@phaserjs/phaser/geom/triangle/TriangleContains.js

Phaser 4

/**
 * @author       Richard Davey <rich@photonstorm.com>
 * @copyright    2020 Photon Storm Ltd.
 * @license      {@link https://opensource.org/licenses/MIT|MIT License}
 */
export function TriangleContains(triangle, x, y) {
  const { x1, y1, x2, y2, x3, y3 } = triangle;
  const v0x = x3 - x1;
  const v0y = y3 - y1;
  const v1x = x2 - x1;
  const v1y = y2 - y1;
  const v2x = x - x1;
  const v2y = y - y1;
  const dot00 = v0x * v0x + v0y * v0y;
  const dot01 = v0x * v1x + v0y * v1y;
  const dot02 = v0x * v2x + v0y * v2y;
  const dot11 = v1x * v1x + v1y * v1y;
  const dot12 = v1x * v2x + v1y * v2y;
  const b = dot00 * dot11 - dot01 * dot01;
  const inv = b === 0 ? 0 : 1 / b;
  const u = (dot11 * dot02 - dot01 * dot12) * inv;
  const v = (dot00 * dot12 - dot01 * dot02) * inv;
  return u >= 0 && v >= 0 && u + v < 1;
}