Hey, welcome to this next masking tutorial. In this case we're going to animate the mask separately from the object. It might be type, it might be a video, it might be a logo. In our case it's going to be monsters. They call them 'Track Mattes' or 'Alpha Mattes'. And this is how they work.

First of all, we're going to bring in one of our monsters. So double click our 'Project' window, or go to 'File', 'Import', jump up to 'Monsters', pick your favorite monster. And there are some goodies. I think I like this guy today. So I've got him in here. Now, I'm going to make a new 'Comp' for it, I don't want to make a 'Comp' from this guy because it's a weird old size. I'm going to go to 'New Composition'. 'New Comp', I should give it a name, I never do. Length, it's going to be, let's make it shorter, it's a bit too long, so it's '5' seconds long. Click 'OK'.

And what I'd like to do is-- Zoom out a little bit. If I drag my-- go on here, he's a bit small. So I drag him up, start dragging. Hold 'Shift' after you've started to get it to lock the height and width, otherwise it gets a bit squidgy. And, it's gone a bit pixelated. You can see it's a bit pixelated here. Let me zoom in here, pixelated. How do I get rid of that? You already know, click this button here. Look at that, super smooth.

So what I'd like to do is, I'd like him to start off screen, and slide in. And now if I attach the mask to it like we did in the last tutorial, ugh, you can't. So what we're going to do is, we're going to do something different. Differently, right? So we're going to grab him, start him off screen, you just start him over here. And I'm going to my 'Transform' window, go to 'Position', and turn this off. So we got a key frame there, and after about 1 second I'm going to get him to slide on, so I'm holding 'Shift' while he drags to get him into the center of the video.

Now, two things I want to do. I want to right click it, and go to 'Velocity'. And I want to change this to '70', so it's got a bit of-- looks nice. What we'll also do is the other magic trick, remember, turn 'Motion Blur' on, both globally, and on the layer. This will make it look a lot cooler when he moves. He's going to get a little blurry there. I like it. So now what we're going to do is, we want to add a mask to it. What you could do is, you could select this and grab this, and you can mask him. But the trouble is, the mask, anyway it's with him. It's not what I wanted. So I want the pothole to kind of stay there, and the guy to slide underneath it.

To do it, I'm just going to deselect everything. There's two ways of creating a Track Matte in terms of creating the shape that I want. If I had this selected, and I click on this guy, we've seen it before, if I click this it just makes a mask on that layer. So what you can do is-- there's the easy way, and the quick way. The easy way is to go to 'Layer', 'New', and then I'm going to go to 'Shape Layer'. Then, we got this new thing called Shape Layer, and we draw our circle on it. Just a regular old circle. And you can do it that way, that's totally perfect.

I'll show you the way that everybody does though. So I'm going to get rid of my 'Shape Layer'. What people do is-- you see, if I grab my circle with the layer selected it masks it bad, what you do is, make sure there's nothing selected, and then if you draw a circle it creates a Shape Layer all in one big go. So just make sure you don't have that layer selected. Click off anywhere in the background, so nothing's highlighted. I'm holding 'Shift' to get a perfect circle. Perfect, that's good. There's my little pothole now. Just going to use his head. So I would like that to mask the thing underneath.

And the way you do it – I'll just twirl that up. - is we're going to switch this thing to toggle the switches. And we're going to say, you, my friend, have a Track Matte of an 'Alpha Matte of Shape Layer1'. That's that guy here. We'll rename it to make it a little easier. That's my mask. Oops, 'undo'. I'm going to make you-- and call him-- just call him 'Mask'. So you my friend, are going to Track Matte of 'Alpha Matte Mask'. And that is how you mask. So, the top layer-- you just got to make sure that this circle here is just above the guy underneath. So, here's my mask, it's right above this 'Monocle.ai'. There he is there. Very James Bondy, he's got the moustache too. And that is a Track Matte.

Next thing we're going to do is, we're going to look at Rotoscoping. Kind of the big boy version of masking. Let's hit 'Save'. I'll see you in the next video.