function ceil(out, a) {
  out[0] = Math.ceil(a[0]);
  out[1] = Math.ceil(a[1]);
  out[2] = Math.ceil(a[2]);
  out[3] = Math.ceil(a[3]);
  return out;
}
Math.ceil the components of a vec4

@param {vec4} out the receiving vector
@param {vec4} a vector to ceil
@returns {vec4} out