(function (global, factory) {
    typeof exports === 'object' && typeof module !== 'undefined' ? module.exports = factory() :
    typeof define === 'function' && define.amd ? define(factory) :
    (global = typeof globalThis !== 'undefined' ? globalThis : global || self, global.polygonClipping = factory());
})(this, (function () { 'use strict';

    /**
     * splaytree v3.1.2
     * Fast Splay tree for Node and browser
     *
     * @author Alexander Milevski <info@w8r.name>
     * @license MIT
     * @preserve
     */

    /*! *****************************************************************************
    Copyright (c) Microsoft Corporation. All rights reserved.
    Licensed under the Apache License, Version 2.0 (the "License"); you may not use
    this file except in compliance with the License. You may obtain a copy of the
    License at http://www.apache.org/licenses/LICENSE-2.0

    THIS CODE IS PROVIDED ON AN *AS IS* BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED
    WARRANTIES OR CONDITIONS OF TITLE, FITNESS FOR A PARTICULAR PURPOSE,
    MERCHANTABLITY OR NON-INFRINGEMENT.

    See the Apache Version 2.0 License for specific language governing permissions
    and limitations under the License.
    ***************************************************************************** */

    function __generator(thisArg, body) {
      var _ = {
          label: 0,
          sent: function () {
            if (t[0] & 1) throw t[1];
            return t[1];
          },
          trys: [],
          ops: []
        },
        f,
        y,
        t,
        g;
      return g = {
        next: verb(0),
        "throw": verb(1),
        "return": verb(2)
      }, typeof Symbol === "function" && (g[Symbol.iterator] = function () {
        return this;
      }), g;
      function verb(n) {
        return function (v) {
          return step([n, v]);
        };
      }
      function step(op) {
        if (f) throw new TypeError("Generator is already executing.");
        while (_) try {
          if (f = 1, y && (t = op[0] & 2 ? y["return"] : op[0] ? y["throw"] || ((t = y["return"]) && t.call(y), 0) : y.next) && !(t = t.call(y, op[1])).done) return t;
          if (y = 0, t) op = [op[0] & 2, t.value];
          switch (op[0]) {
            case 0:
            case 1:
              t = op;
              break;
            case 4:
              _.label++;
              return {
                value: op[1],
                done: false
              };
            case 5:
              _.label++;
              y = op[1];
              op = [0];
              continue;
            case 7:
              op = _.ops.pop();
              _.trys.pop();
              continue;
            default:
              if (!(t = _.trys, t = t.length > 0 && t[t.length - 1]) && (op[0] === 6 || op[0] === 2)) {
                _ = 0;
                continue;
              }
              if (op[0] === 3 && (!t || op[1] > t[0] && op[1] < t[3])) {
                _.label = op[1];
                break;
              }
              if (op[0] === 6 && _.label < t[1]) {
                _.label = t[1];
                t = op;
                break;
              }
              if (t && _.label < t[2]) {
                _.label = t[2];
                _.ops.push(op);
                break;
              }
              if (t[2]) _.ops.pop();
              _.trys.pop();
              continue;
          }
          op = body.call(thisArg, _);
        } catch (e) {
          op = [6, e];
          y = 0;
        } finally {
          f = t = 0;
        }
        if (op[0] & 5) throw op[1];
        return {
          value: op[0] ? op[1] : void 0,
          done: true
        };
      }
    }
    var Node = /** @class */function () {
      function Node(key, data) {
        this.next = null;
        this.key = key;
        this.data = data;
        this.left = null;
        this.right = null;
      }
      return Node;
    }();

