double side myth

by Nally

HTML

<div id="info">double side myth
</div>
<script src="https://cdnjs.cloudflare.com/ajax/libs/three.js/94/three.min.js"></script>
<script src="https://threejs.org/examples/js/controls/OrbitControls.js">


</script>

CSS

#info {
  position: absolute;
  top: 0px;
  width: 100%;
  padding: 10px;
  text-align: center;
  color: #ffff00
}

body {
  overflow: hidden;
}

JavaScript

var camera, scene, renderer, light;

init();
animate();

function init() {
  scene = new THREE.Scene();

  camera = new THREE.PerspectiveCamera(50, window.innerWidth / window.innerHeight, 1, 1000);
  camera.position.z = 80;
  scene.add(camera);

  let light = new THREE.PointLight(0xffffff);
  light.position.set(0, 0, 130);
  scene.add(light);

  var gridXZ = new THREE.GridHelper(100, 10, 'red', 'white');
  scene.add(gridXZ);

  renderer = new THREE.WebGLRenderer();
  renderer.setSize(window.innerWidth, window.innerHeight);
  renderer.setClearColor(0x888888);

  let controls = new THREE.OrbitControls(camera, renderer.domElement);

  document.body.appendChild(renderer.domElement);
  ////////////////////////////////////////////////////////////////////////

  var geometry = new THREE.Geometry();
 	geometry.vertices.push (new THREE.Vector3(-15,10,0))
 	geometry.vertices.push (new THREE.Vector3( -5,10,0))
 	geometry.vertices.push (new THREE.Vector3(  0,10,0))
 	geometry.vertices.push (new THREE.Vector3(  5,10,0))
 	geometry.vertices.push (new THREE.Vector3( 15,10,0))
  	
 	geometry.vertices.push (new THREE.Vector3( 15,0,0))
 	geometry.vertices.push (new THREE.Vector3(  5,0,0))
 	geometry.vertices.push (new THREE.Vector3(  0,0,0))
 	geometry.vertices.push (new THREE.Vector3(-10,0,0))
 	geometry.vertices.push (new THREE.Vector3(-15,0,0))

	let face;
  face = new THREE.Face3(0,9,1)
  geometry.faces.push (face)
  face = new THREE.Face3(2,7,8)
  geometry.faces.push (face)

	face = new THREE.Face3(3,6,4)
  geometry.faces.push (face)
  face = new THREE.Face3(4,5,6)
  geometry.faces.push (face)

	let material = new THREE.MeshLambertMaterial({color:0xffffff, side:THREE.DoubleSide});
  // without these, no shading ...
  geometry.computeBoundingSphere();
  geometry.computeFaceNormals();
  geometry.computeVertexNormals();
  
  let mesh = new THREE.Mesh(geometry, material);
  scene.add(mesh);

}

function animate() {
  requestAnimationFrame(animate);
  render();
}

function...