pocket-physics/src/segment-intersection.ts

Verlet physics extracted from pocket-ces demos

import { sub, v2, Vector2 } from "./v2";

const s1 = v2();
const s2 = v2();

export function segmentIntersection(
  p0: Vector2,
  p1: Vector2,
  p2: Vector2,
  p3: Vector2,
  intersectionPoint: Vector2
) {
  sub(s1, p1, p0);
  sub(s2, p3, p2);

  const s =
    (-s1.y * (p0.x - p2.x) + s1.x * (p0.y - p2.y)) /
    (-s2.x * s1.y + s1.x * s2.y);
  const t =
    (s2.x * (p0.y - p2.y) - s2.y * (p0.x - p2.x)) /
    (-s2.x * s1.y + s1.x * s2.y);

  if (s >= 0 && s <= 1 && t >= 0 && t <= 1) {
    // Collision detected
    intersectionPoint.x = p0.x + t * s1.x;
    intersectionPoint.y = p0.y + t * s1.y;
    return true;
  }

  return false;
}