Learn how to use track mattes in After Effects to control the visibility of layers independently without relying on masks that move with the layer. This article explains how to create and position solid layers to act as reveal guides, similar to clipping masks in Photoshop.
Key Insights
- Track mattes allow a layer's visibility to be controlled by another layer, enabling complex reveal effects that are not possible with masks alone, which move with the layer they are applied to.
- Creating a solid layer—similar to a solid fill layer in Photoshop—lets users define a fixed area in the composition that can be used to reveal or conceal other layers as they animate across it.
- Noble Desktop explains that when creating a new solid for a track matte, it's important to size and position it correctly (e.g., one-fifth the height of a 1080p comp) and place it above the target layer to ensure the animation is visible when expected.
Now, notice as my layer moves, the mask moves with it. Okay, so the mask is a part of the layer, which means it moves when the layer moves. So, it is possible to animate the mask properties, so that you could, like, have the mask, like, large, shrink, rotate to reveal different parts of the layer.
Definitely can, okay? So it's not bad. However, however, however, my next problem is that in the original video, the text is actually hidden when it's down here, and it's only visible when it passes, like, about halfway through up here. My problem is I can't use a mask for that.
Because one, two different layers. Two, the mask will just move with the layer. So I need another way of hiding the layer content until it reaches, let's say, this point up here on top.
It's called a track map. If you use video editing programs, you may be familiar with an effect called the track map key. Track maps, basically, if you use Photoshop, they are equivalent to clipping masks in Photoshop.
They use another layer to control the visibility of this one. So what we're going to do is make a box, with the box up here on top, and we're going to use the track map, so when these layers cross over it, it will be visible. Okay.
Track maps are very common techniques for allowing you to reveal parts of a layer. Well, to reveal other layers. Because they are independent, basically, you can animate either of them.
Okay, which is cool. Now, we need a new layer. I need a new layer for this.
Okay, so I'm going to make a new layer. I want to make a layer that is approximately, let's say, one-fifth the height of this composition. Okay, so it will basically be a little bigger than the one row.
Okay, I like that. So how can I make a new layer that actually looks like something? So, one, I can draw a rectangle. I have a rectangle.
I can draw a rectangle. Like you might in Photoshop or Illustrator. But, there's another way.
Layer, new, solid. That. A solid is basically a color rectangle.
It's a layer that has color. Whatever color you choose. It can take effects.
And it can be used for, like, just color masks. Effectively. For the record, if you use Photoshop, it's literally like a solid layer in Photoshop.
Same concept, okay? Okay, solid. Okay. I don't care about the color.
It's irrelevant to the example. You can make it whatever color you please. The program will not care.
Okay. The name. Okay.
But make comp size. That will make it match the dimensions of the comp. Okay.
Width. And you want it to be the full width. You can make it bigger if you wanted to.
Just change it. Height. I want it to be 1 5th of this.
What is 1080 divided by 5? It's that. And it's that. This is a common feature of software, by the way.
Pretty much any software that has numerical fields does math. Some of them are really advanced. InDesign can do percentage-based math, which is nice, by the way.
Plus and minus are addition and subtraction. Slash is divide. And asterisk is multiply.
It's pretty cool, by the way. That way, I don't have to do math. I hate math.
Okay. So, when I, too, actually name solids, I just name them for whatever their sizes are. Or I just leave the default name.
You don't have to change the color, by the way. Okay. The solid is placed in the middle of the screen.
Here's what everyone misses when they do this. The solid needs to be up there. Otherwise, the text will never cross it.
You'll never see the text. So, whenever you make a new layer, solid, when you drag something in the timeline, it's always centered in the middle of the comp. But for the animation to work, this has got to be up there in Gutwerk.
There's an align option. Right there would do it. You can drag it.
The problem at all, there's a little snap feature when you drag something to make sure it snaps to the edges. Or just use align. I mean, it's fast.
Boom, like this. It's up to you. So, how do you put it up there? Get it up there.
If you want to make it bigger than the comp, that's fine. It's not going to affect anything I'm doing. No problem at all.