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Particles Controls

After you select a particle type in the Workspace panel, you can access the Particles controls for it.

To have a particle type appear in the Workspace panel, you need to add a library emitter that uses that particle type. See Adding Particles to Clips for information on adding emitters.

Note: The Particles controls (and the Behavior controls) are not available when a particle type is not selected in the Workspace panel.

Particle Type Thumbnail

The Particles controls include a thumbnail of the shape assigned to the particle type. When you change the shape (by selecting a shape in the Shape controls and clicking Swap), this thumbnail updates accordingly.

Ref. Point

Enables the red dot for adjusting the reference point. The particles of a particle type spin and are sized around this point.

There are three context menu options for the thumbnail:

To learn more about reference points, see Changing the Particle Reference Point.

Flip X and Flip Y

Use the Flip X and Flip Y options to flip the particle shape. If the shape is symmetrical, you will not see a change.

You can easily add variety to an effect by duplicating a particle type and flipping the shape image for one.

Random Start Frame, Start At, and Hold

These Particles controls are available only when a multi-frame particle shape is used for the particle type.

The particle type thumbnail can show different frames of a multi-frame particle shape. Scrub the thumbnail, and the frame number ("2 of 8," for example) updates.

See Working with Particle Shapes for information about the Shape controls and multi-frame particle shapes.

When a particle uses a multi-frame shape, the first frame of the shape sequence is usually used first. When Random Start Frame is enabled, a random frame is used first instead.

If Random Start Frame is disabled, you can select the frame to use first with the Start At field.

Note: The maximum Start At value is the number of frames that are in the image sequence used for the particle shape.

Use the Hold field to set the number of project frames for which each shape frame is shown. For example, if Hold is set to 2, each frame in a multi-frame shape is shown for two frames in the project. The default value is 1.

The range of values is from 0 to 20, where 0 stops the shape frame from changing (that is, infinite hold).

An easy way to choose a random frame for each particle is to hold a frame in a sequence so that it does not change (that is, set Hold to 0), and then enable Random Start Frame.

You can also use these two features to simplify the organization of shapes for a specific emitter. For example, you create five different shape images of chunks of dirt, and you want to create an emitter that uses all of these shapes. You could create five different particle types, and then assign one of the dirt chunk shapes to each. It is easier to create one particle type with a multi-frame shape, and then set Hold to 0 and enable Random Start Frame.

Note: If you do this, the resolution of each shape needs to be the same—you cannot use shape images of different sizes in a multi-frame shape.

Single Particle

When the Single Particle option is enabled, you see one particle in the preview. Use this option to place a single copy of the particle at the emitter position. This can be used to do sprite animation or to add a glow to the emitter (as in the Shooting Star Trails library emitter).

Sprite animation is moving a single-frame or animated image in your project. For example, you can animate the rotating blades of a helicopter (as seen from below). The body and the blade of the helicopter are two sprites: the body does not move but the blade spins. The sprites do not have to be in the same emitter; you can control the stacking order if they are not.

When the Single Particle option is enabled, the particle type Velocity, Weight, and Motion Rand. properties no longer apply because the particle is fixed to the emitter position. Also, Emission Angle and Emission Range are ignored. The important properties are Size and Spin.

Note: When Single Particle is enabled, Zoom only affects Size since there is no movement (thus, no Velocity property).

The Life property does not matter either, since the life of the particle is tied to the "life" of the emitter as determined by the Active Emitter property. If an emitter is active for 60 frames, the single particle has a life of 60 frames.

If the Active Emitter graph (in the Timeline) has a single keyframe (which means the emitter is active forever), the single particle defaults to a life of 10,000 frames.

Note: You can see this default lifetime in action using the Particles preview. Create an emitter with one particle type that has Single Particle enabled. Animate one of the Over Life properties in the Timeline. Set the preview speed to 40 fps. Start a stop watch and click in the preview. Wait 4 minutes and 10 seconds (10,000 frames / 40 fps / 60 seconds per minute) for the particle to die and disappear. Click the preview again to create another particle.

Intense

The Intense option is used to make particles appear bright by using the Additive transfer mode.

Where the particles overlap, they are added until they become saturated. For this reason, particles with Intense enabled look best when on a dark background (preferably black).

Note: Enable the Collide with Edges option in the preview menu to see the effect of Intense more clearly.

Preserve Color

Since intense particles are additive, they tend to "wash out" on lighter backgrounds. In fact, an intense particle on a white background is completely invisible. You can enable the Preserve Color option to prevent this.

Note: The option is available only when Intense is enabled.

Using the Preserve Color option decreases performance, so you should use it only when needed. It is not needed when using a black or darker background.

Attach to Emitter and Amount

The Attach to Emitter option is used to connect the particles to the emitter so when the emitter moves the particles move with it. Usually, this option is disabled.

Note: You can see the effect of the attachment by dragging an emitter in the preview, first with the option disabled and then with it enabled.

When you enable Attach to Emitter, the Amount field becomes available. This field controls how attached to the emitter the particles are. The default (and most common) value is 100%.