    /* follows "An implementation of top-down splaying"
     * by D. Sleator <sleator@cs.cmu.edu> March 1992
     */
    function DEFAULT_COMPARE(a, b) {
      return a > b ? 1 : a < b ? -1 : 0;
    }
    /**
     * Simple top down splay, not requiring i to be in the tree t.
     */
    function splay(i, t, comparator) {
      var N = new Node(null, null);
      var l = N;
      var r = N;
      while (true) {
        var cmp = comparator(i, t.key);
        //if (i < t.key) {
        if (cmp < 0) {
          if (t.left === null) break;
          //if (i < t.left.key) {
          if (comparator(i, t.left.key) < 0) {
            var y = t.left; /* rotate right */
            t.left = y.right;
            y.right = t;
            t = y;
            if (t.left === null) break;
          }
          r.left = t; /* link right */
          r = t;
          t = t.left;
          //} else if (i > t.key) {
        } else if (cmp > 0) {
          if (t.right === null) break;
          //if (i > t.right.key) {
          if (comparator(i, t.right.key) > 0) {
            var y = t.right; /* rotate left */
            t.right = y.left;
            y.left = t;
            t = y;
            if (t.right === null) break;
          }
          l.right = t; /* link left */
          l = t;
          t = t.right;
        } else break;
      }
      /* assemble */
      l.right = t.left;
      r.left = t.right;
      t.left = N.right;
      t.right = N.left;
      return t;
    }
    function insert(i, data, t, comparator) {
      var node = new Node(i, data);
      if (t === null) {
        node.left = node.right = null;
        return node;
      }
      t = splay(i, t, comparator);
      var cmp = comparator(i, t.key);
      if (cmp < 0) {
        node.left = t.left;
        node.right = t;
        t.left = null;
      } else if (cmp >= 0) {
        node.right = t.right;
        node.left = t;
        t.right = null;
      }
      return node;
    }
    function split(key, v, comparator) {
      var left = null;
      var right = null;
      if (v) {
        v = splay(key, v, comparator);
        var cmp = comparator(v.key, key);
        if (cmp === 0) {
          left = v.left;
          right = v.right;
        } else if (cmp < 0) {
          right = v.right;
          v.right = null;
          left = v;
        } else {
          left = v.left;
          v.left = null;
          right = v;
        }
      }
      return {
        left: left,
        right: right
      };
    }
    function merge(left, right, comparator) {
      if (right === null) return left;
      if (left === null) return right;
      right = splay(left.key, right, comparator);
      right.left = left;
      return right;
    }
    /**
     * Prints level of the tree
     */
    function printRow(root, prefix, isTail, out, printNode) {
      if (root) {
        out("" + prefix + (isTail ? '└── ' : '├── ') + printNode(root) + "\n");
        var indent = prefix + (isTail ? '    ' : '│   ');
        if (root.left) printRow(root.left, indent, false, out, printNode);
        if (root.right) printRow(root.right, indent, true, out, printNode);
      }
    }
    var Tree = /** @class */function () {
      function Tree(comparator) {
        if (comparator === void 0) {
          comparator = DEFAULT_COMPARE;
        }
        this._root = null;
        this._size = 0;
        this._comparator = comparator;
      }
      /**
       * Inserts a key, allows duplicates
       */
      Tree.prototype.insert = function (key, data) {
        this._size++;
        return this._root = insert(key, data, this._root, this._comparator);
      };
      /**
       * Adds a key, if it is not present in the tree
       */
      Tree.prototype.add = function (key, data) {
        var node = new Node(key, data);
        if (this._root === null) {
          node.left = node.right = null;
          this._size++;
          this._root = node;
        }
        var comparator = this._comparator;
        var t = splay(key, this._root, comparator);
        var cmp = comparator(key, t.key);
        if (cmp === 0) this._root = t;else {
          if (cmp < 0) {
            node.left = t.left;
            node.right = t;
            t.left = null;
          } else if (cmp > 0) {
            node.right = t.right;
            node.left = t;
