12 Principles of Animation in After Effects

In this lesson, we're going to learn how to apply the principle of ease in and ease out to our animation. So I've opened up 03_begin. And here we have a very simple movement, probably something very similar to what you've created in the past. We have a rotating object, and the movements are with linear key frames. And it's very mechanical. It does the job, but it's not appealing, it's not entertaining, it's kind of going through the rhythms. So let's come in and let's learn about the principle of ease in and ease out. Now, you're probably thinking, hey, I know how to ease in and ease out. I just hit F9 with the key frame selected. Well, that will make the key frames easy ease. You could also do it by going up to Animation, Key Frame Assistance, and go to Easy Ease, and that will change the key frames. Now, what this is doing is it's saying, OK, slowly move into the acceleration, or move into the speed. So you'll see here that the frame after our key frame is much slower than if we had linear key frame. To change it back, you can hold Control and click on that key frame. You'll notice we had a much greater shift when our key frames are linear. And that's because the motion is the same every single frame. However, with ease in and ease out, the motion is kind of a bell curve. It goes up and achieves maximum speed right here in the middle. And then it slows down into the next key frame. Now, that will give us slightly nicer motion. Technically, more correct, but still it's missing something. It's missing some life. And this is because ease in and ease out isn't as easy as an easy ease key frame. Try saying that sentence 10 times fast. But, what we need to remember is that ease in and ease out is all about motion, and it's about physics. You've probably heard the physics terms that a body in motion wants to stay in motion, and a body at rest, or still, wants to stay at rest. And what that says is, it requires energy or force to start or stop movement. Now, here you can see we are slowly easing into it, but it's really not giving us much time to begin looking at the animation. And at the end here, we stop unnaturally perfectly. In the real world, things don't stop on dime, no matter how much the automobile commercials tell you they can. Everything has a little bit of movement and a little bit of inertia, even when we want to stop it. So let's add this in to our animation. So this last key frame is at negative 29. So let's begin by copying and pasting this key frame a few frames forward. Now, to apply the easy in and ease out in layers, what we can do is we can overdrive the animation, and then have it settle back to where we actually want it. So this animation is going down, it's going negative, it's rotating to the left. So in this key frame, let's actually keep having this rotate to the left. So we'll just overdrive this a little bit, and a light touch is best, and then our object will come to rest. So let's hit zero key and take a look at this new motion. And you can see it looks much, much more natural. We have it trying to slow down, missing or overshooting its target, and then coming back to where it wants to be. Now, this might be a little bit too slow for you, so we can move this key frame back to create a springier motion, or a illusion of a smaller object. Of course, smaller objects are much easier to move and slow down and stop than larger objects. Now, if we increase these, we have what looks like a very heavy object trying to slow down. Now, we can actually also apply ease in and easy out a number of times. We're not just limited to one or two key frames. So if we overdrove it to the left to begin with, let's now move forward a few frames and overdrive it to the right. So our ending value is 29, so let's now get it a little bit higher than 29. Not too far, because that will create a sort of see-sawing motion that's unappealing. And let's even out these key frames so our timing is a little bit more even. And now let's take a look at this. And what we get is this very nice, very natural motion. The clock here stops, it begins trying to stop, overcorrects, overcorrects, and now we have essentially the same animation, but it looks much more appealing because we have a little bit more movement and it is moving as if it was inside of a real world. OK. So now that we've learned one of the ways to apply ease in and ease out, let's take a look at a mathematical way, which is one that I like a little bit more for a simple attribute, like rotation, but works a little bit less useful on things like position. So to do this, let's go to our last key frame of our primary action. So the primary action is whatever your object is doing. And the ease in and ease out are what is going to get us into that action and out of that action. Let's begin by taking this last key frame and setting it to Linear. Now, you might be thinking-- and we're doing ease in and ease out. We're just keeping this around so we could remember what this value is, and sort of have it as our place marker. So like we did before, let's copy and paste the original value forward. And this time I'm going to ease this last key frame. But let's actually calculate how fast this is moving. So to do that, I'm just going to use two frames as a reference. So we have negative 104. Let's go back two frames with the Page Up button. And we have negative 93. So let's see, 104, 93, I think that's a change of 11. So it's moving at about 11 degrees per second. Now, all we need to know about that is after this, let's overdrive it by half of its speed. So after this linear key frame, let's go forward two or three frames. And let's go from negative 104 to half of 11. So negative 104 plus, let's just say 5, for simplicity's sake, and that will give us negative 9, so negative 109. So now we are overdriving it to this next key frame. And again, let's move forward three frames and take another half. So it's going to be 2.5, or 3 if we go closer to our original value. So let's now set it to 104 minus 3. So that would be negative 101. So if you take a look at what we're doing, we're taking this first value, defining how fast it's going, and then we're slowly reversing the speed. So we're easing into something that's a little bit past the speed, and then we're easing back to something that's a little bit before the speed. And then we will ease into our final resting place. So let's hit zero. And you're going to keep repeating this as often as you want. I really don't repeat it when the speed or when the value we're adding or subtracting gets below one. In this case, we could probably add one more key frame. So we can just move this last key forward a few. Go into the middle. And let's say 104-- let's see, our last value was negative 101. So this time, let's set it to something like, let's say 105. I'd say negative 105. OK. So now we're going to be oscillating this slowly back and forth until we finally run out of energy, hit the brakes, and ease into our final pose. OK. So here we can see by just applying this very simple formula, we were able to create ease in and ease out very simply. Now, do you have to use math to use ease in? No. Just remember that when you're trying to slow down an object or speed up an object, you're going to need to give it a little bit of energy, or bleed off the energy. And what's going to happen is that object's probably going to go past where you want it to stop and then it will ease into the final pose. So I would always apply ease in and ease out whenever you're changing speed to an object. And as you can see here, it adds a little complexity to your key frames, so I would do this after you have your motion and what you know your animation to be roughed in at a pretty good level. I wouldn't go in and add ease in and ease out to every little motion until I'm relatively sure that motion is going to stay what it is. So that's how you can apply the principle of ease in and ease out to create some really nice and appealing motion.