- redef fun padded(dist: N): Box3d[N] do return new Box3d[N].lrtbfb(left - dist, right + dist, top + dist, bottom - dist, front + dist, back - dist)
+ redef fun padded(dist): Box3d[N] do return new Box3d[N].lrtbfb(left - dist, right + dist, top + dist, bottom - dist, front + dist, back - dist)