Merge pull request #117 from CypherNaught-0x/feat/profiles-by-curve-ids

Profiles can be picked by the curves around them, and point picks are stored that way

crates/doc/src/document.rs

@@ -79,8 +79,10 @@ pub enum ProfileSel {
     All,
     /// Profiles by index in the solved sketch's profile list.
     Indices { indices: Vec<usize> },
-    /// Profiles whose outer loop is made of exactly these curves (order-insensitive); stable
-    /// across parameter changes.
+    /// Profiles whose outer loop is made of exactly these curves, or pieces of them where other
+    /// curves cut them (order and repeats don't matter; see `sketch::profile_by_curves`). Found
+    /// again on every evaluation, so stable across parameter changes; no match or several is
+    /// an error, never another profile.
     Curves { loops: Vec<Vec<String>> },
     /// The profile containing each sketch point.
     Points { points: Vec<Vec2> },

crates/doc/src/eval.rs

@@ -784,14 +784,8 @@ pub fn select_profiles(ss: &SolvedSketch, sel: &ProfileSel) -> Result<Vec<Region
         ProfileSel::Curves { loops } => {
             let mut v = Vec::new();
             for l in loops {
-                let mut want: Vec<&String> = l.iter().collect();
-                want.sort();
-                let found = ps.iter().find(|p| {
-                    let mut have: Vec<&String> = p.outer_curves.iter().collect();
-                    have.sort();
-                    have == want
-                });
-                v.push(found.ok_or_else(|| DocError::Unknown(format!("profile bounded by {l:?} in {}", ss.name)))?.region.clone());
+                let i = solvecraft_sketch::profile_by_curves(ps, l).map_err(|e| curve_pick_error(e, l, &ss.name))?;
+                v.push(ps.get(i).ok_or_else(|| DocError::Unknown(format!("profile {i} of {}", ss.name)))?.region.clone());
             }
             v
         }
@@ -799,7 +793,7 @@ pub fn select_profiles(ss: &SolvedSketch, sel: &ProfileSel) -> Result<Vec<Region
             let mut v = Vec::new();
             for p in points {
                 // Innermost profile containing the point.
-                let found = ps.iter().filter(|q| q.region.contains(*p)).min_by(|a, b| a.area.total_cmp(&b.area));
+                let found = solvecraft_sketch::profile_at_point(ps, *p).and_then(|i| ps.get(i));
                 v.push(found.ok_or_else(|| DocError::Unknown(format!("profile at {:?} in {}", [p.x, p.y], ss.name)))?.region.clone());
             }
             v
@@ -811,6 +805,18 @@ pub fn select_profiles(ss: &SolvedSketch, sel: &ProfileSel) -> Result<Vec<Region
     Ok(out)
 }
 
+/// The error for a profile picked by curves that no longer names exactly one profile.
+pub fn curve_pick_error(e: solvecraft_sketch::CurvePick, ids: &[String], sketch: &str) -> DocError {
+    match e {
+        solvecraft_sketch::CurvePick::Missing => DocError::Invalid(format!(
+            "no profile of {sketch} is bounded by exactly the curves {ids:?} (a curve was deleted, or another curve now cuts the region)"
+        )),
+        solvecraft_sketch::CurvePick::Ambiguous(n) => DocError::Invalid(format!(
+            "{n} profiles of {sketch} are bounded by exactly the curves {ids:?}; add a curve that tells them apart, or pick by index or point"
+        )),
+    }
+}
+
 fn new_name(state: &mut ModelState, f: &Feature, k: usize) -> String {
     if let Some(n) = f.body_names.get(k)
         && !n.is_empty()

