Nonvanilla mechanics

This page is intended as a reference on the nonvanilla game mechanics that are present on Purity Vanilla, usually necessary to optimize server performance, or to prevent server rule-breaking exploits such as duping. The hope is that this page can server as a useful and technically accurate reference for players building automatic farms, mob farms, and any other builds for which it would be useful to know ahead of time how known designs may deviate in behavior because of various important mechanics like the maximum server view distance, altered spawning rates, various introduced mob caps etc.

Reduced Maximum View Distance
The current setting for maximum view distance on the server is currently 5. This is one of the most important settings for optimizing server performance, as a large area of loaded chunks surrounding each of the logged in players can quickly add up to a huge area for the server to process. Note that it is important to understand that the furthest loaded chunks from a player are not "entity-processing" chunks, but will only process block updates such as redstone signals, moving pistons etc. (these chunks are known as lazy loaded chunks). For a chunk to process mobs or any other type of entity, it needs to be at the center of a 5x5 area of lazy loaded chunks.

[Note: Need to add a simple visual showing the entity-processing / lazy loaded chunks surrounding a player with a view distance of 4]

Altered Mob Spawning \ Despawning
There are various caps that affect spawning rates of mobs, as well as rules for despawning them if too many accumulate in a small area due to breeding or spawning. One example of this is a newly introduced cap on villagers which will cause villagers to despawn if more than 72 are found in a 2 x 2 chunk area.

[Details of all the caps \ spawning rate changes would need to be provided by Penguin if possible; it would be a priority to learn about the mechanics for neutral mobs such as chickens, cows, sheep, pigs, etc. as people seem to have a lot of trouble farming them without despawning and they all seem to share some sort of neutral mob cap not found in vanilla MC. It would be helpful to know exact changed mechanics for any type of mob that can be farmed including: pigmen, guardians, drowned, creepers, ghasts etc.]

Disabled Nether Roof
In order to reduce the strain on the server, the nether roof has been "disabled". Players that try to enter the nether roof will start to take damage and eventually die. This renders nether farms such as ghast and pigmen farms significantly more difficult to create.

Suppressed Remote Chunk Loading
In vanilla Minecraft it is possible to remotely load chunks using various methods that usually involve causing block updates on the borders of already loaded chunks. A simple example of this would be a hopper with an item, on the border of an already loaded chunk, facing into an unloaded chunk: the game would load the neighboring chunk to check whether there is a container for the hopper to deposit the item into. On Purity Vanilla, this could potentially cause performance issues as players could keep an arbitrary number of chunks loaded at all times, so this type of remote chunk loading based on block updates is supressed; loaded chunks are limited to those directly loaded by players and the permanently loaded chunks in the spawn area.

Disabled Spawner Mobs AI
Mobs that spawn from spawners have their AI disabled to improve performance. They will be passive and won't track or attack players even in retaliation. This may affect some mob farm designs that depend on the mobs tracking the player to reach a killing spot, so water streams or pistons may need to be used instead. The scourge of the dreaded cave spider has ended and on Purity Vanilla they are like docile lambs that sit there ready to be slaughtered for their string and eyes; we will fortunately also be spared from seeing amateurish cave spider xp farms where the players can't seem to hit the spiders without being poisoned.

Seed Changes
Due to the two resets of the world seed, players will come upon many strange borders between terrain generated using the initial seed and terrain generated using the current seed. Most players find this adds flair and character to the world because of the interesting history. Some other things the seed change may affect include:

Strange end portal dynamics; many strongholds with portals in them may have and likely were generated before the world seed change, due to proximity to spawn, but if players use eyes of ender to try to find a stronghold the eyes will point them in the direction of portal coordinates calculated using the new seed, where no portals are likely to be found: if terrain was already generated using the old seed in locations where the new seed would like to generate portals, no portal or stronghold will be found there even though the eye of ender is pointing to that location. Most often players are told to use the three widely known portals in close proximity to spawn listed on the wikipedia page.

