text: var scene, camera, renderer, geometry, material, cube, group;
  
  
  init();
  render();
  
  function init() {
      
      scene = new THREE.Scene();
  
      camera = new THREE.PerspectiveCamera( 75, window.innerWidth / window.innerHeight, 0.1, 10000 );
      camera.position.z = 5;
      
      //set background to have transparency - alpha: true
      renderer = new THREE.WebGLRenderer({ alpha: true });
      renderer.setSize(window.innerWidth, window.innerHeight);
      
      document.getElementById("viewport").appendChild(renderer.domElement);
      
      
      geometry = new THREE.CubeGeometry(1, 1, 1);
      material = new THREE.MeshBasicMaterial({
      wireframe: true,
      color: 'black'
      });
      cube = new THREE.Mesh(geometry, material);
  //    scene.add(cube);
      
      group = new THREE.Object3D();
      group.add(cube);
      scene.add( group );
  
  }
  
  
  
  function render() {
      requestAnimationFrame(render);
      cube.rotation.x += 0.01;
      cube.rotation.y += 0.01;
      renderer.render(scene, camera);
      
      
  }