Vertical distance is ignored by the hostile mobs spawning rule

As I commented on this thread, the spawning rule for MCPE seems to be very different from other editions. That is, it seems hostile mobs don't spawn if there is a player within approx 40 horizontal block distance of a spawning block (correction: it turned out to be wrong. See my comment below). I can't say for certain but vertical distance is seemingly ignored by the rule. This is contrary to the following description in the wiki:

There must be no players and no player spawn points within a 24 block distance (spherical) of the spawning block

This would make sense, if that's the case. I'm hoping Mojang will weigh in here and confirm or deny. I'm thinking as a test, I can rebuild my spawn room about five or ten blocks deep, but centered sixty horizontal blocks away from my house. I'd need to have the center of the spawn room drop onto a water conveyer tunnel that moves them to the water elevator under my house. Think that would work? Might be a good weekend project.

The other question is if the PE has the forty block minimum horizontal spawn radius, what is the radius where they start having a chance to despawn?

Yet another question... Do NPC's affect spawn? That makes a difference as to whether I build this horizontally displaced spawn room toward the nearby village, which could help reduce the zombie spawn near the village. Or if I should build it away from the village, so the villagers don't prevent mob spawn by being too close to it.

I investigated this further and found out that my previous hypothesis only partially applies to the current version, 0.13.1 / iOS (I think things have changed somewhere around 0.12). I built 4 spawn pads of 6x6x2 empty area and measured the spawn rate with various distances from the outer boundary of pads. Render distance set to the maximum, difficulty set to easy, game mode creative, "Always Day" enabled in a flat world:

So vertical distance is indeed ignored (which is a bug) but the horizontal limit seems to be 24 blocks as expected. The reason why the spawn rate decreased when I took far away is probably that some mobs were despawning before I see them getting out of the chamber. So I think despawning rule described in the wiki still applies to MCPE:

A mob that has had no player within 32 blocks of it for more than 30 seconds has a 1 in 800 chance of despawning on each game tick (1/20th of a second). Therefore, the half-life of monsters not within 32 blocks of a player is 27.73 seconds (after the initial 30 seconds have elapsed).

I'd need to have the center of the spawn room drop onto a water conveyer tunnel that moves them to the water elevator under my house. Think that would work? Might be a good weekend project.

You'd better wait for 0.14 update which hopefully comes with hoppers for three reasons:

1. A strictly horizontal water item conveyer with unlimited length is actually possible but it's way too hard to explain how to build it. Not a single screenshot will help.

2. Items can not be conveyed upwards. There exists no ways to do that without hoppers or droppers.

3. You won't get any loots from hostile mobs because of MCPE-11086 for now.

Do NPC's affect spawn? That makes a difference as to whether I build this horizontally displaced spawn room toward the nearby village, which could help reduce the zombie spawn near the village.

Mob caps are supposed to be separately calculated for each type of mobs so the number of nearby villagers should not affect the spawning of hostile mobs. I don't know what actually happens in MCPE though. It's time for you to experiment yourself, and please file a separate issue if you find any oddities 🙂

Actually, what I had in mind is transporting the mobs horizontally, then up into a kill device in my house, which I think I know how to do. However, your point number three would kinda kill my system.

I built another mob farm this weekend to test the horizontal distance theory. The it's just like my other one... a 30x30x3 room with 6x6 spawning pads and water channels in between. The difference is, instead of being 24 blocks directly below my house, this one is only about 10 blocks deep but is centered horizontally about 55 blocks away. I'm still seeing zero spawn (except for bats) in this room.

On the bright side, my build for a horizontal transport system was very successful. Or at least, it worked on me and a chicken that had fallen into my room.

@unknown, horizontal 55 blocks away is probably too far, at least in the current version. Try 24 blocks as it was the best distance in my experiment.

I thought about that, and I stood halfway for a game day and checked again. I think one spider had spawned.

Has anyone tested this on 0.14.0 bx ?

I've turned my 0.13.1 one into a mushroom farm now _

Yes, still affects 0.14.0 alpha. Nothing have changed since 0.13.1.

Moderators, please reopen this. It's about vertical distance ignored by the spawning rule, and not the same as MCPE-11112.

Reopened.

Still affects 0.14.1.

Verified on 0.14.2

It is not widely understood why mob farms don't work on MCPE. People on the forums just assume MCPE is different / sucks.

Verified on 0.15.1

Please update.

