The technique I’ll be discussing here was inspired by a great site that sadly seems to have expired: motionsmarts.com. It’s been around for a long time, and I remember reading about something like this there back in the early days of Motion 1 or 2. I’ll be working from both memory and my own extensions to the idea; hope you enjoy it, and thanks to whoever made this site a reality.
This part is easy and quite important. Choose a white fill and no outline in the HUD. Select the Bézier tool, then click and drag a few times in a local area to create a small, squiggly shape.
The Bézier tool
You don’t want it too complex, but about six points should give enough complexity for an interesting result.
The shape it made
With your odd white shape selected, press L to create a Replicator. This repeats your original messy blob in a grid of messy blobs.
Ugly so far
We’ll want to tweak the look quite substantially here — there are so many options that they can feel overwhelming. To change the settings, we’ll use the Inspector, largely staying in the Replicator pane.
One important note: to adjust parameter values, we’ll often need to click and drag sideways on the numbers themselves, ignoring the sliders and the HUD.
Remember: click and drag sideways on the numbers to change them, ignoring the sliders and dials
The first part is easy: choose Wave as the Replicator type. There are many different options, but Wave will do just fine for now. Set Amplitude to about 125, to make the curve more prominent.
Using the Adjust Item tool that Motion has selected for you, drag the endpoint (the crosshair in a circle) at the left of the replicator just outside the left side of the screen. If you can’t see the whole canvas, you may need to zoom out a little with Command-minus or fit the canvas to your view with Shift-Z.
Once you’ve moved the left-hand crosshair, move the right-hand crosshair-in-a-circle to just outside the right side of the screen.
Better than a grid of blobs, but not there yet
Five points just isn’t enough to make this work, so we’re going for at least 150. The Points slider only goes to 20, so click on the number itself and drag to the right, all the way up to 150. We might even go higher, up to 200 or more, but that’s going to depend on the shape you drew and the colors we choose. Speaking of which…
Many more points gives a smoother wave, but it’s all white for now
We’ll now change the colors used in the replicator. Scroll down to Cell Controls and choose Over Pattern as the Color Mode. The default gradient is OK, but we’ll need to tweak it at least a little. First, click the Additive Blend checkbox just above Color Mode. This makes the different overlapping shapes blend with one another, and we’ll need to control opacity alongside the number of points to get the effect we need.
Open the Color Gradient section with the disclosure triangle just to the left of the words “Color Gradient”. In this section, the top part controls opacity and the bottom part controls color, across the replicator. Right-click one of the existing color pots underneath the gradient to access the quick color picker square, then drag to your chosen color. You’ll find that brighter colors will probably blow out the total look, but that’s OK for now. If you want to, left-click on the lower half of the gradient bar to add a new color pot, then change that too.
Right-click the small square on the top half to change opacity or the bottom half to change color
Right-click on the white color pot to the top left of the gradient, then pick one of the greys below the color square. This will darken down the whole replicator, allowing you to add more points to smooth the repeating shapes out.
The right-click quick-change color square looks like this
The more points you use, the brighter the result, so be careful. You want to retain detail and avoid blowing the image out, so experiment with increasing the number of points as you decrease the opacity. With a grey value of 36, I can use 285 points or so.
Getting there, with some new colors
Now, we’ll twist the replicator a little. Change the Angle End property to 200° or so, and you’ll be rotating the shapes along the length of the replicator. Scrolling further down, you can also change Scale End if you want to vary the size of the shape across the replicator. In this example, I’ve chosen 220° for Angle End, 135% for Scale and 60% for Scale End.
It doesn’t move yet, but it looks great
This is the best part of all. Right-click the word Angle, then choose Parameter Behavior, then Ramp. This adds a behavior that will automatically change the Angle parameter over time. It’s similar to changing a parameter over time with keyframes, but the indirect nature of parameter behaviors can be easier to work with — and you can see with a glance at the timeline where they apply.
Right-click on a property name — not the number! — to add a parameter behavior
In the Behaviors tab that Motion opens, you’ll see the Ramp behavior. Here, change the End Value to 200 or so. Changing this value will affect how fast the effect animates.
Here’s the Ramp, set to a much higher value by scrubbing numbers
That’s the basic effect done. I’ve used variations on this in many different contexts; it’s a great way to fill a background. You can use anything you like as the source for the replication, even a word of text, but the traditional squiggle gives good results. Some things to try to produce different effects:
Changing a few suggested parameters
This is a powerful effect, and the closest I’ve seen to it in practice has been in the world of video games. There’s something similar on the PS3 menu screen, and something a little further away in the Assassin's Creed game series menus. With so much flexibility, you should be able to create something truly your own. Go for it!