Default fiddle

by wilt

HTML

<script src="https://rawgit.com/mrdoob/three.js/master/build/three.js"></script>
<script src="https://rawgit.com/mrdoob/three.js/master/examples/js/controls/OrbitControls.js"></script>
<script src="https://rawgit.com/Wilt/ThreeCSG/master/ThreeCSG.js"></script>

CSS

body {
  background-color: #000;
  margin: 0px;
  overflow: hidden;
}

JavaScript

// three.js info box follows shape
var renderer, scene, camera;
var angle = 0;

init();
animate();

function init() {
  // info
  var info = document.createElement('div');
  info.style.position = 'absolute';
  info.style.top = '30px';
  info.style.width = '100%';
  info.style.textAlign = 'center';
  info.style.color = '#fff';
  info.style.fontWeight = 'bold';
  info.style.backgroundColor = 'transparent';
  info.style.zIndex = '1';
  info.style.fontFamily = 'Monospace';
  info.innerHTML = "three.js - texture load demo";
  document.body.appendChild(info);

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

  // scene
  scene = new THREE.Scene();

  // ambient light
  var ambient = new THREE.AmbientLight(0xffffff);
  scene.add(ambient);

  // directional light
  var directionalLight = new THREE.DirectionalLight(0xffffff, 0.5);
  directionalLight.position.set(-1, -1, 1);
  scene.add(directionalLight);

  // camera
  camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 1, 500);
  camera.position.set(100, -100, 50);
  camera.up.set(0, 0, 1);

  // controls
  controls = new THREE.OrbitControls(camera);
  controls.target = new THREE.Vector3(0, 0, 0);
  controls.update();

  // material
  material = new THREE.MeshBasicMaterial({
    shading: THREE.FlatShading
  });

  // MY CUSTOM GEOMETRY
  var geometry = new THREE.Geometry();
  var v0 = new THREE.Vector3(-20, -20, 0);
  var v1 = new THREE.Vector3(20, -20, 0);
  var v2 = new THREE.Vector3(20, 20, 0);
  var v3 = new THREE.Vector3(-20, 20, 0);
  geometry.vertices.push(v0, v1, v2, v3);
  geometry.faces.push(
    new THREE.Face3(0, 1, 2),
    new THREE.Face3(0, 2, 3)
  );
  geometry.computeFaceNormals();
  computeUVs(geometry);
  var aqua_bodengrund = new THREE.Mesh(
    geometry, material
  );
 ...