code: function (bBox) {
          var size = Math.max(bBox[3], bBox[4], bBox[5]);
          var ratio = Math.max(viewer._width, viewer._height) / Math.min(viewer._width, viewer._height);
          viewer._distance = size / Math.tan(viewer.perspectiveCamera.fov * Math.PI / 180.0) * ratio * 1.0;
      }
docs: helper function for setting of the distance based on camera field of view and size of the product's bounding box