MxtLoot: Loot Conditions and Functions

MiXianTu adds a few types to the vanilla loot tables; MxtLoot lets a script provide two of them, so an ordinary loot table can call into a server script without an item or a block being involved.

Methods

Method	Parameters	Return value	Description
condition(id, callback)	Callback ID, (lootContext, params) => boolean	void	Registers the vanilla loot condition type mxt:js.
function(id, callback)	Callback ID, (stack, lootContext, params) => ItemStack	void	Registers the vanilla loot function type mxt:js.

// KubeJS does not bind the vanilla loot parameter keys as a global, so load the class once.
const LootParams = Java.loadClass('net.minecraft.world.level.storage.loot.parameters.LootContextParams')

MxtLoot.condition('example:first_clear', (loot, params) => {
  const player = loot.getParam(LootParams.THIS_ENTITY)
  return player != null && player.tags.contains(`cleared_${params.dungeon}`)
})

MxtLoot.function('example:bless', (stack, loot, params) => {
  stack.grow((params.multiplier || 1) - 1)
  return stack
})

{
  "conditions": [{"condition": "mxt:js", "id": "example:first_clear", "params": {"dungeon": "example:fire_temple"}}],
  "functions": [{"function": "mxt:js", "id": "example:bless", "params": {"multiplier": 3}}]
}

Both callbacks run on the server while loot is generated, and neither receives a FormulaContext: read the vanilla LootContext instead, for example with loot.getParam(LootParams.THIS_ENTITY). A loot function returns the stack to keep — return its argument unchanged to leave the drop alone, return a new stack to replace it, or return null to keep the original. A missing callback makes a condition false and leaves a function's stack untouched, with a warning in the log.

Related

• The loot table itself is vanilla format; only these two types are claimed by mxt:js. Registering an id is described in the mxt:js section of the API Reference.
• MxtTriggers — the other object where a script provides a data pack type.
• KubeJS API Reference.