Exact profiles for splines of any degree (a degree-4…7 Bézier segment kind, Seg2::Bezier, extruded as B-spline edges) and for free-form curves cut by crossings (exact sub-curves whose ends are moved to the true crossing, found by Newton; polylines only where that fails)

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

crates/engine/src/cmd/sketch_freeform.rs

@@ -153,6 +153,15 @@ fn add_pieces(sk: &mut Sketch, segs: &[Seg2], start: Option<usize>, end: Option<
                 let x = sk.add_point(apex, None)?;
                 CurveKind::Conic { a: prev, b: to, apex: x, rho: w / (1.0 + w) }
             }
+            Seg2::Bezier { n, p } => {
+                let k = (n as usize).clamp(1, solvecraft_geom::MAX_BEZIER_DEGREE);
+                let mut pts = vec![prev];
+                for q in p.iter().take(k).skip(1) {
+                    pts.push(sk.add_point(*q, None)?);
+                }
+                pts.push(to);
+                CurveKind::Spline { pts, control: true, degree: n }
+            }
             Seg2::Arc { .. } => return Err(bad("trim", "unexpected arc piece")),
         };
         let c = sk.add_curve(kind, None)?;

crates/engine/src/cmd/sketch_modify_tests.rs

@@ -343,6 +343,35 @@ fn free_form_profiles_extrude_exactly() {
     assert!(m["bodies"][0]["faces"].as_u64().unwrap() <= 5, "{m}");
 }
 
+#[test]
+fn degree_five_and_cut_free_form_profiles_extrude_exactly() {
+    let vol = |s: &mut Session| run(s, "MeasureCommand", json!({}))["total"]["volume_mm3"].as_f64().unwrap();
+    // A degree-5 control spline closed by a line: one B-spline side face.
+    let mut s = new_sketch();
+    let sp = ids(&run(&mut s, "DrawCVMSpline5D", json!({"points": [[0, 0], [4, 10], [10, 12], [16, 12], [22, 10], [26, 0]]}))["curves"])[0].clone();
+    run(&mut s, "DrawPolyline", json!({"points": [format!("{sp}.end"), format!("{sp}.start")]}));
+    let a = profiles(&s)[0];
+    run(&mut s, "SketchStop", json!({}));
+    run(&mut s, "Extrude", json!({"distance": 3}));
+    let v = vol(&mut s);
+    assert!((v - a * 3.0).abs() / (a * 3.0) < 2e-4, "{v} vs {}", a * 3.0);
+    let m = run(&mut s, "MeasureCommand", json!({}));
+    assert_eq!(m["bodies"][0]["faces"], 4, "{m}");
+    // A fit spline arch cut by a line: both sides extrude with exact curved faces.
+    let mut s = new_sketch();
+    let sp = ids(&run(&mut s, "DrawSpline", json!({"points": [[0, 0], [6, 9], [14, 9], [20, 0]]}))["curves"])[0].clone();
+    run(&mut s, "DrawPolyline", json!({"points": [format!("{sp}.end"), format!("{sp}.start")]}));
+    run(&mut s, "DrawPolyline", json!({"points": [[10, -5], [10, 20]]}));
+    let areas = profiles(&s);
+    assert_eq!(areas.len(), 2, "{areas:?}");
+    run(&mut s, "SketchStop", json!({}));
+    run(&mut s, "Extrude", json!({"distance": 2, "profiles": [0]}));
+    let v = vol(&mut s);
+    assert!((v - areas[0] * 2.0).abs() / (areas[0] * 2.0) < 2e-4, "{v} vs {}", areas[0] * 2.0);
+    let m = run(&mut s, "MeasureCommand", json!({}));
+    assert!(m["bodies"][0]["faces"].as_u64().unwrap() <= 7, "no polyline facets: {m}");
+}
+
 #[test]
 fn trim_and_break_free_form_curves_exactly() {
     let pi = std::f64::consts::PI;