Particle systems


An emitter can contain multiple particle systems. A particle system is the visible part of the particle effect.

A default particle system is created inside the default emitter when a new particle simulator is added to the timeline, though you can delete this if you wish.

Properties for particle systems are split into several groups. Most settings only affect particles' initial birth state, after which they are unaffected by keyframed properties.

The Appearance and Movement groups also have variation properties in separate Variation groups. The variation properties increase the range of possible values. For example, if you set Scale to 100% and Scale variation to 10%, the actual scale of particles will vary randomly between 90% and 110%.

General

Active - turns the particle system emission on and off. This does not affect the visibility of particle that have already been born.
Affected by Deflectors - whether the particle system reacts to deflectors.
Affected by Forces - whether the particle system reacts to forces.
Seed - a random number used to generate the particle. Adjust this to vary the distribution of particles without changing the overall appearance.
Particles per second - the number of particles birthed per second. For example, 25pps in a 25 frame per second timeline will result in 1 particle birthed every frame.
Emitter attachment - by default once a particle is birthed, it behaves independently of the emitter. So even if the emitter is animated, the particle will continue according to its own behaviour. By increasing the emitter attachment the already emitted particles will move relative to the emitter movement.
Velocity from emitter - as particles are birthed they will inherit initial velocity from the emitter's movement.

Appearance

Texture sources - see the Particle textures chapter for details.
Intersect layers - when disabled, individual particles can only be behind or in front of another 3D layer. When enabled particles will be positioned more accurately when moving through other 3D layers, but this does take longer to render.
Billboard - billboarding particles forces them to always face the camera, regardless of their movement. Disabling billboarding enables particles to be displayed at any angle.
Align to motion - orients the particle based on its direction. This can be useful for having an arrow texture follow a path, for example. Billboarding must be turned off for this to work correctly.
Texture angle - rotates the texture on the particle.
Texture angle per second - causes the texture to rotate continuously.
Blend - blend method for the particles. Add is useful for gas and light-based effects.
Color source - texture color takes the particle's color from its texture. Birth color uses the color from each particle's birth frame. Current color adjusts all particles to the current color, which is useful for changing the color of all particles simultaneously.
Alpha source - these settings work in the same way as the color source options above.
Alpha boost - when using motion blur particles can become semi-transparent. The alpha boost can be used to return these to full solidity.
Color - sets the color of particles. See also color source above.
Alpha - sets the alpha (transparency) of particles. See also alpha source above.

Movement

Life - the duration of particles in seconds.
Scale - the size of particles.
Speed - the speed of particles.
Acceleration - applies constant acceleration to particles in the given direction.
Center of mass - offsets the texture itself from the origin of the particle.
Rotation (X, Y, Z) - rotates the particle.
Rotation per second (X, Y, Z) - adds constant rotation over time.
Mass - adjusts how forces affect the particles. More mass will result in less impact from forces.
Bounce - the bounce of particles when they collide with a deflector.
Friction - higher friction will cause particles to stop faster, while lower friction will let them continue moving along a deflector surface.

RECAP The particle system properties determine the look and behaviour of each particle.