Thank you thank you thank you for pointing out this problem... I've built so many variations of spawner in so many different places and stood at so many different heights with so many different flushing mechanisms that i was starting to lose the will to mine. Relieved to know the cause of my suffering but i despair that this issue is effectively unfixable until the devs deem it a worthwhile cause. Pleeeeeeeezzzz pleeeez pleeez fix it, i have put literally days into trying to sort this out and was so looking forward to recreating my pc world on my phone now we have pistons... But seeing as this bug is still ruining my life im not gonna bother... May look into making a redesigned spawner around this new found knowledge or i may just give up and throw my phone into the path of a passing cheese wheel and go train a pigeon.

The number of votes should NOT dictate the priority on issues like this.

Most people are aware that "mob farms just don't work" in MCPE. No one understands why or that it is a bug. And few people / no one can find this issue to vote on it. This should be a fairly high priority bug as a major dynamic of the game is very broken here.

Agreed, this isnt just a minor unnoticeable flaw, this is a game breaking problem with a fundamental mechanic of the game not functioning properly.

Mob spawners not functioning correctly may not be high on the issue list but the fact that this bug will be having huge effects on the rest of the game but it has somehow gone unnoticed and nothing is being done about it is frankly rediculous.

0.15.4 confirmed....

As a side note, this makes golem farms work better than normal. There's always a silver lining! 🙂

I have just came across this same problem as i just completed my first mob farm in PE and it is not functional due to the fact that no hostile mobs will spawn in the farm. Very frustrating and i hope this gets fixed.

0.15.6 on Samsung Galaxy Note 5 comfirmed not working

I totally agree with you on this James M, i see this as a major problem due to the fact that minecraft primary functions are to farm passive and hostile mobs. I really hope this issue gets fixed soon as it is a really bad bug. I have tried contacting Mojang and the support team to make them aware of this problem so it can be fixed imediately.

It might be working, if you take into account only 6 hostile mobs can be within your spawn sphere at one time.

I've done some testing. I built a mob spawner on Windows 10 Beta edition, and it didn't seem to be working as well as the videos on YouTube, but it did spawn things once in a while (rarely), but then it wasn't in an area that prohibited spawning in other places (caves for instance). Then I built a donut shaped spawn platform that started at 24 blocks and went to 36 blocks away from a central point out in the middle of an ocean. It had walls so nothing that spawned on it could escape. At no time were there more than 6 mobs. I built pits out in the middle of a large plains area. When mobs would spawn on the plains I would kite them into the pits. I collected 6. So long as I stayed within 36 blocks, they would not despawn, but no more mobs would spawn.

I don't see how that proves it's working. Stand on top of your donut-shaped mob spawner in the ocean and go straight up, 25-35 blocks from the center. Nothing will spawn, even with 0 mobs in the vicinity. I have personally tried this.

Also, couple the aforementioned mentioned fact with this:
I have a mine-cart track sitting at the build height limit in a plains zone which goes 2k blocks in one direction. The plains sit at about sea-level (about 62z) and my track is at 126z (just below build limit) on half-slabs. I get mobs spawning below me on the ground at / about 24-36 blocks either Y or X in-front or behind me constantly. I can sit up there on my track and shoot at them, kill them and watch more spawn.

The game doesn't take into account your z axis for mob spawns and possibly despawns and that seems pretty clear. I believe this relates to at least 3 other issues as well.

It really doesnt prove anything, besides its really not working the way its supposed to. Ive built the exact same farm on another platform in the same exact conditions (over an ocean/light up surrounding areas) and the farm worked great. But the farm on PE will not spawn any mobs at all. And there should be no reason to have to find a perfect horizontal level to the farm, perfectly 24-36 blocks away just to get the farm to work, especially if all land and caves around is lit up for no spawns to occur. It should bot be this hard to get a mob to spawn in a 6×6×4 area that has a light level lower than 2. And it should not be only 6 mobs in that big of an area.. if your farm is centralizing spawns all inside the farm and none outside, it should technechally be trying to put the max number of hostile mobs to spawn all within the farm. And i can gurantee you the max number of hostile mobs spawned in a world at one time is more than 6-15. It seems my skeleton spawner farm will spawn enough skelotons to lag out minecraft.

This bug has been reported to our internal bug tracker for further testing and a fix. It is scheduled to be fixed in one of the future updates (no specific date can be provided).

@nighter

Thanks, you are to be commended for providing an update! It is really appreciated! But, to me this comment implies most confirmed bugs aren't important enough to your team to make it into your internal tracker. Why did this bug make it and others didn't? You see how this perception makes us think we are all wasting our time here?

