Adobe After Effects CS3 - Manual (Page 566)

AFTER EFFECTS CS3
User Guide
561
Represents the layer containing the expression. Because thisLayer is the default object, its use is optional. For
example, you can start an expression with thisLayer.width or width and get the same result.
thisProperty Return type: Property.
Represents the property containing the expression. For example, if you write an expression on the Rotation property,
you can start an expression with
thisProperty to refer to the Rotation property.
time Return type: Number.
Represents the composition time, in seconds, at which the expression is being evaluated.
colorDepth Return type: Number.
Returns the project’s color depth value. For example, colorDepth returns 16 when the project’s color depth is 16 bits
per channel.
posterizeTime(framesPerSecond) Return type: Number.
Argument type: framesPerSecond is a Number.
The framesPerSecond value becomes the frame rate from which the rest of the expression operates. This allows you
to set the expression to a frame rate lower than that of the composition. For example, the following expression
updates the property value with a random value once per second:
posterizeTime(1);
random()
value Return type: Number, Array, or String.
Represents the value at the current time for the property containing the expression.
Time conversion methods
timeToFrames(t = time + thisComp.displayStartTime, fps = 1.0 / thisComp.frameDuration, isDuration = false)
Return type: Number.
Argument type: t and fps are Numbers; isDuration is a Boolean.
Converts the value of t, which defaults to the current composition time, to an integer number of frames. The number
of frames per second is specified in the fps argument, which defaults to the frame rate of the current composition
(
1.0 / thisComp.frameDuration ). The isDuration argument, which defaults to false, should be true if the t value
represents a difference between two times instead of an absolute time. Absolute times are rounded down towards
negative infinity; durations are rounded away from zero (up for positive values).
framesToTime(frames, fps = 1.0 / thisComp.frameDuration) Return type: Number.
Argument type: frames and fps are Numbers.
The inverse of timeToFrames . Returns the time corresponding to the frames argument, which is required. It doesn’t
have to be an integer. See timeToFrames for explanation of the fps argument.
timeToTimecode(t = time + thisComp.displayStartTime, timecodeBase = 30, isDuration = false) Return type: String.
Argument type: t and timecodeBase are Numbers; isDuration is a Boolean.
Converts the value of t to a String representing timecode. See timeToFrames for an explanation of the t and
isDuration arguments. The timecodeBase value, which defaults to 30, specifies the number of frames in one second.
timeToNTSCTimecode(t = time + thisComp.displayStartTime, ntscDropFrame = false, isDuration = false) Return
type: String.