If you use the Particles operator on a layer in a composite, you can animate the position of the layer (or animate the camera's position in a 3D composite) to simulate a camera dolly shot. If you do this, all emitters and particles move together.

However, if the Particles operator is only added to footage (the Particles operator does not flow into a layer), you could not move an emitter across the scene to simulate a change in viewpoint because the emitter would leave a trail of particles. This is one case when you can enable Attach to Emitter.

For example, if the viewpoint needs to move across a waterfall scene, the water would not fall correctly if you simply animated the emitter position. The particles for the waterfall emitter do not trail if Attach to Emitter is enabled, so you would get the required effect.

If you need one emitter in the scene to pan across without leaving a trail and another to leave a trail, you can use Attach to Emitter for one and not the other, which would work better than moving the layer in a composite.

Note: When particles have Attach to Emitter enabled, changes in the Emission Angle property (for the emitter) affect the particles as well. However, if the particles have weight (so they fall or rise) the results may not be consistent.

Particle Angle

Particle angle determines the initial angle of the particles of this type (the angle that the particles are drawn when they are created). The Particle Angle list has three options.

Specify Angle (with Angle field)

All particles have the same initial angle, which is set with the Angle field.

Random Angle

Each particle has a random initial angle, which is often useful to provide more realism in effects such as smoke.

Align to Motion (with Keep Aligned checkbox and Offset field)

Sets the initial angle of each particle to the angle at which it is emitted. The Offset field is used to provide an angle offset so the particle can be rotated an additional number of degrees. Enable Keep Aligned to keep the particle aligned to the direction it is moving throughout its life.

Note: If Single Particle is enabled when Keep Aligned is enabled, the single particle aligns itself to its motion path.

You cannot see any change with a circular particle shape; there must be something asymmetrical in the shape to show the alignment.

Life Color

The Life Color gradient represents the color of the particle throughout its life. Each point that is defined by a color is designated with a color tag. The left end of the gradient represents the start of the particle's life (the instant it is created), and the right end of the gradient represents the end of the particle's life.

For example, this Life Color gradient shows a particle that starts white, changes to green near the halfway point in its life, then changes to black at the end of its life.

Color tags are selected by clicking on them, and can be dragged left and right. Clicking on the gradient where there is no tag creates a new color tag. When you select a tag, you can press Delete to remove it.

Note: There must be at least one color tag. If you delete the last tag, it is added back at the middle of the gradient.

There are two ways to pick a color. You can double-click a tag (or where there is no tag) to show the Pick Color dialog. You can also right-click (Windows) or Ctrl-click (Macintosh) a tag to pick directly from a color palette (by double-clicking a color or clicking one and pressing Enter).

Note: You can see Life Color changes in the preview more clearly if Intense is disabled.

You can also Shift-click more than one tag to move them. When a few tags are selected, you can Alt-drag (Windows) or Option-drag (Macintosh) one (usually an end tag) to expand them proportionally.

When there is only one color tag, the color fills the entire gradient and the particle is that color its entire life.

Random

If Random is enabled, a particle's color does not cycle through the gradient. Instead, each particle remains the same color (a color picked randomly from the gradient) its entire life. Each particle is a different color, though. (The Autumn Leaves library emitter uses random color, for example.) You can add variation to the color in the effect by enabling Random.

Repeat

When Random is disabled, you can adjust the Repeat field between 0 and 10. When Repeat is set to 0, a particle cycles through the Life Color gradient exactly once during its lifetime. The Repeat field is used to repeat the color gradient a number of times over the life of the particle.

Note: If you want the colors to repeat smoothly, make sure that the color tag at the right end of the gradient is the same as the color tag at the left end of the gradient.

One use for the Repeat field is to make particles sparkle. With the Intense option enabled, and Repeat set to 5, the particles in the preview sparkle. If too many of the particles seem to blink on and off at the same time, increase the Life Variation property for the particle type.

Another example is a strobing effect. Set color from white to black to white, then increase the Repeat field.

When particles have Intense enabled, their color also affects their visibility. Since intense particles are additive, a black particle is invisible, regardless of the opacity settings.

Life Opacity

The Life Opacity gradient represents the opacity (or visibility) of a particle over its life. For example, you can use this gradient to make particles fade out as they die.

This gradient works the same way as the Life Color gradient, but the opacity tags are only grayscale colors. Black represents complete transparency and white represents complete opacity.

Note: There must be at least one opacity tag. If you delete the last tag, it is added back at the middle of the gradient.

Link

When Link is enabled, you cannot add or modify opacity tags. In this case, the opacity is linked to the Life Color gradient, so the Life Opacity gradient becomes a grayscale version of the Life Color gradient. Dark particles are more transparent and brighter particles more visible. Thus, you should disable Link if you want to make dark particles that are visible (black smoke, for example). You can enable Link for many other types of particle.

When Link is disabled, you have complete control over the opacity gradient. In addition to moving and deleting selected tags, you can click to add a tag, and right-click (Windows) or Ctrl-click (Macintosh) the tag to pick directly from an opacity palette (by double-clicking an opacity shade or clicking one and pressing Enter).

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