            t.right = null;
          }
          this._size++;
          this._root = node;
        }
        return this._root;
      };
      /**
       * @param  {Key} key
       * @return {Node|null}
       */
      Tree.prototype.remove = function (key) {
        this._root = this._remove(key, this._root, this._comparator);
      };
      /**
       * Deletes i from the tree if it's there
       */
      Tree.prototype._remove = function (i, t, comparator) {
        var x;
        if (t === null) return null;
        t = splay(i, t, comparator);
        var cmp = comparator(i, t.key);
        if (cmp === 0) {
          /* found it */
          if (t.left === null) {
            x = t.right;
          } else {
            x = splay(i, t.left, comparator);
            x.right = t.right;
          }
          this._size--;
          return x;
        }
        return t; /* It wasn't there */
      };
      /**
       * Removes and returns the node with smallest key
       */
      Tree.prototype.pop = function () {
        var node = this._root;
        if (node) {
          while (node.left) node = node.left;
          this._root = splay(node.key, this._root, this._comparator);
          this._root = this._remove(node.key, this._root, this._comparator);
          return {
            key: node.key,
            data: node.data
          };
        }
        return null;
      };
      /**
       * Find without splaying
       */
      Tree.prototype.findStatic = function (key) {
        var current = this._root;
        var compare = this._comparator;
        while (current) {
          var cmp = compare(key, current.key);
          if (cmp === 0) return current;else if (cmp < 0) current = current.left;else current = current.right;
        }
        return null;
      };
      Tree.prototype.find = function (key) {
        if (this._root) {
          this._root = splay(key, this._root, this._comparator);
          if (this._comparator(key, this._root.key) !== 0) return null;
        }
        return this._root;
      };
      Tree.prototype.contains = function (key) {
        var current = this._root;
        var compare = this._comparator;
        while (current) {
          var cmp = compare(key, current.key);
          if (cmp === 0) return true;else if (cmp < 0) current = current.left;else current = current.right;
        }
        return false;
      };
      Tree.prototype.forEach = function (visitor, ctx) {
        var current = this._root;
        var Q = []; /* Initialize stack s */
        var done = false;
        while (!done) {
          if (current !== null) {
            Q.push(current);
            current = current.left;
          } else {
            if (Q.length !== 0) {
              current = Q.pop();
              visitor.call(ctx, current);
              current = current.right;
            } else done = true;
          }
        }
        return this;
      };
      /**
       * Walk key range from `low` to `high`. Stops if `fn` returns a value.
       */
      Tree.prototype.range = function (low, high, fn, ctx) {
        var Q = [];
        var compare = this._comparator;
        var node = this._root;
        var cmp;
        while (Q.length !== 0 || node) {
          if (node) {
            Q.push(node);
            node = node.left;
          } else {
            node = Q.pop();
            cmp = compare(node.key, high);
            if (cmp > 0) {
              break;
            } else if (compare(node.key, low) >= 0) {
              if (fn.call(ctx, node)) return this; // stop if smth is returned
            }
            node = node.right;
          }
        }
        return this;
      };
      /**
       * Returns array of keys
       */
      Tree.prototype.keys = function () {
        var keys = [];
        this.forEach(function (_a) {
          var key = _a.key;
          return keys.push(key);
        });
        return keys;
      };
      /**
       * Returns array of all the data in the nodes
       */
      Tree.prototype.values = function () {
        var values = [];
        this.forEach(function (_a) {
          var data = _a.data;
          return values.push(data);
        });
        return values;
      };
      Tree.prototype.min = function () {
        if (this._root) return this.minNode(this._root).key;
