9002f86f73
regions() made one linesweeper contour pass per distinct coverage mask, and each pass walks the whole arrangement, so finding the regions cost masks x segments. Two crossing blends make thousands of both: the Ribbons example's EPS export never finished, and Flatten Transparency, the Flattener Preview, Divide, Shape Builder and Live Paint slowed down the same way on dense art. The masks now go into batches whose faces share no vertex (a greedy colouring of the masks meeting at each vertex), one contour pass per batch. A face's contours are walked as in its own mask's pass, since no other face of the batch touches it; each contour's mask is the one of its batch at its first point (a vertex of the arrangement), and contours group under the nearest enclosing contour of the same mask, as grouped() does in that mask's pass. The regions come out identical, in the same order. Fixes #173. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01U9TrG4w49oSRYbP3cqxA3D |
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| Cargo.toml | ||
| README.md | ||
README.md
vectorcraft-pathops
Path operations for VectorCraft: booleans, the Pathfinder panel, Shape Builder regions, offset path, outline stroke, simplify and the other Object → Path commands. Everything takes and returns vectorcraft_geom::PathData.
Booleans (curve-preserving)
pub enum BoolOp { Union, Intersect, Difference, Xor }
pub fn boolean(a: &PathData, a_rule: FillRule, b: &PathData, b_rule: FillRule, op: BoolOp) -> PathData;
pub fn try_boolean(.., precision: f64) -> Result<PathData, PathOpsError>; // errors on NaN/inf
pub fn boolean_n(paths: &[(&PathData, FillRule)], pred: impl Fn(&[bool]) -> bool) -> PathData;
pub fn unite_all(paths: &[(&PathData, FillRule)]) -> PathData; // fast many-shape union
pub fn normalize(path: &PathData, rule: FillRule) -> PathData; // resolve self-overlaps
pub fn area(path: &PathData, rule: FillRule) -> f64; // exact filled area
The engine is linesweeper (a robust sweep line that works directly on cubic Béziers, so there's no polygon flattening). The sweep splits curves at intersections and y-extrema. Afterwards:
- pieces that lie on one input cubic are rebuilt exactly as a single sub-curve of that cubic;
- other smooth joints (for example, in stroker output) are refitted by least squares within
DEFAULT_PRECISION(0.01 pt); - collinear line pieces are merged;
- the inputs' own anchors are always kept;
- slivers narrower than the precision are dropped.
Output contours are simple and consistently oriented: outer contours and holes wind in opposite directions, so the result fills the same under either fill rule. Open subpaths are closed implicitly because they're treated as filled.
Pathfinder / Shape Builder
pub struct Shape { pub path: PathData, pub rule: FillRule, pub key: u64 } // key = paint identity
pub enum PathfinderOp { Unite, MinusFront, Intersect, Exclude, Divide, Trim, Merge, Crop, Outline, MinusBack }
pub fn pathfinder(op: PathfinderOp, shapes: &[Shape] /* back → front */) -> Vec<Shape>;
pub struct Region { pub path: PathData, pub sources: Vec<usize> }
pub fn regions(shapes: &[Shape]) -> Vec<Region>; // all faces of the arrangement
pub fn region_at(shapes: &[Shape], p: Point) -> Option<Region>;
pub fn merge_regions(regions: &[&Region]) -> PathData; // Shape Builder merge = union
Each result takes its key as follows:
| Operation | Result |
|---|---|
| Unite, Intersect, Exclude, Minus Back | Takes the front-most key |
| Minus Front | Takes the back-most key |
| Divide | One shape per face, keyed by the front-most shape that covers the face |
| Trim | One shape for each object that is still visible |
| Merge | Joins touching visible parts that share a key; each connected component becomes one shape |
| Crop | Keeps the visible parts of the lower objects inside the front-most object |
| Outline | Returns open edge paths, split at every junction; coincident edges are de-duplicated, and each keeps the front-most key |
Offset / stroke
pub use kurbo::{Cap, Join};
pub fn offset_path(path: &PathData, delta: f64, join: Join, miter_limit: f64) -> PathData; // delta < 0 insets
pub fn outline_stroke(path: &PathData, width: f64, cap: Cap, join: Join, miter_limit: f64) -> PathData;
outline_stroke passes the path to kurbo::stroke and then normalizes the result, which removes the overlaps at joins. offset_path computes fill ∪ stroke(2|d|) for a positive offset and fill − stroke(2|d|) for a negative one.
Path editing
pub fn simplify(path: &PathData, tolerance: f64) -> PathData;
pub fn simplify_with(path: &PathData, opts: &SimplifyOptions) -> PathData; // tolerance, corner_angle_deg, straight_lines
pub fn smooth(path: &PathData, amount: f64) -> PathData;
pub fn remove_redundant_points(path: &PathData, tolerance: f64) -> PathData;
pub fn add_anchor_points(path: &PathData) -> PathData;
pub fn average(path: &PathData, selection: &[(usize, usize)], axis: AverageAxis) -> PathData;
pub fn join(paths: &[PathData], tolerance: f64) -> PathData;
pub fn split_into_grid(rect: Rect, rows: usize, cols: usize, gutter: f64) -> Vec<PathData>;
simplify fits least-squares cubics with fixed end tangents, then reparameterizes with Newton steps and splits at the point of worst error. Any anchor that turns more than the corner threshold (30° by default) stays a corner.
Caveats
- linesweeper is still in beta. When two identical curves overlap, the sweep can leave a tiny lens between them; the sliver filter removes it.
- The Outline op finds split points by snapping to arrangement junctions with a small tolerance.
- The quality of offsets depends on kurbo's parallel-curve stroker. Its output is refitted, so offset results have more anchors than boolean results.