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Browse / github.com/storytold/vectorcraft / patch
Fix #3773: Offset Path offsets a path whose ends meet as a closed shape
Offset Path produces an incorrect result for a supplied closed path A community report says Object > Path > Offset Path turns a single closed path into the incorrect geometry shown in the attached before/after screenshot. The reporter also supplied the native `.vectorcraft` document in Discord. Reported 2026-10-23 in the VectorCraft community channel. Expected: Offset Path preserves a sensible parallel offset for this closed path. Actual: the result has visibly incorrect geometry. Needs reproduction from the supplied document, then a regression fixture/test if confirmed.
- Status
- open
- Score
- 0.00
- Adopters
- 0 other operators
- Author
- dotCooCoo (imported from pull request #4362, open)
- Base
8622d0c71c18a166d666314058be7f0e3e9b290f- Size
- +55 −3 in 3 files
- Review
- pending
- Shared
- 2026-10-28
- Id
6d6445a55d76308c96af6098
How it went
No other operator has reported using it yet.
Diff
raw · crates/engine/src/tests/pathops.rs crates/pathops/src/offset.rs crates/pathops/tests/it/ops.rs
@@ -430,6 +430,17 @@ fn offset_rect_grows_bounds() { assert!(close(bounds(&s, r[0]), Rect::new(105.0, 105.0, 145.0, 135.0), 1e-2)); } +/// #3773: an open path whose last anchor sits on its first is offset as the closed shape, not as a+/// ring around its outline.+#[test]+fn offset_open_path_whose_ends_meet_grows_the_shape() {+ let mut s = session();+ s.execute("path.create", &json!({"d": "M0 0 L40 0 L40 40 L0 40 L0 0"})).unwrap();+ let r = ids(&s.execute("object.path.offsetPath", &json!({"offset": 2, "joins": "miter"})).unwrap());+ assert!((area_of(&s, r[0]) - 44.0 * 44.0).abs() < 1e-3, "{}", area_of(&s, r[0]));+ assert_eq!(path_of(&s, r[0]).0.subpaths.len(), 1);+}+ #[test] fn outline_stroke_of_line() { let mut s = session();@@ -94,13 +94,15 @@ pub fn stroke_region(outlines: &[BezPath]) -> PathData { /// Object → Path → Offset Path. Positive `delta` grows the filled area, negative insets it. /// Closed subpaths are treated as a non-zero filled region; open subpaths are outlined with a-/// stroke of width `2|delta|` (butt caps).+/// stroke of width `2|delta|` (butt caps). An open subpath whose last anchor sits on its first is+/// offset as a closed one. pub fn offset_path(path: &PathData, delta: f64, join: Join, miter_limit: f64) -> PathData { if !delta.is_finite() || path.is_empty() { return PathData::default(); }- let closed = PathData::new(path.subpaths.iter().filter(|s| s.closed && s.anchors.len() > 1).cloned().collect());- let open: Vec<SubPath> = path.subpaths.iter().filter(|s| !s.closed && s.anchors.len() > 1).cloned().collect();+ let subpaths: Vec<SubPath> = path.subpaths.iter().map(close_if_ends_meet).collect();+ let closed = PathData::new(subpaths.iter().filter(|s| s.closed && s.anchors.len() > 1).cloned().collect());+ let open: Vec<SubPath> = subpaths.into_iter().filter(|s| !s.closed && s.anchors.len() > 1).collect(); let d = delta.abs(); let fill = fill_bezpath(&closed); let ring = if d > 0.0 { stroke_bez(&closed.to_bezpath(), 2.0 * d, Cap::Butt, join, miter_limit) } else { BezPath::new() };@@ -128,6 +130,23 @@ pub fn offset_path(path: &PathData, delta: f64, join: Join, miter_limit: f64) -> contours_to_path(&c, keep, &Tidy::free(DEFAULT_PRECISION)) } +/// An open subpath of three or more anchors whose last anchor lies within 1e-6 of its first (the+/// test Object → Path → Join applies to one path) as a closed subpath: the last anchor is merged+/// into the first, which takes its in-handle. Any other subpath is returned unchanged.+fn close_if_ends_meet(sp: &SubPath) -> SubPath {+ let mut sp = sp.clone();+ if !sp.closed+ && sp.anchors.len() > 2+ && sp.anchors.first().zip(sp.anchors.last()).is_some_and(|(f, l)| f.p.distance(l.p) < 1e-6)+ && let Some(last) = sp.anchors.pop()+ && let Some(first) = sp.anchors.first_mut()+ {+ first.h_in = last.h_in;+ sp.closed = true;+ }+ sp+}+ fn has_marked_ancestor(c: &Contours, mut i: usize, marked: &[bool]) -> bool { loop { if marked[i] {@@ -294,6 +294,28 @@ fn offset_rect_joins() { assert!(offset_path(&r, -6.0, Join::Miter, 4.0).is_empty()); } +#[test]+fn offset_of_an_open_path_whose_ends_meet_is_the_closed_shape_offset() {+ // Issue #3773: an open path whose last anchor sits on its first offsets like the closed shape,+ // not as a ring around its outline.+ let corners = [Point::new(0.0, 0.0), Point::new(20.0, 0.0), Point::new(20.0, 10.0), Point::new(0.0, 10.0), Point::new(0.0, 0.0)];+ let r = PathData::single(SubPath::polyline(&corners, false));+ let grown = offset_path(&r, 2.0, Join::Miter, 4.0);+ assert!(close(ar(&grown), 24.0 * 14.0, 1e-6), "{}", ar(&grown));+ assert_eq!(grown.subpaths.len(), 1);+ assert_eq!(grown.anchor_count(), 4);+ assert!(close(ar(&offset_path(&r, -2.0, Join::Miter, 4.0)), 16.0 * 6.0, 1e-6));+ // A curved outline: the last anchor's in-handle shapes the closing curve.+ let mut sp = circle(0.0, 0.0, 10.0).subpaths.remove(0);+ let first = sp.anchors[0];+ sp.anchors.push(vectorcraft_geom::Anchor::with_handles(first.p, first.h_in, first.p));+ sp.anchors[0].h_in = first.p;+ sp.closed = false;+ let o = offset_path(&PathData::single(sp), 3.0, Join::Round, 4.0);+ assert!(close(ar(&o), PI * 169.0, 2e-3), "{}", ar(&o));+ assert_eq!(o.subpaths.len(), 1);+}+ #[test] fn outline_stroke_of_line() { let l = PathData::single(SubPath::polyline(&[Point::new(0.0, 0.0), Point::new(30.0, 40.0)], false));