Physics Controls For The Foam Effect - Adobe AFTER EFFECTS 7.0 Manual

Specifies the maximum life of a bubble. This value is not absolute; if it were, the bubbles would all pop after
Lifespan
the same lifespan, as if they were hitting a wall. Rather, this value is a target lifespan; some bubbles pop early, and
others may last until the end.
Specifies how fast a bubble reaches full size. When a bubble is released from the producer
Bubble Growth Speed
point, it generally starts out rather small. If you set this value too high and you specify a small producer area, the
bubbles pop each other, and the effect generates fewer bubbles than expected.
Influences how likely a bubble is to pop before it reaches its Lifespan limit. Lowering a bubble's Strength
Strength
makes it more likely to pop early in its life, when forces like wind and flow maps act upon it. Lower values are good
for soap bubbles. The highest value is recommended for flocking animations.
Set this value low, and set Pop Velocity high to create chain reactions of popping bubbles.

Physics controls for the Foam effect

The Physics controls specify the motion and behavior of the bubbles:
Sets the speed of the bubble as it is emitted by the producer point. This speed is affected by the other
Initial Speed
Physics parameters.
Low Initial Speed values in conjunction with the default producer size don't affect the results much because the
bubbles bounce off each other. For more control over initial speed, increase the values for Producer X Size and
Producer Y Size.
Sets the initial direction in which the bubble moves as it emerges from the producer point. This is
Initial Direction
affected by other bubbles and other Physics controls.
Sets the speed of the wind that pushes the bubbles in the direction specified by Wind Direction.
Wind Speed
Sets the direction in which the bubbles blow. Animate this control to create turbulent wind effects.
Wind Direction
Bubbles are affected by wind as long as Wind Speed is greater than 0.
Applies small random forces to the bubbles, making them behave chaotically.
Turbulence
Randomly changes the shape of bubbles from perfectly round to a more natural elliptical shape.
Wobble Amount
Controls whether bubbles bounce off each other, stick to each other, or pass through each other. With a
Repulsion
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.
Controls how popping bubbles affect each other. When a bubble pops, it affects other bubbles around
Pop Velocity
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.
Specifies the rate at which bubbles decelerate after being released from the producer point, and controls
Viscosity
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.
Causes bubbles to clump together and makes them less vulnerable to other Physics controls like Wind
Stickiness
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.
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User Guide