CHANGELOG.md

cavalier_contours changelog

All notable changes to the cavalier_contours crate will be documented in this file.

0.9.0 - 2026-08-19

Focus of this release is on robustness and performance of polyline offset generation.

The main changes are:

• Invalid slices are detected and tracked in raw offset creation to filter out invalid slices.
• Slices are stitched together using intersect topology rather than global geometric queries.

Both changes improve robustness for heavily overlapping or degenerate inputs. They also remove the need for slice_join_eps and enable options for handling coincident segments (keep or discard) and "touching loops" (longest continuation or split) in offset results.

The intersect topology approach may also improve robustness in boolean operations in a future refactor (not yet updated). The Shape offset algorithm has not yet been updated either.

Other changes avoid or defer square roots and trigonometric work in low-level segment and intersection functions. This significantly improves performance for arc-heavy inputs and raw offsets with many self-intersection points.

The following benchmarks compare release 0.8.0 with this release:

Negative differences mean this release is faster.

Case	Before (f5fe179)	After (5d0749c)	Difference
profile1	319.45 µs	202.42 µs	-36.63%
profile2	673.86 µs	428.44 µs	-36.42%
profile1_no_arcs	4.387 ms	4.025 ms	-8.25%
profile2_no_arcs	9.270 ms	8.562 ms	-7.64%
floor_plan	157.83 µs	158.15 µs	+0.20%
mechanical_bracket	105.23 µs	91.04 µs	-13.48%
road_centerline	823.36 µs	812.69 µs	-1.30%
bezier_enclosure	3.481 ms	3.279 ms	-5.81%
involute_gear	4.395 ms	4.145 ms	-5.69%
involute_gear_with_arcs	3.453 ms	3.300 ms	-4.43%
pathological1	62.825 ms	18.498 ms	-70.56%
pathological1_no_arcs	245.604 ms	96.917 ms	-60.54%
invalid_line_zigzag	9.851 ms	4.102 ms	-58.36%
invalid_line_arc_zigzag	19.296 ms	5.638 ms	-70.78%
closed_invalid_runs	12.569 ms	6.822 ms	-45.72%
tapered_link_strip/128	890.35 µs	685.12 µs	-23.05%
tapered_link_strip/512	4.710 ms	3.444 ms	-26.87%
tapered_link_strip/2048	20.045 ms	15.642 ms	-21.96%
tapered_link_strip/4096	42.864 ms	33.826 ms	-21.08%

Added ⭐

• Added TouchingLoopBehavior and CoincidentSegmentBehavior to polyline offset options. The defaults preserve tangent-touching loops and coincident spans. Callers can instead separate tangent-touching loops or discard every coincident raw span. The C FFI exposes matching constants and option fields.
• Two new dependencies: ahash and smallvec. These provide meaningful speedups and are both small and popular crates.

Changed 🔧

• ⚠️ BREAKING: Removed PlineOffsetOptions::slice_join_eps and the matching cavc_pline_parallel_offset_o field. Polyline offset slices now connect through explicit intersection topology and use pos_equal_eps only to clean repeated positions. The separate ShapeOffsetOptions::slice_join_eps field remains unchanged.
• ⚠️ BREAKING: Replaced PlineIntersectVisitor::visit_basic_intr and visit_overlapping_intr with a single visit(PlineIntersect) method. Custom visitors must now match the Basic and Overlapping variants. The trait also has an optional filter_map hook.
• ⚠️ BREAKING: Removed the unused public PlineVertexVisitor and PlineSegVisitor traits.
• ⚠️ BREAKING: Changed cavc_pline_parallel_offset_o::to_internal to return Option when behavior values are invalid. The C cavc_pline_parallel_offset function can now return error code 2 for an unrecognized behavior value.

