code: function proj (u, v) {
    return u.clone().multiplyScalar(u.dot(v) / u.dot(u));
  }
docs: Computes the projection of one vector against another.
  @memberof Helpers
  @param {Vector2|Vector3|Vector4} u The vector to project.
  @param {Vector2|Vector3|Vector4} v The vector to be projected against.