Emitter Controls

When you select an emitter in the Workspace panel or the emitter library (in the Library controls), the properties for the emitter appear in the Emitter controls.

Emitter Shape List

The Shape list shows the shape of the selected emitter, which can be Point, Line, Circle, or Area.

Emission Options

The emission options include In, Out, At Points, and the fields for At Points.

In and Out

Control the side(s) of the emitter that particles emit from. When both In and Out are enabled, particles emit from both sides. In and Out cannot both be disabled at the same time.

For line emitters, you need to keep track of which side is "in" and which is "out." For example, if you add the Matrix Falls emitter (as a line emitter), you can see the difference between In and Out.

Note: The In and Out options are not available for point emitters since they do not have two sides to emit from. They are also not available for area emitters.

At Points

When this option is enabled, the particles emit at discrete points along the emitter instead of anywhere along the emitter.

For line and circle emitters, the field determines the number of points used for emission. When the At Points option is enabled for an area emitter, two fields appear; use one field for each side to create an array (or matrix) of emission points.

Note: A point emitter is by definition already emitting at a point (so At Points is not possible).

Emission Angle and Emission Range

The Emission Angle and Emission Range properties determine the direction in which particles are emitted.

Angle defines where on the emitter the particles originate. Angles larger than 360 degrees allow you to easily do multiple rotations. For example, the angle can be animated from 0 to 900 degrees. The Angle value can also be negative.

Range is the spread, or variation of the angle, at which particles are emitted. The range must be between 0 and 360 degrees. When the range is 0, all particles emit parallel to each other.

Note: The emitter icon for a point emitter and area emitter shows the emission angle and range.

Emitter Visibility

Visibility controls the overall transparency of the emitter, which means the transparency of all the particles emitting from it. The particles become less opaque as you decrease visibility.

The visibility of particles is set initially by the corresponding particle type Visibility property (in the Behavior controls). The emitter Visibility property is a scaling factor that scales particle type visibility.

Note: Many of the emitter properties are scaling factors like Visibility. The other eight are Life, Number, Size, Velocity, Weight, Spin, Motion Rand., and Bounce.

Preload Frames

Preload Frames is the number of frames that you want the emitter to emit before it activates.

By default, emitters start emitting particles from the frame where the emitter is added to the clip. At first there are no particles, then you see the first particles emerge.

For example, if the scene requires a waterfall or a smoking fire, these emitters should be "fully emitting" the moment they start; you do not want the amount of particles to start increasing only at the first frame.

Active Emitter

This property determines when an emitter is on (creating particles) and off. When an emitter turns off, all its particles disappear instantly.

Note: There are very few cases where you animate the Active Emitter property. Usually, you want particles to linger and fade out, so you animate Number instead.

If you add an emitter at frame 20, Active Emitter is disabled until frame 20, from which point it remains enabled.

Preserve Alpha

Preserves the transparency (alpha channel) of the Footage operator or image stream that is the input for the Particles operator.

Ignore Motion Blur

Enable this option so motion blur is not calculated for the selected emitter. If it is disabled and the Enable option in the Global Motion Blur settings (in the Settings controls) is turned on, then motion blur is calculated.

Particle Ordering

The Particle Ordering list includes None, Oldest in Back, and Oldest in Front.

Particle ordering is a way of overriding how the Particles operator manages memory for new and dead particles. Use this feature only in special cases where the exact method of freeing up memory makes a difference to the look of a particle effect.

Note: You should use Particle Ordering only when necessary because it uses more memory. Usually, you should leave it set to None.

When a new particle is created by an emitter, the particle is added to a "drawing list" in memory. Drawing starts with the first particle in the list and ends with the last.

Initially, this means that the oldest particles are drawn first, and the newest particles are drawn last. After some time, the life of some of the particles expires. To conserve memory, the "dead" particles are reused by creating new particles from them. The new particle remains in the same place in the drawing list, so some of the newer particles are being drawn before some of the older particles; the drawing list is no longer "in order." As more time passes and more particles die, the drawing list becomes disordered.

In most cases, this mixing up of the drawing list makes no difference; the particles appear the same regardless of the order in which they are drawn. In some cases, though, the order that the particles are drawn in does make a difference.

For Oldest in Back, the oldest particles are drawn first so the emitter appears to be coming toward you. For Oldest in Front, the newest particles are drawn first so the emitter appears to be going away from you. In both cases, more memory is used since dead particles are not reused.

Tint and Tint Strength

Tint Strength works with Tint Color to "colorize" an emitter. The Tint Strength property determines how much of the emitter tint color is blended into the particle type colors.

The default tint color is gray. Tinting is usually the easiest way to change the color of an emitter's particles. It can also be used to help simulate distance; applying a slight blue or gray tint to an emitter may make it appear to be far away (when used in combination with the Visibility and Zoom properties).

You may not always get the colors that you expect since the tint color does not replace the original particle colors; it is blended with them. Only when the tint strength is set relatively high does the color take effect.

Note: Usually, you avoid high tint strengths because subtlety is better when your goal is realism.

For more information on color, see Changing Particle Colors.

Emitter Life

This scaling factor (in percentage) scales the Life property of all the particle types of this emitter.

Note: Many of the emitter properties are scaling factors like Life. The other eight are Visibility, Number, Size, Velocity, Weight, Spin, Motion Rand., and Bounce.

Emitter Number

This scaling factor (in percentage) scales the Number property of all the particle types of this emitter.

You can animate Number so the number of particles trails off instead of coming to a sudden halt. When an emitter turns off with the Active Emitter property, all its particles disappear instantly.

Emitter Size

This scaling factor (in percentage) scales the Size property of all the particle types of this emitter.

Emitter Velocity

This scaling factor (in percentage) scales the Velocity property of all the particle types of this emitter.

Emitter Weight

This scaling factor (in percentage) scales the Weight property of all the particle types of this emitter.

Emitter Spin

This scaling factor (in percentage) scales the Spin property of all the particle types of this emitter.

Emitter Motion Randomness

This scaling factor (in percentage) scales the Motion Randomness property of all the particle types of this emitter.

Emitter Bounce

This scaling factor (in percentage) scales the Bounce property of all the particle types of this emitter.

Zoom

This emitter property scales both the Size and Velocity properties of all the particle types of this emitter. Note that there is no corresponding Zoom property for particle types.

Use this property to make the particles appear closer or farther away from the viewer. Specifically, Zoom changes the size of the entire emitter output to simulate distance from the viewer. When Zoom is high, the output appears close, and when low, it appears farther away.