Expressions will look pretty familiar to most of the readers that frequent the Giant Robots blog. They’re very similar to scripts you would use on the web, but rather than acting on the application itself, they define how a property should behave. Adobe based their expression language on JavaScript, so writing and editing the code should also feel very familiar. Expressions are by no means a requirement for prototyping animations, but I’ve found them very helpful when trying to recreate effects like inertia or bouncing without specifying a bunch of additional keyframes.

1. PRAKTIKUM 7 - ANIMASI 2D
(Delay Expression pada Kinetic Falling Text)
2 D3 TEKNOLOGI MULTIMEDIA BROADCASTING A
KELOMPOK 3
Risca Zuliana (4103151001)
Natasha Savira (4103151020)
Arvin Janathan Adhim (4103151021)

2. What is an expression (Adobe After Effects)?
Expressions will look pretty familiar to most of the readers that
frequent the Giant Robots blog. They’re very similar to scripts you
would use on the web, but rather than acting on the application itself,
they define how a property should behave. Adobe based their
expression language on JavaScript, so writing and editing the code
should also feel very familiar. Expressions are by no means a
requirement for prototyping animations, but I’ve found them very
helpful when trying to recreate effects like inertia or bouncing without
specifying a bunch of additional keyframes.

3. Adding expressions in After Effects
• First, right-click on the final keyframe, open the Keyframe Assistant
menu, and choose Easy Ease Out. This last step is optional, but
specifying Easy Ease Out will slow the animation down towards the
end, which works well with the inertia expression we’re working with.

4. • Next, hold ‘alt’ and left click the stop watch icon next to “Position”.
This should enable expressions on this layer and open a textarea-style
field where you’ll put the expression.

5. • Go ahead and copy and paste the above script, replacing what’s
already in the expression input.
• Feel free to add motion blur at this point, too. It’s a toggle on each
layer, just click the box below the motion blur icon to enable it for
that layer. It simply smoothes out the animation and makes it look
less jarring.

6. • Now you’re free to jump into the code to change how your animation
looks. Below is a reference for what changing the different variables
will do to your animation, with the other variables left the same.
• You can add a lot of life to your animations with just two keyframes
and an expression. We also only animated the position property here,
but you can add this same expression to other properties as well.
With just a few additional keyframes and a few tweaks to the
variables for each property, the animation really begins to come to
life.

7. Script Delay Expression (Kinetic Falling Text)
Delay = .1;
myDelay = delay*textIndex;
t = (time – inPoint) – myDelay;
if (t >= 0){
freq =3
amplitude = 150;
decay = 8.0;
s = amplitude*Math.cos(freq*t*2*Math.PI)/Math.exp(decay*t);
[s,s]
}else{
value
}

8. Sumber :
• https://robots.thoughtbot.com/using-expressions-in-after-effects
• https://forums.creativecow.net/thread/227/18564
• https://helpx.adobe.com/after-effects/using/expression-basics.html