Fixed 🐛

• Fixed repeated polyline offsets dropping a valid small-loop span when two loops touch at a tangent point. The default result keeps the full self-touching path, while separate-touch mode returns the two closed loops.
• Fixed parallel offsets containing locally inverted source spans, which could pass the global distance checks to produce invalid outputs (this is also a significant optimization). This fixes the "wifi leaking" pattern with repeated offsets reported (#79).
• Fixed visible arc distortion in the UI at high zoom by using a more accurate shared arc approximation for polyline and raw offset rendering.

Optimizations ⚡

• Improved polyline offset stitching by following recorded intersections directly instead of searching for nearby endpoints or sorting temporary candidate lists.
• Reduced time and memory use for offsets with many intersections or coincident segments.
• Sped up common polyline arc operations, including bounds, closest points, splits, lengths, and distance checks.
• Sped up line-line, line-circle, circle-circle, and polyline segment intersections by deferring geometric setup, reusing division results, and simplifying tangent and same-circle arc cases.
• Sped up arc sweep checks by comparing squared boundary distances.
• Sped up round joins in raw offsets.
• Reused temporary storage when finding open-offset end-circle intersections.
• Sped up arc winding checks by avoiding unneeded center and radius calculations.
• Reduced allocations when finding all self-intersections in a polyline.
• Sped up two-polyline intersection duplicate cleanup by sorting candidate segment indexes instead of storing them in hash sets.

Internal

• Added Criterion benchmarks for polyline area, polyline segment geometry, raw round joins, raw and final parallel offset creation, offset topology scaling, intersection duplicate cleanup, core intersections, and arc-sweep paths; split the suite into source-aligned modules.
• Added initial AGENTS.md.
• Refactored raw offset slice validation to share common logic between single and dual raw offsets.
• Marked workspace-only algorithm APIs as hidden from generated documentation.

0.8.0 - 2026-08-09

Changed 🔧

• ⚠️ BREAKING: Normalized C FFI container counts, lengths, capacities, and indexes to size_t from uint32_t or uintptr_t, and updated the generated header accordingly.
• ⚠️ BREAKING: Changed Shape::parallel_offset to borrow ShapeOffsetOptions instead of taking it by value.
• ⚠️ BREAKING: Changed Shape::stitch_slices_together to borrow a slice of DissectedSlice values instead of taking a Vec by value.
• Changed the public boolean slice pruning helpers under polyline::internal to use explicit pruning modes, grouped slice boundaries, and a separate intersection lookup helper.
• Added #[must_use] to public functions and types, which may affect users of -D warnings.
• Updated static_aabb2d_index from 2.0 to 2.1.

Fixed 🐛

• Fixed how position epsilon is applied to line-circle intersections so distinct near-tangent intersections are not merged.
• Fixed how position epsilon is applied to arc sweep checks so they behave consistently at different scales and small negative offsets are no longer dropped (#82).
• Improved parallel_offset robustness for repeat-position input by sanitizing repeat vertices before offsetting.
• Fixed collapsed near-vertex offset slices that could cause a debug panic (#83).
• Fixed C FFI shape API documentation to reference shape parameters and cavc_shape_create instead of their polyline counterparts.
• Fixed the UI polyline editor failing to detect pending changes when polylines were added or removed.

Internal

• Updated the UI crate to Rust 1.95.0.
• Updated the UI crate to egui 0.36.1 and matching support crates.
• Enabled workspace-wide Clippy pedantic lints and fixed the reported warnings.
• Added a checked-in cbindgen configuration for C header generation.
• Updated the GitHub Actions checkout and Rust toolchain actions.

0.7.0 - 2026-01-02

Added ⭐

• ⚠️ BREAKING: Added collapsed area parameter to pline boolean options to allow for pruning collapsed polylines from results. This is only breaking due to struct initialization, if you use default initialization this defaults to no change in behavior (#71).
• Added examples crate to workspace to demonstrate cavalier_contours functionality (#74).

