function color(value) {
          bgColor =  value;
          back[0].appearance.material.emissiveColor = value;
          //print('bgcolor ' + value);
          }
  function alpha(value) {
          bgTransparency = value;
          back[0].appearance.material.transparency = value;
          //print('alpha ' + value);
          }
  
  function startTime(value) {
          if (bgType == 3) back[0].startTime = value;
          }
  function stopTime(value) {
          if (bgType == 3) back[0].stopTime = value;
          }