2D/2.5D Character IK & Viseme Lip-Sync (character-ik-lip-sync)

Use this skill whenever a prompt calls for animated characters, mascots, explainers with a speaking presenter, limb/joint kinematics, or lip-synced dialogue.

1. Analytic 2-Bone Inverse Kinematics (solveTwoBoneIK)

Never animate multi-segment limbs with disconnected rotations that drift at the elbow or knee. Compute the exact joint position (jx, jy) from shoulder/hip (x0, y0), target hand/foot (tx, ty), and bone lengths (L1, L2) using the Law of Cosines:

import { solveTwoBoneIK, AnimatedCharacterRig } from "./engine";