[MC-3524] Structure related mobs do not spawn in flat type world generation

Structure related mobs can not spawn in superflat worlds.
This is true for:

Pillager
Witches
Guardians

Steps taken to confirm this:

Forward Confirmation

Generated World on any Seed with Superflat (flat) World Generation and included all available structures (default spawn ratio)
Using admist and /locate to find nearest structure, teleport to it, and confirm no spawning
Save and exit.
Using NBTExplorer change world generation type from 'flat' to 'default'
Join world and confirm spawning entities
Confirm changed world-gen by loading new chunks

Backward Confirmation

Generated new default World on any Seed
Using /locate to find and teleport to nearest structure. Confirm through admist as well.
Save and exit.
Using NBTExplorer change world generation type from 'default' to 'flat'
Join world and kill all Entities (except player) to confirm no spawning entities.
Confirm changed world-gen by loading new chunks

In addition, seed-changes were tested, as well as importing confirmed-working chunks into superflat world and manually creating structures through NBTExplorer.

In all these cases structure entities consistently did not spawn while level.dat contained 'flat' - type world generation.

Attachments

Comments 21

Fredrik Olsson 2012-11-20T08:19:25Z

The witch pressent in the pic "Can't reproduce in 1.4.5.jpg" is generated with the hut and not spawned in in the hut.

In the screenshot i posted a skeleton has spawned in the hut, and that only happens in flat worlds.
In normal worlds the only mob that can spawn in a hut is the witch!

So i still claim this to be a bug.

Chalmes (Jon) 2012-11-20T23:11:04Z

You've convinced me, confirmed 🙂

Poking in the code it seems that yes there is a witch spawned by the world generator by default when the hut is initially created, but after that, only the regular mobs would spawn in there. I tried deconstructing the hut and rebuilding the floor at different heights, but nothing would force another witch to spawn there.

Tails 2012-12-06T01:58:30Z

Removed "CLONE" in the title.

Tails 2013-03-15T19:13:15Z

Is this still a concern in the current Minecraft version? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.

Fredrik Olsson 2013-03-18T06:34:13Z

Tested in 1.5 and the bug is still there!

11 more comments

Fredrik Olsson 2013-10-29T12:22:56Z

Still a bug in 1.7.2

The strange part is that the "area" in Temple.dat under the data folder is generated and looks to be correct.
But the flatland code seems to ignore that data.

galaxy_2alex 2014-01-21T22:40:37Z

Is this still a concern in the current Minecraft version 1.7.4 / Launcher version 1.3.8 or later? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.

Brad Corbin 2014-05-02T01:49:34Z

Can confirm, still a problem in release 1.7.9.

I also was able to confirm that this is directly a result of the world generation settings. I generated a flatland using the settings in the description above, normal mobs spawned (see image generator_flat.png).

I then used NBTExplorer and edited the "generatorName" value in level.dat from "flat" to "default". After reloading the world, only witches spawned (see generator_default.png).

galaxy_2alex 2014-10-24T21:04:24Z

Is this still a concern in the current Minecraft version 1.8.1 Prerelease 3 / Launcher version 1.5.3 or later? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.

Brad Corbin 2014-10-25T02:59:24Z

Yes, confirmed that it is still a problem for 1.8.1 Prerelease 3

Above directions still apply, use the following for superflat preset:
3;2*minecraft:bedrock,60*minecraft:dirt,minecraft:stone_slab;6;biome_1

Brad Corbin 2014-10-25T22:29:30Z

Seems similar in many ways to MC-59314 (Guardians not spawning on superflat worlds).

Different details, also much easier to test (just create a superflat world using preset "Water World").

Someone 3x7 2015-02-18T23:15:50Z

Still an issue in 1.8.2-pre7

Fredrik Olsson 2015-05-04T09:50:43Z

Still an issue in 1.8.4

Smokey95dog 2015-11-05T20:30:01Z

Still an issue in 1.8.8 and the newest 1.9 snapshot 15w45a.

Dracconis69 2019-09-15T17:13:54Z

Can confirm that this issue is still present in all versions after the OP's reported versions. For creators trying to make a superflat void world for their Skyblock maps only regular mobs will spawn and Guardian Temples will not even spawn in.

Jack Flint 2020-01-11T20:17:03Z

~~Testing regarding this issue, this issue is superseded by issue~~ ~~MC-169728~~

Edit: No longer the case, as moderator merged posts.

W_V 2020-03-22T18:14:04Z

Confirmed for 1.15.2 and 20w12a

Alexis Evelyn 2020-06-08T09:43:39Z

Can confirm, this is still an issue for 1.16 pre-2. I spent a few hours pouring over nbt data trying to figure out why my outpost wasn't working and weeded it out to world type. Also, I tried a superflat preset explicitely telling the game to generate the outposts to find out it didn't work anyway.

W_V 2020-07-09T06:00:28Z

In 1.16.1 and 20w28a

W_V 2021-05-21T04:57:21Z

Can confirm for 21w20a

Daniel Jansson 2022-02-06T12:43:40Z

Still the case in 1.18.1