Fixed 🐛

• Fixed bug in pline segment intersection when two arcs only touch at endpoints at one point, have the same arc radius and center, and are in opposite directions. This also fixes some cases for algorithms that depend on finding interescts (boolean, offset, etc.) (#71).
• Fixed offset slice stitching to use consistent epsilon (join_eps) when removing repeat vertices, preventing tiny segments at slice boundaries when offsetting polylines with close vertices (#77).

0.6.0 - 2025-07-08

Added ⭐

• Added egui interactive demo UI crate and auto deployment to GitHub pages for the demo page is here.
• Added visit_intersects, contains, and scan_for_self_intersect to pline traits (#68).
• Added user_data to traits for tracking data through operations (#63).
• Added multi polyline offset algorithm to c ffi (#63).
• Added more doc comments/tests for PlineSource and PlineSourceMut.
• Added README.md file to cavalier_contours_ffi crate.

Changed 🔧

• ⚠️ BREAKING: Updated MSRV to 1.88 and Rust edition 2024. Only breaking if unable to compile with Rust 1.88 or later.
• Refactored multipolyline offset algorithm to be step-by-step.
• Simplified prune_slices function in pline_boolean.
• Refactored two-polyline intersection visitation to use visitor pattern and eliminated allocation inside loop (#68).

Fixed 🐛

• ⚠️ BREAKING: Fix memory leak in cavc_plinelist by implementing Drop trait (#64). This is not likely breaking for most users but if you are calling cavc_pline_f on each pline in a cavc_plinelist without removing them from the list then you will get a double free on the plines not removed when the cavc_plinelist is freed/dropped.
• Improved offset slice validation by checking multiple segment midpoints (#69). Fixes bug reported in issue #66.

0.5.0 - 2025-07-08

• cargo release got so excited it jumped a version! Nothing to see here...

0.4.0 - 2024-02-21

Added ⭐

• Added Shape type and parallel offset method on shape type to perform simultaneous multi/island polyline parallel offsetting (#7).

Changed 🔧

• ⚠️ BREAKING: Removed slice_join_eps from PlineBooleanOptions. This is breaking for any code that interacts with this option struct directly (does not use defaults). slice_join_eps was also removed from the equivalent cavc_pline_boolean_o struct in the C FFI. (#31)
• ⚠️ BREAKING: PlineSource::create_aabb_index and PlineSource::create_approx_aabb_index now just return a StaticAABB2DIndex rather than an Option<StaticAABB2DIndex>. The equivalent C api calls cavc_pline_create_aabbindex and cavc_pline_create_approx_aabbindex also no longer return an error code of 2 when polyline has less than 2 vertexes (empty aabb index is returned). (#29)
• Updated StaticAABB2DIndex dependency to version 2.0.
• Bumped rust edition to 2021.
• Use with_capacity instead of reserve in some places to avoid over allocation behavior of Vec (minor performance improvement).

Fixed 🐛

• Fixed PlineView::from_slice_points to handle wrapping on same segment (#28).
• Fixed line_circle_intr accuracy in cases with nearly vertical line (#30).

0.3.0 - 2023-02-18

Added ⭐

• Added BooleanResultInfo enum used for new result_info field on BooleanResult. The enum is used to return information about what happened during the boolean operation.
• Added doc tests and improved documentation to intersect functions circle_circle_intr, line_circle_intr, and line_line_intr (#18).
• Added #![forbid(unsafe_code)] to main cavalier_contours crate to ensure no use of unsafe (obviously does not apply to the cavalier_contours_ffi crate).

