_init()

in packages/charts/src/utils/d3-delaunay/index.ts [866:926]

• 55 lines of code
• 6 McCabe index (conditional complexity)

  _init() {
    const {
      delaunay: { points, hull, triangles },
      vectors,
    } = this;

    // Compute circumcenters.
    const circumcenters = (this.circumcenters = this._circumcenters.subarray(0, (triangles.length / 3) * 2));
    for (let i = 0, j = 0, n = triangles.length, x, y; i < n; i += 3, j += 2) {
      const t1 = triangles[i] * 2;
      const t2 = triangles[i + 1] * 2;
      const t3 = triangles[i + 2] * 2;
      const x1 = points[t1];
      const y1 = points[t1 + 1];
      const x2 = points[t2];
      const y2 = points[t2 + 1];
      const x3 = points[t3];
      const y3 = points[t3 + 1];

      const dx = x2 - x1;
      const dy = y2 - y1;
      const ex = x3 - x1;
      const ey = y3 - y1;
      const bl = dx * dx + dy * dy;
      const cl = ex * ex + ey * ey;
      const ab = (dx * ey - dy * ex) * 2;

      if (!ab) {
        // degenerate case (collinear diagram)
        x = (x1 + x3) / 2 - 1e8 * ey;
        y = (y1 + y3) / 2 + 1e8 * ex;
      } else if (Math.abs(ab) < 1e-8) {
        // almost equal points (degenerate triangle)
        x = (x1 + x3) / 2;
        y = (y1 + y3) / 2;
      } else {
        const d = 1 / ab;
        x = x1 + (ey * bl - dy * cl) * d;
        y = y1 + (dx * cl - ex * bl) * d;
      }
      circumcenters[j] = x;
      circumcenters[j + 1] = y;
    }

    // Compute exterior cell rays.
    let h = hull[hull.length - 1];
    let p0,
      p1 = h * 4;
    let x0,
      x1 = points[2 * h];
    let y0,
      y1 = points[2 * h + 1];
    vectors.fill(0);
    for (let i = 0; i < hull.length; ++i) {
      h = hull[i];
      (p0 = p1), (x0 = x1), (y0 = y1);
      (p1 = h * 4), (x1 = points[2 * h]), (y1 = points[2 * h + 1]);
      vectors[p0 + 2] = vectors[p1] = y0 - y1;
      vectors[p0 + 3] = vectors[p1 + 1] = x1 - x0;
    }
  }