crates/doc/src/lib.rs

@@ -34,9 +34,9 @@ pub mod sheet;
 pub use assembly::{IDENTITY, Mat, Occurrence, apply_point, apply_vector, is_identity, map_point_expr, mat_inverse, mat_mul, rigid};
 pub use document::*;
 pub use eval::{
-    EdgeRef, FeatureResult, Model, ModelBody, ModelState, RevolveExtent, SolvedSketch, ThreadInfo, edge_names_for, edge_refs, object_height,
-    parse_metric_thread, pattern_matrices, revolve_extent, revolve_extent_with_convention, select_profiles, state_in_frame, state_in_frame_at,
-    through_all_distance, world_state,
+    EdgeRef, FeatureResult, Model, ModelBody, ModelState, RevolveExtent, SolvedSketch, ThreadInfo, curve_pick_error, edge_names_for, edge_refs,
+    object_height, parse_metric_thread, pattern_matrices, revolve_extent, revolve_extent_with_convention, select_profiles, state_in_frame,
+    state_in_frame_at, through_all_distance, world_state,
 };
 pub use params::{ParamRow, ParamUser, cycles};
 pub use solvecraft_kernel as kernel;

crates/engine/src/cmd/edit.rs

@@ -195,6 +195,29 @@ fn merge(dst: &mut Value, src: &Value, depth: usize) {
     }
 }
 
+/// `profiles` (also a loft section's) given as the feature commands take it (`"all"`,
+/// `[index]`, `[{curves}]`, `[{point}]`...) becomes the stored form; the stored form passes.
+fn command_profiles(set: &Value, cmd: &str) -> Result<Value> {
+    let conv = |v: &mut Value| -> Result<()> {
+        if let Some(pv) = v.get("profiles").filter(|x| x.get("type").is_none()) {
+            let sel = super::features::profiles(&json!({"profiles": pv}), cmd)?;
+            let sv = serde_json::to_value(sel).map_err(|e| EngineError::Other(e.to_string()))?;
+            if let Some(o) = v.as_object_mut() {
+                o.insert("profiles".into(), sv);
+            }
+        }
+        Ok(())
+    };
+    let mut set = set.clone();
+    conv(&mut set)?;
+    if let Some(secs) = set.get_mut("sections").and_then(Value::as_array_mut) {
+        for sec in secs.iter_mut().take(10_000) {
+            conv(sec)?;
+        }
+    }
+    Ok(set)
+}
+
 /// Fields of a stored feature left out of its definition: bookkeeping timeline.edit recomputes, and
 /// the name and suppression, which timeline.rename and timeline.suppress change.
 const NOT_EDITABLE: &[&str] = &["id", "type", "name", "suppressed", "param_names", "edge_refs", "edge_names", "face_names"];
@@ -247,6 +270,7 @@ fn edit_feature(s: &mut Session, p: &Value) -> Result<Value> {
     let set = p.get("set").filter(|v| v.is_object()).ok_or_else(|| bad(cmd, "`set` must be an object of fields"))?;
     let f = s.doc.feature(id).cloned().ok_or_else(|| bad(cmd, "feature"))?;
     let mut v = serde_json::to_value(&f).map_err(|e| EngineError::Other(e.to_string()))?;
+    let set = &command_profiles(set, cmd)?;
     merge(&mut v, set, 0);
     let mut nf: Feature = serde_json::from_value(v).map_err(|e| bad(cmd, format!("invalid feature: {e}")))?;
     nf.id = f.id;
@@ -273,6 +297,10 @@ fn edit_feature(s: &mut Session, p: &Value) -> Result<Value> {
         nf.edge_refs = solvecraft_doc::edge_refs(&before, body, a);
         nf.edge_names = solvecraft_doc::edge_names_for(&before, body, a);
     }
+    // Profiles picked by index or point are kept by their curves, as when the feature was made.
+    if nf.kind.clone().profile_sels_mut() != f.kind.clone().profile_sels_mut() {
+        super::features::stable_profiles(s, &mut nf.kind)?;
+    }
     // New face points: their faces' names now.
     if nf.kind.face_points() != f.kind.face_points() {
         nf.face_names = solvecraft_doc::naming::face_names_at(&s.model.state_before(id), &nf.kind.face_points());