Does this still affect the latest version? Please respond if it does.

Looks like it's affecting 0.16.0 based on comparison of a 10x10 dark room 24 blocks above my head (no spawns across ~10 checks) versus an identical box 24 blocks to the side of me (2-7 spawns on all but 2 of those checks, switching to peaceful and back to clear old spawns between checks).

This bug is still affecting alpha 0.17.0.2
...doubting Mojang at this point...

Attached a test world.

Still affecting Minecraft PE 1.0 Final

I made a Duplicate post seems like this has been an issue for about a year now, really hoping for a fix.

I have built and tested the mob farm design by Mumbo Jumbo in several worlds. My most recent test is about 130 blocks from the highest ground. I stand on top of the farm which would be about 150 blocks from ground and maybe 1 mob will spawn in 10 minutes. I stand to the side on one end and will get about 1 spawn per minute. But it's nothing like the 10,000+ drops per hour boasted by the designer. I put a ten block tower on top and stood up there for 10 minutes and didn't get a single drop. It seems to only spawn slowly when I am at the same level as the chambers. This makes survival worlds difficult because you can't farm stuff like bone meal which means you can't farm anything else in any significant quantities.

I have confirmed that it works best when I'm standing at one end. Standing directly above or directly below seems to not work at all. Also I confirmed another bug about half slabs disabling spawning completely throughout the entire system.

I can't explain it but the farm worked pretty well for a couple of days. I left the realm on and went to bed once. I found out the next morning that realms has a timeout of 20 minutes. But during that time I got nearly a full stack of bones, arrows, gun powder and string and almost two stacks of zombie flesh. When I was booted out and logged back in a redstone glitch that has also been reported caused some of my dispensers to fire leaving water out on some of the spawning pads. But, I turned on the hopper timer and let it run for another 30 minutes this time keeping the connection alive. I nearly matched the above stated results. I'm thinking, "this is great, I've figured it out". So I build a bottom slab scaffold around the structure, open up several place and fix the dispensers, and return to my afk platform. Spawning stopped cold. I have absolutely no idea what changed. I'm continuing to test but thought the odd flurry of good results should be shared in case it was a clue. I'm wondering if there is a long term light setting that was reset when I opened the sides. I'll continue to test and report.

Ok, I've found something. I started this whole thing on a realm. Then downloaded the realm to my iPad (Copy 1) to experiment with, then downloaded it a second time (Copy 2) after doing some updates to the spawner on the realm. So, on Copy 2 I experimented with a water funneling system and had to use eggs to get some skeletons to test with. I tried a different water method on Copy 1 and suddenly it started dropping out 3 or 4 mobs every 10 seconds, no real explanation. Copy 2 still wasn't working at all. I messed with Copy 2 for a long time and finally figured out that it works if I stand on the opposite side. I tested in the realm from the opposite side and I started getting drops! I have some screenshots but am not sure about attaching them to this thread. Why does one Copy work when I stand on one side, but the other Copy only works on the other side? It's baffling.

Re-attached bugtest world download, since the previous one was incorrectly packaged as a .mcpack, when it was really supposed to be a .mcworld file.

Cannot reproduce on Apple iPad mini with iOS 9.3.5, but I can on iPad Air with iOS 10.2.1

The bug looks like it only happens on 64-bit devices, if this works on any 32-bit device, correct me

@unknown I was able to reproduce this bug in Windows 10 Edition on a 32-bit device. I haven't tried it on a 32-bit Android device, however.

Thanks for correcting me there, I have been able to reproduce some issues on one device but not the other

According to the official changelog of 1.0.5 Beta Build 1, this bug has been 'fixed'.

I have come across this bug again on both Windows 10 64-bit and Android, on 1.2.3.

To test this, I created a superflat, peaceful world and a stick 140 blocks high, then a small platform 30 x 30 on top of that, which I stood at the edge of. I then put the difficulty on easy and set the time to night, then waited for 5 minutes.

What should have happened is monsters spawn on the platform that I made, and no monsters spawn beneath, as the platform was higher than 128 blocks above the ground.

However, after I set the time to day (to stop monsters spawning) I went back to ground level and found many monsters, showing that monsters are spawning lower than 128 blocks below the player.

Please refer to ticket MCPE-28352 that describes the behaviour of mobs spawning more than 128 blocks away vertically.