Mob Skills

A library mod to control mob spawning using skill-based restrictions created in KubeJS scripts. If you've seen Mob Stages in 1.12, then you have a rough idea of what this mod does.

xSkills Mods

Concepts

This mod leans extensively on Player Skills by creating and consuming the Skill-based Restrictions. Out of the box, it can restrict mob spawning and player-mob interaction (i.e. right-clicking to trade with a villager).

KubeJS API

Register

We use the MobSkillEvents.register server event to register mob restrictions.

Spawn restrictions are then calculated at spawn time based on the players in the entity's despawn range (i.e. 128 blocks for most mobs). If the players match the conditions, the restrictions are applied.

Other restrictions are calculated when the player attempts to interact with the mob. If the player matches the conditions, the restriction is applied.

Restrictions can cascade with other restrictions, so any restrictions which disallow an action will trump any which do allow it. We also expose these methods to indicate what restrictions are in place for when a player meets that condition. By default, no restrictions are set, so be sure to set actual restrictions. See Player Skills documentation for the shared API.

Allow Restriction Methods

nothing() - shorthand to apply all "allow" restrictions
spawnable(matchAllInsteadOfAny?: boolean) - The mob can spawn if any (or all) players in range match the criteria
usable() - Players that meet the condition can interact with the entity (e.g. trade with a villager)

Deny Restriction Methods

everything() - shorthand to apply the below "deny" abilities
unspawnable(matchAllInsteadOfAny?: boolean) - The mob cannot spawn if any (or all) players in range match the criteria
unusable() - Players that meet the condition cannot interact with the entity (e.g. trade with a villager)

Additional Methods

always() - Change spanwable/unspawnable into an absolute value instead of a condition
fromSpawner(spawner: string) - Add a spawn type

Spawn Types

We have a shortened list of spawn types which we are allowing granular spawn restrictions. We want to keep breeding, spawn eggs, direct summons, and more interaction-based spawns as-is.

natural - A normal, random spawn
spawner - A nearby mob spawner block
structure - A spawn related to a structure (e.g. guardians, wither skeletons)
patrol - Really a subset of "natural" but related to illager patrols
chunk - A natural spawn from when the chunk generates (e.g. villager)

Examples

MobSkillEvents.register(event => {
  // Always prevent blazes from spawning
  event.restrict('minecraft:blaze', is => is.unspawnable().always());

  // Prevent all vanilla mobs from spawning
  event.restrict('@minecraft', is => is.unspawnable().always());

  // Prevent all illagers from spawning
  event.restrict('#raiders', is => is.unspawnable().always());

  // Prevent all vanilla illager patrols from spawning
  event.restrict('minecraft:*', is => is.unspawnable().fromSpawner("patrol").always());

  // ALLOW creepers to spawn IF ALL players in range have the `started_quest` skill
  event.restrict("minecraft:creeper", is => is.spawnable(true).if(player => player.can("skills:started_quest")));

  // ALLOW cows to spawn UNLESS ANY players in range have the `started_quest` skill
  event.restrict("minecraft:cow", is => is.spawnable().unless(player => player.can("skills:started_quest")));

  // DENY zombies from spawning IF ANY player in range has the `started_quest` skill
  event.restrict('minecraft:zombie', is => is.unspawnable().if(player => player.can('skills:started_quest')));

  // DENY sheep from spawning UNLESS ALL player in range has the `started_quest` skill
  event.restrict('minecraft:sheep', is => is.unspawnable(true).unless(player => player.can('skills:started_quest')));

  // Players cannot interact with villagers unless they have `started_quest` skill
  event.restrict("minecraft:villager", is => is.unusable().unless(player => player.can("skills:started_quest")));
});

Caveats

Because of the way we're handling spawn conditions, if you are using an unless condition, you should not also manipulate usable in the same restriction. Just keep the two restrictions separate.

In-Game Commands

We expose a handful of in-game commands for players and mods:

/mobskills debug: Toggles debug-level logging for Mob Skills. Requires mod permissions.

Developers

Add the following to your build.gradle. I depend on Architectury API, KubeJS, and PlayerSkills, so you'll need those as well.

dependencies {
    // Common should always be included 
    modImplementation "net.impleri:mob-skills-${minecraft_version}:${mobskills_version}"
    // Plus forge
    modApi "net.impleri:mob-skills-${minecraft_version}-forge:${mobskills_version}"
    // Or fabric
    modApi "net.impleri:mob-skills-${minecraft_version}-fabric:${mobskills_version}"
}
repositories {
    maven {
        url = "https://maven.impleri.org/minecraft"
        name = "Impleri Mods"
        content {
            includeGroup "net.impleri"
        }
    }
}

Modpacks

Want to use this in a modpack? Great! This was designed with modpack developers in mind. No need to ask.

impleri/mob-skills