Emitters are a special type of controller that create new particles in a group. They can be configured to emit particles at a specific rate, or can be used to emit a burst of particles at will.

As factories for particles, emitters have several features for specifying the initial particle parameters. A template particle is provided as a basis for the particles emitted. Specified alone, each particle emitted is an exact clone of this template. The basic template may be augmented by a deviation template, which specifies the statisical deviation of the Particle attributes. This allows you to easily express how much, and in what way each particle differs from one another.

class lepton.Particle(**kwargs)

A template for particle creation. Parameters are specified as keyword arguments to the constructor:


The position of the particle, as a 3-item tuple.


The velocity of the particle, as a 3-item tuple.


The size of the particle, as a 3-item tuple.


The current orientation of the particle, as a 3-item tuple of euler angles.

If using the Billboard renderer, only the z component is in fact relevant; the other components are discarded.

The other renderers do not support rotation.


The rotation of the particle, as a 3-item tuple of euler angular velocities.


The color of the particle, as a 4-item tuple.


The mass of the particle as a float.


The age of the particle as a float.

Particle attribute values may also be expressed as a sequence of discrete values (e.g., the colors of the rainbow, discrete sizes, etc). This is done by passing a list of values as a keyword argument to the emitter, for example:

emitter = StaticEmitter(
    position=[(0, 0, 0), (100, 0, 0), (200, 0, 0)]

Particle attribute values may also be generated randomly within a Domain:

jet = StaticEmitter(
        (0, 0, -50),  # center
        (0, 0, 1),  # normal
        1.5,  # inner radius
        1.5  # outer radius

This flexibility allows powerful control over the desired range of composite attributes, such as position, velocity and color vectors.

Two emitters are currently included with lepton:

  • StaticEmitter – Emits particles at a regular rate over time, or can emit an arbitrary number at once
  • PerParticleEmitter – Emits particles originating from the positions of all existing particles in a group. Useful for creating trails of particles, like, for example, fireworks.