function addSphere1() {
  let shape = new CANNON.Sphere(radius); // Step 1
  var body = new CANNON.Body({ mass: 0 });
  body.addShape(shape);
  body.position.set(0,0,0);
  world.addBody(body);
}

function addSphere2() {
  var shape = new THREE.SphereGeometry( radius, 32, 32 );
  var mat = new THREE.MeshNormalMaterial();
  var mesh = new THREE.Mesh( shape, mat );
  mesh.position.set(0, 0, 0);
  scene2.add( mesh );
}