        return null;
      };
      Tree.prototype.max = function () {
        if (this._root) return this.maxNode(this._root).key;
        return null;
      };
      Tree.prototype.minNode = function (t) {
        if (t === void 0) {
          t = this._root;
        }
        if (t) while (t.left) t = t.left;
        return t;
      };
      Tree.prototype.maxNode = function (t) {
        if (t === void 0) {
          t = this._root;
        }
        if (t) while (t.right) t = t.right;
        return t;
      };
      /**
       * Returns node at given index
       */
      Tree.prototype.at = function (index) {
        var current = this._root;
        var done = false;
        var i = 0;
        var Q = [];
        while (!done) {
          if (current) {
            Q.push(current);
            current = current.left;
          } else {
            if (Q.length > 0) {
              current = Q.pop();
              if (i === index) return current;
              i++;
              current = current.right;
            } else done = true;
          }
        }
        return null;
      };
      Tree.prototype.next = function (d) {
        var root = this._root;
        var successor = null;
        if (d.right) {
          successor = d.right;
          while (successor.left) successor = successor.left;
          return successor;
        }
        var comparator = this._comparator;
        while (root) {
          var cmp = comparator(d.key, root.key);
          if (cmp === 0) break;else if (cmp < 0) {
            successor = root;
            root = root.left;
          } else root = root.right;
        }
        return successor;
      };
      Tree.prototype.prev = function (d) {
        var root = this._root;
        var predecessor = null;
        if (d.left !== null) {
          predecessor = d.left;
          while (predecessor.right) predecessor = predecessor.right;
          return predecessor;
        }
        var comparator = this._comparator;
        while (root) {
          var cmp = comparator(d.key, root.key);
          if (cmp === 0) break;else if (cmp < 0) root = root.left;else {
            predecessor = root;
            root = root.right;
          }
        }
        return predecessor;
      };
      Tree.prototype.clear = function () {
        this._root = null;
        this._size = 0;
        return this;
      };
      Tree.prototype.toList = function () {
        return toList(this._root);
      };
      /**
       * Bulk-load items. Both array have to be same size
       */
      Tree.prototype.load = function (keys, values, presort) {
        if (values === void 0) {
          values = [];
        }
        if (presort === void 0) {
          presort = false;
        }
        var size = keys.length;
        var comparator = this._comparator;
        // sort if needed
        if (presort) sort(keys, values, 0, size - 1, comparator);
        if (this._root === null) {
          // empty tree
          this._root = loadRecursive(keys, values, 0, size);
          this._size = size;
        } else {
          // that re-builds the whole tree from two in-order traversals
          var mergedList = mergeLists(this.toList(), createList(keys, values), comparator);
          size = this._size + size;
          this._root = sortedListToBST({
            head: mergedList
          }, 0, size);
        }
        return this;
      };
      Tree.prototype.isEmpty = function () {
        return this._root === null;
      };
      Object.defineProperty(Tree.prototype, "size", {
        get: function () {
          return this._size;
        },
        enumerable: true,
        configurable: true
      });
      Object.defineProperty(Tree.prototype, "root", {
        get: function () {
          return this._root;
        },
        enumerable: true,
        configurable: true
      });
      Tree.prototype.toString = function (printNode) {
        if (printNode === void 0) {
          printNode = function (n) {
            return String(n.key);
          };
        }
        var out = [];
        printRow(this._root, '', true, function (v) {
          return out.push(v);
        }, printNode);
        return out.join('');
      };
      Tree.prototype.update = function (key, newKey, newData) {
        var comparator = this._comparator;
