CavalierContours 0.1.0

CavalierContours.NET

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.

Features

• 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: StaticAABB2DIndex for accelerated queries on high-vertex-count polylines
• Generic math: All algorithms work with any IFloatingPointIeee754<T> type (double, float, etc.)

Quick Start

Prerequisites

• .NET 10 SDK or later

Build

dotnet build

Run Tests

dotnet test

Interactive Demo

The 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.csproj

Usage Example

using 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) { /* ... */ }

Bulge values

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).

API Overview

Core Types

Polyline Operations

Acknowledgements

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.

License

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.