Method add

src/core/a-entity.js:190–196

* Add child entity. * * @param {Element} el - Child entity.

(el)

   * @param {Element} el - Child entity.
   */
  add (el) {
    if (!el.object3D) {
      throw new Error("Trying to add an element that doesn't have an `object3D`");
    }
    this.object3D.add(el.object3D);
    this.emit('child-attached', {el: el});
  }

  /**
   * Tell parentNode to add this entity to itself.