Emitter components

The emitter is the invisible spawner behind every particle effect. Its components decide when it runs, how many particles it makes and where they start. They all go in the components block of a particle file, next to the particle components.

New to particles? Start with Your first particle, which builds a full ruby sparkle step by step.

Most number fields on this page accept either a plain number or a Molang string like "math.random(1, 3)". The tables mark when a field is worked out: once when the emitter starts, per loop, or per particle each time one spawns.

Setup

These run before anything spawns. You can use them together with any other components.

Setting variables

emitter_initialization is the place to roll a random number once and share it with every particle:

"minecraft:emitter_initialization": {
  "creation_expression": "variable.ruby_hue = math.random(0.2, 0.4);"
}

Every particle from this emitter can now read variable.ruby_hue, for example in its tint.

Local space

By default, particles start at the emitter and then live on their own in the world. If a mob walks away, its old particles stay behind, like a trail.

• position: true makes particles move with the mob. Use it for a glow that should stay wrapped around it.
• rotation: true also turns them with the mob. It only works together with position: true.
• velocity: true adds the mob's speed to each new particle, so sparks thrown by a running mob fly forward.

"minecraft:emitter_local_space": {
  "position": true,
  "rotation": true
}

Rate

The rate decides how many particles appear and how fast. Pick one.

Instant: a burst

"minecraft:emitter_rate_instant": {
  "num_particles": 12
}

If the emitter loops, it bursts again at the start of each loop.

Steady: a stream

"minecraft:emitter_rate_steady": {
  "spawn_rate": 20,
  "max_particles": 40
}

This makes 20 particles per second, but stops adding new ones while 40 are alive. max_particles is a safety limit: keep it low, because hundreds of particles can slow down weaker phones.

Manual: for events

emitter_rate_manual is used by built-in effects that the game spawns one particle at a time, like rain splashes. For your own effects, you will mostly use it for small effects that other effects spawn with an event of type particle (see events). For anything you play yourself, use instant or steady.

Lifetime

The lifetime decides how long the emitter keeps working. Pick one, then add lifetime events if you need them.

Once

The best choice for a one-time effect from a command or script:

"minecraft:emitter_lifetime_once": {
  "active_time": 1
}

With emitter_rate_instant, the burst happens at the start, so active_time can be short.

Looping

"minecraft:emitter_lifetime_looping": {
  "active_time": 2,
  "sleep_time": 3
}

This sparkles for 2 seconds, rests for 3, and repeats. Use looping for effects attached to a mob or played from an animation controller, where the game removes the emitter for you when the mob or state goes away.

Expression

Great for effects that follow a mob and switch on and off by themselves:

"minecraft:emitter_lifetime_expression": {
  "activation_expression": "query.ground_speed > 0.1",
  "expiration_expression": 0
}

This only sparkles while the mob is walking, and never removes itself. Queries like query.ground_speed read the mob the effect is attached to.

Events

emitter_lifetime_events points at names in the events block of the same file. Each field takes one event name or a list of names.

"minecraft:emitter_lifetime_events": {
  "creation_event": "flash",
  "expiration_event": "pop",
  "timeline": {
    "0.5": "twinkle",
    "1.0": ["twinkle", "chime"]
  },
  "travel_distance_events": {
    "4.0": "dust"
  },
  "looping_travel_distance_events": [
    { "distance": 1.0, "effects": ["dust"] }
  ]
}

Shape

The shape decides where each particle starts and which way it points. That direction is what particle_initial_speed pushes it along. Pick one.

Fields shared by the shapes

The point and custom shapes only take an [x, y, z] direction, because they have no centre to point away from.

Point

"minecraft:emitter_shape_point": {
  "offset": [0, 0.5, 0],
  "direction": [0, 1, 0]
}

Every particle starts half a block above the emitter and points straight up.

Sphere

"minecraft:emitter_shape_sphere": {
  "radius": 0.5,
  "surface_only": true,
  "direction": "outwards"
}

A hollow ball of sparkles that flies apart. Try "inwards" with a short lifetime for a "gathering power" effect.

Box

"minecraft:emitter_shape_box": {
  "offset": [0, 0.5, 0],
  "half_dimensions": [0.5, 0.5, 0.5],
  "direction": [0, 1, 0]
}

half_dimensions is measured from the centre, so 0.5 on every side fills exactly one block. Good for an effect that covers a whole block, like a glowing ore.

Disc

"minecraft:emitter_shape_disc": {
  "radius": 1.5,
  "plane_normal": "y",
  "surface_only": true,
  "direction": "outwards"
}

plane_normal is the axis the disc faces. "y" (the default) makes it lie flat like a rug, "x" and "z" stand it up like a wall. You can also give your own [x, y, z]. This example makes a ring on the ground that spreads outwards: a nice landing effect.

Custom

"minecraft:emitter_shape_custom": {
  "offset": [
    "math.random(-0.1, 0.1)",
    "math.random(0, 2)",
    "math.random(-0.1, 0.1)"
  ],
  "direction": [0, 1, 0]
}

With a custom shape, you work out the spot yourself, as [x, y, z]. This places each particle at a random height up to 2 blocks, but keeps it close to the middle sideways: a thin pillar of sparkles, like a beam of light. Each value is worked out again for every particle.

Entity box

"minecraft:emitter_shape_entity_aabb": {
  "surface_only": false,
  "direction": [0, 0.2, 0]
}

This uses the mob's own hitbox (its collision box), so the same effect fits a chicken and a ruby golem without changes. If the effect is not attached to a mob, the particles come out of the emitter's point instead.

A full emitter

Putting one of each group together. This aura loops while a mob is around and sticks to it:

"minecraft:emitter_local_space": {
  "position": true,
  "rotation": false
},
"minecraft:emitter_lifetime_looping": {
  "active_time": 1
},
"minecraft:emitter_rate_steady": {
  "spawn_rate": 8,
  "max_particles": 20
},
"minecraft:emitter_shape_entity_aabb": {
  "surface_only": true,
  "direction": [0, 1, 0]
}

Add the particle side (lifetime, look and motion) from Particle components and play it from a mob's animation, as shown in Your first particle.