12 Principles of Animation Skill

12 Principles of Animation

Review animation code for compliance with Disney's 12 principles adapted for web interfaces.

How It Works

Read the specified files (or prompt user for files/pattern)
Check against all rules below
Output findings in file:line format

Rule Categories

| Priority | Category | Prefix | |----------|----------|--------| | 1 | Timing | timing- | | 2 | Easing | easing- | | 3 | Physics | physics- | | 4 | Staging | staging- |

Rules

Timing Rules

`timing-under-300ms`

User-initiated animations must complete within 300ms.

Fail:

.button { transition: transform 400ms; }

Pass:

.button { transition: transform 200ms; }

`timing-consistent`

Similar elements must use identical timing values.

Fail:

.button-primary { transition: 200ms; }
.button-secondary { transition: 150ms; }

Pass:

.button-primary { transition: 200ms; }
.button-secondary { transition: 200ms; }

`timing-no-entrance-context-menu`

Context menus should not animate on entrance (exit only).

Fail:

<motion.div initial={{ opacity: 0 }} animate={{ opacity: 1 }} />

Pass:

<motion.div exit={{ opacity: 0 }} />

Easing Rules

`easing-entrance-ease-out`

Entrances must use ease-out (arrive fast, settle gently).

Fail:

.modal-enter { animation-timing-function: ease-in; }

Pass:

.modal-enter { animation-timing-function: ease-out; }

`easing-exit-ease-in`

Exits must use ease-in (build momentum before departure).

Fail:

.modal-exit { animation-timing-function: ease-out; }

Pass:

.modal-exit { animation-timing-function: ease-in; }

`easing-no-linear-motion`

Linear easing should only be used for progress indicators, not motion.

Fail:

.card { transition: transform 200ms linear; }

Pass:

.progress-bar { transition: width 100ms linear; }

`easing-natural-decay`

Use exponential ramps, not linear, for natural decay.

Fail:

gain.gain.linearRampToValueAtTime(0, t + 0.05);

Pass:

gain.gain.exponentialRampToValueAtTime(0.001, t + 0.05);

Physics Rules

`physics-active-state`

Interactive elements must have active/pressed state with scale transform.

Fail:

.button:hover { background: var(--gray-3); }
/* Missing :active state */

Pass:

.button:active { transform: scale(0.98); }

`physics-subtle-deformation`

Squash/stretch deformation must be subtle (0.95-1.05 range).

Fail:

<motion.div whileTap={{ scale: 0.8 }} />

Pass:

<motion.div whileTap={{ scale: 0.98 }} />

`physics-spring-for-overshoot`

Use springs (not easing) when overshoot-and-settle is needed.

Fail:

<motion.div transition={{ duration: 0.3, ease: "easeOut" }} />
// When element should bounce/settle

Pass:

<motion.div transition={{ type: "spring", stiffness: 500, damping: 30 }} />

`physics-no-excessive-stagger`

Stagger delays must not exceed 50ms per item.

Fail:

transition={{ staggerChildren: 0.15 }}

Pass:

transition={{ staggerChildren: 0.03 }}

Staging Rules

`staging-one-focal-point`

Only one element should animate prominently at a time.

Fail:

// Multiple elements with competing entrance animations
<motion.div animate={{ scale: 1.1 }} />
<motion.div animate={{ scale: 1.1 }} />

`staging-dim-background`

Modal/dialog backgrounds should dim to direct focus.

Fail:

.overlay { background: transparent; }

Pass:

.overlay { background: var(--black-a6); }

`staging-z-index-hierarchy`

Animated elements must respect z-index layering.

Fail:

.tooltip { /* No z-index, may render behind other elements */ }

Pass:

.tooltip { z-index: 50; }

Output Format

When reviewing files, output findings as:

file:line - [rule-id] description of issue

Example:
components/modal/index.tsx:45 - [timing-under-300ms] Exit animation 400ms exceeds 300ms limit
components/button/styles.module.css:12 - [physics-active-state] Missing :active transform

Summary Table

After findings, output a summary:

| Rule | Count | Severity | |------|-------|----------| | timing-under-300ms | 2 | HIGH | | physics-active-state | 3 | MEDIUM | | easing-entrance-ease-out | 1 | MEDIUM |

Agent Skills: 12 Principles of Animation

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