Masks are shapes that are applied to layers using the Pen tool or any of the Shape tools. In this tutorial, we're going to use masks applied to layer solids to build a colorful transition. Since the Timeline panel is active, all I have to do is press the Spacebar to preview the animation. And you can see right around three seconds, I have a hard wipe transition revealing a logo. That's where we want to create our animated colors. So, I'll press the Spacebar to stop playback. And let's scrub with the Current Time Indicator in the Timeline until it reaches 0:00:03:07. This is where I want the transition to start. Let's turn the Visibility on for Layer 4 to reveal our Purple Solid 1 layer. To apply a mask to this layer, we'll select the layer first, then go up to the Shape tools and I'll click and hold on my Shape tools here making sure that I'm choosing the Rectangle tool. Now, I can drag in the Composition panel to apply the mask. But before I do that, I'll position my cursor off the upper right edge of my composition and then I'll press the Comma key to zoom out because I want to make sure the mask covers all edges of this layer. So, starting in the upper right area here, I'll click and drag down to the left and notice as I drag over the Composition panel, I'm revealing that Purple Solid 1. Since we want the animation to start off the right side of the composition, let's make sure and draw our path off the right side of the composition until it looks something like this. Press M on your keyboard to reveal Mask 1 in the Timeline. And click on the Stopwatch to set our first keyframe for the Mask Path. I want this animation to be kind of fast. So, I'll go to the time and click and type +10 to only move ten frames down the Timeline. Press Enter to move the Current Time Indicator. And to change the mask shape I'll go up to my Tool panel and make sure I have my Selection tool selected. Now, if we go over to the mask, you'll notice all of the points are filled, meaning they're all selected. So, if I clicked on one of the points of my mask and started to move it, they'll all move at the same time. I don't want to do that, so I'll just reposition off the edge here and I'll deselect all the points by clicking outside of the Mask Path. And now, if I click on one of the points and drag, notice I'm just moving that one independently. I still don't want to do that, so I'll press Control + Z on Windows or Command + Z on the Mac to undo. If you double click on any of the points, you'll get Transform controls. So, make sure to double click on one of the points and you'll know you have Transform controls when you see these handles in the middle of the masks. So, let's hover over this left middle handle until we see the double arrows. Once you see the double arrows, click and drag the mask to cover the entire Composition panel. Make sure it goes way off the left edge of the composition. Now, let's move ten frames down the Timeline so click on the time and type +10 and press Enter to move the Current Time Indicator. We can go back up to the Mask Path and just double click on any of the points. Since we have our Transform controls applied here, now I'll hover over the right middle handle here and click and drag off the left side of the composition. Once I've got it set up, I can press Enter to set that last transformation. To preview our animation, I'll move the Current Time Indicator back to the beginning of the Timeline, and press the Spacebar. Notice now we have a color that wipes across the scene. Which is exactly what I want. But I want to make this a little more dynamic. So, I'll press the Spacebar to stop playback. If you click on the words Mask Path in the Timeline, all three of the keyframes will be selected. That means when we press Control + C on Windows or Command + C on the Mac, you'll copy the keyframes. So, go ahead and press Control + C or Command + C to copy the keyframes. Let's move our Current Time Indicator roughly in between the first and the second keyframe. So, I'll position mine to about frame 0:00:03:12, and I'll select Layer 3, and turn its Visibility on so we see it in the Timeline. And I'll press Control + V on Windows or Command + V on the Mac to paste the Mask Path. If you press M on your keyboard, you'll see those keyframes that have just been pasted. So, to preview our animation, let's move our Current Time Indicator back to the beginning of the Timeline and press the Spacebar. Now, you've not only created one mask animation but two because you've copied and applied the mask keyframes to another layer. So, remember when it comes to applying masks to a layer, it's just a matter of making sure that you have the layer selected before you go up to the Tool panel and choose either a Shape tool or a Pen tool to apply your mask.

