How to make a bouncing ball animation.

Animating a bouncing ball sounds easy enough, and to most seasoned animators it is like breathing to us. While it is effortless to achieve, we still need to understand the main animation guiding principles in order to make the motion feel believable: whether it is as light and bouncy as a ping pong ball or dense and heavy like a bowling ball. Let me talk through some tips on how we do that.

When you drop a football compared to a ping pong ball how long does it take to hit the ground? How long is each bounce and how long does it take for the motion to stop? These questions form the basis in which we build upon to make appealing motion design. Studying from real life and understanding the fundamentals of the laws of physics help keep it rooted in reality.

The speed in which the ball falls and loses its energy changes its weight, scaling compared to other objects around it and the emotion the audience has to it. Especially in motion graphics when sometimes all we have to play with are shapes, it is important to plan ahead how you want your objects to move. So that they communicate the correct weighting and/or emotion to the viewer.

If we take example on the right, look at how different it feels to the first two.

The motion is more energetic and because it doesn’t lose that energy on the bounce up, it has a weightlessness to it – akin to a ping pong ball.

Once we know how we want our ball to move, the next step is to understand how to achieve it. And to do this we need spacing. Spacing is quite literally the space between each frame.For example if our ball bounced up in 12 frames (half a second) most of the frames will be concentrated where we want the ball to slow (losing its energy) at the height of its motion.

The closer the spacing of each frame, the slower the motion will be. The further apart the spacing, the faster the motion is. Frequently in animation we use the terms ‘easing in’ or‘ easing out’ to describe how we want spacing to be. To ‘ease in’ or ‘ease out’ simply means to have more frames at the start (in) or the end (out) of the motion, which makes movement feel more akin to how we move in real life.

The action starts slow (ease in) and picks up speed before slowing down again (ease out).

Linear motion means that frames are spaced equally apart.

This is something we try to avoid, unless it has creative intent. It can show constant velocity but can feel mechanical if used on all if your motion in your scene.

As the ball is coming back to the ground, it is gaining energy before the impact and then that energy is transferred back upward (depending on the weight of the ball).

So there is less spacing between frames towards the impact point which means the ball is speeding up.

With some understanding about spacing and timing, animating a basic bouncing ball in AE is simple. The first thing that can help is splitting up the dimensions on position. Sometimes splitting up the dimensions on the position value helps because it allows us to break up the motion between the y and x axis. This works particularly well when we want the ball to bounce a distance or we want to just focus on it bouncing on the spot. It also allows us to use the value graph editor to really control our spacing.

Next is to plot out some rough timing by placing a few keyframes down on the y axis. In this case, let’s say the ball bounces up and back down in 1 second. This means our ball needs to be up in the air around the half second mark. With that done, select the key frames and hit F9 to add in some basic easing. Notice if you press play that the motion doesn’t feel quite right yet because the ball slows down too much at the start and the end. It is time to hop into the graph editor. Position only works in the value graph editor when we split the dimensions (right click position and select ‘separate dimensions’).

However you can use the speed graph with them both intact if you wish. There is a key difference between the two in how the graphs represent velocity. In the case of the value graph editor, the steeper the graph, the faster the motion will be (and your frames will be spaced out further). When the graph evens out to a flat line is where the motion will slow (and more frames are spaced together).

Remember, we want the spacing to be its most dense where we want the ball to slow down, so making sure that there is more easing on the middle keyframe will ensure this.

Finally, it is important to loop the animation. The motion finishes and starts on the same frame, so we just need to make sure that the in and out of the work area create a loop. To create a seamless loop you will need to have the work area end a frame before the final frame to avoid having a duplicate frame at the beginning and end.

And there you have it!

There is so much that goes into animation and even the smallest of actions need to be deliberate for it to feel believable. So go, be free and experiment with different weights and styles of motion.

If you’re feeling adventurous, you can add another dimension…! Check out the difference between 2D and 3D above.

Don’t worry, we’ll be posting another ‘how to’ focussed on how to make your ball 3D soon so keep an eye out…

In the meantime, if you’d like to know more about the principles of animation like squash and stretch, I highly recommend Richard Williams Animator’s Survival Kit.

Your friendly neighbourhood animator,

Tara.