crates/engine/src/cmd/features.rs

@@ -13,7 +13,7 @@ pub static COMMANDS: &[CommandSpec] = &[
         .at("SOLID", "CREATE")
         .icon("extrude")
         .key("E")
-        .params("distance: expr (or through_all: true); taper?: angle expr; sketch?: id|name (default: active or last sketch); profiles?: all | [index] | [[curve ids]] | [{point:[x,y]}]; face?: [x,y,z] (extrude a planar body face instead of a sketch profile); direction?: positive|negative|symmetric; distance2?; start_offset?: expr (along the sketch normal, also with direction: negative); to?: [x,y,z] (To Object: a face, vertex or point; to_offset?: expr past it); from?: [x,y,z] (From Object: start at that face or point); operation?: new|join|cut|intersect|auto (cut into a body, otherwise join existing solids; new in an empty component); targets?: [body]; name?; body_name?"),
+        .params("distance: expr (or through_all: true); taper?: angle expr; sketch?: id|name (default: active or last sketch); profiles?: all | [index] | [{curves: [ids]}] (the profile whose outer loop is made of exactly these curves, or pieces of them; found again on every recompute, so it follows parameter changes; islands inside are its holes; an error when no profile or several match) | [{point:[x,y]}] (index and point picks are stored by their curves when that finds the same profile); face?: [x,y,z] (extrude a planar body face instead of a sketch profile); direction?: positive|negative|symmetric; distance2?; start_offset?: expr (along the sketch normal, also with direction: negative); to?: [x,y,z] (To Object: a face, vertex or point; to_offset?: expr past it); from?: [x,y,z] (From Object: start at that face or point); operation?: new|join|cut|intersect|auto (cut into a body, otherwise join existing solids; new in an empty component); targets?: [body]; name?; body_name?"),
     CommandSpec::new("solid.revolve", "Revolve", revolve)
         .at("SOLID", "CREATE")
         .icon("revolve")
@@ -124,18 +124,7 @@ fn extrude_base(s: &Session, p: &Value) -> Option<(Vec3, Vec3)> {
         ProfileSel::All => ps.first()?.region.interior_point(),
         ProfileSel::Indices { indices } => ps.get(*indices.first()?)?.region.interior_point(),
         ProfileSel::Points { points } => *points.first()?,
-        ProfileSel::Curves { loops } => {
-            let mut want: Vec<&String> = loops.first()?.iter().collect();
-            want.sort();
-            ps.iter()
-                .find(|x| {
-                    let mut have: Vec<&String> = x.outer_curves.iter().collect();
-                    have.sort();
-                    have == want
-                })?
-                .region
-                .interior_point()
-        }
+        ProfileSel::Curves { loops } => ps.get(solvecraft_doc::sketch::profile_by_curves(ps, loops.first()?).ok()?)?.region.interior_point(),
     };
     Some((ss.plane.to_world(q), ss.plane.normal()))
 }
@@ -212,37 +201,55 @@ pub(super) fn feature_sketch(s: &Session, p: &Value, cmd: &str) -> Result<u64> {
         .ok_or_else(|| bad(cmd, "there is no sketch to use (create one first)"))
 }
 
