Chunk



Chunks are segments of the virtually infinite Minecraft maps. They are 16 blocks wide, 16 blocks long, and 256 blocks deep (As of version 1.2), which is 65,536 blocks total. Chunks are generated around players when they first enter the world. As they wander that world, nearby chunks are generated as needed.

The exact number of generated chunks varies in single player mode, depending on view distance and movement. In multiplayer mode, a grid with a default radius of 10 (for a total of 21x21 or 441 chunks) is loaded around each player and sent to the player by default, although this radius can be configured to be between 3 and 15, usually only lowered with a poor connection home server. These chunks may have activity (mobs spawning, trees growing, water flowing, dropped items disappearing etc.), while the other world chunks are inactive, stored on your hard drive. Chunks will not save again if they were saved in the last 30 seconds.

Slimes can only spawn in specific chunks, determined by a calculation performed on the chunk coordinates. There are a number of utilities and mods which allow the player to tell which chunks they can spawn in; see the Slime article for details.

Minecraft's renderer divides a world chunk into eight 16x16x16 render chunks, which are compiled OpenGL display lists, to speed up rendering significantly. They need to be rebuilt each time when blocks within these chunks are changed.

Creation of Chunks
Chunks are created with the help of the Map Seed, which means that the chunks are always the same if you would use the same Seed again (on the same Minecraft version and world generator at least).

Finding Chunk Edges

 * Pressing the "F3" button opens the Debug screen which shows the player's X, Y, and Z coordinates. These coordinates will change as the player moves around. X and Z coordinates that are divisible by 16 represent the boundaries between chunks.  EG:  (96, -32) is a corner where four chunks meet. One of those chunks is between X coordinates 80 to 96 and Z coordinates -48 to -32. Another one is between X coordinates 96 to 112 and Z coordinates -32 to -16, and so on. When either X or Z crosses a multiple of 16, the player is moving across chunks.
 * There is also a bug that allows players to see chunk borders through Ice in snow biomes. These borders can only be viewed from the side.

Chunk error


A chunk error (also known as a missing chunk or world hole) is a common error found in multiplayer mode. They are typically client side, meaning that they are caused by the user's software, and not a server software. Reconnecting to the server or reloading the map usually fixes chunk errors. Players can jump or fall into an errored chunk, since some players have reported falling and some have reported warping similar to arrows. Rarely, chunk errors can occur server-side, and they can be fallen into. Due to the way fluids are displayed, any fluids on the border of the chunk error will look as if they are flowing downwards. On non-modded servers the teleport command can be used to escape such a glitch. Items dropped on an errored chunk in singleplayer mode will fall and cannot be retrieved, however. Also, non-solid blocks can't flow into one. Blocks that are in a chunk error can reappear if you place a block in a chunk error (it gets overwritten, so the block you place gets turned into what was there) or blow it up with TNT. Chunk errors have been noticeably less common since Beta. If you walk far enough from a chunk error then come back the chunk will either disappear or move, chunks that move will rarely change shape (Expanding), normally containing two chunk errors, sometimes three.

When in SMP, it is noted that some items remain visible within a chunk error. This tends to apply to items like paintings or redstone components/wiring. This does not always occur, however.

Chunk error Work-arounds
Because chunk errors are usually temporary bugs where the Minecraft client was unable to load a chunk, logging out and logging back in is often all that is required to fix one. However, there are also other things a player can do to work around chunk errors.

Players are able to walk into a chunk error, but will only glitch out. If you walk into the chunk until you get stuck in a falling animation hit esc and disconnect. Once you re-connect the chunk will be filled in. They are able to ride through them in a boat or minecart - provided there are pre-existing rails. While the track will remain invisible to you, your cart will follow it. If your destination happens to be in an errored chunk, simply re-connect to the server or reload the map upon arrival to avoid falling into the errored chunk and losing your minecart.

Lighting, explosions, and other processes that update blocks within a chunk can cause chunks to re-load, making them visible. Because of this, placing torches can be used to make localized parts of chunk errors visible. Also you can right-click (or use your custom action or "place" button) on a visible block in a seperate chunk to the one missing. The block next to it will appear. This works with a fist or any equipped item or block.

Another type of chunk error is when a player is on a SMP server and sees a chunk that is empty. If the player walks on it, the chunk will act as if it was visible. Resending the chunks by moving away(or other means) will usually fix this. Waiting may also fix this.

Resetting your render distance causes the chunks to refresh, so this can be used as well.

Usage of chunk errors
Often, a chunk error will allow you to see a cross-section of the world, making it easy to locate ores, caves, dungeons, and other hidden structures underground. This can be exploited by marking the surface above any interesting looking veins, caverns, dungeons or other structures before re-loading the map.

Sometimes on lower end computers, chunks will glitch in a way that the chunk will still be visible; however, if a block is mined, it will still be visible, but without a collision box. If you dig out a space when this happens and stand in it, you will be able to see mineshaft parts, chests, particles, the figure spinning inside spawners(it won't be spinning), caves, and certain areas of blocks.

If you have a buddy on a multiplayer server with a chunk error, they are useful for guiding you from along the sides of a chunk error as they can see where you are digging. This means that your friends can point you to resources they cannot reach because of the chunk error.

Fake Chunks
Fake Chunks are non-solid chunks that generate past 30,000,000 meters from the spawn. A sure sign that one has reached the edge of the map is that blocks appear fully lit past the 30,000,000 mark. If the player walks into the fake chunks, the player will fall through them into the Void and be killed. When the player flies about 34 blocks past this perimeter the game freezes and begins to jitter with severe lagging, the player cannot be seen in 3rd person mode and cannot move. There is no way to escape this and the player has to start a new world or edit their position in the level.dat file. Fake Chunks also generate in the nether and have the same effects as in the Overworld.

In snapshot 12w25a, this is prevented by the save (due to single player games functioning like the client side of a multiplayer server) kicking the player out of the game for being in an illegal position and respawning the player back within the 30,000,000 mark. This prevents the world from being "killed" and the player from locked movement.

Effects Near Fake Chunks

The world starts to act slowly and unresponsive with unintended results if a player goes past 12,550,820 meters from the spawn point. Known effects are:


 * When pistons extend, the rod section of the piston extension block (see Data values) vanishes, but its collision box is still there.


 * Redstone wire will have distorted textures and appear stretched.


 * Falling sand and gravel appear in an incorrect position (miscalculation in x and y values) until they fall completely down and turn back from an entity into a block, except for TNT.


 * The fire particles in redstone torches and normal torches appear in incorrect positions.


 * A great amount of lag is given to the player if one waits past the 12,550,820 meter point for a period of time. A short-term remedy for this is by using a mod that can use a command to remove every entity in the world and make all blocks fully lit.