Introduction to 3D Animation - Bouncing A Ball

 Animating a bouncing ball sounds like a simple task when you think about it. Although it is the things that you don't think about which will trip you up. First you should block out the animation of the ball bouncing, the highest point of the ball and the point at which the ball is on the ground should be key frames.




Once you have the ball moving as it were, you then need to think about energy. The ball should accelerate faster towards the ground and slow down as it comes to its highest point. To do this you need to break the tangent curves by using the graph editor. The motion curve should look like this, with a sharp point where the ball hits the ground. Notice how the tops of the motion curve are not as steep.

Now comes the extremely difficult part....I jest, it is just as easy. You need to add squash and stretch to the object, visualising the build up and release of energy that allows the object to bounce. This is done by scaling the object and setting key frames at specific points on the timeline. Here you can see that the motion curves for the X,Y and Z scale attributes are symmetrical. This is because the object should never change volume, if you scale the object in the Y axis then you must also scale the object in the X and Z axis in order to maintain this volume. Usually you will find the the scale values on the X and Z axis will be equal to each other, unless the object hits something other than the floor or your animating jelly because you are cool.


In this example you can see the stages of the ball as it travels through the bounce. Notice that the ball stretches in anticipation of the bounce. This does not happen in real life but many animations will include it because it mimics motion blur. As the ball hits the floor it gets squashed but maintains its volume.