Changed 🔧

• Added epsilon parameter to PlineSource::closest_point method to allow for consistency with other calculations using epsilon values for fuzzy comparing.
• line_line_intr function now scales parametric t values by segment lengths before fuzzy comparing with epsilon value to avoid introduced error when line segments are very long or very short.
• pline_seg_intr function now scales parametric t values by segment lengths and angle values by arc radii before fuzzy comparing with epsilon value to avoid introduced error when line segments are very long or very short, or arc radius is very small or very large.
• Reimplemented line_circle_intr function for improved numerical stability.
• Added epsilon parameter to parametric_from_point function to allow consistency with other calculations using epsilon values for fuzzy comparing.
• Reduce error in calculation done in parametric_from_point by using larger component difference rather than explicitly checking for vertical line case.
• Added epsilon parameter to point_within_arc_sweep function to allow for consistency with other calculations using epsilon values for fuzzy comparing.
• Added #[inline] attribute to all of the small Vector2 and base math functions.
• Updated static_aabb2d_index crate to 0.7.0 (for use of IndexableNum::total_cmp).
• Replaced all uses for PartialOrd::partial_cmp with IndexableNum::total_cmp to avoid panics when partial_cmp returns None (e.g., if float is a NaN) and to eliminate branch in compare.

Fixed 🐛

• Fixed PlineSource::remove_redundant to use epsilon values in all fuzzy compares. Previously used default epsilon value from Num trait in some comparisons. If epsilon value passed in is less than default Num trait value (1e-8 for f32 and f64 values) then it is more aggressive in removing vertexes.
• Fixed pline find_intersects function to use epsilon parameter in all cases.
• Fixed boolean operation bugs caused by line_circle_intr numerical stability problem, inconsistencies between epsilon values used across functions, and lack of scaling parametric t values and angles for fuzzy comparing with epsilon values (#23).
• Fixed some of the doc comments around pline boolean operation types.
• Fixed polyline find_intersects to use pos_equal_eps passed in options for querying bounding boxes (#22).
• Fixed PlineViewData::from_new_start to not discard bulge value if start point lies on top of the first vertex of a closed polyline, and added tests to cover case.
• Fixed pline remove_redundant panic when there was more than 2 equal points at start (#26).

0.2.0 - 2022-05-12

Added ⭐

• Added CHANGELOG.md file for tracking changes and releases.
• New traits PlineSource, PlineSourceMut, and PlineCreation for sharing methods across different polyline data views (for example sub views/selections over polylines or direction inversion).
• PlineViewData and PlineView types. PlineView implements PlineSource trait allowing for flexible views over polyline data to be processed with all the shared behavior/methods. PlineViewData holds the data used to index into an underlying source polyline to form a PlineView.

Changed 🔧

• All Polyline methods have moved to the appropriate trait (PlineSource, PlineSourceMut, or PlineCreation).
• Slices used in offset and boolean operations now all use new PlineViewData and PlineView types.
• Changed polyline methods that returned Cow types to return Option types to indicate if changes were done on the input polyline or not.
• Changed intersect functions (circle_circle_intr, line_circle_intr, and line_line_intr) to accept epsilon value parameter for fuzzy float comparisons.
• Changed polyline offset and boolean operations to use pos_equal_eps epsilon value in intersect functions.
• Changed pline_seg_intr function to avoid inconsistencies between intersect functions in some cases involving line-arc intersects due to fuzzy comparing - this fixes problems that can arise in operations that depend on finding intersects.
• Added include_overlapping parameter to all_self_intersects_as_basic function.

Fixed 🐛

• Fixed arc overlap intersects not being found in some cases and segment intersects disagreeing due to fuzzy comparing causing incorrect output for polyline boolean operations and added test cases that found the issue.
• Fixed bug in parallel offset caused when raw offset polyline produced an overlapping self intersect. Parallel offset algorithm no longer includes overlapping intersects when finding self intersects of raw offset polyline for creating slices.

Removed 🔥

• Polyline::visit_segments (use PlineSource::iter_segments instead).
• Polyline::len method removed (use PlineSource::vertex_count instead).
• PolylineSlice trait and OpenPlineSlice type (covered by new view types and polyline traits).
• PolylineSlice::stitch_onto and PolylineSlice::to_polyline removed, to get same functionality construct the view with PlineData::view and pass it to PlineSourceMut::extend_remove_repeat or PlineCreation::create_from_remove_repeat.