int needs_free;

/* reinitialize object derived mesh */
if(ob->derivedFinal) {
	ob->derivedFinal->release(ob->derivedFinal);
	ob->derivedFinal = NULL;
}
ob->derivedFinal = mesh_get_derived_final(ob, &needs_free);

if(ob->derivedDeform) {
	ob->derivedDeform->release(ob->derivedDeform);
	ob->derivedDeform = NULL;
}
ob->derivedDeform = mesh_get_derived_deform(ob, &needs_free);