2.name]
			end
			if def and def.walkable and def2 and not def2.walkable and not def.groups.fences and n.name ~= "default:fence_wood" then-- 
				self.object:setvelocity({x=self.object:getvelocity().x*2.2,y=jump_y,z=self.object:getvelocity().z*2.2})
			end
		end
	end
end

function creatures.follow(self, items, radius)
	local current_pos = self.object:getpos()
	-- seach for players
	for  _,object in ipairs(minetest.env:get_objects_inside_radius(current_pos, radius)) do
		if object:is_player() then			
			local item = object:get_wielded_item()
			local item_name = item:get_name()
			if item and item_name and item_name ~= "" then
				local quit = true
				for _,food in ipairs(items) do
					if food.name == item_name then
						quit = false
					end
				end
				if quit then return end
				NPC = current_pos
				PLAYER = object:getpos()
				self.vec = {x=PLAYER.x-NPC.x, y=PLAYER.y-NPC.y, z=PLAYER.z-NPC.z}
				self.yaw = math.atan(self.vec.z/self.vec.x)+math.pi^2
				if PLAYER.x > NPC.x then
					self.yaw = self.yaw + math.pi
				end
				self.yaw = self.yaw - 2
				self.object:setyaw(self.yaw)
				self.feeder = object
			end
		end
	end
end

-- hostile mobs
dofile(minetest.get_modpath("creatures").."/ghost.lua")
dofile(minetest.get_modpath("creatures").."/zombie.lua")

-- friendly mobs
dofile(minetest.get_modpath("creatures").."/sheep.lua")

-- spawning
dofile(minetest.get_modpath("creatures").."/spawn.lua")
dofile(minetest.get_modpath("creatures").."/spawners.lua")
-- other stuff
dofile(minetest.get_modpath("creatures").."/items.lua")