Sketch UI: click a constraint glyph to select it, Delete removes the constraint; glyphs sit half way along their curve; lighter randomized sketch test

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01AS5Tn3xieewUSg3uxrMVdL

crates/engine/src/cmd/sketch_constraints.rs

@@ -403,9 +403,19 @@ fn toggle_driven(s: &mut Session, p: &Value) -> Result<Value> {
 /// or at its point.
 fn anchor(sk: &Sketch, k: &ConstraintKind) -> Option<Vec2> {
     use ConstraintKind::*;
+    // Half way along the curve.
     let mid = |c: usize| -> Option<Vec2> {
         let poly = sk.polyline(c);
-        poly.get(poly.len() / 2).copied()
+        let total: f64 = poly.windows(2).map(|w| w[0].dist(w[1])).sum();
+        let mut acc = 0.0;
+        for w in poly.windows(2) {
+            let l = w[0].dist(w[1]);
+            if acc + l >= total * 0.5 && l > 0.0 {
+                return Some(w[0].lerp(w[1], (total * 0.5 - acc) / l));
+            }
+            acc += l;
+        }
+        poly.first().copied()
     };
     let pt = |p: usize| sk.point(p);
     match *k {

crates/engine/src/cmd/sketch_fuzz_tests.rs

@@ -41,12 +41,12 @@ fn entities(s: &Session) -> (Vec<String>, Vec<String>, Vec<String>) {
 
 #[test]
 fn random_sketch_editing_never_breaks() {
-    for seed in 1..=4u64 {
+    for seed in 1..=2u64 {
         let mut r = Rng(0x9E37_79B9_7F4A_7C15 ^ seed);
         let mut s = Session::default();
         let _ = s.execute("PrimitiveBox", &json!({"length": 30, "width": 20, "height": 10}));
         let _ = s.execute("SketchCreate", &json!({"plane": {"face": [15, 10, 10]}}));
-        for step in 0..150 {
+        for step in 0..120 {
             let (curves, points, cons) = entities(&s);
             let c = |r: &mut Rng| r.pick(&curves).cloned().unwrap_or_default();
             let p = |r: &mut Rng| r.pick(&points).cloned().unwrap_or_default();

crates/ui-egui/src/sketch_tools.rs

@@ -18,6 +18,30 @@ thread_local! {
     static TEXT: RefCell<Option<(Vec2, String)>> = const { RefCell::new(None) };
     /// Shift held this frame.
     static SHIFT: Cell<bool> = const { Cell::new(false) };
+    /// Glyphs drawn this frame (constraint id, screen centre) and the selected one.
+    static GLYPHS: RefCell<Vec<(String, Pos2)>> = const { RefCell::new(Vec::new()) };
+    static PICKED: RefCell<Option<String>> = const { RefCell::new(None) };
+}
+
+/// A click on a constraint glyph selects it (true: the click was used).
+pub fn click_glyph(app: &mut SolveApp, _proj: &Proj, pos: Pos2) -> bool {
+    if app.session.active_sketch.is_none() {
+        return false;
+    }
+    let hit = GLYPHS.with(|g| g.borrow().iter().find(|(_, c)| c.distance(pos) <= 7.0).map(|(id, _)| id.clone()));
+    let used = hit.is_some();
+    PICKED.with(|p| *p.borrow_mut() = hit.clone());
+    if let Some(id) = hit {
+        app.set_status(format!("Constraint {id} selected: Delete removes it"), false);
+    }
+    used
+}
+
+/// Delete the selected constraint glyph (true when one was selected).
+pub fn delete_glyph(app: &mut SolveApp) -> bool {
+    let Some(id) = PICKED.with(|p| p.borrow_mut().take()) else { return false };
+    let _ = app.run("sketch.delete", json!({"entities": [id]}));
+    true
 }
 
 /// What the extra tools do with clicks.
@@ -513,6 +537,8 @@ fn glyphs(app: &SolveApp, painter: &egui::Painter, proj: &Proj) {
     let Some(ss) = st.sketch(sid) else { return };
     let tk = crate::theme::Tokens::get();
     let mut placed: Vec<Pos2> = Vec::new();
+    let picked = PICKED.with(|p| p.borrow().clone());
+    let mut drawn: Vec<(String, Pos2)> = Vec::new();
     for c in &ss.sketch.constraints {
         if c.kind.is_dimension() {
             continue;
@@ -526,12 +552,21 @@ fn glyphs(app: &SolveApp, painter: &egui::Painter, proj: &Proj) {
         }
         placed.push(sp);
         let failing = ss.report.failing.contains(&c.id);
-        let col = if failing { tk.error } else { tk.text_dim };
+        let selected = picked.as_deref() == Some(c.id.as_str());
+        let col = if failing {
+            tk.error
+        } else if selected {
+            tk.accent
+        } else {
+            tk.text_dim
+        };
+        drawn.push((c.id.clone(), sp));
         let r = egui::Rect::from_center_size(sp, egui::vec2(12.0, 12.0));
         painter.rect_filled(r, 2.0, tk.panel.gamma_multiply(0.85));
         painter.rect_stroke(r, 2.0, Stroke::new(0.8, col), egui::StrokeKind::Inside);
         painter.text(sp, egui::Align2::CENTER_CENTER, glyph_letter(c.kind.name()), egui::FontId::proportional(9.0), col);
     }
+    GLYPHS.with(|g| *g.borrow_mut() = drawn);
 }
 
 fn glyph_letter(name: &str) -> &'static str {
@@ -555,9 +590,19 @@ fn glyph_letter(name: &str) -> &'static str {
 
 fn glyph_anchor(sk: &solvecraft_engine::sketch::Sketch, k: &solvecraft_engine::sketch::ConstraintKind) -> Option<Vec2> {
     use solvecraft_engine::sketch::ConstraintKind::*;
+    // Half way along the curve.
     let mid = |c: usize| -> Option<Vec2> {
         let poly = sk.polyline(c);
-        poly.get(poly.len() / 2).copied()
+        let total: f64 = poly.windows(2).map(|w| w[0].dist(w[1])).sum();
+        let mut acc = 0.0;
+        for w in poly.windows(2) {
+            let l = w[0].dist(w[1]);
+            if acc + l >= total * 0.5 && l > 0.0 {
+                return Some(w[0].lerp(w[1], (total * 0.5 - acc) / l));
+            }
+            acc += l;
+        }
+        poly.first().copied()
     };
     match *k {
         Coincident { p, .. } | Fix { p } | Midpoint { p, .. } | PointOnCurve { p, .. } => sk.point(p),

crates/ui-egui/src/viewport.rs

@@ -774,6 +774,9 @@ pub fn sketch_point_at(app: &SolveApp, proj: &Proj, pos: Pos2) -> Option<(Vec2,
 }
 
 pub fn delete_selection(app: &mut SolveApp) {
+    if crate::sketch_tools::delete_glyph(app) {
+        return;
+    }
     let sel = app.session.selection.clone();
     if sel.is_empty() {
         return;
@@ -930,7 +933,9 @@ pub fn show(app: &mut SolveApp, ui: &mut egui::Ui) {
                     app.dialog = Some(d);
                 }
             } else {
-                select(app, cand.and_then(|c| c.1), add);
+                if !crate::sketch_tools::click_glyph(app, &proj, p) {
+                    select(app, cand.and_then(|c| c.1), add);
+                }
             }
         }
         if resp.secondary_clicked() && delta == egui::Vec2::ZERO {