Structure spawn overrides
Generated from the 26.3 decompile by
tools/gen_reference.py. Do not edit by hand.
Which structures replace a biome’s spawn list, for which mob category, and with what. A structure JSON’s spawn_overrides map is read into Structure.spawnOverrides; when NaturalSpawner builds a spawn list, ChunkGenerator.getMobsAt walks the structures that chunk references, in no fixed order, and the first that declares an override for the category and whose box contains the position answers; the biome’s list is then not consulted. An override with an empty spawn list is therefore a ban, not a no-op. The one exception is the creatures a chunk gets while it generates: NaturalSpawner.spawnMobsForChunkGeneration draws the creature category from the biome’s list and reads no override. box is piece (only inside a piece’s own bounding box) or full (anywhere in the structure’s box, which for a structure that adapts the terrain around it is grown by twelve blocks on every side). The mechanism is on entity lifecycle; the nether fortress has a second, hard-coded list in front of this one.
52 structures carry the field · 6 declare an override · 23 overrides in all
| structure | category | box | what spawns instead (weight, min–max) |
|---|---|---|---|
ancient_city | ambient | full | nothing — the category is suppressed inside the box |
ancient_city | axolotls | full | nothing — the category is suppressed inside the box |
ancient_city | creature | full | nothing — the category is suppressed inside the box |
ancient_city | misc | full | nothing — the category is suppressed inside the box |
ancient_city | monster | full | nothing — the category is suppressed inside the box |
ancient_city | underground_water_creature | full | nothing — the category is suppressed inside the box |
ancient_city | water_ambient | full | nothing — the category is suppressed inside the box |
ancient_city | water_creature | full | nothing — the category is suppressed inside the box |
fortress | monster | piece | blaze (10, 2–3), zombified_piglin (5, 4–4), wither_skeleton (8, 5–5), skeleton (2, 5–5), magma_cube (3, 4–4) |
monument | axolotls | full | nothing — the category is suppressed inside the box |
monument | monster | full | guardian (1, 2–4) |
monument | underground_water_creature | full | nothing — the category is suppressed inside the box |
pillager_outpost | monster | full | pillager (1, 1–1) |
swamp_hut | creature | piece | cat (1, 1–1) |
swamp_hut | monster | piece | witch (1, 1–1) |
trial_chambers | ambient | piece | nothing — the category is suppressed inside the box |
trial_chambers | axolotls | piece | nothing — the category is suppressed inside the box |
trial_chambers | creature | piece | nothing — the category is suppressed inside the box |
trial_chambers | misc | piece | nothing — the category is suppressed inside the box |
trial_chambers | monster | piece | nothing — the category is suppressed inside the box |
trial_chambers | underground_water_creature | piece | nothing — the category is suppressed inside the box |
trial_chambers | water_ambient | piece | nothing — the category is suppressed inside the box |
trial_chambers | water_creature | piece | nothing — the category is suppressed inside the box |
The other 46 structures carry the field empty — the field is required — and the biome’s list stands.