Pattern on Path (PatternOnPath: spacing or first-to-last distance, flip, identical or path orientation; instance k moves by path(k·d) − path(0)), rectangular/circular/path patterns of bodies; recipes: path_pattern (oracle 53 passes)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AS5Tn3xieewUSg3uxrMVdL

crates/engine/src/cmd/patterns_tests.rs

@@ -0,0 +1,75 @@
+use std::f64::consts::PI;
+
+use serde_json::{Value, json};
+
+use crate::Session;
+
+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 volume(s: &mut Session) -> f64 {
+    run(s, "MeasureCommand", json!({}))["total"]["volume_mm3"].as_f64().unwrap_or(f64::NAN)
+}
+
+fn rel(a: f64, b: f64) -> f64 {
+    (a - b).abs() / b.abs().max(1e-12)
+}
+
+/// A 100 x 50 x 5 plate with a hole at the start of a straight path (10,10) → (90,10).
+fn plate_with_hole() -> Session {
+    let mut s = Session::default();
+    run(&mut s, "PrimitiveBox", json!({"length": 100, "width": 50, "height": 5, "corner": [0, 0, 0]}));
+    run(&mut s, "SketchCreate", json!({"plane": "XY", "name": "Path"}));
+    run(&mut s, "DrawPolyline", json!({"points": [[10, 10], [90, 10]], "ids": ["l1"]}));
+    run(&mut s, "CircleCenterRadius", json!({"center": [10, 10], "radius": 2, "id": "c1"}));
+    run(&mut s, "SketchStop", json!({}));
+    run(&mut s, "Extrude", json!({"sketch": "Path", "through_all": true, "operation": "cut", "name": "Hole1"}));
+    s
+}
+
+const PLATE: f64 = 100.0 * 50.0 * 5.0;
+const HOLE: f64 = PI * 4.0 * 5.0;
+
+#[test]
+fn pattern_on_path_spacing_extent_and_flip() {
+    let mut s = plate_with_hole();
+    assert!(rel(volume(&mut s), PLATE - HOLE) < 1e-4);
+    run(&mut s, "PatternOnPath", json!({"features": ["Hole1"], "path_sketch": "Path", "path": ["l1"], "count": 5, "spacing": 20}));
+    assert!(rel(volume(&mut s), PLATE - 5.0 * HOLE) < 1e-4);
+    // The count is a parameter like any other input.
+    let n = s.doc.features.last().and_then(|f| f.param_names.first().cloned()).unwrap_or_default();
+    run(&mut s, "ChangeParameterCommand", json!({"name": n, "expression": "3"}));
+    assert!(rel(volume(&mut s), PLATE - 3.0 * HOLE) < 1e-4);
+    // Instances past the end of the path are an error.
+    run(&mut s, "ChangeParameterCommand", json!({"name": n, "expression": "6"}));
+    let err = s.model.results.last().and_then(|r| r.error.clone()).unwrap_or_default();
+    assert!(err.contains("past the end of the path"), "{err}");
+
+    // Distance = first to last instance.
+    let mut s = plate_with_hole();
+    run(&mut s, "PatternOnPath", json!({"features": ["Hole1"], "path_sketch": "Path", "path": ["l1"], "count": 3, "distance": 80}));
+    assert!(rel(volume(&mut s), PLATE - 3.0 * HOLE) < 1e-4);
+
+    // Flipped, the path runs from (90,10) back toward (10,10).
+    let mut s = plate_with_hole();
+    run(&mut s, "PatternOnPath", json!({"features": ["Hole1"], "path_sketch": "Path", "path": ["l1"], "count": 2, "spacing": 30, "flip": true}));
+    // The copy moves by path(30) − path(0) = (60,10) − (90,10) = −30: off the plate side → only 1 hole.
+    assert!(rel(volume(&mut s), PLATE - HOLE) < 1e-4);
+}
+
+#[test]
+fn patterns_of_bodies() {
+    let mut s = Session::default();
+    run(&mut s, "PrimitiveBox", json!({"length": 10, "width": 10, "height": 10, "corner": [20, 0, 0], "body_name": "Cube"}));
+    run(&mut s, "PatternCircular", json!({"bodies": ["Cube"], "axis": "Z", "count": 4}));
+    let m = run(&mut s, "MeasureCommand", json!({}));
+    assert_eq!(m["body_count"], 4, "{m}");
+    assert!(rel(volume(&mut s), 4000.0) < 1e-4);
+    run(&mut s, "PatternRectangular", json!({"bodies": ["Cube"], "dir1": [0, 0, 1], "count1": 3, "spacing1": 20}));
+    assert!(rel(volume(&mut s), 6000.0) < 1e-4);
+    assert!(s.execute("PatternRectangular", &json!({"bodies": ["Nope"], "dir1": [1, 0, 0], "count1": 2, "spacing1": 5})).is_err());
+}