squash-stretch-mastery
Use when implementing deformation effects, bounce animations, impact responses, or any motion requiring organic elasticity and weight expression.
What this skill does
# 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.
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