The Bouncing Ball

In Animation, it is customary to practice animation concepts by creating an animation of a bouncing ball. The act of animating a bouncing ball teaches you about important animation skills:

• Frame rate
• Timing
• Arcs
• Squash and Stretch
• Volume/scale
• Keyframes
  

The frame rate of your animation is important. Traditional animations use 24 frames per second. This would be a lot of work for an animator, if every frame was a different image.

7 frames out of 24 frames.

Now we actually use 12 frames where each frame is duplicated once. This allows animators to use only 12 images to create the full 24 frames and saves a lot of time, yet looks the same visually.

7 frames out of 24, where each image is repeated once.

Timing is closely related to frame rate. Because we have so many frames moving so quickly, we can create the illusion of smooth motion, even with gaps in the animation. The more frames you use to show one action, the slower it will look. A smaller number of frames to complete the same action will look faster. 

More frames will look slower while fewer frames will look faster for one action.

Keep in mind the laws of thermodynamics and gravity and etc. as you work on timing. Everything being evenly spaced like above will look often look unnatural. Assuming that this ball was thrown and is in the act of bouncing off of the floor, the spacing might look more like this:

Closely related to timing is movement. Most movement occurs along an arc of some kind. Our bodies are full of joints and wherever you have a joint or pivot, movement is most likely going to be in an arc. Movement that is too straight often looks unnatural.

Unless an object is completely solid like wood or metal, the principle of squash and stretch often applies. Forces acting upon objects often effect the exact shape. If you sit on a cushion, the cushion sinks down a little under the weight of your body. Often in real life this is very subtle but slightly exaggerating the effect in an animation can add realism.  

Since this is a bouncy ball, it will squash as the ball hits a surface and stretch as the ball bounces up. 

As you work on squash and stretch be careful of the volume of your ball or other object. If the volume is different or the scale is off, your object will look like it is closer or farther away. Also, be careful not to exaggerate the squash and stretch too much.

In traditional animation, a keyframe is the beginning or end of movement for an action. Frames that are between keyframes are called "inbetweens" or in animation programs like Flash, "tweens". In Flash, keyframes are any frames where something is different. Since we will be using Flash to create our bouncing ball animation, every frame will be a keyframe.