minetest.register_lbm

Syntax

minetest.register_lbm(lbm_defintion_table)

Description

The Loading Block Modifier consists of a function that is executed when the server loads nodes that match a passed filter.

The LBM registered with the callback will only take effect if register_lbm gets called while the mod is loading.

lbm_defintion_table is a table which can contain following fields:

index	description
name	an unique name for the LBM. It must be in "modname:something" notation. The name is used to distinguish the LBM from the others, thus changing the name resets the introducement time for the LBM.
nodenames	a list of the nodenames that should execute the function. "group:groupname" is also possible, as well as names of non-registered nodes.
action	the function that is executed. The parameters are (pos, node) pos is the position of the node node is the node

Use cases

Originally, LBMs were written for legacy replacement jobs like when a mod defines a new node or to remove nodes from a removed mod for the world. This is still the main use case for LBMs.

Example

A cleanup LBM useful to execute after removal of the fire mod in order to clean up the world from the now unknown nodes:

minetest.register_lbm({
	name = "modname:remove_fire",
	nodenames = {"fire:basic_flame", "fire:permanent_flame"},
	action = function(pos, node, active_object_count, active_object_count_wider)
		minetest.set_node(pos, {name = "air:air"})
	end,
})