        var _a = split(key, this._root, comparator),
          left = _a.left,
          right = _a.right;
        if (comparator(key, newKey) < 0) {
          right = insert(newKey, newData, right, comparator);
        } else {
          left = insert(newKey, newData, left, comparator);
        }
        this._root = merge(left, right, comparator);
      };
      Tree.prototype.split = function (key) {
        return split(key, this._root, this._comparator);
      };
      Tree.prototype[Symbol.iterator] = function () {
        var current, Q, done;
        return __generator(this, function (_a) {
          switch (_a.label) {
            case 0:
              current = this._root;
              Q = [];
              done = false;
              _a.label = 1;
            case 1:
              if (!!done) return [3 /*break*/, 6];
              if (!(current !== null)) return [3 /*break*/, 2];
              Q.push(current);
              current = current.left;
              return [3 /*break*/, 5];
            case 2:
              if (!(Q.length !== 0)) return [3 /*break*/, 4];
              current = Q.pop();
              return [4 /*yield*/, current];
            case 3:
              _a.sent();
              current = current.right;
              return [3 /*break*/, 5];
            case 4:
              done = true;
              _a.label = 5;
            case 5:
              return [3 /*break*/, 1];
            case 6:
              return [2 /*return*/];
          }
        });
      };
      return Tree;
    }();
    function loadRecursive(keys, values, start, end) {
      var size = end - start;
      if (size > 0) {
        var middle = start + Math.floor(size / 2);
        var key = keys[middle];
        var data = values[middle];
        var node = new Node(key, data);
        node.left = loadRecursive(keys, values, start, middle);
        node.right = loadRecursive(keys, values, middle + 1, end);
        return node;
      }
      return null;
    }
    function createList(keys, values) {
      var head = new Node(null, null);
      var p = head;
      for (var i = 0; i < keys.length; i++) {
        p = p.next = new Node(keys[i], values[i]);
      }
      p.next = null;
      return head.next;
    }
    function toList(root) {
      var current = root;
      var Q = [];
      var done = false;
      var head = new Node(null, null);
      var p = head;
      while (!done) {
        if (current) {
          Q.push(current);
          current = current.left;
        } else {
          if (Q.length > 0) {
            current = p = p.next = Q.pop();
            current = current.right;
          } else done = true;
        }
      }
      p.next = null; // that'll work even if the tree was empty
      return head.next;
    }
    function sortedListToBST(list, start, end) {
      var size = end - start;
      if (size > 0) {
        var middle = start + Math.floor(size / 2);
        var left = sortedListToBST(list, start, middle);
        var root = list.head;
        root.left = left;
        list.head = list.head.next;
        root.right = sortedListToBST(list, middle + 1, end);
        return root;
      }
      return null;
    }
    function mergeLists(l1, l2, compare) {
      var head = new Node(null, null); // dummy
      var p = head;
      var p1 = l1;
      var p2 = l2;
      while (p1 !== null && p2 !== null) {
        if (compare(p1.key, p2.key) < 0) {
          p.next = p1;
          p1 = p1.next;
        } else {
          p.next = p2;
          p2 = p2.next;
        }
        p = p.next;
      }
      if (p1 !== null) {
        p.next = p1;
      } else if (p2 !== null) {
        p.next = p2;
      }
      return head.next;
    }
    function sort(keys, values, left, right, compare) {
      if (left >= right) return;
      var pivot = keys[left + right >> 1];
      var i = left - 1;
      var j = right + 1;
      while (true) {
        do i++; while (compare(keys[i], pivot) < 0);
        do j--; while (compare(keys[j], pivot) > 0);
        if (i >= j) break;
        var tmp = keys[i];
        keys[i] = keys[j];
        keys[j] = tmp;
        tmp = values[i];
        values[i] = values[j];
        values[j] = tmp;
      }
      sort(keys, values, left, j, compare);
      sort(keys, values, j + 1, right, compare);
    }

