GLTF Posisi Three.js

var scene, camera, renderer;
function init() {
  scene = new THREE.Scene();
  camera = new THREE.PerspectiveCamera(
    75,
    window.innerWidth / window.innerHeight,
    0.1,
    1000
  );

  scene.background = new THREE.Color("#111214");
  camera.position.set(100, 100, 100);

  renderer = new THREE.WebGLRenderer({ antialias: true });
  renderer.setSize(window.innerWidth, window.innerHeight);
  document.body.appendChild(renderer.domElement);

  var avtar;
  var loader = new THREE.GLTFLoader();
  loader.load("name.gltf", function (gltf) {
    avtar = gltf.scene;
    scene.add(avtar);
  });
  
  controls = new THREE.OrbitControls(camera, renderer.domElement);
  document.onkeydown = function (e) {
    switch (e.keyCode) {
      case 37:
        avtar.scale.z += 0.1;
        break;
      case 39:
        avtar.scale.z -= 0.1;
        break;
    }
  };

  function animate() {
    requestAnimationFrame(animate);
    renderer.render(scene, camera);
  }

  animate();
}
init();
Undefined