-/// Profile indices become the curve ids of each profile's loops as the sketch is now solved.
-fn stable_profiles(s: &Session, kind: &mut FeatureKind) -> Result<()> {
+/// Profiles picked by index or point are stored by the curve ids of each profile's outer loop
+/// as the sketch is now solved, so they follow the geometry when parameters move it. A pick
+/// whose curves would not find that same profile again (two profiles bounded by the same
+/// curves) stays as given. Curve picks are checked: one that names no profile, or several, is
+/// refused now rather than failing later.
+pub(super) fn stable_profiles(s: &Session, kind: &mut FeatureKind) -> Result<()> {
+    use solvecraft_doc::sketch::{distinct_curves, profile_at_point, profile_by_curves};
     let st = s.model.state();
     'sels: for (sketch, sel) in kind.profile_sels_mut() {
-        let ProfileSel::Indices { indices } = sel else { continue };
         let Some(ss) = st.sketch(sketch) else { continue };
-        let mut loops = Vec::with_capacity(indices.len());
-        for i in indices.iter() {
-            let pr = ss
-                .profiles
-                .get(*i)
-                .ok_or_else(|| EngineError::Other(format!("no profile {i} in sketch `{}` (it has {})", ss.name, ss.profiles.len())))?;
-            // Two profiles with the same outer curves (one inside the other's holes cannot be):
-            // keep the index then.
-            if pr.outer_curves.is_empty() || ss.profiles.iter().filter(|q| same_loop(&q.outer_curves, &pr.outer_curves)).count() != 1 {
+        let picked: Vec<usize> = match sel {
+            ProfileSel::Indices { indices } => indices
+                .iter()
+                .map(|i| {
+                    if *i < ss.profiles.len() {
+                        Ok(*i)
+                    } else {
+                        Err(EngineError::Other(format!("no profile {i} in sketch `{}` (it has {})", ss.name, ss.profiles.len())))
+                    }
+                })
+                .collect::<Result<_>>()?,
+            ProfileSel::Points { points } => {
+                let Some(v) = points.iter().map(|q| profile_at_point(&ss.profiles, *q)).collect::<Option<Vec<_>>>() else { continue };
+                v
+            }
+            ProfileSel::Curves { loops } => {
+                for l in loops.iter() {
+                    profile_by_curves(&ss.profiles, l)
+                        .map_err(|e| EngineError::Other(solvecraft_doc::curve_pick_error(e, l, &ss.name).to_string()))?;
+                }
+                continue;
+            }
+            ProfileSel::All => continue,
+        };
+        let mut loops = Vec::with_capacity(picked.len());
+        for i in picked {
+            let Some(pr) = ss.profiles.get(i) else { continue 'sels };
+            let ids = distinct_curves(&pr.outer_curves);
+            // Keep the pick as given when its curves don't lead back to this profile.
+            if ids.is_empty() || profile_by_curves(&ss.profiles, &ids) != Ok(i) {
                 continue 'sels;
             }
-            loops.push(pr.outer_curves.clone());
+            loops.push(ids);
         }
         *sel = ProfileSel::Curves { loops };
     }
     Ok(())
 }
 
-fn same_loop(a: &[String], b: &[String]) -> bool {
-    let (mut a, mut b) = (a.to_vec(), b.to_vec());
-    a.sort();
-    b.sort();
-    a == b
-}
-
 pub(super) fn profiles(p: &Value, cmd: &str) -> Result<ProfileSel> {
     let Some(v) = p.get("profiles") else { return Ok(ProfileSel::All) };
     match v {

crates/engine/src/lib.rs

@@ -638,6 +638,8 @@ mod extent_tests;
 #[cfg(test)]
 mod pattern_suppress_tests;
 #[cfg(test)]
+mod profile_curves_tests;
+#[cfg(test)]
 mod profile_refs_tests;
 #[cfg(test)]
 mod split_face_tests;

