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Geometry

@oh-just-another/math is the L0 geometry toolkit underpinning the scene model. It is a pure, DOM-free collection of namespaced modules: vec2, scalar, matrix, bounds, hitTest, bezier, intersect, color, and polygon.

Vectors​

The vec2 module operates on { x, y } points: add, sub, mul, dot, cross, length, normalize, lerp, rotate, rotateAround, distance, and more.

import { vec2 } from "@oh-just-another/math";

const a = vec2.of(3, 4);
const len = vec2.length(a); // 5
const mid = vec2.midpoint(a, vec2.ZERO);
const turned = vec2.rotate(a, Math.PI / 2);

Bounds​

The bounds module works with axis-aligned { x, y, width, height } rectangles: fromPoints, union, intersection, intersects, contains, containsBounds, expand, and centerOf.

import { bounds } from "@oh-just-another/math";

const box = bounds.fromPoints([
  { x: 0, y: 0 },
  { x: 10, y: 20 },
]);
const hit = bounds.contains(box, { x: 5, y: 5 }); // true
const merged = bounds.union(box, bounds.of(8, 8, 4, 4));

Matrices and intersection​

matrix provides the 2D affine Transform algebra — translation, rotation, scaling, multiply, inverse, applyToPoint, applyToBounds, and decompose. The intersect module computes lineLine, segmentSegment, segmentQuadratic, and segmentCubic crossings.

import { matrix, intersect } from "@oh-just-another/math";

const t = matrix.multiply(matrix.translation(10, 0), matrix.rotation(Math.PI / 4));
const p = matrix.applyToPoint(t, { x: 1, y: 0 });

const x = intersect.segmentSegment(
  { x: 0, y: 0 },
  { x: 10, y: 10 },
  { x: 0, y: 10 },
  { x: 10, y: 0 },
); // { x: 5, y: 5 }

scalar rounds out the kit with clamp and clamp01.