    /**
     * A bounding box has the format:
     *
     *  { ll: { x: xmin, y: ymin }, ur: { x: xmax, y: ymax } }
     *
     */

    const isInBbox = (bbox, point) => {
      return bbox.ll.x <= point.x && point.x <= bbox.ur.x && bbox.ll.y <= point.y && point.y <= bbox.ur.y;
    };

    /* Returns either null, or a bbox (aka an ordered pair of points)
     * If there is only one point of overlap, a bbox with identical points
     * will be returned */
    const getBboxOverlap = (b1, b2) => {
      // check if the bboxes overlap at all
      if (b2.ur.x < b1.ll.x || b1.ur.x < b2.ll.x || b2.ur.y < b1.ll.y || b1.ur.y < b2.ll.y) return null;

      // find the middle two X values
      const lowerX = b1.ll.x < b2.ll.x ? b2.ll.x : b1.ll.x;
      const upperX = b1.ur.x < b2.ur.x ? b1.ur.x : b2.ur.x;

      // find the middle two Y values
      const lowerY = b1.ll.y < b2.ll.y ? b2.ll.y : b1.ll.y;
      const upperY = b1.ur.y < b2.ur.y ? b1.ur.y : b2.ur.y;

      // put those middle values together to get the overlap
      return {
        ll: {
          x: lowerX,
          y: lowerY
        },
        ur: {
          x: upperX,
          y: upperY
        }
      };
    };

    /* Javascript doesn't do integer math. Everything is
     * floating point with percision Number.EPSILON.
     *
     * https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/EPSILON
     */

    let epsilon$1 = Number.EPSILON;

    // IE Polyfill
    if (epsilon$1 === undefined) epsilon$1 = Math.pow(2, -52);
    const EPSILON_SQ = epsilon$1 * epsilon$1;

    /* FLP comparator */
    const cmp = (a, b) => {
      // check if they're both 0
      if (-epsilon$1 < a && a < epsilon$1) {
        if (-epsilon$1 < b && b < epsilon$1) {
          return 0;
        }
      }

      // check if they're flp equal
      const ab = a - b;
      if (ab * ab < EPSILON_SQ * a * b) {
        return 0;
      }

      // normal comparison
      return a < b ? -1 : 1;
    };

    /**
     * This class rounds incoming values sufficiently so that
     * floating points problems are, for the most part, avoided.
     *
     * Incoming points are have their x & y values tested against
     * all previously seen x & y values. If either is 'too close'
     * to a previously seen value, it's value is 'snapped' to the
     * previously seen value.
     *
     * All points should be rounded by this class before being
     * stored in any data structures in the rest of this algorithm.
     */

    class PtRounder {
      constructor() {
        this.reset();
      }
      reset() {
        this.xRounder = new CoordRounder();
        this.yRounder = new CoordRounder();
      }
      round(x, y) {
        return {
          x: this.xRounder.round(x),
          y: this.yRounder.round(y)
        };
      }
    }
    class CoordRounder {
      constructor() {
        this.tree = new Tree();
        // preseed with 0 so we don't end up with values < Number.EPSILON
        this.round(0);
      }

      // Note: this can rounds input values backwards or forwards.
      //       You might ask, why not restrict this to just rounding
      //       forwards? Wouldn't that allow left endpoints to always
      //       remain left endpoints during splitting (never change to
      //       right). No - it wouldn't, because we snap intersections
      //       to endpoints (to establish independence from the segment
      //       angle for t-intersections).
      round(coord) {
        const node = this.tree.add(coord);
        const prevNode = this.tree.prev(node);
        if (prevNode !== null && cmp(node.key, prevNode.key) === 0) {
          this.tree.remove(coord);
          return prevNode.key;
        }
        const nextNode = this.tree.next(node);
        if (nextNode !== null && cmp(node.key, nextNode.key) === 0) {
          this.tree.remove(coord);
          return nextNode.key;
        }
        return coord;
      }
    }

    // singleton available by import
    const rounder = new PtRounder();

    const epsilon = 1.1102230246251565e-16;
    const splitter = 134217729;
    const resulterrbound = (3 + 8 * epsilon) * epsilon;

