Multiblocks

A multiblock is a structure of several blocks that works as one machine: a tank, a reactor, an altar. Each of its blocks is a machine with the machineengine:multiblock_member behavior. One of them, the anchor, holds the structure's storages.

• The structure forms as soon as its last block is placed, and unforms when one is broken.
• The anchor checks the structure again every few seconds (a block placed inside, a part added).
• While formed, the anchor's storages are sized by capacities.

Formed multiblocks, seen from outside.

Declare structures in the multiblocks: section of a definitions file. Two shapes:

Boxes

A hollow box (Mekanism's tanks and reactors are boxes): casing blocks on the edges and corners, walls of allowed blocks, and an interior.

multiblocks:
  mypack:vat:
    box:
      casing: mypack:vat_casing # edges and corners
      faces: [mypack:vat_casing, mypack:vat_valve, minecraft:glass]
      interior: [minecraft:air] # optional, default any block
    capacities: {fluid: {per-block: 16000}} # per interior block

Key	Default	Meaning
casing	—	Required. Block of the edges and corners.
faces	—	Blocks allowed in the walls.
interior	any	Blocks allowed inside.
min-size	3	Smallest side, in blocks (at least 3).
max-size	18	Largest side.
width	0	Fixed width; 0 for any.
open-top	false	No top layer.
controller	none	A block that must appear exactly once in the walls.

The anchor of a box is its lowest corner casing block, so the casing's machine type declares the structure's storages.

Patterns

Any fixed shape, written as layers of rows with a character key — like a crafting recipe in 3D. It is found in any of the four horizontal rotations.

multiblocks:
  mypack:altar:
    pattern:
      layers: # bottom up; rows north to south; characters west to east
        - ['CCC', 'C#C', 'CCC']
        - ['   ', ' G ', '   '] # a space is any block
      key:
        C: mypack:altar_casing
        '#': mypack:altar_core
        G: [minecraft:glass, minecraft:tinted_glass] # any of these
      anchor: '#'
      rotate: true # optional, default true
    capacities: {mana: 64000}

The anchor character must appear exactly once, and must be a member machine.

capacities

The anchor's storages while the structure is formed, by storage id: a number, or { per-block: N } for N per interior block (boxes).

The member blocks

Every block of the structure that is a machine uses the machineengine:multiblock_member behavior:

machines:
  mypack:altar_core:
    storages: {mana: {capacity: 1}} # the anchor declares the storages
    behavior:
      type: machineengine:multiblock_member
      multiblocks: [mypack:altar]
  mypack:altar_casing:
    behavior:
      type: machineengine:multiblock_member
      multiblocks: [mypack:altar]
  mypack:altar_valve:
    behavior:
      type: machineengine:multiblock_member
      multiblocks: [mypack:altar]
      role: valve
      storages: [mana]

Key	Default	Meaning
multiblocks	—	Required. The structures this block can be part of.
role	frame	frame (casing, glass…), valve or port.
storages	none	Valves and ports: the anchor's storages they pass through, on all their sides (pipes and cables connect there).
exclusive	false	Valves: the structure holds one of those storages at a time (a tank holds a fluid or a chemical).
output-rate	—	Ports: amount per tick pushed to neighbors when the port is in output mode.

A port is in input mode by default; an addon's tool (Mekanized's configurator) switches it to output.

In Java

Addons build the same structures with api.multiblock: MultiblockType, MultiblockShape and MultiblockMember.of(types).