Individual skill

arc-mastery

Use when designing motion paths, character movement trajectories, gesture animations, or any motion that should feel natural rather than robotic.

skills/11-by-principle-focus/arc-mastery/SKILL.md

Read pinned source

Source commit 83597134ba8ff59838270f94d7ac7282ffa3b54d

What was checked

Matches the observed repository HEAD: Yes
Scanner rules are current: No
Repository scan complete: No
Skill scan complete: Yes
Observed behavior: Not checked yet
Last checked: Nov 6, 2026

These are observations at the recorded commit, not a guarantee of safety. Review the source before running it.

Install this skill

Choose an agent in your Stack or copy a command below. Commands fetch the pinned commit and copy only this skill directory. Existing destinations are refused. Copying a command does not install anything.

An install command is unavailable: current rules, complete repository and skill scans, an eligible behavior level and a permitted license are required.

Repository context

Repository stars (not skill ratings): 147
Repository last updated: Dec 30, 2025
License: MIT

Observed agent integration: No specific integration evidence. Standard SKILL.md installation does not imply verified compatibility.

ai Repository topic
animation Repository topic
claude Repository topic
disney Repository topic
skills Repository topic
principles-of-animation Repository topic
engineering Derived category

Files and excerpt

File metadata and permitted, redacted excerpts come from the recorded scan. Source links are pinned to that commit.

Browse files

SKILL.mdcore · 4,372 bytes

Read excerpt


# Arc Mastery

## The Natural Path Principle

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.

## Core Theory

**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.

## Arc Types