From dylantarre-animation-principles
Use when designing motion paths, character movement trajectories, gesture animations, or any motion that should feel natural rather than robotic.
npx claudepluginhub joshuarweaver/cascade-content-creation-misc-1 --plugin dylantarre-animation-principlesThis skill uses the workspace's default tool permissions.
Almost all natural movement follows curved paths. Arms swing in arcs. Heads turn on arcs. Thrown objects travel parabolic arcs. When animation moves in straight lines, it immediately feels mechanical and artificial. Arcs are the signature of organic motion.
Generates design tokens/docs from CSS/Tailwind/styled-components codebases, audits visual consistency across 10 dimensions, detects AI slop in UI.
Records polished WebM UI demo videos of web apps using Playwright with cursor overlay, natural pacing, and three-phase scripting. Activates for demo, walkthrough, screen recording, or tutorial requests.
Delivers idiomatic Kotlin patterns for null safety, immutability, sealed classes, coroutines, Flows, extensions, DSL builders, and Gradle DSL. Use when writing, reviewing, refactoring, or designing Kotlin code.
Almost all natural movement follows curved paths. Arms swing in arcs. Heads turn on arcs. Thrown objects travel parabolic arcs. When animation moves in straight lines, it immediately feels mechanical and artificial. Arcs are the signature of organic motion.
Anatomical basis: Bodies are systems of hinges and pivots. When a joint rotates, everything attached to it moves in an arc centered on that joint. Straight lines require mechanical rails—biology doesn't have those.
Physics basis: Gravity creates parabolic curves on projectiles. Momentum creates curved paths when direction changes. Straight-line direction changes require infinite force.
Circular arcs: Pure rotation around a single pivot (pendulum, door swing) Parabolic arcs: Projectile motion under gravity (jumps, throws) S-curves: Complex motion through multiple pivots (whip crack, spine movement) Figure-8 patterns: Continuous flowing motion (hips during walk, flowing cloth)
Understanding arcs requires understanding pivot hierarchies:
Each joint adds complexity to the motion path of everything downstream.
Follow through follows arcs: Appendages settle along curved paths, not straight returns.
Anticipation creates arc initiation: The wind-up often establishes the arc's direction.
Timing affects arc perception: Fast motion through arcs needs exaggerated curves to read clearly.
Overlapping action creates offset arcs: Secondary elements trace their own arc patterns behind the primary.
In 3D, arcs must read from camera view. A perfect arc in world space may look straight or even reversed from certain angles. Always verify arc readability from final camera.
Traditional method: Draw through the motion path with a single stroke. If your pencil naturally curves, the arc is working. If you must consciously redirect, the motion is likely too linear.
For any point-to-point motion: add a control point to create a curve. The control point should be offset perpendicular to the direct line, placed closer to the start for ease-out feeling, closer to end for ease-in. For complex motions, trace the intended path first—if it's not curved, it needs work.
Default arc height: 10-20% of travel distance for subtle organic feel, 30-50% for dramatic sweeping motion.