Exercise 2.2 The Bouncing Ball

Ease In & Ease Out Assignment.

This is a classic beginner animation assignment: the bouncing ball. We’ll build on this exercise in the next lesson as well.

The goal for this assignment will be for you to create two animations (or three if you like) of a bouncing ball, but use different timing and easing to make the balls appear to be different weights.

Part 1

Start with the reference above and try to recreate it.

Basic Rules for Bouncing ball:

It will take several bounces to come to a stop. Each bounce takes some energy from the ball, so each bounce will get slightly lower than the previous one.

(How “efficient” the bounce is at reversing the energy depends on the material. Rubber will absorb and redirect the energy upward better than stone would. So a rubber ball would have more bounces than a stone ball would.

For this assignment let’s assume the balls are a material that bounces.)

• • Each time the ball hits the ground, it will lose energy, so each successive bounce will be lower and lower.

  • Each bounce will take less time (fewer frames) than the previous one.

  • Gravity causes the ball to accelerate as the ball falls, so the fastest part of each fall is just before it hits the ground.

  • The bounce reverses the direction of the ball, so the fastest part of the upward journey of the ball is just after the bounce.

  • The ball will be moving at its slowest at the top of each bounce (the apex) where it transitions from moving upward to moving downward.

  • ANIMATOR PRO TIP: The ball’s vertical movement and horizontal movement should be considered independently. The vertical movement is affected by gravity and the force of the bounce, but the horizontal progress of the ball isn’t affected by gravity, so it should just gradually ease-out because of other forces. (air resistance/friction)

Part 2 - Changing the weights

After the baseline ball-bounce, try to depict a bouncing ball that seems lighter than the baseline, and another that seems heavier tha the baseline. The balls should start from the same height.

Tips for Depicting Weight

• The heavier ball will tend to lose more of its energy when it contacts the ground, so the height of each bounce will diminish much faster, and there will be fewer bounces before it stops. The lighter ball will lose less energy and height and go through more bounces before stopping.

• The heavier ball’s horizontal motion will also have more pronounced deceleration, because there will be more friction each time it hits the ground. At the end of the bounce when it rolls it will also slow faster because of increased friction.

• TIPS AND TRICKS - Light ball will be about 160 frames. Heavy ball be about 50 frames