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name: squash-stretch-mastery description: Use when implementing deformation effects, bounce animations, impact responses, or any motion requiring organic elasticity and weight expression.

Squash & Stretch Mastery

The Foundation Principle

Squash and stretch is considered the most important of Disney's 12 principles because it solves animation's fundamental problem: making rigid objects feel alive. Developed in the 1930s at Disney, it emerged from observing how real flesh and rubber deform under force while maintaining constant volume.

Core Theory

Volume Preservation: When an object squashes, it must widen. When it stretches, it must narrow. This constraint creates believability—violate it and objects appear to grow or shrink rather than deform.

Force Visualization: Squash and stretch makes invisible forces visible. A ball squashing on impact shows us the floor's resistance. A character stretching mid-leap reveals velocity and momentum.

The Elasticity Spectrum

Not all objects deform equally:

• High elasticity: Rubber balls, cartoon characters, jelly (extreme deformation)
• Medium elasticity: Human faces, cloth, muscle (subtle deformation)
• Low elasticity: Wood, metal, bone (minimal but present micro-deformation)

Even "rigid" objects benefit from 1-2% deformation—it prevents the dead, mechanical feel.

Interaction with Other Principles

Timing amplifies squash/stretch: Fast impacts demand more squash; slow floats need gentle stretch. The deformation amount must match velocity.

Anticipation uses stretch: A character winding up for a jump often stretches slightly before the motion begins.

Follow-through extends it: After landing, the squash ripples through secondary elements (hair, clothing, flesh).

Domain Applications

UI/Motion Design

• Button press: subtle squash (95-98% height) on tap
• List items: stretch slightly when pulled beyond bounds (rubber-band scroll)
• Notifications: squash on arrival, bounce to rest

Character Animation

• Facial expressions: cheeks squash on smile, stretch on surprise
• Walk cycles: torso compresses on contact, extends on passing
• Emotional beats: extreme stretch for shock, squash for dejection

Logo Animation

• Bouncing logos: exaggerated squash creates playful personality
• Subtle breathing: micro-squash/stretch keeps static logos alive

Game Feel

• Jump arcs: stretch on ascent, squash on landing
• Hit reactions: brief squash sells impact before knockback
• Collectibles: rhythmic pulse using gentle squash/stretch

Common Mistakes

1. Breaking volume: Objects appear to grow/shrink instead of deform
2. Uniform deformation: Real objects deform more where force is applied
3. Over-application: Subtle contexts need 1-5%, not cartoon 50%
4. Static extremes: Deformation should ease in/out, never snap

Implementation Heuristic

Start with 10% deformation for energetic motions, 2-3% for subtle polish. Adjust based on material and tone. When in doubt, less is more—squash/stretch should be felt, not consciously noticed.