What one face of a shape is like, read in one pass with every other face: the kind of surface it
lies on, its area, its centre of area, the unit normal at the middle of its parameter range pointing
out of the material ([0, 0, 0] where it has none), and a box holding it, which may be loose on a
curved face. index is its index as shapes.face.getFaces and the selectors number it.
What one face of a shape is like, read in one pass with every other face: the kind of surface it lies on, its area, its centre of area, the unit normal at the middle of its parameter range pointing out of the material ([0, 0, 0] where it has none), and a box holding it, which may be loose on a curved face.
indexis its index asshapes.face.getFacesand the selectors number it.