message: Create volume child "filter" so that it's UI adjustable.
diff: @@ -10,6 +10,7 @@ namespace ospray {
  {
  setValue(cpp::Volume(osp_type));
  createChild("visible", "bool", true);
  + createChild("filter", "int", "0 = nearest, 100 = trilinear", 0);
  }
  NodeType Volume::type() const
  