+ void read_properties(gzFile fp, int nproperties);
+
+ void read_object( gzFile fp,
+ int obj_type,
+ int nproperties,
+ int nelements,
+ group_list& vertices,
+ group_list& normals,
+ group_list& colors,
+ group_list& texCoords,
+ string_list& materials);
+
+ void write_header(gzFile fp, int type, int nProps, int nElements);
+ void write_objects(gzFile fp, int type, const group_list& verts,
+ const group_list& normals, const group_list& colors,
+ const group_list& texCoords, const string_list& materials);
+
+ unsigned int count_objects(const string_list& materials);