Clueless cartographers; players have at times used woodland cartographer maps only to find that there is no woodland mansion present where the map claims it should be. This is most likely caused by a cartographer "created" after the seed change pointing to a new seed location of a woodland mansion, where however the terrain was already generated by the old seed and so no mansion can be generated. It might also be caused by a cartographer "created" before the seed change and still trying to point to a location based on the old seed, but the terrain generated at the location now being generated by the new seed. Either way, this should be a rare problem, because most players will travel very far out to find cartographers and woodland mansions anyway, so both the cartographers and mansions will most likely be in newly generated areas. [Would be good to add an example screenshot of a old seed \ new seed chunk interface; other examples of things affected by seed change?]

Reduced Hopper Speed
Hoppers seem to pass items more slowly on Purity Vanilla, probably as a way to prevent lag.This has the potential to affect many redstone designs that depend on exact timing using hoppers. Some examples include:

Hopper Minecart Collection Systems: many and some of the simplest designs for hopper minecart collection systems use a hopper with a comparator underneath the first rail to detect when the hopper minecart needs to stop to unload its items. Because of the slower hopper speed (this refers to the hopper below taking items out of the minecart, not the hopper minecart itself), the system may activate slower by which time the minecart is already halfway off the first rail of the track, and too far from the solid block at the start of the track to start again when the power rail is reactivated. There are various solutions to this problem, one of which is to make the second rail in the collection system downwards sloping, so that the minecart can use gravity to restart itself when the system is reactivated. Either way, some collection systems used by farms built using Youtube videos will need to be adjusted.

Hopper Timers: a commonly used and very versatile component of many redstone circuits. If a hopper timer needs to measure a very precise amount of time, the number of items it will need to use will vary widely from Vanilla Minecraft and will need to be figured out for the server.

Hopper Loops: in a hopper loop, an item is passed between a circle of 8 hoppers facing into each other, and various circuits can be activated based on which of the 8 hoppers the item is in at any given time. The hoppers are locked most of the time so the item doesn't circulate freely, but is moved 1 hopper at a time by occasional brief redstone pulses unlocking the hoppers. Because of the slower hopper speed, some redstone pulse circuits will not allow the hoppers to pass the items all the time, in a seemingly block update \ location-dependent pattern (some hoppers will pass the items, and some won't, even though they are right next to each other and are both being unpowered \ powered using the same circuit). What seems to work is to use a pulse circuit that itself uses a hopper, giving power for the exact duration it takes a hopper to pass a single item.

[could add a screenshot of a hopper-based pulse circuit]

Voting Rewards
Voting rewards are a non-vanilla feature that we accept as a necessary evil to maintain and increase the player base. You should go vote here right now to support the server!

Disabled Pack Animals
Due to the use of a duping method involving donkeys and llamas with chests, adding chests to these animals has been disabled entirely. ​​​​It is unknown whether a future plugin may allow the use of pack animals.

Wither Explosion!?
For some odd reason, withers seem to produce large explosions when summoned. Normally in vanilla Minecraft, pro players like Frazzle53 easily defeat the Wither by charging it to get free sword swipes in while it's in the process of spawning, however Frazzle was blown up by a Wither because of this unintended nonvanilla explosion mechanic when trying this tactic.

Farm-relevant 1.16 data
Unfortunately, much of the above was written during the 1.13.2 patch. As the server is now on 1.16, and many optimization tweaks have happened, changes important to people building farms as of March 2021 are as follows:


 * shorter render distance
 * mobs despawn past 48 spherical instead of 128 (measured empirically by RobertD in summer 2020; please measure it yourself and update wiki with confirmation or additional data points)
 * mob caps are quite stark
 * mob AI activation range is very short, and mob AI is non-existent for spawner-generated mobs (leading to bias towards forced-movement instead of AI-based farms)
 * villager AI activation range is very short (important for iron farms and raid farms) (again, you measure distance yourself and update this article)
 * certain things cause pistons to vanish (important for flying-machine based farms)
 * non-vanilla hopper speed.