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  • License MIT

Inverse kinematics for 2D and 3D applications

Package Exports

  • inverse-kinematics

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (inverse-kinematics) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

IK - Inverse Kinematics

Inverse kinematics for 2D and (soon) 3D applications.

Quickstart 2D

https://codesandbox.io/s/quickstart-2d-ob7yw?file=/src/index.ts

import { V2, Solve2D } from 'inverse-kinematics'

// Create a list of 'links'
// Three links, of 50 units long, all pointing in the same direction
const bones: Solve2D.Link[] = [
  { rotation: 0, length: 50 },
  { rotation: 0, length: 50 },
  { rotation: 0, length: 50 },
]

// Define the base of the links
const base: Solve2D.JointTransform = { position: [0, 0], rotation: 0 }

// Define a target for the 'end effector' or the tip of the last link to move to
const target: V2 = [50, 50]

// Iterate until the error is within acceptable range
const acceptedError = 10
function loop() {
  const error = Solve2D.getErrorDistance(bones, base, target)
  if (error < acceptedError) return

  Solve2D.solve(bones, base.position, target)
  setTimeout(loop, 100)
  console.log(error.toFixed(0))
}
loop()

Examples

Check out https://tmf-code.github.io/inverse-kinematics or find them in the folder /example

Terminology

Base

The starting point of the link chain

A Link can be thought of as a connecting bar, that extends from it's joint, to the joint of the next link in the chain.

Joint

Occurs at the tip of the preceding link, and at the base of the following link. We've chosen to consider ownership of the joint to the following link. So that itself can be considered a Base to the remaining links.

Visulization of terminology

You could visualize a link chain like so:

Base
  -> rotate(link_1.rotation) [joint_1] -> translate(link_1.length)
  -> rotate(link_2.rotation) [joint_2] -> translate(link_2.length)