function create(x, y, z) {
    var dst = new VecType(3);
    if (x) {
      dst[0] = x;
    }
    if (y) {
      dst[1] = y;
    }
    if (z) {
      dst[2] = z;
    }
    return dst;
  }
Creates a vec3; may be called with x, y, z to set initial values.
@return {Vec3} the created vector
@memberOf module:twgl/v3