Adobe After Effects CS4 Manual de usuario descargar pdf (Pagina 692)

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USING AFTER EFFECTS CS4

Expressions

Last updated 12/21/2009

More Help topics

“Add, edit, and remove expressions” on page 647

“Create a camera layer and change camera settings” on page 186

Expression example: Flip layer horizontally if facing away from camera

❖ Apply the following expression to the Scale property of a 3D layer:

if (toCompVec([0, 0, 1])[2] > 0 ) value else [-value[0], value[1], value[2]]

More Help topics

“Add, edit, and remove expressions” on page 647

“Create a camera layer and change camera settings” on page 186

Expression example: Animate scale at each layer marker

❖ Apply the following expression to a Scale property to make a layer wobble at each marker:

n = 0;

t = 0;

if (marker.numKeys > 0){

n = marker.nearestKey(time).index;

if (marker.key(n).time > time) n--;

}

if (n > 0) t = time - marker.key(n).time;

amp = 15;

freq = 5;

decay = 3.0;

angle = freq * 2 * Math.PI * t;

scaleFact = (100 + amp * Math.sin(angle) / Math.exp(decay * t)) / 100;

[value[0] * scaleFact, value[1] / scaleFact];

More Help topics

“Add, edit, and remove expressions” on page 647

Expression example: Start or stop wiggle at specific time

You can use any expression in place of the wiggle expression used here, to begin and end the influence of any

expression at a specific time.

• Apply the following expression to a property to wiggle it beginning at time 2 seconds:

timeToStart = 2;

if (time > timeToStart){

wiggle(3,25);

}else{

value;

}

• Apply the following expression to a property to stop wiggling it at time 4 seconds:

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