fix: a hole placed on a face follows the face along its axis only, and warns when off the face (#510)

A hole positioned on a face now follows that face along the hole's own axis instead of sliding to the face's nearest point. When the face no longer reaches the position, the hole stays where it was placed and the feature says so.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

crates/doc/src/eval.rs

@@ -924,7 +924,14 @@ impl Model {
             let f = if !explicit_emboss && f.face_names.iter().any(|n| !n.is_empty()) {
                 let mut g = f.clone();
                 let mut notes = Vec::new();
-                for (p, n) in g.kind.face_points_mut().into_iter().zip(&f.face_names) {
+                // A hole's position is a place on its face, not a pick of the face: it follows
+                // the face along the hole's axis and never slides sideways to the face's nearest
+                // point when the face no longer reaches it.
+                let hole_axis = match &f.kind {
+                    FeatureKind::Hole { direction, points: None, .. } => direction.normalized(),
+                    _ => None,
+                };
+                for (k, (p, n)) in g.kind.face_points_mut().into_iter().zip(&f.face_names).enumerate() {
                     if n.is_empty() {
                         continue;
                     }
@@ -933,7 +940,18 @@ impl Model {
                             if let Some(note) = hit.note(n) {
                                 notes.push(note);
                             }
-                            *p = hit.point;
+                            match (k, hole_axis) {
+                                (0, Some(axis)) => match hit.along(&state, *p, axis) {
+                                    Some(q) => *p = q,
+                                    // The place still lies on the face (the axis may run along it).
+                                    None if hit.on_point => {}
+                                    None => notes.push(format!(
+                                        "the hole's position [{}, {}, {}] is no longer on face `{n}`: it stays where it was placed",
+                                        p.x, p.y, p.z
+                                    )),
+                                },
+                                _ => *p = hit.point,
+                            }
                         }
                         None => notes.push(format!("face `{n}` no longer exists; using the face at the picked point")),
                     }