code: function( polyOffsetFactor, polyOffsetUnits )
    {
      this._dat[ 0|POLYOFF_FACTOR] = encodeHalf( polyOffsetFactor );
      this._dat[ 0|POLYOFF_UNITS ] = encodeHalf( polyOffsetUnits );
      this._set |= POLYOFF_SET|0;
      return this;
    }
docs: polygon offset