Hi there, in this tutorial we're going to look at masking that inner liquid. We're also going to try and do that little liquidy bounce thing that's part of that as well. So let's go and do that now in this tutorial.

The first thing we need to do is open up this exercise file. So go to your 'Exercise Files', open up '08 Masking', there's one in there called 'Pint Glass.aep'. That's the After Effects project. I've got him open. And I've just added some stuff to get us going, some Illustrator icons. And what have we got? We've got the middle of our glass, we've got the outside of our glass, and a couple of text layers. So to get started though, we're not going to need any of those layers. What we're going to do is grab the rectangle tool. Make sure you've got nothing selected, and pick a Fill color of anything. It can be anything because it's going to be transformed into a Mask later on. So it doesn't really matter. Green is just good because it's nice and clear, and obvious. The Stroke is going to be down to '0'.

And what we need to do is draw a square or a rectangle that is exactly the same height as this inside liquid here. It needs to be over the edges a little bit as well. You might have to practice a couple of times. It needs to be kind of like this, so it's the same height, so I know that's my 100%, makes it easy to work out my 53%. And I'll needle over the edges on here. Why? Because I need to use one of my effects in a second, called Pucker & Bloat. And it needs a little bit of extra stuff on the side. So maybe not perfectly square like my first one, but maybe something like this, a little bit taller than it is skinny. Let's rename this Layer. I'm going to call this one 'Liquid Mask'.

Next thing we need to do is, when we draw a rectangle freehand you can see, the anchor point here has not ended up in the center of the rectangle. It's ended up in the center of the Comp. So what we need to do is grab the 'Pan Behind' tool. And we're going to hold down 'Command' on a Mac or 'Control' on a PC. Click, hold, and drag this guy here and try to get him to the center of this rectangle. Now with 'Liquid Mask' selected, we're going to adjust this scale. We need to work out what 53% is. So I'm going to click 'S' for Scale. And Playhead's back at 0. We're going to start the Keyframes by clicking on this stopwatch. We're going to break the link between the height and width. I just want to work with the height, and I'm going to make it 53%. So that's 53% of my glass.

Now to make this effect work, we need to drag this a little bit lower. So we're going to go back to my Selection tool. This needs to be a bit lower. So, what I need to do is, actually mark where the 53% is. And it's easily done through 'View', we're going to go to 'Show Guides'. And up here, in these guides, in this black area here, click, hold, and drag anywhere in this black area, and line it up to the top of your box. Now when we move it, at least we'll always know where the 53% is. So what we need to do, 'Selection' tool, bring it down a little bit. We just need a bit to cover the bottom. This effect needs a little bit of extra room around the outside.

So the next thing we need to do is we need to get this back up to that line there. So, where it says Scale, I'm just going to drag it up. And I know, 61% is kind of where it needs to be. So, Frame 1, I've got my Keyframes going already. I'm going to start it at 0, then after some time, 7 frames, we're guessing now, I'm going to put it back up to 61. So now I know, 0 to 61 is going to give me my 53%. And it's animated. And this could be-- actually you could just decide that's perfect, that's what you need to do. Click on 'Middle Outlines', switch it to 'Modes', and go to 'Track Matte', I'd like to use the thing above it. And that's it. That's basically what we're doing, right?

But I want to add that kind of flippity floppity liquid stuff. So, I'm going to undo that, go back. First of all let's add some Easing. Actually no, let's add the Easing later. We're going to have to get it so it's kind of maybe just hitting up the glass a little bit. And then click on 'Liquid Mask', twirl it up. Twirl it back down to get the full set, and we're going to click 'Add'. Now in here, we're going to use this one called 'Pucker & Bloat'. We've used Repeater, we've used Trim Paths, we're going to use 'Pucker & Bloat' now. Here it is, twirl that down. By default it's bloated up a little bit. So anything that is positive, if it's negative, it's going to be Pucker. So it's going to get down like that. That's what we kind of want to get started. And we'll set a Keyframe. Actually let's get it going along so it's just about to get to the top. And you can see here, my Pucker's a bit too much because actually I'm starting to see the bottom here.

So I'm going to have to make it a little less. That's it, just so it covers the whole base. So what I'm going to do is set the Keyframe for Pucker & Bloat. And then, maybe just-- so where does it go? It goes along there. So this one needs to be a little bit further. Closer to where it kind of stops in terms of Scale, maybe just before it. Then just after, we need to go a bit past. So we're going to go to 'Bloat'. How far we're going to bloat? Eventually go too far, and it starts going back on itself and does some weird stuff. It's like a shamrock. But I'm going to get it so it goes that far. And then--

So what's that? That is positive 46. So I'm going to go a few more frames along, then go backwards. So I go back again, not fully back. It's going to go back a little less every single time. So we're going to go back, maybe a bit more, and back this way. We're going to have to play with the timing loads, eventually it's going to look a little naff when I'm finished. And maybe back to eventually 0, where it's flat. We're going to give this a test run, don't laugh, let's see how it goes. It's not my worst, not my best either. If you're finding yours is terrible I've taught this exercise loads, often, if you have a really big first gap it does look a little funny.

So I'm going to separate these all out. Remember, if you want to expand or contract these you can select them all, hold down the 'Alt' key on a PC, or 'Option' key on a Mac. And they all expand and contract. Just play around until you get a feeling of it. And what I do find as well, just this first Keyframe needs Easing. Why? Just because I've played around with it lots. And I feel like, if you ease them all, they don't look as good, but if you ease this first one, 75 and 75, and it does makes it, I feel it does.

Next thing we need to do is apply it as a Mask. So let’s twirl this up, and the guy underneath, he needs to be directly underneath this Middle Outlines of our Mask. So click on this guy, make sure we're on Modes, and not Switches, and on the Track Matte. Who we're going to say? We're going to say, the guy just above him called Liquid Mask is going to be my Mask. Kick back, and… Ah, it could be better. It's okay. So that is the Pucker & Bloat.

So we've used the mask, which is kind of cool, and we also used that Pucker & Bloat. I now probably, if I was going to do it again, I might make the Pucker and the Bloat maybe a bit more. Doesn't kind of go enough for me, it's okay. What we also might do is, just check to see. Let's go back to 'Modes', turn on 'Motion Blur'. Let's just check to see if it's any good with that Motion Blur. It does look better, my timing's not quite there though.

All right, that is going to be it for this exercise. Let's get on to the next tutorial.