Real Mob Filter
Server-side filter for natural spawns, per entity type.
No Fabric API, no commands. No /reload, restart after editing.
Works for any entity, vanilla or not, as long as the spawn goes through the natural spawner (NaturalSpawner).
Config
config/realmobfilter.json (written on first launch)
enabled defaults to false. While it stays false, the filter does nothing.
{
"enabled": false,
"entities": {
"minecraft:phantom": 0.0,
"minecraft:creeper": 0.25
}
}
The value is the chance to allow the natural spawn. The roll is uniform in [0, 1).
| Value | Effect |
|---|---|
0.0 |
the attempt is cancelled every time |
0.1 |
allowed 10% of the time, cancelled 90% |
1.0 |
always allowed |
| missing key | always allowed |
An invalid id is ignored. A value outside [0, 1] is clamped.
Mobcap
Cancellation happens after Vanilla has picked the type. The attempt is not replaced and there is no second roll.
The mobcap therefore fills more slowly, but it still fills: only with rolls that pass, plus anything that is not in the config.
ToDo
Make the filter point configurable:
- after (current): Vanilla picks, we cancel. Throughput drops.
- before: remove or reweight the type in the biome list, before the roll. Throughput stays at the mobcap rate; only the mix changes.
However, not now; plenty of mods already rewrite that list. Feel free to test and submit a PR.
Where it cuts
Mixin on NaturalSpawner.getMobForSpawn, at the head of the method, before EntityType.create.
Vanilla already does if (mob == null) return;, so the attempt stops before the entity is created, before the collision test, and before finalizeSpawn.
Eggs, spawners, trial spawners, commands and bosses do not go through this method.
Compatibility
- ✅ Real Mobcap: fine. The cap and the filter stack.
- ✅ Carpet: fine.
- ✅ Serilum spawn mods: tested, no issue.
- 🔜 Mob Filter: not tested yet. Can be complementary.
Real Mob Filter Team
