+/**
+ * gis_viewer_add:
+ * @viewer: the viewer
+ * @object: the object to add
+ * @level: the level to add the object to
+ * @sort: %TRUE if the object should be depth-sorted prior to being drawn
+ *
+ * Objects which are added to the viewer will be drawn on subsequent renderings
+ * if their level of details is adequate.
+ *
+ * The @level represents the order the object should be drawn in, this is
+ * unrelated to the objects actual position in the world.
+ *
+ * Semi-transparent objects should set @sort to %TRUE so that they are rendered
+ * correctly when they overlap other semi-transparent objects.
+ *
+ * The viewer steals the objects reference. Call g_object_ref if you plan on
+ * holding a reference as well.
+ *
+ * Returns: a handle to be pass to gis_viewer_remove()
+ */