Adobe AFTER EFFECTS 7.0 Manual page 516

Copies the amount of inertia that holds a stationary particle in place, typically within a range of 0.0–
Static Friction
1.0. At zero, a particle moves when any other force, such as gravity, is present. If you increase this value, a stationary
particle requires more of another force to start moving.
Copies the direction in which the particle points, in degrees relative to the particle's original angle. The angle
Angle
is easily observable when a particle is a text character or a layer without radial symmetry.
Copies the velocity of particle rotation in degrees per second. This determines how fast a particle
Angular Velocity
rotates around its own axis.
Copies the force of particle rotation. The angular velocity of a particle is increased by a positive torque and
Torque
is increased more slowly for particles of greater mass. Brighter pixels affect angular velocity more forcefully; if
enough torque is applied against angular velocity, the particle starts spinning in the opposite direction.
Copies the scale value of a particle along both the x and y axes. Use this to stretch a particle proportionally. A
Scale
value of 1.0 scales the particle to its full size; a value of 2.0 scales it 200%, and so on.
Copy the scale value of a particle along the x or y axis. Use these to stretch a particle horizontally or
X Scale, Y Scale
vertically.
Copy the position of a particle along the x or y axis in the frame, in pixels. A value of zero specifies a position
X, Y
at the left of the frame (for X) or at the top of the frame (for Y).
Copies the velocity adjustment based on areas of a layer map on both the x and y planes of motion.
Gradient Velocity
Copy the horizontal speed (x-axis velocity) or vertical speed (y-axis velocity) of a particle in pixels
X Speed, Y Speed
per second.
Copies the force adjustment based on areas of a layer map on both the x and y planes of motion. The
Gradient Force
pixel brightness values in the color channel define the resistance to particle force at each pixel, so the color channel
acts like a layer map of hills and valleys that decrease or increase particle force. In the layer map, areas of equal
brightness result in no adjustment, similar to flat land. Lower pixel values represent less resistance to a particle's force,
similar to a downhill grade. Higher pixel values represent more resistance to a particle's force, similar to an uphill
grade. For best results, use a soft-edged layer map image.
If you are using a layer map for Gradient Force where flat areas equal no adjustment, and you are using the Min and
Max controls (not the Min or Max operators) to set the range of values for Gradient Force, set them to positive and
negative values of the same number (for example, –30 and +30). This ensures that the middle of the range remains
centered at zero.
Copies the coercion along the x axis of motion. Positive values push a particle to the right.
X Force
Copies the coercion along the y axis of motion. Positive values push a particle down.
Y Force
Copies the transparency of a particle, where zero is invisible, and 1 is solid. Adjust this value to fade particles
Opacity
in or out.
Copies the particle mass, which interacts with all properties that adjust force, such as Gravity, Static Friction,
Mass
Kinetic Friction, Torque, and Angular Velocity. It takes greater force to move particles with a larger mass.
Copies the elapsed length of time a particle exists, in seconds. At the end of its lifespan, the particle is
Lifespan
removed from the layer. The default lifespan is effectively immortal.
Copies the value that corresponds to an ASCII text character, making it replace the current particle.
Character
Applies only if you're using text characters as particles. You can specify which text characters appear by painting or
drawing shades of gray on the layer map that correspond to the ASCII characters you want. A value of zero produces
no character. For US English characters, use values between 32 and 127. The range of possible values can accom-
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