crates/engine/src/profile_curves_tests.rs

@@ -0,0 +1,176 @@
+//! Profiles picked by the curves around them stay the same region when a parameter moves the
+//! sketch, where a pick by point can land in another region.
+
+use serde_json::{Value, json};
+
+use crate::Session;
+use solvecraft_doc::{FeatureKind, ProfileSel};
+
+fn run(s: &mut Session, id: &str, p: Value) -> Value {
+    match s.execute(id, &p) {
+        Ok(v) => v,
+        Err(e) => panic!("{id} {p}: {e}"),
+    }
+}
+
+fn volumes(s: &Session) -> Vec<f64> {
+    s.model.state().bodies.iter().map(|b| b.body.tessellate(1e-2).unwrap().measure().volume).collect()
+}
+
+fn last_error(s: &Session) -> Option<String> {
+    let id = s.doc.features.last().unwrap().id;
+    s.model.result(id).and_then(|r| r.error.clone())
+}
+
+/// A 60 × 20 tray split in two by a divider `split` mm from its left side: the left bay is
+/// bounded by the left side, the divider and the pieces of the bottom and top the divider cuts.
+fn tray() -> Session {
+    let mut s = Session::default();
+    run(&mut s, "parameters.change", json!({"name": "split", "expression": "30 mm"}));
+    run(&mut s, "sketch.create", json!({"plane": "XY", "name": "Tray"}));
+    run(&mut s, "sketch.line", json!({"points": [[0, 0], [60, 0], [60, 20], [0, 20]], "closed": true, "ids": ["bottom", "right", "top", "left"]}));
+    run(&mut s, "sketch.constraint.fix", json!({"entities": ["bottom", "right", "top", "left"]}));
+    run(&mut s, "sketch.line", json!({"points": [[30, 0], [30, 20]], "ids": ["div"]}));
+    run(&mut s, "sketch.constraint.coincident", json!({"a": "div.start", "b": "bottom"}));
+    run(&mut s, "sketch.constraint.coincident", json!({"a": "div.end", "b": "top"}));
+    run(&mut s, "sketch.constraint.horizontal_vertical", json!({"line": "div"}));
+    run(&mut s, "sketch.dimension", json!({"entities": ["left", "div"], "value": "split"}));
+    run(&mut s, "sketch.finish", json!({}));
+    s
+}
+
+fn extrude_kind(s: &Session) -> ProfileSel {
+    match &s.doc.features.last().unwrap().kind {
+        FeatureKind::Extrude { profiles, .. } => profiles.clone(),
+        k => panic!("{k:?}"),
+    }
+}
+
+/// The user's case: the left bay picked by its curves keeps extruding the left bay when
+/// `split` moves the divider past the old pick point; a pick by that point (as a design saved
+/// before picks were stored by curves holds it) silently extrudes the right bay instead.
+#[test]
+fn a_profile_picked_by_curves_follows_a_parameter_change() {
+    let mut s = tray();
+    run(&mut s, "solid.extrude", json!({"sketch": "Tray", "profiles": [{"curves": ["left", "bottom", "div", "top"]}], "distance": 10}));
+    let v = volumes(&s);
+    assert_eq!(v.len(), 1);
+    assert!((v[0] - 30.0 * 20.0 * 10.0).abs() < 1.0, "{v:?}");
+    run(&mut s, "parameters.change", json!({"name": "split", "expression": "20 mm"}));
+    assert_eq!(last_error(&s), None);
+    let v = volumes(&s);
+    assert!((v[0] - 20.0 * 20.0 * 10.0).abs() < 1.0, "still the left bay, now 20 wide: {v:?}");
+
+    // The same bay picked by a point (25, 10), stored as a point.
+    let mut s = tray();
+    run(&mut s, "solid.extrude", json!({"sketch": "Tray", "profiles": [{"point": [25, 10]}], "distance": 10}));
