Struct LengthLine2

Namespace

Thunder.UnitsNET.Vectors.Geometry

Assembly

Thunder.UnitsNET.Vectors.Geometry.dll

Represents an infinite line in 2D space, defined by any point on the line and its direction.

Unlike a LengthSegment2, a line extends infinitely in both directions from its defining point. It is useful for intersection queries, perpendicular projections, and computing whether a point is to the left or right of a boundary.

public readonly record struct LengthLine2 : IEquatable<LengthLine2>

Implements

IEquatable<LengthLine2>

Inherited Members

ValueType.Equals(object)

ValueType.GetHashCode()

ValueType.ToString()

object.Equals(object, object)

object.GetType()

object.ReferenceEquals(object, object)

Extension Methods

PrimitiveDebugDrawExtensions.DebugDraw(LengthLine2, SpriteBatch, Texture2D, Transform2, Color, float, float)

PrimitiveDebugDrawExtensions.GetDebugScreenPoints(LengthLine2, Transform2, float)

Examples

// Horizontal line through the origin
var line = new LengthLine2(LengthPoint2.Origin, Direction2.FromDegrees(0));

Constructors

LengthLine2(LengthPoint2, Direction2)

Represents an infinite line in 2D space, defined by any point on the line and its direction.

Unlike a LengthSegment2, a line extends infinitely in both directions from its defining point. It is useful for intersection queries, perpendicular projections, and computing whether a point is to the left or right of a boundary.

public LengthLine2(LengthPoint2 Point, Direction2 Direction)

Parameters

Point LengthPoint2

Any point that lies on the line.

Direction Direction2

The direction the line points. The line also extends in the opposite direction.

Examples

// Horizontal line through the origin
var line = new LengthLine2(LengthPoint2.Origin, Direction2.FromDegrees(0));

LengthLine2(LengthPoint2, LengthPoint2)

Creates a LengthLine2 passing through two distinct points. The direction is computed from point1 towards point2.

public LengthLine2(LengthPoint2 point1, LengthPoint2 point2)

Parameters

point1 LengthPoint2

The first point on the line.

point2 LengthPoint2

The second point on the line. Must be distinct from point1.

Examples

var line = new LengthLine2(LengthPoint2.FromMeters(0, 0), LengthPoint2.FromMeters(4, 0));
// line.Direction.Angle ≈ 0° (rightward)

Properties

Direction

The direction the line points. The line also extends in the opposite direction.

public Direction2 Direction { get; init; }

Property Value

Direction2

Point

Any point that lies on the line.

public LengthPoint2 Point { get; init; }

Property Value

LengthPoint2

Methods

Contains(LengthPoint2, Length)

Returns true when point lies on this infinite line within tolerance (perpendicular distance ≤ tolerance). This delegates to HasPoint(LengthPoint2, Length).

public bool Contains(LengthPoint2 point, Length tolerance)

Parameters

point LengthPoint2

The point to test.

tolerance Length

Maximum perpendicular distance for the point to be "on" the line.

Returns

bool

true if the point is within tolerance of the line.

Examples

var line = new LengthLine2(LengthPoint2.Origin, Direction2.East);
line.Contains(LengthPoint2.FromMeters(5, 0),   Length.FromMeters(0.001)); // true
line.Contains(LengthPoint2.FromMeters(5, 0.5), Length.FromMeters(0.001)); // false

DistanceTo(LengthPoint2)

Returns the perpendicular distance from point to this infinite line.

public Length DistanceTo(LengthPoint2 point)

Parameters

point LengthPoint2

The world-space query point.

Returns

Length

The perpendicular distance from the point to the line.

Examples

var line = new LengthLine2(LengthPoint2.Origin, Direction2.East);
line.DistanceTo(LengthPoint2.FromMeters(3, 4)); // 4 m

FindClosestPositionToPoint(LengthPoint2)

Returns the point on this line that is closest to point — i.e. the perpendicular projection of point onto the line.

This is computed by projecting the vector from Point to point onto the line's direction and adding the result back to Point. Because the line is infinite, the result is never clamped.

public LengthPoint2 FindClosestPositionToPoint(LengthPoint2 point)

Parameters

point LengthPoint2

The query point.

Returns

LengthPoint2

The nearest point on the infinite line to point.

Examples

var line   = new LengthLine2(LengthPoint2.FromMeters(0, 1), Direction2.FromDegrees(0)); // y=1
var result = line.FindClosestPositionToPoint(LengthPoint2.FromMeters(3, 5));
// result ≈ (3, 1) — projects straight down to the line

GetClosestPoint(LengthPoint2)

Returns the point on this infinite line nearest to point — the foot of the perpendicular from the point to the line. This delegates to FindClosestPositionToPoint(LengthPoint2).

public LengthPoint2 GetClosestPoint(LengthPoint2 point)

Parameters

point LengthPoint2

The world-space query point.

Returns

LengthPoint2

The nearest point on the infinite line.

Examples

var line    = new LengthLine2(LengthPoint2.Origin, Direction2.East);
var closest = line.GetClosestPoint(LengthPoint2.FromMeters(3, 4)); // (3, 0)

GetIntersection(LengthLine2)

Returns the intersection point of this line with other, or null when the lines are parallel (or coincident).

Uses the determinant method: for lines with direction vectors d₁ and d₂, the parameter is t = cross(delta, d₂) / cross(d₁, d₂), where delta = other.Point − this.Point. Parallel lines have cross(d₁, d₂) ≈ 0.

public LengthPoint2? GetIntersection(LengthLine2 other)

Parameters

other LengthLine2

The other infinite line to intersect with.

Returns

LengthPoint2?

The intersection LengthPoint2, or null if the lines are parallel.

Examples

var a = new LengthLine2(LengthPoint2.Origin,             Direction2.FromDegrees(0));  // y=0
var b = new LengthLine2(LengthPoint2.FromMeters(2, 2), Direction2.FromDegrees(90)); // x=2
LengthPoint2? pt = a.GetIntersection(b); // (2, 0)

GetPerpendicularLineAt(LengthPoint2)

Returns a new LengthLine2 that passes through position and is perpendicular to this line.

public LengthLine2 GetPerpendicularLineAt(LengthPoint2 position)

Parameters

position LengthPoint2

The point through which the perpendicular line passes.

Returns

LengthLine2

A LengthLine2 through position, rotated 90° counter-clockwise from this line's direction.

Examples

var horiz = new LengthLine2(LengthPoint2.Origin, Direction2.FromDegrees(0));
var perp  = horiz.GetPerpendicularLineAt(LengthPoint2.FromMeters(3, 0));
// perp.Direction.Angle ≈ 90° (vertical through x=3)

HasPoint(LengthPoint2, Length)

Returns true when point lies on this line within tolerance.

Checks whether the distance from point to its projection on the line is less than or equal to tolerance.

public bool HasPoint(LengthPoint2 point, Length tolerance)

Parameters

point LengthPoint2

The point to test.

tolerance Length

The maximum perpendicular distance from the line for a point to be considered "on" the line.

Returns

bool

true if point is within tolerance of the line; false otherwise.

Examples

var line = new LengthLine2(LengthPoint2.Origin, Direction2.FromDegrees(0));
bool on  = line.HasPoint(LengthPoint2.FromMeters(5, 0),   Length.FromMeters(0.001)); // true
bool off = line.HasPoint(LengthPoint2.FromMeters(5, 0.5), Length.FromMeters(0.001)); // false