<!doctype html>
    <title>Jointed leg</title>
      body { max-width: 100%; }
      /* feel free to style the canvas any way you want. If you want it to
      use the entire window, set width: 100% and height: 100%. */
      canvas {
          width: 80%;
          height: 500px;
          display: block;
          margin: 10px auto;

  <h1>Jointed leg</h1>
  <p>Demonstrates a multi-segment object with multiple joints nesting several objects and frames deep.</p>

function makeLeg(scene,parameters) {
    /* Makes a leg going down from the origin, with joints rotating around
     * z, so we are seeing the leg from its right side, and the foot is
     * roughly parallel to the x axis. Meshes are shoe, calf, and
     * thigh. Composite objects are foot, lowerleg, and leg. Composite
     * objects have the relevant joints: ankle, knee, and hip,
     * respectively, which the GUI lets you control. */

    var shoe = TW.createMesh(new THREE.CylinderGeometry(2, 1, parameters.footLength));

    foot = new THREE.Object3D();
    foot.name = "foot";
    shoe.position.x = parameters.footLength/2;
    shoe.rotation.z = Math.PI/2;

    foot.rotation.z = parameters.ankleRotation;

    var calf = TW.createMesh(new THREE.CylinderGeometry(3, 2, parameters.calfLength));

    lowerleg = new THREE.Object3D();
    lowerleg.name = "lowerleg";
    calf.position.y = -parameters.calfLength/2;
    foot.position.y = -parameters.calfLength;

    lowerleg.rotation.z = parameters.kneeRotation;

    var thigh = TW.createMesh(new THREE.CylinderGeometry(5, 4, parameters.thighLength));

    leg = new THREE.Object3D();
    leg.name = "leg";
    thigh.position.y = -parameters.thighLength/2;
    lowerleg.position.y = -parameters.thighLength;

    leg.rotation.z = parameters.hipRotation;


var scene = new THREE.Scene();

var parameters = {
    ankleRotation: TW.degrees2radians(-10),
    kneeRotation: TW.degrees2radians(-30),
    hipRotation: TW.degrees2radians(45),
    footLength: 10,
    calfLength: 20,
    thighLength: 25


var renderer = new THREE.WebGLRenderer({antialias: true});


               {minx: 0, maxx: 5,
                maxy: 0, miny: -(parameters.thighLength+parameters.calfLength),
                minz: -3, maxz: 3});

function redraw() {
    // this variant of re-draw just adjusts the current geometry instead
    // of discarding it and creating a new one
    var foot = scene.getObjectByName("foot",true);
    var lowerleg = scene.getObjectByName("lowerleg",true);
    var leg = scene.getObjectByName("leg",true);
        foot.rotation.z = parameters.ankleRotation;
    lowerleg.rotation.z = parameters.kneeRotation;
         leg.rotation.z = parameters.hipRotation;

var gui = new dat.GUI();
gui.add(parameters,'kneeRotation', -2*Math.PI/3, 0.1).step(0.001).onChange(redraw);
gui.add(parameters,'hipRotation', -Math.PI/6,Math.PI).step(0.001).onChange(redraw);

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

  1. https://s3.amazonaws.com/m.mr-pc.org/t/cisc3620/2020sp/three.min.js
  2. https://s3.amazonaws.com/m.mr-pc.org/t/cisc3620/2020sp/OrbitControls.js
  3. https://s3.amazonaws.com/m.mr-pc.org/t/cisc3620/2020sp/tw.js
  4. https://s3.amazonaws.com/m.mr-pc.org/t/cisc3620/2020sp/dat.gui.min.js