+    let id = s.doc.features.last().unwrap().id;
+    if let Some(f) = s.doc_mut().feature_mut(id)
+        && let FeatureKind::Extrude { profiles, .. } = &mut f.kind
+    {
+        *profiles = ProfileSel::Points { points: vec![solvecraft_geom::Vec2::new(25.0, 10.0)] };
+    }
+    s.refresh();
+    assert!((volumes(&s)[0] - 6000.0).abs() < 1.0);
+    run(&mut s, "parameters.change", json!({"name": "split", "expression": "20 mm"}));
+    let v = volumes(&s);
+    assert!((v[0] - 40.0 * 20.0 * 10.0).abs() < 1.0, "the point now sits in the right bay: {v:?}");
+}
+
+/// A pick by point is stored by the curves around the picked profile, so it follows too.
+#[test]
+fn a_point_pick_is_stored_by_curves() {
+    let mut s = tray();
+    run(&mut s, "solid.extrude", json!({"sketch": "Tray", "profiles": [{"point": [25, 10]}], "distance": 10}));
+    let ProfileSel::Curves { loops } = extrude_kind(&s) else { panic!("{:?}", extrude_kind(&s)) };
+    let mut ids = loops[0].clone();
+    ids.sort();
+    assert_eq!(ids, ["bottom", "div", "left", "top"]);
+    run(&mut s, "parameters.change", json!({"name": "split", "expression": "20 mm"}));
+    assert_eq!(last_error(&s), None);
+    assert!((volumes(&s)[0] - 4000.0).abs() < 1.0, "{:?}", volumes(&s));
+}
+
+/// Curves cut into several pieces of one loop still name it: a line ending on the square's
+/// bottom from outside cuts the bottom in two, both pieces on the square's loop.
+#[test]
+fn a_curve_cut_into_pieces_still_names_its_profile() {
+    let mut s = Session::default();
+    run(&mut s, "sketch.create", json!({"plane": "XY", "name": "S"}));
+    run(&mut s, "sketch.line", json!({"points": [[0, 0], [10, 0], [10, 10], [0, 10]], "closed": true, "ids": ["a", "b", "c", "d"]}));
+    run(&mut s, "sketch.line", json!({"points": [[5, -5], [5, 0]], "ids": ["stub"]}));
+    run(&mut s, "sketch.finish", json!({}));
+    let ps = &s.model.state().sketches[0].profiles;
+    assert_eq!(ps.len(), 1);
+    assert_eq!(ps[0].outer_curves.iter().filter(|c| *c == "a").count(), 2, "the bottom is in two pieces: {:?}", ps[0].outer_curves);
+    run(&mut s, "solid.extrude", json!({"sketch": "S", "profiles": [{"curves": ["a", "b", "c", "d"]}], "distance": 2}));
+    assert_eq!(last_error(&s), None);
+    assert!((volumes(&s)[0] - 200.0).abs() < 1e-3, "{:?}", volumes(&s));
+}
+
+/// Both halves of a circle cut by a line are bounded by the same two curves: an error, not one
+/// of them. A list no profile matches is an error too.
+#[test]
+fn ambiguous_and_missing_curve_picks_are_errors() {
+    let mut s = Session::default();
+    run(&mut s, "sketch.create", json!({"plane": "XY", "name": "S"}));
+    run(&mut s, "sketch.circle.center", json!({"center": [0, 0], "radius": 10, "id": "ring"}));
+    run(&mut s, "sketch.line", json!({"points": [[-20, 0], [20, 0]], "ids": ["cut"]}));
+    run(&mut s, "sketch.circle.center", json!({"center": [40, 0], "radius": 3, "id": "dot"}));
+    run(&mut s, "sketch.finish", json!({}));
+    let e = s.execute("solid.extrude", &json!({"sketch": "S", "profiles": [{"curves": ["ring", "cut"]}], "distance": 2})).unwrap_err().to_string();
+    assert!(e.contains("2 profiles"), "{e}");
+    assert!(s.model.state().bodies.is_empty());
