--- a/src/cube.rs	Tue Oct 22 08:27:45 2024 -0500
+++ b/src/cube.rs	Tue Oct 22 08:39:46 2024 -0500
@@ -1,3 +1,6 @@
+/*!
+Implementation of the surface of the 3D cube as a [`ManifoldPoint`].
+*/
 
 use serde_repr::*;
 use serde::Serialize;
@@ -5,6 +8,7 @@
 use alg_tools::norms::{Norm, L2};
 use crate::manifold::{ManifoldPoint, EmbeddedManifoldPoint};
 
+/// All the difference faces of a [`OnCube`].
 #[derive(Copy, Clone, Debug, Eq, PartialEq, Serialize_repr, Deserialize_repr)]
 #[repr(u8)]
 pub enum Face {F1 = 1, F2 = 2, F3 = 3, F4 = 4, F5 = 5, F6 = 6}
@@ -180,10 +184,17 @@
         }
     }
 
+    /// Indicates whether an unfolded point `p` is on this face, i.e.,
+    /// has coordinates in [0,1]².
     pub fn is_in_face(&self, p: &Point) -> bool {
         p.iter().map(|t| t.abs()).all(|t| 0.0 <= t && t <= 1.0)
     }
 
+    /// Given an unfolded point `p`, possibly outside this face, finds
+    /// the edge, presented by an adjacent face, in whose direction it is.
+    ///
+    /// **TODO:** this does not correctly handle corners, i.e., when the point is not in
+    /// the direction of an adjacent face.
     pub fn find_crossing(&self, p : &Point) -> Face {
         let &Loc([x, y]) = p;
         use std::cmp::Ordering::*;
@@ -246,6 +257,7 @@
         (best_tan, best_len)
     }
 
+    /// Returns the face of this point.
     pub fn face(&self) -> Face {
         self.face
     }