Simulation distance doesn't effect mobs

I believe you're misinterpreting what is happening. Simulation Distance doesn't have any affect on visibility, only on whether blocks and entities receive update ticks. The mobs disappearing is caused by a different rule that only renders entities within a certain distance of the player. This rendering rule cannot be altered in Settings. The rule doesn't apply to blocks, which is why your redstone circuit remains visible.

The Simulation Distance setting (which I'll henceforth abbreviate to SD) applies to chunks, so its effect area shape is what you might call a "squared cylinder" that extends from Y=0 to the top of the world. The entity rendering radius (henceforth ERR) shape is a true sphere with a radius of ~70 blocks. The difference in shapes between the two ranges means that an entity can be in one of four states:

• Normal: Inside both ranges, and therefore visible and active

• Out of Range: Outside both ranges, and therefore invisible and inactive

• Frozen: Outside the SD range but inside the ERR range, thus visible but inactive

• Stealthy: Outside the ERR range but inside the SD range, thus invisible but active

The first three of these states are familiar and well understood by experienced players, so I assume you recognize them. I think what's happening is that you're seeing evidence of the Stealthy state, which is less familiar because it's harder to observe. Because the mobs are invisible, players often assume that Stealthy mobs are Out of Range, when in fact they're still active.

The Stealthy state can occur at any SD setting of 4 chunks or higher. Larger SD settings increase the area within which a mob can be Stealthy, and thus the chance of noticing the difference. People will be discovering this more now that we can set SD to higher values.

To demonstrate the Stealthy state,

1. Create a flat world with the Simulation Distance set to 6 chunks and Show Coordinates set to True.

2. Place fences at (0, 4, 0), (0, 4, 15), (15, 4, 15), and (15, 4, 0). Connect these with additional fences to make a pen that's entirely within one chunk.

3. Spawn 15-20 cows within the pen.

4. Fly to (8, 24, 75) and look north at the pen. In this position, the ERR ends approximately in the middle of the pen, while the SD covers the entire pen. If you move backward and forward, you can see the rendering range encompass fewer or more cows, respectively.

5. Watch the cows walk around. Some will disappear as they move into the back part of the pen and reappear as the come back to the front. This proves that they're still active after they disappear, since otherwise they would freeze and would not be able to return to the active area.

Your report includes a request to make mobs be active within the simulation distance. Since this has demonstrated that they already are, your other request, to stop them from disappearing, applies, but since this is not a bug it's not something we handle on the bug tracker; you should request that on the feedback site, along with the request for more comprehensive documentation of the settings.

I believe you're misinterpreting what is happening. Simulation Distance doesn't have any affect on visibility, only on whether blocks and entities receive update ticks. The mobs disappearing is caused by a different rule that only renders entities within a certain distance of the player. This rendering rule cannot be altered in Settings. The rule doesn't apply to blocks, which is why your redstone circuit remains visible.

The Simulation Distance setting (which I'll henceforth abbreviate to SD) applies to chunks, so its effect area shape is what you might call a "squared cylinder" that extends from Y=0 to the top of the world. The entity rendering radius (henceforth ERR) shape is a true sphere with a radius of ~70 blocks. The difference in shapes between the two ranges means that an entity can be in one of four states:

• Normal: Inside both ranges, and therefore visible and active

• Out of Range: Outside both ranges, and therefore invisible and inactive

• Frozen: Outside the SD range but inside the ERR range, thus visible but inactive

• Stealthy: Outside the ERR range but inside the SD range, thus invisible but active

The first three of these states are familiar and well understood by experienced players, so I assume you recognize them. I think what's happening is that you're seeing evidence of the Stealthy state, which is less familiar because it's harder to observe. Because the mobs are invisible, players often assume that Stealthy mobs are Out of Range, when in fact they're still active.

The Stealthy state can occur at any SD setting of 4 chunks or higher. Larger SD settings increase the area within which a mob can be Stealthy, and thus the chance of noticing the difference. People will be discovering this more now that we can set SD to higher values.