+    let e = s.execute("solid.extrude", &json!({"sketch": "S", "profiles": [{"curves": ["ring"]}], "distance": 2})).unwrap_err().to_string();
+    assert!(e.contains("no profile"), "{e}");
+    let e = s.execute("solid.extrude", &json!({"sketch": "S", "profiles": [{"curves": ["dot", "cut"]}], "distance": 2})).unwrap_err().to_string();
+    assert!(e.contains("no profile"), "{e}");
+    // A closed curve alone.
+    run(&mut s, "solid.extrude", json!({"sketch": "S", "profiles": [{"curves": ["dot"]}], "distance": 2}));
+    assert!((volumes(&s)[0] - std::f64::consts::PI * 9.0 * 2.0).abs() < 0.5, "{:?}", volumes(&s));
+}
+
+/// An island inside the picked outline is its hole, as with a pick by point; the island is a
+/// profile of its own, picked by its curve.
+#[test]
+fn a_curve_pick_keeps_islands_as_holes() {
+    let mut s = Session::default();
+    run(&mut s, "sketch.create", json!({"plane": "XY", "name": "S"}));
+    run(&mut s, "sketch.line", json!({"points": [[0, 0], [20, 0], [20, 20], [0, 20]], "closed": true, "ids": ["a", "b", "c", "d"]}));
+    run(&mut s, "sketch.circle.center", json!({"center": [10, 10], "radius": 5, "id": "hole"}));
+    run(&mut s, "sketch.finish", json!({}));
+    run(&mut s, "solid.extrude", json!({"sketch": "S", "profiles": [{"curves": ["a", "b", "c", "d"]}], "distance": 1}));
+    let disc = std::f64::consts::PI * 25.0;
+    assert!((volumes(&s)[0] - (400.0 - disc)).abs() < 0.5, "{:?}", volumes(&s));
+    run(&mut s, "solid.extrude", json!({"sketch": "S", "profiles": [{"curves": ["hole"]}], "distance": 1, "operation": "new"}));
+    assert!((volumes(&s)[1] - disc).abs() < 0.5, "{:?}", volumes(&s));
+}
+
+/// Curve picks are saved in the design file and read back; timeline.edit takes the command's
+/// `profiles` form.
+#[test]
+fn curve_picks_save_load_and_edit() {
+    let mut s = tray();
+    run(
+        &mut s,
+        "solid.extrude",
+        json!({"sketch": "Tray", "profiles": [{"curves": ["left", "bottom", "div", "top"]}], "distance": 10, "name": "Bay"}),
+    );
+    let text = serde_json::to_string(&*s.doc).unwrap();
+    let doc = solvecraft_doc::format::read(&text).unwrap();
+    let mut t = Session::new(doc);
+    assert_eq!(extrude_kind(&t), extrude_kind(&s));
+    run(&mut t, "parameters.change", json!({"name": "split", "expression": "20 mm"}));
+    assert!((volumes(&t)[0] - 4000.0).abs() < 1.0, "{:?}", volumes(&t));
+    // Switch to the right bay through timeline.edit.
+    run(&mut t, "timeline.edit", json!({"feature": "Bay", "set": {"profiles": [{"curves": ["div", "bottom", "right", "top"]}]}}));
+    assert!((volumes(&t)[0] - 8000.0).abs() < 1.0, "{:?}", volumes(&t));
+    run(&mut t, "timeline.edit", json!({"feature": "Bay", "set": {"profiles": [{"point": [5, 5]}]}}));
+    assert!(matches!(extrude_kind(&t), ProfileSel::Curves { .. }), "{:?}", extrude_kind(&t));
+    assert!((volumes(&t)[0] - 4000.0).abs() < 1.0, "{:?}", volumes(&t));
+    // An old design's point pick still loads and evaluates.
+    let old = text.replace(r#"{"type":"curves","loops":[["left","bottom","div","top"]]}"#, r#"{"type":"points","points":[[25.0,10.0]]}"#);
+    assert_ne!(old, text);
+    let t = Session::new(solvecraft_doc::format::read(&old).unwrap());
+    assert!((volumes(&t)[0] - 6000.0).abs() < 1.0, "{:?}", volumes(&t));
+}

