A pure C# port of the cavalier_contours Rust library for 2D polyline offsetting and boolean operations, targeting .NET 10+ with full generic math support.
- Polylines with arcs: Vertices carry a bulge value defining circular arc segments (not approximated as line segments)
- Parallel offset: Robust polyline offsetting for open, closed, and self-intersecting polylines
- Boolean operations: Union, intersection, difference, and XOR between two closed polylines
- Containment tests: Determine if one polyline is inside another
- Winding number: Fast point-in-polygon test
- Geometric utilities: Area, path length, redundant vertex removal, closest point, and more
- Spatial indexing:
StaticAABB2DIndexfor accelerated queries on high-vertex-count polylines - Generic math: All algorithms work with any
IFloatingPointIeee754<T>type (double,float, etc.)
- .NET 10 SDK or later
dotnet builddotnet testThe CavalierContours.Example project is a full-featured interactive application for exploring the library's capabilities in real time.
dotnet run --project CavalierContours.Example/CavalierContours.Example.csprojusing CavalierContours.Polyline;
// Create a closed polyline (circle with radius 1 centered at (1, 0))
var pline = new Polyline<double>(true);
pline.Add(0.0, 0.0, 1.0); // arc bulge = 1.0 means semicircle
pline.Add(2.0, 0.0, 1.0);
// Compute parallel offset inward by 0.2
var options = new PlineOffsetOptions<double>();
var offsets = PlineOffset.ParallelOffset<Polyline<double>, double>(pline, 0.2, options);
// Compute area and path length
double area = pline.Area(); // ~3.14159 (pi)
double length = pline.PathLength(); // ~6.28318 (2*pi)
// Boolean union of two closed polylines
var boolOptions = new PlineBooleanOptions<double>();
var result = PlineBoolean.PolylineBoolean<Polyline<double>, double>(
plineA, plineB, BooleanOp.Or, boolOptions);
// Result contains positive (solid) and negative (hole) polylines
foreach (var pos in result.PosPlines) { /* ... */ }
foreach (var neg in result.NegPlines) { /* ... */ }The bulge on a vertex controls the arc from that vertex to the next.
0 = straight line, 1 = semicircle, 0.414 = quarter-circle arc.
Positive = counter-clockwise, negative = clockwise. Defined as tan(sweep_angle / 4).
| Type | Description |
|---|---|
Vector2<T> |
2D vector with generic math |
AABB<T> |
Axis-aligned bounding box |
Polyline<T> |
Mutable polyline with vertices and bulge values |
PlineVertex<T> |
Immutable vertex (X, Y, Bulge) |
StaticAABB2DIndex<T> |
Packed R-tree spatial index |
| Method | Description |
|---|---|
PlineOffset.ParallelOffset(...) |
Compute parallel offset curves |
PlineBoolean.PolylineBoolean(...) |
Boolean operations (union, intersection, difference, xor) |
PlineContains.Contains(...) |
Containment test between polylines |
pline.Area() |
Signed area of a closed polyline |
pline.PathLength() |
Total path length |
pline.WindingNumber(point) |
Winding number for point-in-polygon test |
pline.RemoveRepeatPos(eps) |
Remove duplicate consecutive vertices |
pline.RemoveRedundant(eps) |
Remove collinear/redundant vertices |
pline.RotateStart(...) |
Rotate the starting vertex of a closed polyline |
pline.FindPointAtPathLength(...) |
Find point at a given distance along the polyline |
pline.CreateApproxAabbIndex() |
Build a spatial index for accelerated queries |
This is a C# port of the excellent cavalier_contours Rust library by Jedidiah Buck McCready. The core algorithms for polyline offsetting and boolean operations are based on the original implementation.
This project (CavalierContours.NET) is licensed under the ISC License. See LICENSE for the full text.
The original cavalier_contours Rust library by Jedidiah Buck McCready is dual-licensed under MIT and Apache-2.0. The original MIT license and copyright notice are included in the LICENSE file as required by the MIT license terms.