[MCPE-41996] Mob spawner collision box is smaller than a full block on all sides.

I was playing on a survival world with no cheats on but coordinates were on. Also no resource packs or behavior packs were enabled.

I was standing on cobblestone next to a spawner I found at Y level 37 and then I jumped on top of the spawner and I was still at level 37 even though i was a block higher than that. I tried this with both a skeleton and a zombie spawner and both did the same thing.

How to recreate this bug
Step 1:
Stand by a spawner in survival mode(any mob)
Step 2:
Look at your Y Level
Step 3
Jump on top of the spawner
Step 4 look at your Y level again.

To put this short the Y level didnt change when I jumped on or off the spawner and this only worked with a spawner no other block I tried did this.

I was playing on my Galaxy S7

Linked issues

is duplicated by 8

MCPE-47153 mob spawner doesn't give the correct y coordinate Resolved

MCPE-52616 Y coordinate level on top of spawner Resolved

MCPE-60491 Y-axis coordinate doesn't increase when you jump on a chest Resolved

MCPE-66828 Mob spawner has incorrect collision box Resolved

MCPE-100197 Items go through blocks when on top of spawner Resolved

3 more links

relates to 1

MCPE-13451 Trapdoor has incorrect hitbox Resolved

Attachments

Before 2048 vs After 2048.mp4

MCPE-41996.mp4

MCPE-41996 minecart stuck.mp4

YouCut_20200514_125034329.mp4

Comments 19

migrated 2019-02-13T05:24:09Z

[^275165_scaffolding+structure[1].png]

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Auldrick 2019-02-14T18:22:03Z

This happens because the spawner's collision box is a tiny fraction (.0001 block) less than a block high. Therefore, the bottoms of your feet are actually in the block below your legs when you stand on a spawner. The coordinates on screen are actually the coordinates of the block the bottoms of your feet are in, so they always round toward negative infinity, which means you can't see that your Y coordinate is actually 37.99990. You should find that if you put a carpet, pressure plate, etc. on top of the spawner and stand on that, your coordinates will show Y=38.

We're investigating whether this tiny difference is intentional or a bug. However, as far as we know at present it should have no negative consequences other than the confusion around your coordinates.

Austen Cudmore 2019-03-10T08:20:02Z

Thank you for replying. Sorry this is a late reply. Thanks for letting me know this. I didn't know if this was a bug or not either but I thought it was strange so just wanted to let you know.

[Mojang] Mega_Spud (Jay) 2019-06-07T15:29:01Z

Thank you for your report!
However, this issue has been closed as Won't Fix.

If you'd like to post a suggestion or give further feedback, please visit the Minecraft Feedback Site or choose a link below.

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bugsbugsbugs 2020-03-30T12:40:18Z

Why is this resolved as won't fix? Trapdoors have the same issue and it got fixed for them in the beta.

9 more comments

bugsbugsbugs 2020-03-30T12:40:56Z

Here the bug for trapdoors MCPE-13451

silentwisperer 2020-03-30T23:39:03Z

It should be noted that the collision box is smaller on the sides as well, similar to how the trap doors had a slightly smaller collision box than they should have. so when a spawner is on top of a full block, you can still stand on the edge of that full block, even though you shouldn't be able to. This is such a small thing, theres really no reason not to fix it.

bugsbugsbugs 2020-05-11T15:30:31Z

Can this please be reopened? It doesn’t make sense to fix the bug for trapdoors, but not for mob spawners which have exactly the same bug.

[Mojang] Mega_Spud (Jay) 2020-05-11T15:37:50Z

Reopened for review.

bugsbugsbugs 2020-05-14T10:56:09Z

If you have mob spawner next to a slab or stairs you can also walk up on the stairs or slab without jumping, by walking against the mob spawner, as you can see in the video I have attached. To do that you have to not walk in the middle of the mob spawner, you have to collide with the stairs or slab. You also can do the same thing with trapdoors in the versions where trapdoors are also smaller.

bugsbugsbugs 2020-06-25T05:05:23Z

Confirmed for 1.16

[Mojang] Mega_Spud (Jay) 2021-02-05T11:47:35Z

Could you please mention the impact that this has on gameplay, if any?

Auldrick 2021-02-05T15:18:59Z

MCPE-45875 reported an issue where a block whose top surface was below the top of its block frame (as for the spawner in this report) allows the player to walk into the side of a scaffolding block and therefore fall through the scaffolding, possibly to their death. The following attachment from MCPE-45875 illustrates this.

[media]

If you substitute a spawner for the trapdoor at the center of the top, attempting to walk from the top of the spawner to the top of the scaffolding beside it causes you to fall through the scaffolding.

bugsbugsbugs 2021-02-05T16:00:47Z

This is only an issue on the top, the bottom and east and west side, but not on the north and south side. And like I already said if you have stairs or slabs next to the spawner if you walk to east or west, you will be able to walk up the stairs even though you shouldn’t be able to. This is most noticible with the stairs in the end portal room of a stronghold.

[media]

Also minecarts and boats (and other entities that don’t have the ability to "step" up stairs) can get stuck on top of a mob spawner when next to a full block, causing you to be unable to move it away, like show in this video:

[media]

tryashtar 2021-02-05T19:02:26Z

If you or another entity is standing partially on the spawner, you can't place blocks next to it (like this)

[media]

If you ride a boat on a spawner you can't move off of it onto adjacent blocks

If you stand on a spawner and a piston pushes you onto an adjacent block, you clip through it

Mobs standing on spawners refuse to pathfind off of them

[media]

bugsbugsbugs 2021-03-15T16:41:04Z

Now in 1.16.210 it affects all 6 sides and not only 4.

SomeonePLaysMC 2021-06-01T14:53:50Z

Doing more research and more reproduction tests:

The sides affected depends on position.

If the spawner is before both X and Z coordinate 2048, then 6 sides are affected.

If the spawner is after X or Z 2048 on ONE axis, and before 2048 in THE OTHER axis, then 4 sides are affected.

If the spawner is after both X and Z coordinate 2048, then only the bottom and the top side is affected. (2 sides are affected)

From what i know, this happens because of precision loss. After 2048, the precision error is bigger than the difference between a full block and a mob spawner, making the mob spawner full on some axises.

So @bugsbugsbugs nothing changed in 1.16.210.

DeeFeeCee 2022-09-07T06:39:17Z

This no longer appears to be a bug in 1.19.22. The spawner seems to have normal block dimensions.

GoldenHelmet 2023-09-15T21:30:44Z

Resolving as Fixed. I cannot find a changelog entry for it. There was a change to spawners dropping XP in 1.19.10, so this issue may have been fixed at the same time.