large_slugs

This is a mod for Minetest that adds large slugs of several species, implemented as different nodes. They very slowly wander around, sticking to surfaces, and asexually reproduce up to an approximate population density. This behavior can be tweaked or disabled if it becomes detrimental to performance.

Species

Different species spawn on different surfaces, and their movement is restricted to these different surfaces.

Grass Slug

The light brown grass slug spawns on regular grass on the surface. It can only move on grass and dirt.

Grass slugs can be cooked and eaten for two food points.

Pine Slug

The dark brown pine slug spawns in pine forests. It can only move on dirt, pine trees trunks, and the ground covering of the pine forests.

Pine slugs can be cooked and eaten for two food points.

Rainforest Slug

The yellow rainforest slug spawns in rainforests. It can only move on dirt, jungle tree trunks, and the ground covering of the rainforests.

Rainforest slugs can be cooked and eaten for three food points.

Cave Slug

The gray cave slug spawn at level -32 and below on stone. It can only move on stone, cobblestone, and coal-bearing stone.

Cave slugs can be cooked and eaten for three food points. Two cave slugs can be crafted into a lump of coal.

Iron Slug

The rust-colored iron slug spawns at level -128 and below on stone. It can only move on stone, cobblestone, and iron ore.

Two iron slugs can be crafted into a lump of iron.

Mese Slug

The bright yellow mese slug spawns at level -512 and below on stone. It can only move on stone, cobblestone, and mese-bearing stone.

Three mese slugs can be crafted into a mese crystal fragment.

Performance

Again, you can disable slug behavior entirely in the mod settings. However, I have not observed a huge performance cost.

Implemented as nodes, slugs are less expensive to simulate than regular entities. An ABM runs every 5 seconds* to update active slugs. In a given update, one out of every 5 slugs* is actually updated**. Only one out of every 5 updated slugs* tries to reproduce, while the rest just try to move. Reproduction is more expensive than movement, since a birthing slug must check up to 11 nodes* around it in every direction to determine that it is the only one of its species in the area.

* These are default values. They can be changed in the settings.

** The lower this value is, the more likely slugs are to double-move, due to the way ABMs work.

Mod dependencies

large_slugs depends on the mod "default" because it refers to materials from that mod. However, it would not be hard to adapt large_slugs to a different environment. You could keep the files api.lua, behavior.lua, and settingtypes.txt but define your own slugs. To see how to do this, look in slugs.lua. In order to make your slugs spawn in the world, I would recommend registering them as decorations, as is done in mapgen.lua.

The optional dependency on the mod "ethereal" is just to fix a bug. It seems that large_slugs must load after ethereal in order for slugs to spawn properly. I'm not sure why.

Licenses

Source code

The source code of this project is licensed under the LGPL v3 (or later,) as stated in the source code files themselves.

Images and other files not otherwise licensed

These files are licensed under a CC BY-SA 3.0 license.

They are also under the same copyright as the source files:

Copyright © 2021 Jude Melton-Houghton