text: import freezeObject from '../Core/freezeObject.js';
  
      /**
       * Represents the position relative to the terrain.
       *
       * @exports HeightReference
       */
      var HeightReference = {
          /**
           * The position is absolute.
           * @type {Number}
           * @constant
           */
          NONE : 0,
  
          /**
           * The position is clamped to the terrain.
           * @type {Number}
           * @constant
           */
          CLAMP_TO_GROUND : 1,
  
          /**
           * The position height is the height above the terrain.
           * @type {Number}
           * @constant
           */
          RELATIVE_TO_GROUND : 2
      };
  export default freezeObject(HeightReference);
  