mod-slingshot/api.lua

-- Functions for slingshot mod

--- Slingshot mod API.
--
--  @module api


local tmp_throw = {}
local tmp_throw_timer = 0

local registered_ammos = {}

--- Register an item as ammunition for slingshot.
--
--  Any item can be thrown, but registering as ammo
--  allows custom attack value to be set.
--
--  @function slingshot.register_ammo
--  @tparam string name Item technical name.
--  @tparam int damage Damage value addon.
function slingshot.register_ammo(name, damage)
	registered_ammos[name] = damage
end

if slingshot.ammos and slingshot.ammos:trim() ~= "" then
	local ammos = string.split(slingshot.ammos:trim(), ",")
	for _, a in ipairs(ammos) do
		if a:find("=") then
			a = string.split(a, "=")
			local aname = a[1]:trim()
			local aval = tonumber(a[2]:trim()) or 0
			slingshot.register_ammo(aname, aval)
		end
	end
end


-- Registers 'cooldown' time for repeat throws
--
-- FIXME: using  on_globalstep causes attack to miss when in sync
core.register_globalstep(function(dtime)
	tmp_throw_timer = tmp_throw_timer + dtime
	if tmp_throw_timer < 0.2 then return end

	-- Reset cooldown
	tmp_throw_timer = 0
	for i, t in pairs(tmp_throw) do
		local puncher = core.get_player_by_name(t.user)
		t.timer = t.timer-0.25
		if t.timer <= 0 or t.ob == nil or t.ob:get_pos() == nil then table.remove(tmp_throw, i) return end
		for ii, ob in pairs(core.get_objects_inside_radius(t.ob:get_pos(), 1.5)) do
			if (not ob:get_luaentity()) or (ob:get_luaentity() and (ob:get_luaentity().name ~= "__builtin:item")) then
				-- Which entities can be attacked (mobs & other players unless PVP is enabled)
				if (not ob:is_player()) or (ob:is_player() and ob:get_player_name(ob) ~= t.user and slingshot.enable_pvp) then
					ob:punch(puncher, 1.0, {damage_groups=t.damage_groups}, nil)
					t.ob:set_velocity({x=0, y=0, z=0})
					t.ob:set_acceleration({x=0, y=-10, z=0})
					t.ob:set_velocity({x=0, y=-10, z=0})
					table.remove(tmp_throw, i)
					core.sound_play("slingshot_hard_punch", {pos=ob:get_pos(), gain=1.0, max_hear_distance=5,})
					break
				end
			end
		end
	end
end)


--- Action to take when slingshot is used.
--
--  @local
--  @function on_throw
--  @param itemstack
--  @param user
--  @param veloc
local function on_throw(itemstack, user, veloc, wear_rate, damage_groups)
	local pos = user:get_pos()
	local upos = {x=pos.x, y=pos.y+2, z=pos.z}
	local dir = user:get_look_dir()
	local item = itemstack:to_table()

	-- Throw items in slot to right
	local item = user:get_inventory():get_stack("main", user:get_wield_index()+1):get_name()

	if item == "" then return itemstack end

	local e = core.add_item({x=pos.x, y=pos.y+2, z=pos.z}, item)
	if e then
		e:set_velocity({x=dir.x*veloc, y=dir.y*veloc, z=dir.z*veloc})
		e:set_acceleration({x=dir.x*-3, y=-5, z=dir.z*-3})
		e:get_luaentity().age = slingshot.thrown_duration

		local dg = table.copy(damage_groups)

		if dg == nil then
			dg = {fleshy=1}
		end

		local addon = registered_ammos[item]
		if addon then
			for k, v in pairs(dg) do
				dg[k] = v + addon
			end
		end

		table.insert(tmp_throw, {ob=e, timer=2, user=user:get_player_name(), damage_groups=dg})

		if not slingshot.creative then
			if slingshot.enable_wear then
				if wear_rate == nil then
					wear_rate = 100
				end

				slingshot.log("debug", "Wear rate: " .. tostring(wear_rate))

				itemstack:add_wear(wear_rate)
			end

			user:get_inventory():remove_item("main", item)
		end

		core.sound_play("slingshot_throw", {pos=pos, gain=1.0, max_hear_distance=5,})
		return itemstack
	end
end


local register_repairable
if core.global_exists("xdecor") and xdecor.register_repairable then
	register_repairable = xdecor.register_repairable
elseif core.global_exists("workbench") and workbench.register_repairable then
	register_repairable = workbench.register_repairable
elseif core.global_exists("WB") and WB.register_repairable then
	register_repairable = WB.register_repairable
end


--- Registers a new slingshot.
--
--  'def' should include 'description', 'damage_groups', & 'velocity'.
--
--  @function slingshot.register
--  @tparam string name Name of the slingshot (e.g. ***"iron"***).
--  @tparam table def Slingshot definition table (see [slingshot.register.def](#slingshot.register.def)).
function slingshot.register(name, def)
	if def.inventory_image then
		-- Inventory image will override image if set
		def.image = def.inventory_image
	end

	if not def.image then
		-- The default slingshot
		if name == "slingshot" then
			def.image = "slingshot.png"
		else
			def.image = "slingshot_" .. name .. ".png"
		end
	end

	if not def.wield_image then
		-- Use inventory image
		def.wield_image = def.image
	end

	local sname = "slingshot:" .. name

	core.register_tool(sname, {
		description = def.description,
		range = 4,
		inventory_image = def.image,
		wield_image = def.wield_image,

		on_use = function(itemstack, user, pointed_thing)
			--[[ Disabled picking up items with slingshot in hand
			if pointed_thing.ref and pointed_thing.ref:is_player() == false and pointed_thing.ref:get_luaentity().name == "__builtin:item" then
				pointed_thing.ref:punch(user, {full_punch_interval=1.0, damage_groups=def.damage_groups}, "", nil)
				return itemstack
			end
			]]
			on_throw(itemstack, user, def.velocity, def.wear_rate, def.damage_groups)
			return itemstack
		end,
	})

	if register_repairable then register_repairable(nil, sname) end

	if def.recipe then
		slingshot.log("warning", "\"recipe\" attribute no longer supported in registration")
	end
	if def.ingredient then
		slingshot.log("warning", "\"ingredient\" attribute no longer supported in registration")
	end
	if def.aliases then
		slingshot.log("warning", "\"aliases\" attribute no longer supported in registration")
	end
end


--- Function Definition Tables.
--
--  @section fdtables

--- Slingshot definition table.
--
--  @table slingshot.register.def
--  @tfield string description Human-readable description of slingshot (e.g. ***"Wooden Slinghot"***).
--  @tfield table damage_groups
--  - Same as [minetest.register_tool.tool_capabilities.damage_groups](https://github.com/minetest/minetest/blob/71b02d6/doc/lua_api.txt#L1551)
--  - Default: {fleshy=1}
--  @tfield int velocity Speed & distance at which items will be thrown.
--  @tfield int wear_rate Rate at which the slingshot will wear & break.
--  @see slingshot.register