init.lua

local have_creative = minetest.get_modpath("creative")

local function try_staple(itemstack, placer, pointed)
	if pointed.type ~= "node" then
		return
	end
	if pointed.above.y - pointed.under.y ~= 0 then
		return
	end

	-- Node under must be a tree
	local node_under = minetest.get_node(pointed.under)
	local def_under = minetest.registered_nodes[node_under.name] or {}
	if not def_under.groups or not def_under.groups.tree then
		return
	end
	if def_under.paramtype2 == "facedir"
			or def_under.paramtype2 == "colorfacedir" then
		-- Only vertical facedirs are allowed
		local dir = minetest.facedir_to_dir(node_under.param2)
		if dir.y ~= 0 then
			return
		end
	end

	-- Node above must be airlike, but not ignore
	local node_above = minetest.get_node(pointed.above)
	local def_above = minetest.registered_nodes[node_above.name] or {}
	if node_above.name == "ignore" or not def_above.buildable_to then
		return
	end

	-- Staple to the tree
	local dir = vector.direction(pointed.above, pointed.under)
	local pos = minetest.pointed_thing_to_face_pos(placer, pointed)
	pos.x = pos.x + (math.random() - 0.5) / 100 -- avoid Z-fighting
	pos.z = pos.z + (math.random() - 0.5) / 100
	local obj = minetest.add_entity(
		vector.add(pos, vector.multiply(dir, -0.01)),
		"stapled_bread:bread_slice"
	)
	if obj then
		local entity = obj:get_luaentity()
		entity.object:set_yaw(math.atan2(-dir.x, dir.z))
		entity.object:set_properties({
			textures = { itemstack:get_name() }
		})

		-- Take the item *after* specifying the texture
		-- or we might up with stapled hands (ouch!!)
		if not have_creative or not creative.is_enabled_for(
				placer:get_player_name()) then
			itemstack:take_item(1)
		end
	end
	return itemstack
end

local function staple_place_wrapper(itemstack, placer, pointed)
	return try_staple(itemstack, placer, pointed) or itemstack
end

local extent = 0.12
local box = {-extent, -extent, -extent, extent, extent, extent}
minetest.register_entity("stapled_bread:bread_slice", {
	initial_properties = {
		visual = "wielditem",
		textures = { "unknown_node.png" },
		visual_size = {x = 0.2, y = 0.2},
		physical = false,
		collisionbox = box,
		selectionbox = box
	},
	get_staticdata = function(self)
		return self.object:get_properties().textures[1]
	end,
	on_activate = function(self, staticdata, dtime_s)
		if staticdata and staticdata ~= "" then
			self.object:set_properties({
				textures = { staticdata }
			})
		end
	end,
	on_punch = function(self, puncher, _, _, dir, _)
		local obj_dir = minetest.yaw_to_dir(self.object:get_yaw())
		local diff = vector.dot(obj_dir, dir)
		if diff > 0.2 then
			return
		end
		if math.random() > 0.4 then
			return
		end

		local itemname = self.object:get_properties().textures[1]
		local stack = ItemStack(itemname)
		if minetest.registered_items[stack:get_name()] then
			-- I would not recommend eating this piece
			puncher:get_inventory():add_item("main", stack)
		end
		self.object:remove()
	end
})

-- REGISTER BREAD STUFF

local function make_stapleable(itemname)
	minetest.override_item(itemname, {
		on_place = staple_place_wrapper
	})
end

if minetest.get_modpath("farming") then
	make_stapleable("farming:bread")

	minetest.register_craftitem("stapled_bread:bread_slice", {
		description = "Bread Slice",
		inventory_image = "stapled_bread_slice.png",
		on_use = minetest.item_eat(1),
		on_place = staple_place_wrapper
	})

	minetest.register_craft({
		type = "shapeless",
		output = "stapled_bread:bread_slice 5",
		recipe = {
			"farming:bread"
		}
	})

	if farming.mod == "redo" then
		make_stapleable("farming:bread_slice")
		make_stapleable("farming:garlic_bread")
	end
end

if minetest.get_modpath("sandwiches") then
	make_stapleable("sandwiches:bread_slice")
end