Expressions in After Effects: Animating without Keyframes
Expressions in After Effects: Animating without Keyframes
by Roland R. Kahlenberg, Singapore, Singapore
Video * Motion Graphics * Original Music
©2001 by Roland R. Kahlenberg. All rights are reserved. Used at CreativeCow.net by kind permission of the author.
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Article Focus:
As many of you know by now, AE 5.0 has introduced a new feature called Expressions. Experienced users akin it to Motion Math, although they are quite different. In this tutorial, Roland Kahlenberg, who is a non-programmer, intends to show other similarly inclined users of AE 5.0 that Expressions do offer quite a bit to the toolset of the conventional designer.
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Here are the project files: Download them so you can follow along. These are .sit files, if you're on Windows and don't have the Stuffit Expander, download it here. It's free!
All of the more difficult Expressions were culled from AE 5.0's online help file. Hopefully there will be more forthcoming from Adobe or from other users, be it for free or at a reasonable fee. But do read the help files before charging into the tutorial. It'll help you get a better understanding.
Alright then, enough of the pep talk and let's get on with it. This tutorial will animate a line of text and give it that cool nervy look, complete with blurs - without keyframes!
Let's begin by creating a comp to contain our source layer. Apply the Basic Text filter and type in your text. Let's change the Text Color to white and our Comp Background Color to black for clarity.
Next create a new Comp, and call it FinalComp and Nest our Source Comp here. Apply the FastBlur filter and duplicate the layer twice so that we now have three layers in FinalComp. We're gonna rename our source layers as it can get quite confusing if all the layers share the same name. Click on the SourceName to change it to LayerName.
Next rename the layers accordingly starting from the top layer down: 3 Wiggle_Source Comp, 2 Wiggle_Source Comp, and 1 Wiggle_Source Comp. Don't worry about the FastBLur for now. Just leave it at its default of zero for the moment. Now select the bottom most layer and hit the P key to open up the Poition parameter in the Timeline. Alt(PC), Opt(Mac) on the StopWatch next to the Position parameter to initialize Expressions for the said parameter.
Note: For purposes of this tutorial all Expressions written hereforth will be written in bold. Expressions use the characters "", and . and we don't want to confuse the matter.
The Graphic above shows the timeline and the various expressions added. For a better view, look at the timeline in the project file you downloaded.
We're gonna type in an Expression to Wiggle the position of this layer.
Type in: position.wiggle(7,40,1) . Hit the 0 key on the numeric keypad to see a RAM Preview. The wiggle Expression requires three parameters to make it work. The first parameter tells AE how frequent you want it to kick in, the second affects the variation of the effect, and the third tells AE when in time you want it to work.
Next we're going to do something really cool by using Expressions to tell another layer to follow the position (motion) of this wiggling layer but offset in time.
Select the middle layer and initiate Expressions for its Position parameter. Type in the following: this_comp.layer("1 Wiggle_Source Comp").position.value_at_time(time-1)
This Expression tells AE to animate the affected layer according to the layer 1 Wiggle_Source Comp's motion and to do this by sampling the motion one second behind the source's current position, whatever that may be.
Hit the RAM Preview key.
Now we're going to tell the top most layer to animate itself based on the motion of the other two layers. Specifically, we want it to animate such that at any point in time, it is at the midpoint of the other two layers.
Select the layer and initiate an Expression for its Position parameter.
Type in the following: mul(.5, add(this_comp.layer("1 Wiggle_Source Comp").position,this_comp.layer("2 Wiggle_Source Comp").position))
Now I did tell you that I'm not a programmer so I can't tell you much about what's happening here. The Expression was taken from the help files from AE 5.0. However, studying the Expression a little bit closer, you can tell that the result is achieved by sampling information from the two layers we worked on earlier and that their respective positions are the source for the Expression. Further, their respective positions have been acted upon by a mathematical formula.
Do a RAM Preview.
The motion looks quite interesting but the esthetics require more work. So let's act on the FastBlur parameter. We want to soften it yet make it legible so a small dose of blur should do. I've set mine to 2 for this exercise.
Select the second layer and initiate an Expression for its FastBlur parameter. We will use the Random Expression to randomize this layer's blur setting. Type the following: random(2,25) . This one's simple. :-)
What this Expression is doing is randomizing the Blur parameter a setting of between 2 and 25.
Repeat this step for the bottom most layer, except this time, have it randomize between the values 4 and 8.
Do a RAM Preview. And no keyframes too. :-)
Watch the movie:
If you want to lessen the grungy feel, then just edit the wiggle Expression for the bottom most layer since all the other layers' position (motion) are based on this one Expression. Edit either the first, second, or both wiggle parameters to smaller numbers. Specifically 2 and 30 respectively. Feel free to experiment with these numbers and why not apply random or wiggle Expressions to BasicText's Tracking/Size parameters. Or maybe even use PathText instead where you can create more havoc with all the parameters available there.
Well, that's all folks. I hope that you've enjoyed working with Expressions. And remember I'm no programmer. And if you're one, you're gonna be a very happy AE user. For the rest of us; a little ingenuity, gung ho and the right attitude can still go a long way towards using adopting Expressions in our current workflow.
And don't forget to come back to the COW for more good stuff. And if you've got some nice Expressions that you are allowed to share, then PLEASE by all means do so. I've got a couple of other nice things done with Expression this past weekend and hope to have the time to put them into a tutorial.
Thanks for reading this far and I hope that you'll enjoy using this effect. I know I have. Cheers, and as always, God Bless.
---Roland R. Kahlenberg
Roland Kahlenberg is the co-founder www.aefreemart.com and is now a herd leader in the Adobe After Effects COW. Pop in to comment on this article or ask questions.
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