Thunder.UnitsNET.Vectors.Geometry 0.5.0

Thunder.UnitsNET.Vectors.Geometry

Unit-aware 2D geometry library built on Thunder.UnitsNET.Vectors. Shapes, directions, and spatial primitives where all distances are Length, all areas are Area, and all angles are Angle — dimensional errors in geometric code are impossible by construction.

Supported frameworks: net8.0, net10.0

Quick start

// dotnet add package Thunder.UnitsNET.Vectors.Geometry

using Thunder.UnitsNET.Vectors.Geometry;
using UnitsNet;

// Circle
var circle = new Circle2(LengthPoint2.FromMeters(0, 0), Radius.FromMeters(5));
bool hit = circle.Contains(LengthPoint2.FromMeters(3, 4)); // true

// Direction2 — a unit-magnitude direction
var dir = Direction2.FromDegrees(45); // North-East
var rotated = dir.Rotate(Angle.FromDegrees(90)); // North-West (135°)

// Collision manifold — penetration depth, contact normal, contact point
var a = Rectangle2.FromCenterAndSize(LengthPoint2.Origin, Length.FromMeters(2), Length.FromMeters(2));
var b = Rectangle2.FromCenterAndSize(LengthPoint2.FromMeters(1, 0), Length.FromMeters(2), Length.FromMeters(2));
if (a.TryGetManifold(b, out var manifold))
{
    Length depth = manifold.PenetrationDepth;
    Direction2 normal = manifold.ContactNormal;
    LengthPoint2 contact = manifold.ContactPoint;
}

// Raycasting
var ray = new LengthRay2(LengthPoint2.FromMeters(-10, 0), Direction2.East);
if (ray.TryIntersect(circle, out var hit2))
{
    Length distance = hit2.Distance;
    LengthPoint2 point = hit2.Point;
    Direction2 surfaceNormal = hit2.Normal;
}

// Path following
var path = new LengthPath2(new[] {
    LengthPoint2.FromMeters(0, 0),
    LengthPoint2.FromMeters(5, 0),
    LengthPoint2.FromMeters(5, 5),
});
LengthPoint2 pos = path.Evaluate(Length.FromMeters(3));   // 3 m along the path
Direction2 tangent = path.TangentAt(Length.FromMeters(3));

Primitive types

Collision detection

All shapes support TryGetManifold(other, out CollisionManifold) for every pairing:

Supported pairings: Circle↔Circle, Circle↔Rectangle, Circle↔Triangle, Circle↔Capsule, Circle↔Polygon, Rectangle↔Rectangle, Rectangle↔Triangle, Rectangle↔Capsule, Rectangle↔Polygon, Triangle↔Triangle, Triangle↔Capsule, Triangle↔Polygon, Capsule↔Capsule, Capsule↔Polygon, Polygon↔Polygon. All zero-heap-allocation on the hot path.

Raycasting

LengthRay2.TryIntersect(shape, out RaycastHit) for all 5 shapes:

MonoGame integration

Add Thunder.UnitsNET.Vectors.Geometry.MonoGame to convert geometry types to XNA rendering primitives, and for DebugDraw extension methods that render all shapes as wireframes via SpriteBatch.

What's new in v0.5.0

Spline types — BezierCurve2 and CatmullRomSpline2 with unit-aware control points (LengthPoint2). Evaluate(Ratio t) → LengthPoint2, TangentAt(Ratio t) → Direction2, ToPath(resolution) → LengthPath2. LengthPath2.FromCatmullRom(waypoints) factory for converting a waypoint list directly to an arc-length path.

Arc2 parametric traversal — Arc2.PointAt(Ratio t) and TangentAt(Ratio t) for smooth arc traversal (train-on-track style). Arc2.FromPoints(circle, start, end) infers direction and returns the shorter arc. CalculateArcPoints(n) generates a polyline approximation.

LengthVector2 dot-product and projections — Dot(LengthVector2) → Area (unit-preserving), Dot(ForceVector2) → Energy, Project(direction) → LengthVector2, PerpendicularDot(LengthVector2) → Area. No SI round-trips.

Polar constructors and dimension lifting — LengthVector2.FromPolar(Radius, Angle), LengthVector2.Extend(z) → LengthVector3, LengthVector3.Truncate() → LengthVector2. Available in the core Thunder.UnitsNET.Vectors package.

LengthSegment2.End — .Target renamed to .End (and AsRayFromStartToEnd / AsRayFromEndToStart for the ray-conversion methods). Hard rename — update call sites.

Radius unit properties — .Meters, .Centimeters, .Millimeters, .Feet, .Inches, .Kilometers pass-through properties for improved discoverability.

See also — CHANGELOG.md for full Phase 5 release notes (M27–M31.2).

What's new in v0.4.0

Collision manifolds — TryGetManifold between all 15 shape pairings. Returns penetration depth, contact normal, and contact point. Zero heap allocation.

Raycasting — LengthRay2.TryIntersect for all 5 shapes. Returns distance, contact point, and surface normal. Zero heap allocation.

Path following — LengthPath2: arc-length parameterised polyline with Evaluate(Length) → LengthPoint2, TangentAt(Length) → Direction2, and Project(LengthPoint2) for path snapping.

DebugDraw — Draw all geometry shapes and Transform2 axes as wireframes via SpriteBatch (Geometry.MonoGame package).

Performance — All hot paths profiled and optimised. Zero allocation. Rectangle_Rectangle manifold: 1,466 ns → 124 ns (colliding, 11.8×) / 27 ns (non-colliding, 44×).

See also — CHANGELOG.md for full Phase 4 release notes (M19–M26.2).

📖 API docs · 💻 Source

Packages in this family

	Thunder.UnitsNET.Vectors — Core vector types
	Thunder.UnitsNET.Vectors.MonoGame — XNA/MonoGame conversions
	Thunder.UnitsNET.Vectors.Geometry — Unit-aware 2D geometry (this package)
	Thunder.UnitsNET.Vectors.Geometry.MonoGame — Geometry → MonoGame