function init() {
  class Point {
    constructor(x, y) {
      this.x = x;
      this.y = y;
    }

    add(that) {
      return new Point(
        this.x + that.x,
        this.y + that.y
      );
    }

    sub(that) {
      return new Point(
        this.x - that.x,
        this.y - that.y
      );
    }

    dist(that) {
      let a = this.x - that.x;
      let b = this.y - that.y;
      return Math.sqrt(a * a + b * b)
    }
  }

  let mousePos = new Point();

  const scene = new THREE.Scene();
  const camera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 0.1, 1000);

  const renderer = new THREE.WebGLRenderer();
  renderer.setSize(window.innerWidth, window.innerHeight - 200);
  document.getElementById("threejscontainer").appendChild(renderer.domElement);

  const directionalLight = new THREE.DirectionalLight(0xffffff, 1);
  scene.add(directionalLight);

  const geometry = new THREE.BoxGeometry();
  const material = new THREE.MeshBasicMaterial({ color: 0x00ff00 });
  const cube = new THREE.Mesh(geometry, material);
  scene.add(cube);

  camera.position.z = 5;

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

  let canvas = document.getElementsByTagName("canvas")[0];
  let resize = function () {
    w = window.innerWidth;
    h = window.innerHeight - 200;
    canvas.width = w;
    canvas.height = h;
  }
  window.onresize = resize;
  resize();
  if (canvas.getContext) {
    ctx = canvas.getContext('2d');
    animate(performance.now());
  }
  canvas.onmousemove = (evt) => {
    mousePos.x = evt.clientX;
    mousePos.y = evt.clientY;
  };
}