function expandRLEData(rleData, padding) {
    padding = padding || [];
    var data = [];
    for (var ii = 0; ii < rleData.length; ii += 4) {
      var runLength = rleData[ii];
      var element = rleData.slice(ii + 1, ii + 4);
      element.push.apply(element, padding);
      for (var jj = 0; jj < runLength; ++jj) {
        data.push.apply(data, element);
      }
    }
    return data;
  }
Expands RLE data
@param {number[]} rleData data in format of run-length, x, y, z, run-length, x, y, z
@param {number[]} [padding] value to add each entry with.
@return {number[]} the expanded rleData