Nodes #

Nodes (also called blocks by players) are what make up the voxel terrain in Luanti. They are generally cubic in shape, with a full node being considered one cubic meter in volume, and make up the voxel world. Only one node can exist in a particular position in the voxel grid, but can extend into other cells and take wildly different shapes. In most games, the player is able to break and place nodes to shape the terrain into what they see fit, or can be interacted with to provide different gameplay functions.

Usually games and mods register their own nodes, but the engine also registers some technical nodes.

Built-in nodes #

Air #

Air (itemstring air, CONTENT_AIR in C++) is a technical node that exists in every generated area that no other node exists in. It is a fully transparent node, using the airlike drawtype and being unpointable.

There is a node in every position of the voxel grid, i.e. there cannot be “nothing” somewhere. If it looks like nothing, it’s usually Air. When the player digs a node, that node is usually replaced by Air.

Ignore #

Ignore (itemstring ignore, CONTENT_IGNORE in C++) is an airlike technical node that exists in place of ungenerated and unloaded mapblocks. If core.get_node is called on an unloaded mapblock, it will return Ignore.

Unknown Node #

An unknown node takes the place of any node that exists in the world that is no longer being registered, whether it be due to a mod being removed of updates to a game changing itemstrings. Unknown Node is not a node in itself, but can be any node with an unregistered itemstring. If you have disabled mods that provided the nodes then enabling the mod again will make the node reappear just like how it was before, as all metadata is preserved even in its unknown state.

Punching the node will show the itemstring of the original node and breaking it will give you an Unknown Item with the same itemstring, but will erase any additional metadata associated with the node.

For developers working on mods and games that have existed for a while, you should always implement compatibility code for migrating old worlds when you release updates that may change itemstrings and cause Unknown Nodes to appear - ideally players should never have to see one in their world.