ConvexHull2

ConvexHull2 (from scenerystack/dot) is a namespace object (not a class you instantiate) with a single method, grahamScan(), implementing the Graham Scan algorithm: given an arbitrary set of 2D points, it returns the ordered subset of those points that form the smallest convex polygon containing all of them.

import { ConvexHull2, Vector2 } from 'scenerystack/dot';
import { Shape } from 'scenerystack/kite';

const points = [
  new Vector2( 0, 0 ), new Vector2( 4, 0 ), new Vector2( 2, 2 ),
  new Vector2( 2, 4 ), new Vector2( 1, 1 ) // interior point - excluded from the hull
];

const hullPoints = ConvexHull2.grahamScan( points, false );
// an ordered Vector2[] tracing the outer boundary, excluding the interior point

const hullShape = Shape.polygon( hullPoints ); // draw it with kite

grahamScan( points, includeCollinear )

Parameter	Effect
points	The Vector2[] to compute a hull over
includeCollinear	If true, points lying exactly along a hull edge (not at a vertex) are kept in the result; if false, only the "true" corner vertices are kept

Returns an ordered Vector2[] (counter-clockwise) tracing the hull boundary. Arrays of 2 or fewer points are returned unchanged (there's no meaningful "hull" to compute).

When you'd reach for this

Convex hulls come up whenever you need the smallest polygon enclosing a scattered set of points — for example, drawing a boundary/highlight around a cluster of draggable objects, computing a rough bounding shape for collision purposes that's tighter than an axis-aligned Bounds2 but simpler than the objects' exact outlines, or building the correct arm/interaction shape for a Voronoi- or hull-based interactive diagram.

Collinear points are excluded by default

Pass includeCollinear: false (as most callers do) unless you specifically need every point that lies exactly on a hull edge represented in the result — the default (excluding them) gives you the minimal vertex set describing the same polygon, which is usually what you want for drawing or further geometric processing.