Adobe After Effects CS3 - Manual (Page 499)

AFTER EFFECTS CS3
User Guide
494
Repulsion Controls whether bubbles bounce off each other, stick to each other, or pass through each other. At a value
of 0, bubbles don’t collide; they pass through each other. The higher the Repulsion value, the more likely bubbles are
to interact with each other when they collide.
Pop Velocity Controls how popping bubbles affect each other. When a bubble pops, it affects other bubbles around
it by leaving a hole that other bubbles can fill, pushing other bubbles away, or popping other bubbles. The higher the
value, the more popping bubbles affect one another.
Viscosity Specifies the rate at which bubbles decelerate after being released from the producer point, and controls
the speed of the flow of the bubbles. A high Viscosity value creates resistance as the bubbles get farther away from
the producer point, causing them to slow down. If Viscosity is set high enough, the bubbles stop. The thicker the
substance, the higher the Viscosity. For example, if you want to create the effect of bubbles traveling through oil, set
Viscosity fairly high, so that the bubbles meet resistance as they travel. To create the effect of bubbles floating in air,
set Viscosity fairly low.
Stickiness Causes bubbles to clump together and makes them less vulnerable to other Physics controls like Wind
Direction. The higher the Stickiness, the more likely the bubbles are to form clusters and cling. Use Stickiness and
Viscosity to create a bubble cluster.
Zoom and Universe Size controls
Zoom Zooms in or out around the center of the bubble universe. To create really large bubbles, increase the Zoom
value instead of the Size value because large bubble sizes can be unstable.
Universe Size Sets the boundaries of the bubble universe. When bubbles completely leave the universe, they pop and
are gone forever. By default, the universe is the size of the layer. Values greater than 1 create a universe that stretches
beyond the borders of the layer. Use higher values to make bubbles flow in from off-screen, or make it possible to
zoom out and bring them back into the picture. Using a value lower than 1 clips the bubbles before they reach the
edge of the layer. For example, when you want to confine bubbles to a specific area, such as inside a mask shape, set
Universe Size a little larger than the mask size to remove all the extra bubbles and speed up the rendering process.
Rendering controls
The Rendering controls specify the appearance of the bubbles, including their texture and reflection:
Blend Mode Specifies the relative transparency of bubbles as they intersect. Transparent blends the bubbles
smoothly together, allowing you to see the bubbles through each other. Solid Old On Top makes a younger bubble
appear to be underneath an older bubble and eliminates transparency. Use this setting to simulate bubbles flowing
toward you. Solid New On Top makes younger bubbles appear to be on top of older bubbles and also eliminates
transparency. Use this setting to make bubbles appear as if they are flowing downhill.
Bubble Texture Specifies the bubble texture. Use a preset texture, or create your own. To see the texture, make sure
that View is set to Rendered. To create your own texture, select User Defined, and from the Bubble Texture Layer
menu, choose the layer you want to use as the bubble.
Note: The preset bubble textures are prerendered 64 x 64 images. If you zoom in above 64 x 64, the bubble appears blurry.
To avoid this, use a higher-resolution custom bubble.
Bubble Texture Layer Specifies the layer you want to use as the bubble image. To use this control, choose User
Defined from the Bubble Texture menu. If you want the layer to appear only as a bubble, turn off the video switch
for the layer in the Timeline panel.
Note: You can use any file type that After Effects supports. If you plan on zooming in or using a large bubble size, make
sure that the resolution of the layer is high enough to avoid blurring. Remember, this doesn’t have to be a normal bubble.
You can make blood cells, starfish, bugs, space aliens, or flying monkeys. If it’s a layer in your composition, it can be a
bubble.