crates/sketch/src/lib.rs

@@ -32,7 +32,7 @@ pub use link::{Link, LinkGeom, LinkKind, LinkSource, MAX_LINK_ENTITIES};
 pub use model::{Constraint, ConstraintKind, Curve, CurveKind, SPoint, Sketch, SketchError, SketchView};
 pub use offset::OffsetChain;
 pub use periodic::periodic_beziers;
-pub use profiles::{Profile, find_drawn_profiles, find_profiles, merge_regions};
+pub use profiles::{CurvePick, Profile, distinct_curves, find_drawn_profiles, find_profiles, merge_regions, profile_at_point, profile_by_curves};
 pub use shape::{Shape, intersections};
 pub use solver::{Hold, SolveReport, SolveStatus, measure_dimension, solve, solve_holding};
 pub use text::{MAX_TEXT_CHARS, text_geometry};

crates/sketch/src/profiles.rs

@@ -829,6 +829,69 @@ pub fn find_profiles(sk: &Sketch) -> Vec<Profile> {
     out
 }
 
+/// Why no single profile is bounded by a list of curves.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum CurvePick {
+    /// No profile's outer loop is made of exactly those curves.
+    Missing,
+    /// This many profiles are (e.g. both halves of a circle cut by a line).
+    Ambiguous(usize),
+}
+
+/// The profile picked by the curves around it, by index into `profiles`. A profile matches when
+/// its outer loop is made of the listed curves and no others: every listed curve, or a piece of
+/// it where other curves cut it, lies on the loop, and every piece of the loop belongs to a
+/// listed curve. Order and repeats don't matter. Holes don't take part (islands inside a profile
+/// are its holes, as for a profile picked by a point). When several profiles match, one whose
+/// loop has exactly the listed pieces (a curve listed twice for two pieces) wins; otherwise the
+/// pick is ambiguous, never a guess.
+pub fn profile_by_curves(profiles: &[Profile], ids: &[String]) -> Result<usize, CurvePick> {
+    use std::collections::BTreeSet;
+    let want: BTreeSet<&str> = ids.iter().map(String::as_str).collect();
+    if want.is_empty() {
+        return Err(CurvePick::Missing);
+    }
+    let hits: Vec<usize> = profiles
+        .iter()
+        .enumerate()
+        .filter(|(_, p)| p.outer_curves.iter().map(String::as_str).collect::<BTreeSet<_>>() == want)
+        .map(|(i, _)| i)
+        .collect();
+    match hits.as_slice() {
+        [] => Err(CurvePick::Missing),
+        [i] => Ok(*i),
+        _ => {
+            fn sorted(v: &[String]) -> Vec<&str> {
+                let mut v: Vec<&str> = v.iter().map(String::as_str).collect();
+                v.sort_unstable();
+                v
+            }
+            let exact = sorted(ids);
+            let same: Vec<usize> = hits.iter().copied().filter(|i| profiles.get(*i).is_some_and(|p| sorted(&p.outer_curves) == exact)).collect();
+            match same.as_slice() {
+                [i] => Ok(*i),
+                _ => Err(CurvePick::Ambiguous(hits.len())),
+            }
+        }
+    }
+}
+
+/// The innermost profile containing a sketch point, by index into `profiles`.
+pub fn profile_at_point(profiles: &[Profile], p: Vec2) -> Option<usize> {
+    profiles.iter().enumerate().filter(|(_, q)| q.region.contains(p)).min_by(|a, b| a.1.area.total_cmp(&b.1.area)).map(|(i, _)| i)
+}
+
+/// The distinct curve ids of a loop, in loop order (a curve cut into pieces is listed once).
+pub fn distinct_curves(ids: &[String]) -> Vec<String> {
+    let mut out: Vec<String> = Vec::with_capacity(ids.len());
+    for id in ids {
+        if !out.contains(id) {
+            out.push(id.clone());
+        }
+    }
+    out
+}
+
 fn same_seg(a: &Seg2, b: &Seg2, tol: f64) -> bool {
     match (*a, *b) {
         (Seg2::Line { a: p, b: q }, Seg2::Line { a: r, b: s }) => p.dist(r) <= tol && q.dist(s) <= tol,

crates/ui-egui/src/dialogs.rs

@@ -2923,19 +2923,8 @@ pub(crate) fn profile_indices(ss: &solvecraft_engine::doc::SolvedSketch, sel: &P
     match sel {
         ProfileSel::All => (0..ps.len()).collect(),
         ProfileSel::Indices { indices } => indices.iter().copied().filter(|i| *i < ps.len()).collect(),
-        ProfileSel::Curves { loops } => loops
-            .iter()
-            .filter_map(|l| {
-                let mut want: Vec<&String> = l.iter().collect();
-                want.sort();
-                ps.iter().position(|p| {
-                    let mut have: Vec<&String> = p.outer_curves.iter().collect();
-                    have.sort();
-                    have == want
-                })
-            })
-            .collect(),
-        ProfileSel::Points { points } => points.iter().filter_map(|q| ps.iter().position(|p| p.region.contains(*q))).collect(),
+        ProfileSel::Curves { loops } => loops.iter().filter_map(|l| solvecraft_engine::doc::sketch::profile_by_curves(ps, l).ok()).collect(),
+        ProfileSel::Points { points } => points.iter().filter_map(|q| solvecraft_engine::doc::sketch::profile_at_point(ps, *q)).collect(),
     }
 }
 

docs/book/src/guide/sketching.md

@@ -83,3 +83,12 @@ constraint while you drag.
 
 Closed loops become profiles automatically, including regions split by crossing lines and
 islands inside outlines. Extrude, revolve, sweep and loft pick profiles.
+
+A feature remembers a picked profile by the curves around it, not by where it was clicked:
+`"profiles": [{"curves": ["l1", "l2", "a1", "l3"]}]` (or `[{"curves": ["c1"]}]` for a circle)
+picks the region whose outer loop is made of exactly those curves, or the pieces of them that
+other curves cut off. It is found again on every recompute, so the feature keeps the same region
+when a parameter moves the geometry. Islands inside the region are its holes. When no region, or
+more than one (both halves of a circle cut by a line), is bounded by exactly those curves, the
+feature reports an error rather than taking another region. Profiles picked by index or by point
+(`[{"point": [x, y]}]`) are stored the same way when the feature is made.