|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!
Create a gradient (use either Photoshop or the Ramp plug) from black to white, left to right. You don't have to start with full black or white, grey tones will do the trick too but with more subtlety.
Animate the gradient going from left to right. Use Hold Keyframes to repeat the movement. See the Animated Gradient Comp for an example.
Drop the Animated Gradient Comp into a new comp. Switch off its eyeball. Create a new layer and apply Particle Playground. We will be using the Grid settings so it's wise to switch off the Canon. Do so by setting the Particle per Second and Particle Radius parameters to zero.
Click on Options and select the Grid button. Type in your text. Deselect Loop Text and Select Center. Click OK. Enable Field Rendering if required. Click OK.
In the Effects Window, click on the Grid setting. Create a keyframe for Font Size. 20 - 30 will do for now. Move one frame ahead in the Timeline. Set Font Size to zero. Select both keyframes and change them to Hold Keyframes.
Twirl down the Ephemeral Properties Parameter. Click on the downward arrow next to Use Layer as Map parameter. Select the Animated Gradient as your Map. Map the Red Channel to Character. Set Min. to 48 and Max. to 49.
Map the Green Channel to Scale. Set Min. to 1 and Max. to 1.3 .
Do a RAM Preview. In fact, you could even do a video scrub to obtain near realtime previews. PP can be decently fast. If you like what you see so far, then read on.
Particle Playground uses the ASCII character set. Check out http://www.bbsinc.com/symbol.html for a list of ASCII characters.
Zero is character numbered as 48 and One is 49. What we've done thus far is to tell PP to change our initial characters into zeros and ones and that the animated gradient (our Map) is to be used as the influencer. The Ephemeral Parameter ensures that our initial characters are 'switched' back once the Map is off screen and momentarily doesn't exist. If we had used Persistent Properties, the zeros and ones would still be present even when our Map disappears offscreen.
Take a look at the two finished compositions: PP Simple Comp and PP Experimental Ground. With the latter, I've played around with the Operator Settings (and nothing else) to obtain slightly different, yet interesting results. You can actually create Keyframes for these Operators, including the Min and Max properties. Hold Keyframes are more appropriate but as always, feel free to experiment with the Operators. Check out your AE PB manual for more on these Operators and PP in general. My movie is the PP Experimental Comp render. See below.
FWIW, Set doesn't perform as advertised. It will occasionally stray away from your instructions. But the digression is not that great as to inhibit its use entirely.
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.