When people say an animation looks "cartoony," they often mean that animators use exaggerated squash and stretch effects throughout.
Animators call squash and stretch the most important of the 12 principles because it's such an iconic characteristic of Western animation, though it's pretty simple in practice―just imagine the object or character has the physical properties of a rubber ball! Every action or force applied to a character should slightly deform it before it regains its original shape.
I can list at least three reasons why squash and stretch is such an important principle to master, even with more realistic animations.
Why Squash & Stretch
The squash and stretch principle helps convey the mass and weight of objects and characters to make movements look more grounded in physics: as a ball hits the ground, it should squash to show the impact force and compression under its weight. As the ball rebounds, it should stretch to convey the speed and energy of the bounce. This tells the audience a lot about the object's properties—whether it is heavy or light, rigid or flexible.
Animators also use squash and stretch to animate emotions. When a character is surprised, their eyes widen, and their mouth stretches open. But when a character is sad, their face squashes inward with drooping eyelids and a downturned mouth. These exaggerated facial features communicate the character’s emotional state to the audience without needing to explain anything.
Even in more realistic animations, squash and stretch contribute to the quality of an animation by preventing it from appearing too stiff or mechanical. When a person runs, their muscles and skin will naturally squash and stretch. The head will also bob from side to side like a bouncing ball.
Preserving Volume
When an object or character moves, its volume should stay consistent. But its shape can change to reflect forces like gravity and momentum.
As a rubber ball hits the ground and squashes, it should get wider, not just flatter, to maintain the same overall mass. When it stretches as it rebounds, it should become taller without losing mass. To keep this in check, you need to constantly visualize the object's volume as a fixed quantity that reshapes but doesn’t vanish.
Guides can be incredibly helpful to ensure that your character or object retains its volume during transformations.
For example, basic volume shapes like cubes, spheres, or cylinders can be used to serve as anchors while animating. These guides can be adjusted along the animation path to assist you in maintaining proper proportions.
A classic exercise is to animate a bag of flour or water balloon that is being bounced around and distorted. Animators focus on how the mass inside the object flows and reshapes.
Timing and Spacing
Timing is how long an action takes, while spacing is where the object is placed from frame to frame.
When working with squash and stretch, timing and spacing are adjusted to reflect the object's characteristics like speed and weight: a quick, sharp stretch suggests speed, while a slower, smaller squash indicates a heavy object.
As a rule of thumb, heavier objects require less squash and stretch and move with quick timing, while lighter objects need more exaggerated distortions and slower movements.
The amount of squash and stretch should also reflect the object's material properties. Even if they have the same mass, a rubber ball would show significant squash and stretch, while a bowling ball would barely change shape.
Squash occurs when there's a force or contact with another surface. Stretch typically occurs before and after the contact during anticipation and follow-through, respectively. The transitions need to be smooth to pull off the effect effectively. Example for a character jump:
- Anticipation - Add a few frames where your character crouches to load energy before your character jumps. The squashing of the leg can serve as a visual cue to the viewer that a big action is about to happen.
- Squash and stretch - As they leap, use the stretch in the upward motion to emphasize the speed and direction of the movement.
- Follow-through - When they land, use squash as they bend their knees to cushion the impact and naturally lead into a stand.
A Tool For Expression
As previously mentioned, the squash and stretch principle is great at expressing emotions and personalities effectively by exaggerating movements: different levels of compression and elasticity reflect different emotional and mental states.
A character that is feeling excited or joyful could be depicted almost as light as a feather, with more stretch in the animation.
A heavy, grumpy character might use squash and stretch more in the squash side when they move, with minimal stretch to indicate their heavy, sluggish personality by keeping most of their body condensed and low to the ground.
Anime aesthetics heavily leverage temporary facial exaggeration to emphasize sudden emotional changes to draw the viewer's attention, most notably by squashing or stretching the eyes and the mouth.
Usage in Animation Cycles
Movements rarely progress linearly, so animators experiment with different easing curves in their animation software to see what best matches the timing of the movement they're aiming for. For example, you have to display more energy at the beginning of the sprint when a character runs, so the animator would add more squash and stretch within a shorter time.
Talking about running, balance is crucial in loop animations (cycles): too much repetition leads to monotony so you need to introduce variation.
Minor tweaks in the squash and stretch timing or scale for different cycles add a lot to the quality of the animation. It's as simple as changing the speed of a step, a posture, or the amplitude of squash and stretch. For example:
Pay particular attention to how the body compresses and elongates naturally. The body's weight shifts with each step in a walk cycle. As the character's foot touches the ground, introduce a slight squash to convey impact. As the character pushes off the ground, you can slightly stretch the leading leg to show propulsion.
Conclusion
Mastering the squash and stretch principle is key for animators, whether you're aiming for a cartoony or realistic aesthetic.
It's a cornerstone of animation because it allows animators to convey not only the physical properties of objects like weight and speed but also the emotional states of characters through visual cues. You just have to be mindful of volume, timing, and applied forces to bridge the gap between art and physics.
Combined with the other 11 principles of animation, squash, and stretch is a great way to level up your animation!
