Adobe AFTER EFFECTS 5.5 Help Manual page 371

Adobe After Effects Help
Using Help | Contents
Gradient Force Copies the force adjustment based on areas of a layer map on both the X
and Y planes of motion. The pixel brightness values in the color channel define the resis-
tance 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 properties (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.
Gradient Velocity Copies the velocity adjustment based on areas of a layer map on both
the X and Y planes of motion. See Gradient Force.
X Force Copies the coercion along the X axis of motion. Positive values push a particle to
the right.
Y Force Copies the coercion along the Y axis of motion. Positive values push a particle
down.
Opacity Copies the transparency of a particle, where zero is invisible and 1 is solid. Adjust
this value to fade particles in or out.
Mass Copies the particle mass, which interacts with all properties that adjust force, such
as Gravity, Static Friction, Kinetic Friction, Torque, and Angular Velocity properties. It takes
greater force to move particles with a larger mass.
Lifespan Copies the elapsed length of time a particle will exist, in seconds. At the end of
its lifespan, the particle is removed from the layer. The default lifespan is effectively
immortal.
Character Copies the value that corresponds to an ASCII text character, making it replace
the current particle. 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
U.S. English characters, use values between 32 and 127. The range of possible values can
accommodate Japanese characters. For more information about the ASCII character
values for a font you're using, see the documentation for the font, use a utility such as
Character Map (Windows), or contact the font manufacturer.
Note: If you simply want to make certain characters spell a message, it's much easier to
type the text directly in the Options dialog box. The Character property is more useful as a
secret message effect in which you scramble text characters. For more information, see
"Replacing default particles with text (PB only)" on page 361.
Font Size Copies the point size of characters. Applies only if you're using text characters
as particles. Increase this value to make characters larger.
Time Offset Copies the Time Offset value used by the Layer Map property. Applies only if
you used the Layer Map property to specify a multiframe layer (such as a movie) as a
particle source (see "Replacing default particles with a layer (PB only)" on page 358).
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