To demonstrate the Stealthy state,

1. Create a flat world with the Simulation Distance set to 6 chunks and Show Coordinates set to True.

2. Place fences at (0, 4, 0), (0, 4, 15), (15, 4, 15), and (15, 4, 0). Connect these with additional fences to make a pen that's entirely within one chunk.

3. Spawn 15-20 cows within the pen.

4. Fly to (8, 24, 75) and look north at the pen. In this position, the ERR ends approximately in the middle of the pen, while the SD covers the entire pen. If you move backward and forward, you can see the rendering range encompass fewer or more cows, respectively.

5. Watch the cows walk around. Some will disappear as they move into the back part of the pen and reappear as the come back to the front. This proves that they're still active after they disappear, since otherwise they would freeze and would not be able to return to the active area.

Your report includes a request to make mobs be active within the simulation distance. Since this has demonstrated that they already are, your other request, to stop them from disappearing, applies, but since this is not a bug it's not something we handle on the bug tracker; you should request that on the feedback site, along with the request for more comprehensive documentation of the settings.

Thanks for that detailed help!

I did have an unrelated query, just thought if you saw it here I wouldn't end up creating another bug...

When I set the SD to max (12 chunks or whatever) I swear less hostile mobs spawn at night... I'm guessing that the same number is spawning, but now spawning within a much larger radius, thus many are spawning far away where I can't see them. Does this sound like a possibility? or something you've (or anyone) has experienced? I haven't done any solid tests, just a hunch.

Thanks for that detailed help!

I did have an unrelated query, just thought if you saw it here I wouldn't end up creating another bug...

When I set the SD to max (12 chunks or whatever) I swear less hostile mobs spawn at night... I'm guessing that the same number is spawning, but now spawning within a much larger radius, thus many are spawning far away where I can't see them. Does this sound like a possibility? or something you've (or anyone) has experienced? I haven't done any solid tests, just a hunch.

Sorry for the delay, I haven't revisited this ticket for a while.

SD settings in the range from 4 to 6 chunks have a big effect, because they can reduce the spawn area without reducing the number of spawns. Above 6 chunks (96 blocks), this effect disappears because the spawn area never goes above 96 blocks.

However, there are other effects that can explain what you're seeing. Notably, depending on how you move around during the day, many mobs spawned the previous night are likely to still be around, and in many cases they'll be out of sight. Some may be stuck in a hole or pond, some are hidden from you by terrain, and some may even be outside your ticking area (i.e. SD range) where they don't contribute to the specific mob cap but they do take up space under the "mob density cap", which is just as effective at suppressing spawns. The takeaway is that some of these other effects aren't SD dependent, so you should see some reduction in spawning from one night to the next just from how you move around during the day. Increasing the SD setting should indeed tend to reduce the spawned mob density, but it's only one of the factors, and there's a certain amount of randomness involved too.

Sorry for the delay, I haven't revisited this ticket for a while.

SD settings in the range from 4 to 6 chunks have a big effect, because they can reduce the spawn area without reducing the number of spawns. Above 6 chunks (96 blocks), this effect disappears because the spawn area never goes above 96 blocks.

However, there are other effects that can explain what you're seeing. Notably, depending on how you move around during the day, many mobs spawned the previous night are likely to still be around, and in many cases they'll be out of sight. Some may be stuck in a hole or pond, some are hidden from you by terrain, and some may even be outside your ticking area (i.e. SD range) where they don't contribute to the specific mob cap but they do take up space under the "mob density cap", which is just as effective at suppressing spawns. The takeaway is that some of these other effects aren't SD dependent, so you should see some reduction in spawning from one night to the next just from how you move around during the day. Increasing the SD setting should indeed tend to reduce the spawned mob density, but it's only one of the factors, and there's a certain amount of randomness involved too.

This issue is resolved as Working as Intended based on the comments above which suggest that the issue can be explained by intended game mechanics. If you feel anything remains unaddressed, feel free to comment and it will be reviewed.

This issue is resolved as Working as Intended based on the comments above which suggest that the issue can be explained by intended game mechanics. If you feel anything remains unaddressed, feel free to comment and it will be reviewed.