success/packages/math/segment.test.ts

import { point } from "./point";
import { lineSegment, segmentsIntersectAt } from "./segment";
import type { GlobalPoint, LineSegment } from "./types";

describe("segment intersects segment", () => {
  const lineA: LineSegment<GlobalPoint> = lineSegment(point(1, 4), point(3, 4));
  const lineB: LineSegment<GlobalPoint> = lineSegment(point(2, 1), point(2, 7));
  const lineC: LineSegment<GlobalPoint> = lineSegment(point(1, 8), point(3, 8));
  const lineD: LineSegment<GlobalPoint> = lineSegment(point(1, 8), point(3, 8));
  const lineE: LineSegment<GlobalPoint> = lineSegment(point(1, 9), point(3, 9));
  const lineF: LineSegment<GlobalPoint> = lineSegment(point(1, 2), point(3, 4));
  const lineG: LineSegment<GlobalPoint> = lineSegment(point(0, 1), point(2, 3));

  it("intersection", () => {
    expect(segmentsIntersectAt(lineA, lineB)).toEqual([2, 4]);
    expect(segmentsIntersectAt(lineA, lineC)).toBe(null);
    expect(segmentsIntersectAt(lineB, lineC)).toBe(null);
    expect(segmentsIntersectAt(lineC, lineD)).toBe(null); // Line overlapping line is not intersection!
    expect(segmentsIntersectAt(lineE, lineD)).toBe(null);
    expect(segmentsIntersectAt(lineF, lineG)).toBe(null);
  });
});