Gravity Controls For Particle Playground (Pro Only); Repel Controls For Particle Playground (Pro Only) - Adobe AFTER EFFECTS 7.0 Manual

At particle creation, the Cannon and Grid set no rotation; the Particle Exploder takes rotation from the
Rotation
exploded dot, layer, or character. Use Auto-Orient Rotation to make particles rotate automatically along their
respective trajectories. For instance, a particle can point up as it climbs an arc, and point down as it descends.
Rotation isn't easily visible for a dot particle. It is easier to observe only when you replace the dot particle with text
characters or a layer. After particle creation, use a layer map to set values for the Angle, Angular Velocity, and Torque
property in the Property Mappers.
Note: The appearance and rotation of a layer map particle changes in relation to the mapped layer's original appearance
and rotation. For instance, if you replace the default dot particles with a movie of a spinning wheel, the spinning-wheel
particles appear to spin when no particle rotation is applied.

Gravity controls for Particle Playground (Pro only)

Use Gravity controls to pull existing particles in a direction you specify. Particles accelerate in the direction of gravity.
Apply in a vertical direction to create falling particles such as rain or snow, or rising particles such as champagne
bubbles. Apply in a horizontal direction to simulate wind.
Specifies the force of gravity. Positive values increase the force, pulling particles more strongly. Negative values
Force
reduce the force.
Specifies a range of randomness for the Force. At zero, all particles fall at the same rate. At a
Force Random Spread
higher value, particles fall at slightly different rates. Although pure gravity accelerates all objects equally, increasing
the Force Random Spread value can produce more realistic results with subjects such as leaves falling through air,
where there is enough air resistance to vary the leaves' rates of descent.
Specifies the angle along which gravity pulls. The default is 180 degrees, which simulates the real world by
Direction
pulling particles toward the bottom of the frame.
Specifies a subset of the layer's particles to which Gravity applies. (See "Affects controls for Particle
Affects
Playground (Pro only)" on page 508.)

Repel controls for Particle Playground (Pro only)

Repel controls specify how nearby particles repel or attract each other. This feature simulates adding a positive or
negative magnetic charge to each particle. You can specify which particles, layers, or characters are the repelling force
and which are repelled.
Note: If you want to repel an entire layer of particles away from a specific area, use the Property Mapper controls, Wall
or Gradient Force. (See "Wall controls for Particle Playground (Pro only)" on page 508 and "About Property Mappers
and Particle Playground (Pro only)" on page 508.)
Specifies the repel force. Greater values repel particles with more force. Negative values result in particle
Force
attraction.
Specifies the radius (measured in pixels) within which particles are repelled. Another particle must be
Force Radius
within this radius to be repelled.
Specifies which particles act as the repellers or attractors to another subset you specify by using the Affects
Repeller
control.
Specifies a subset of the layer's particles to which repulsion or attraction applies. (See "Affects controls for
Affects
Particle Playground (Pro only)" on page 508.)
ADOBE AFTER EFFECTS 7.0
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User Guide