cga/fromcrackpot.kintsugi.cga.d2.shapes.composites/Polygon

Polygon

open class Polygon(val vertices: List<FlatPoint>) : Composite

Closed loop of straight edges through a cycle of vertices.

The closed sibling of Polyline: N vertices make N edges, the last edge closing back to the first vertex implicitly. Starting vertex and traversal direction are data — the rounded identity of equals distinguishes both. Counter-clockwise winding is the documented convention but is not enforced; to read the actual winding, test signedArea's sign. Convexity is not required: self-intersecting (a pentagram) and self-touching (revisiting a vertex mid-loop — a figure-eight, a slit) loops are legal; only consecutive coincident vertices are rejected at construction.

Throws

DegeneratePolygonException

When fewer than 3 vertices are given, a vertex lies at infinity, or two consecutive vertices coincide at the SCALE quantum — including the last and first, whose implicit closing edge would collapse.

Constructors

Polygon

constructor(vertices: List<FlatPoint>)

Validates the vertex list and throws on degenerate input.

Types

Companion

object Companion

Properties

centroid

val centroid: FlatPoint

The area centroid — the balance point of the enclosed region — as a finite FlatPoint.

edges

val edges: List<Segment>

The edges, one Segment per consecutive vertex pair — N for N vertices, the last edge wrapping back to the first vertex.

isInsideOut

val isInsideOut: Boolean

Whether this polygon is inside-out — wound clockwise, its solid region the closed complement of the loop's bounded one.

signedArea

val signedArea: Double

The signed area of the loop — raw; positive when the winding is counter-clockwise, negative when clockwise.

toPolyline

val toPolyline: Polyline

The open Polyline over the same walk.

vertices

val vertices: List<FlatPoint>

The points the loop passes through — finite FlatPoints in traversal order, closing implicitly.

Functions

collide

infix fun Polygon.collide(collider: Polygon): Penetration?

Polygon collide Polygon => Penetration?
Returns the penetration where this polygon reaches into collider's solid region, or null when the two are clear of each other, touching included.

contains

infix operator fun Polygon.contains(point: FlatPoint): Boolean

Polygon contains FlatPoint => Boolean
Returns whether the point lies within the polygon's solid region, boundary included.

infix operator fun Polygon.contains(point: RoundPoint): Boolean

Polygon contains RoundPoint => Boolean
Returns whether the point lies within the polygon's solid region, boundary included.

copy

open fun copy(polygon: Polygon): Polygon

Returns this object rebuilt around the replacement geometry polygon — the hook the shape-preserving operations return through.

equals

open operator override fun equals(other: Any?): Boolean

Rounded identity over the vertex cycle: equal when the vertex lists match pairwise at the SCALE quantum.

escape

infix fun Polygon.escape(boundary: Polygon): Penetration?

Polygon escape Polygon => Penetration?
Returns the penetration where this polygon reaches out of boundary's solid region, or null when it lies within, touching included.

gap

infix fun Polygon.gap(other: Polygon): Segment?

Polygon gap Polygon => Segment?
Returns the shortest segment from this polygon to other — from a point of one boundary to the nearest point of the other's — or null when their solid regions share any point, touching included.

hashCode

open override fun hashCode(): Int

Returns the hash of the rounded vertices, consistent with equals.

intersects

infix fun Polygon.intersects(other: Polygon): Boolean

Polygon intersects Polygon => Boolean
Returns whether the two solid regions share any point — touching boundaries count.

infix fun Polygon.intersects(segment: Segment): Boolean

Polygon intersects Segment => Boolean
Returns whether the segment touches the polygon's boundary or lies within its solid region.

infix fun Polygon.intersects(line: Line): Boolean

Polygon intersects Line => Boolean
Returns whether the line reaches the polygon's solid region.

toString

open override fun toString(): String

Returns the vertices — raw components, full stored precision.

toStringRounded

fun toStringRounded(): String

Returns the vertices rounded at the SCALE quantum — the debug-output convention of every shape.