Squash and stretch is at the core of the animation principles. It is what gives some elasticity and flexibility to your animation. When an object hits the ground, the impact drawing will be really squashed. As it bounces off the ground, it will stretch in the opposite direction. The stronger the squash and stretch is, the smoother and bouncier the animation will look. Also, hard objects such as a bowling ball require less squashing or stretching so that the heavy and solid illusion remains. As you squash and stretch an object, it is really important to maintain the volume of the object. When you squash something down, you need to proportionally stretch it sideways, otherwise, the object will look like it is getting smaller.
Squash and stretch adds reality to the animated drawing, with more levels of action and emotion included in every action.
Consider these points:
- Living shapes are organic, therefore they don't progress from position to position rigidly. For example, smiling changes the shape of the cheeks, while bending an arm causes the muscles on both sides of the elbow to change shape.
- Exaggeration: The more squash and stretch, the more cartoony the animation will feel.
- It is important to consider the composition of the object when squashing and stretching.
- Volume must be conserved throughout the operation. You don't want your characters to gain weight every time they smile!