Geom2D

Geom2D is a computational geometry library for Go, designed for 2D polygon operations and other fundamental geometric types, and is currently reaching its release candidate phase, nearing production readiness.

As of April 2025, this package is actively in development. The base geometric types (circle, linesegment, point and rectangle) are well documented and functional. The sweep line method of finding line segment intersections (FindIntersections) now supports line segments in general position, but may have issues with handling edge cases like collinear segments and segment endpoints on other segments. The FindIntersectionsBruteForce method (O(n²)) is also available.

Table of Contents

• Geom2D
• Project Goals
• Getting Started
• Documentation
• Geometric Relationships
• Acknowledgments
• License

Project Goals

Geom2D aims to provide a robust, flexible, and efficient implementation of 2D geometric operations, featuring:

• Geometry Types:
  • ✅ Point: Complete 2D point representation with vector operations, transformations, and distance calculations.
  • ✅ LineSegment: Fully functional line segments with intersection detection (both brute force and sweep line methods), containment checks, and transformations.
  • ✅ Circle: Complete circle operations including area, circumference, relationships with points, and transformations.
  • ✅ Rectangle: Axis-aligned bounding box with methods for containment, intersection, and transformation.
  • 🚧 Polygons: Support polygons with holes and nested structures, with methods for orientation, correction, and Boolean operations.
• 🚧Polygon Boolean Operations: Union, intersection, and subtraction.
• ✅Geometry to Geometry Relationships: Well-documented, consistent relationship types (Disjoint, Intersection, ContainedBy, Contains, Equal) between geometric entities.

Getting Started

To install Geom2D, use go get:

go get github.com/mikenye/geom2d

Documentation & Examples

The library is thoroughly documented with Go doc comments. For comprehensive API documentation and usage examples, visit the geom2d documentation at the Go Package Discovery and Documentation site.

Key Packages

• geom2d - Core package with global settings like epsilon for floating-point precision
• point - 2D point representation with vector operations
• linesegment - Line segment operations including intersection detection
• circle - Circle operations
• rectangle - Axis-aligned rectangle operations
• types - Common types and relationships between geometric entities
• numeric - Utilities for handling floating-point precision

Geometric Relationships

Geom2D provides a consistent system for expressing spatial relationships between geometric entities, using standardized relationship types:

• Disjoint: The geometries do not intersect or overlap.
• Intersection: The geometries share common points (without either containing the other).
• ContainedBy: The first geometry is fully contained by the second.
• Contains: The first geometry fully contains the second.
• Equal: The geometries are equivalent.

Currently implemented relationship methods:

• Point to Point: Equality or disjoint
• Point to shapes: All geometric types implement RelationshipToPoint to determine how a point relates to them

Future development will expand the relationship system to include full inter-type relationships (e.g., Circle to LineSegment, Rectangle to Circle, etc.).

Contributing

Contributions are welcome! Please see CONTRIBUTING.md for details.

License

See the LICENSE file for details.