Fantasy-Map-Generator/src/scripts/findAll.js

import * as d3 from "d3";

// findAll d3.quandtree search from https://bl.ocks.org/lwthatcher/b41479725e0ff2277c7ac90df2de2b5e
export function addFindAll() {
  const Quad = function (node, x0, y0, x1, y1) {
    this.node = node;
    this.x0 = x0;
    this.y0 = y0;
    this.x1 = x1;
    this.y1 = y1;
  };

  const tree_filter = function (x, y, radius) {
    var t = {x, y, x0: this._x0, y0: this._y0, x3: this._x1, y3: this._y1, quads: [], node: this._root};
    if (t.node) {
      t.quads.push(new Quad(t.node, t.x0, t.y0, t.x3, t.y3));
    }
    radiusSearchInit(t, radius);

    var i = 0;
    while ((t.q = t.quads.pop())) {
      i++;

      // Stop searching if this quadrant can’t contain a closer node.
      if (
        !(t.node = t.q.node) ||
        (t.x1 = t.q.x0) > t.x3 ||
        (t.y1 = t.q.y0) > t.y3 ||
        (t.x2 = t.q.x1) < t.x0 ||
        (t.y2 = t.q.y1) < t.y0
      )
        continue;

      // Bisect the current quadrant.
      if (t.node.length) {
        t.node.explored = true;
        var xm = (t.x1 + t.x2) / 2,
          ym = (t.y1 + t.y2) / 2;

        t.quads.push(
          new Quad(t.node[3], xm, ym, t.x2, t.y2),
          new Quad(t.node[2], t.x1, ym, xm, t.y2),
          new Quad(t.node[1], xm, t.y1, t.x2, ym),
          new Quad(t.node[0], t.x1, t.y1, xm, ym)
        );

        // Visit the closest quadrant first.
        if ((t.i = ((y >= ym) << 1) | (x >= xm))) {
          t.q = t.quads[t.quads.length - 1];
          t.quads[t.quads.length - 1] = t.quads[t.quads.length - 1 - t.i];
          t.quads[t.quads.length - 1 - t.i] = t.q;
        }
      }

      // Visit this point. (Visiting coincident points isn’t necessary!)
      else {
        var dx = x - +this._x.call(null, t.node.data),
          dy = y - +this._y.call(null, t.node.data),
          d2 = dx * dx + dy * dy;
        radiusSearchVisit(t, d2);
      }
    }
    return t.result;
  };

  d3.quadtree.prototype.findAll = tree_filter;

  var radiusSearchInit = function (t, radius) {
    t.result = [];
    (t.x0 = t.x - radius), (t.y0 = t.y - radius);
    (t.x3 = t.x + radius), (t.y3 = t.y + radius);
    t.radius = radius * radius;
  };

  var radiusSearchVisit = function (t, d2) {
    t.node.data.scanned = true;
    if (d2 < t.radius) {
      do {
        t.result.push(t.node.data);
        t.node.data.selected = true;
      } while ((t.node = t.node.next));
    }
  };
}