code: function negate(out, a) {
      out[0] = -a[0]
      out[1] = -a[1]
      out[2] = -a[2]
      return out
  }
docs: Negates the components of a vec3
  
  @param {vec3} out the receiving vector
  @param {vec3} a vector to negate
  @returns {vec3} out