Emitter


An emitter is where all particle effects begin, specifying where the particles appear and affecting their initial trajectory.

A default emitter is added automatically to a new particle simulator, but this can be deleted if you wish.

See also Mobile emitters.

Shape

Emitters can be several shapes. You can choose the emitter shape using the Shape menu.

Each shape has its own properties to define its size and position.
Shapes can be attached to another layer in the same composite shot, such as a point layer. The emitter will then animate to stay in the same relative position to the parent layer.
The Boundary option forces particles to only be birthed around the edge of the shape, rather than inside the shape.

Clicking on any shape properties will display a wireframe outline of the shape in the Viewer.

Shape layers

If you set your emitter shape to a layer you access additional settings.

Use Layer Color uses the source to color the particles. This is a highly effective way to create a range of color within a particle effect and can be used to blend particles in with the source.

Use Layer Alpha uses the alpha channel in the source to define where the particles are born. The Threshold is then used to adjust the minimal alpha value required for particle birth. This makes it possible to confine an emitter to a specific shape, such as a greenscreen actor or a custom gradient.

Trajectory

When particles are birthed they need an initial trajectory, to determine which direction they move in.

Some shapes do not support all trajectory types.

Cone - emit in a funnel shape.
Explode - emit in a direction away from the center of the shape.
Implode - emit in a direction towards the center of the shape.
Disc - emit in a flattened disc shape.
Random - emit in random directions.
Target - emit particles towards a specified 3D point.

Expanding the Trajectory group will give you access to the controls for your selected trajectory.

General

The General group contains a single Active property. This turns the emitter on and off and is used for controlling the visibility of all existing particles.