One of the biggest reasons why I love animating Illustrator CC layers inside of an After Effects CC project, is the fact that you can convert Illustrator CC layers into shape layers. And that's what we're going to do in this tutorial. Let's animate the appearance of this layer into the scene, by converting this diamond shape into a shape layer. Go to the Timeline and select Layer 2. To convert this to a shape layer, right click on the layer, and choose Create Shapes from Vector Layer, or with the layer selected, you can go up to the Layer menu, and go down and choose Create Shapes from Vector Layer. Once you've converted the layer, you'll notice the icon has changed for Layer 2. It's now a shape layer. And the original Illustrator CC layer is still in the Timeline with its Visibility turned off. Open the options for Layer 2 and you can see we have Contents and Transform. And if we go over to the right, we also have the Add fly-out button. Now, I would usually click this button to create what's called a repeater. But I want to draw your attention to the fact that there is another way to get access to this button. I'll collapse Layer 2 for now. And since the shape layer is already selected in the Timeline, all I need to do is go up to the upper right part of the interface and sure enough, there is an Add button right up here. So, I'll click on that. And go down and choose Repeater. Once I chose the Repeater, if we look in the Timeline here, you can see Repeater 1 has been added to the shape layer. Let's open up the options for Repeater 1. And you can see immediately, there are three Copies that have been added. Now, it's hard to distinguish the three copies because they're all 100% white, and 100% opaque. So, let's open up the Transform options for the Repeater 1. But before I do that, I want to make my Timeline a little larger. So, I'll hover over the top part of the Timeline, and when I get the double arrows, I'll make the Timeline a little larger. Notice Repeater 1 has its own set of Transform options. Let's open the Transform options. And this controls exactly what each duplicate is going to do as it's being created. So, every time a duplicate is being created it's offset 100.0 pixels on the X parameter. Let's go down and change the Start Opacity to a setting of 50.0%, and then press Tab, and change the End Opacity, to a value of 0.0%. Press Enter when you're done and you can see now with our three copies, they're a little more clearly defined. Let's add some more elements to our graphic. Go back to the Copies area, and increase the setting from 3.0 to 15.0, and press Enter on your keyboard to set it. To animate the appearance of this end of the scene, let's go to the Offset parameter, click and drag until the graphics disappear off the right side of the Composition panel. Go ahead and add a keyframe by clicking the Stopwatch to the left of the word Offset. Let's move our Current Time Indicator down to about 2 seconds in the Timeline. To create animation, go back to the Offset parameter, click and drag to the left, to scrub the graphics through the scene. Just make sure to stop scrubbing once the graphics disappear off the left side of the Composition panel. I'll use a value of -35.0. Now, let's move the Current Time Indicator back to the beginning of the Timeline, and press the Spacebar to preview the animation. It may take a second to load up the initial preview, but once the frames are loaded into cache, the Current Time Indicator will loop back through the scene and we'll be able to see how things look in real-time. I think this looks pretty good. But I need to trim when this logo appears. And add the white diamond shape back into the background. So, I'll press the Spacebar to stop playback. And scrub with my Current Time Indicator back to about frame 0:00:00:17. I think this looks pretty good because I've got a pretty good white background behind the logo. So, with Layer 2 selected, I'm going to scroll up in my Timeline here, and collapse Layer 2. Select Layer 3 and turn its Visibility on. Then hold down Control on Windows, or Command on the Mac, to select Layer 1 without deselecting Layer 3. To trim the start point of both of those layers, hold down Alt on Windows, or Options on the Mac, and then press the Left Bracket key which is the key just to the right of the letter P on your keyboard. Once those layers have been trimmed, move your Current Time Indicator back to the beginning of the Timeline, and press the Spacebar to preview. Now remember, whenever a shape layer is selected in the Timeline, you can change the shape fill and stroke colors as well as have direct access to the Add button, right up in the upper right corner of the interface, without ever having to open the shape layers options themselves.

There are many different ways to exchange information between layers in the composition in After Effects CC. And in this tutorial, we're going to focus on how to exchange transparency data between the layers. The easiest way to understand this is to actually explore channels. So, let's go to the bottom of the Composition panel and click on this red green and blue button right here. This is the Channel drop-down menu and it gives you the ability to look at each individual channel that's required to create the image that we're looking at right now. The default setting shows you all three channels: The red channel, the green channel and the blue channel, all mixed together to create our image. But there's actually a fourth channel. This is called the Alpha channel and it determines transparency of an image. Let's go down and enable the Alpha channel. Now, we'll see a representation of transparency in black and white. Whatever's 100% white is 100% opaque. Anything that's 100% black is 100% transparent. Let's go ahead and select Layer 6 in the Timeline and press T to open its Opacity settings. Let's change the Opacity down to a setting of 50%, and now you can see we have 50% gray pixels. Now, let's work on building our project. Go back to the Channel drop-down and make sure RGB is enabled. Let's also click on the background layer in the Composition panel and drag it over to the left, making sure to cover the entire background, left to right, top to bottom. Go back down to the Opacity settings for Layer 6 and bring the Opacity up to 100%. Now, let's create some animation. In the Timeline, enable the Visibility for Layer 5. Then, press the Spacebar on your keyboard to playback. And you see, I've already got large-type animated from the left to the right. I'll press the Spacebar to stop playback, anywhere in the middle of the Timeline, just as long as I can see these letters in my Composition panel. I want to fill these letters with the background and have the background be transparent. To do that, I need to make sure that I Toggle Switches / Modes and I'm actually in the Mode area. Instead of focusing on the modes, let's go to the right side of this section. Go down to Layer 6, and click on the drop-down where it says None. We have four different options for exchanging transparency data between the layer above Layer 6, and Layer 6 itself. So, let's choose Alpha Matte "LANEKA'S 2". Now, press the Spacebar to begin playback and you can see we've successfully filled our type with the background layer. I'll press the Spacebar to stop playback one more time. Again, making sure my Current Time Indicator is positioned anywhere where I can see these background layers. Even though Alpha channel data is being transmitted between both Layers 5 and 6, they're still independent layers. So, if I want to blur the background a little bit I can just select Layer 6 and then go up under the Effect menu, Blur & Sharpen, and choose Fast Box Blur. In the Effect Controls panel, just click and drag on the Blur Radius to increase the blur. And I'll set mine to a rather modest 7.0. Now, we can press the Spacebar one more time, and you can see our animation. We've successfully pulled the transparency data from Layer 5, and applied it to Layer 6 using a track matte. So, images are made up of a red, a green and a blue channel. And those channels blend together to create the image that you're looking at. But there's also a fourth channel, the Alpha channel, that determines the transparency. So, when you create something like text in After Effects CC, the Alpha channel is automatically created for that layer. So, text is always ready to use as a source for an alpha matte.