Sketch: symmetry about the origin point or an origin axis (#1318)

Fixes #1075. sketch.constraint.symmetry takes a centre point (the origin or any sketch point) as well as a line; the Symmetry tool's third pick may be the origin point or the sketch's own X/Y origin axis. Checked on main + this branch: cargo check --workspace, the engine cmd::sketch tests (257) and the UI symmetry pick tests.

crates/ui-egui/src/symmetry_pick_tests.rs

@@ -0,0 +1,46 @@
+//! The Symmetry tool's third pick may be the origin point or an origin axis (#1075).
+
+use serde_json::json;
+use solidcraft_engine::geom::Vec2;
+
+use crate::scenario::Harness;
+
+/// An XY sketch with points p (10, 5) and q (-12, -3), the Symmetry tool started and both picked.
+fn two_points_picked() -> Harness {
+    let mut h = Harness::new();
+    h.app.ui.show_origin = true;
+    h.app.run("sketch.create", json!({"plane":"XY"})).unwrap();
+    h.app.run("sketch.point", json!({"point":[10,5],"id":"p"})).unwrap();
+    h.app.run("sketch.point", json!({"point":[-12,-3],"id":"q"})).unwrap();
+    h.app.cam.distance = 120.0;
+    h.settle();
+    h.app.start("sketch.constraint.symmetry");
+    for xy in [[10, 5], [-12, -3]] {
+        let at = h.call("ui.at", json!({ "sketch": xy }))["result"].clone();
+        h.step(&json!({ "click": at })).unwrap();
+    }
+    h
+}
+
+fn point(h: &Harness, id: &str) -> Vec2 {
+    let sk = h.app.session.doc.sketch(h.app.session.active_sketch.unwrap()).unwrap();
+    sk.point(sk.resolve_point(id).unwrap()).unwrap()
+}
+
+#[test]
+fn symmetry_about_the_origin_point() {
+    let mut h = two_points_picked();
+    let at = h.call("ui.at", json!({"sketch":[0,0]}))["result"].clone();
+    h.step(&json!({ "click": at })).unwrap();
+    assert!((point(&h, "p") + point(&h, "q")).len() < 1e-6, "{:?} {:?}", point(&h, "p"), point(&h, "q"));
+}
+
+#[test]
+fn symmetry_about_an_origin_axis() {
+    let mut h = two_points_picked();
+    // On the Y axis, away from the origin point and from p and q.
+    let at = h.call("ui.at", json!({"sketch":[0,6]}))["result"].clone();
+    h.step(&json!({ "click": at })).unwrap();
+    let (p, q) = (point(&h, "p"), point(&h, "q"));
+    assert!((p.x + q.x).abs() < 1e-6 && (p.y - q.y).abs() < 1e-6, "mirrored in the Y axis: {p:?} {q:?}");
+}

crates/ui-egui/src/tools.rs

@@ -16,6 +16,10 @@ mod display_preview_tests;
 #[path = "sketch_neutral_click_tests.rs"]
 mod neutral_click_tests;
 
+#[cfg(test)]
+#[path = "symmetry_pick_tests.rs"]
+mod symmetry_pick_tests;
+
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
 pub enum Kind {
     /// Click points; `n` points complete the shape (0 = chain until finished).
@@ -189,8 +193,12 @@ pub fn on_click(app: &mut SolveApp, proj: &Proj, pos: Pos2) {
         }
         Kind::Pick(n) => {
             let hits = pick(app, proj, pos);
+            // Symmetry's third pick may be an origin axis lying along the sketch's own x or y
+            // (#1075); the command names those `x` / `y`.
+            let axis_ok = tool.cmd == "sketch.constraint.symmetry" && tool.picks.len() == 2;
             if let Some(id) = hits.iter().find_map(|h| match h {
                 Hit::SketchPoint { id, .. } | Hit::SketchCurve { id, .. } => Some(id.clone()),
+                Hit::Axis { name } if axis_ok => sketch_axis_of(app, name).map(str::to_string),
                 _ => None,
             }) {
                 tool.picks.push(id);
@@ -455,6 +463,31 @@ pub(crate) fn projection_preselection(selection: &[solidcraft_engine::Sel]) -> O
         .collect()
 }
 
+/// `x` or `y` when the origin axis `name` is the active sketch's own x or y axis: along it, and
+/// through the sketch's origin.
+fn sketch_axis_of(app: &SolveApp, name: &str) -> Option<&'static str> {
+    use solidcraft_engine::geom::Vec3;
+    let dir = match name {
+        "X" => Vec3::X,
+        "Y" => Vec3::Y,
+        "Z" => Vec3::Z,
+        _ => return None,
+    };
+    let st = app.session.world_state();
+    let plane = st.sketch(app.session.active_sketch?)?.plane;
+    let o = plane.origin;
+    if (o - dir * o.dot(dir)).len() > 1e-6 {
+        return None;
+    }
+    if plane.x.dot(dir).abs() > 1.0 - 1e-9 {
+        Some("x")
+    } else if plane.y.dot(dir).abs() > 1.0 - 1e-9 {
+        Some("y")
+    } else {
+        None
+    }
+}
+
 fn run_pick(app: &mut SolveApp, t: &Tool) {
     let k = &t.picks;
     let params = match t.cmd {