    // fast_expansion_sum_zeroelim routine from oritinal code
    function sum(elen, e, flen, f, h) {
      let Q, Qnew, hh, bvirt;
      let enow = e[0];
      let fnow = f[0];
      let eindex = 0;
      let findex = 0;
      if (fnow > enow === fnow > -enow) {
        Q = enow;
        enow = e[++eindex];
      } else {
        Q = fnow;
        fnow = f[++findex];
      }
      let hindex = 0;
      if (eindex < elen && findex < flen) {
        if (fnow > enow === fnow > -enow) {
          Qnew = enow + Q;
          hh = Q - (Qnew - enow);
          enow = e[++eindex];
        } else {
          Qnew = fnow + Q;
          hh = Q - (Qnew - fnow);
          fnow = f[++findex];
        }
        Q = Qnew;
        if (hh !== 0) {
          h[hindex++] = hh;
        }
        while (eindex < elen && findex < flen) {
          if (fnow > enow === fnow > -enow) {
            Qnew = Q + enow;
            bvirt = Qnew - Q;
            hh = Q - (Qnew - bvirt) + (enow - bvirt);
            enow = e[++eindex];
          } else {
            Qnew = Q + fnow;
            bvirt = Qnew - Q;
            hh = Q - (Qnew - bvirt) + (fnow - bvirt);
            fnow = f[++findex];
          }
          Q = Qnew;
          if (hh !== 0) {
            h[hindex++] = hh;
          }
        }
      }
      while (eindex < elen) {
        Qnew = Q + enow;
        bvirt = Qnew - Q;
        hh = Q - (Qnew - bvirt) + (enow - bvirt);
        enow = e[++eindex];
        Q = Qnew;
        if (hh !== 0) {
          h[hindex++] = hh;
        }
      }
      while (findex < flen) {
        Qnew = Q + fnow;
        bvirt = Qnew - Q;
        hh = Q - (Qnew - bvirt) + (fnow - bvirt);
        fnow = f[++findex];
        Q = Qnew;
        if (hh !== 0) {
          h[hindex++] = hh;
        }
      }
      if (Q !== 0 || hindex === 0) {
        h[hindex++] = Q;
      }
      return hindex;
    }
    function estimate(elen, e) {
      let Q = e[0];
      for (let i = 1; i < elen; i++) Q += e[i];
      return Q;
    }
    function vec(n) {
      return new Float64Array(n);
    }

    const ccwerrboundA = (3 + 16 * epsilon) * epsilon;
    const ccwerrboundB = (2 + 12 * epsilon) * epsilon;
    const ccwerrboundC = (9 + 64 * epsilon) * epsilon * epsilon;
    const B = vec(4);
    const C1 = vec(8);
    const C2 = vec(12);
    const D = vec(16);
    const u = vec(4);
    function orient2dadapt(ax, ay, bx, by, cx, cy, detsum) {
      let acxtail, acytail, bcxtail, bcytail;
      let bvirt, c, ahi, alo, bhi, blo, _i, _j, _0, s1, s0, t1, t0, u3;
      const acx = ax - cx;
      const bcx = bx - cx;
      const acy = ay - cy;
      const bcy = by - cy;
      s1 = acx * bcy;
      c = splitter * acx;
      ahi = c - (c - acx);
      alo = acx - ahi;
      c = splitter * bcy;
      bhi = c - (c - bcy);
      blo = bcy - bhi;
      s0 = alo * blo - (s1 - ahi * bhi - alo * bhi - ahi * blo);
      t1 = acy * bcx;
      c = splitter * acy;
      ahi = c - (c - acy);
      alo = acy - ahi;
      c = splitter * bcx;
      bhi = c - (c - bcx);
      blo = bcx - bhi;
      t0 = alo * blo - (t1 - ahi * bhi - alo * bhi - ahi * blo);
      _i = s0 - t0;
      bvirt = s0 - _i;
      B[0] = s0 - (_i + bvirt) + (bvirt - t0);
      _j = s1 + _i;
      bvirt = _j - s1;
      _0 = s1 - (_j - bvirt) + (_i - bvirt);
      _i = _0 - t1;
      bvirt = _0 - _i;
      B[1] = _0 - (_i + bvirt) + (bvirt - t1);
      u3 = _j + _i;
      bvirt = u3 - _j;
      B[2] = _j - (u3 - bvirt) + (_i - bvirt);
      B[3] = u3;
      let det = estimate(4, B);
      let errbound = ccwerrboundB * detsum;
      if (det >= errbound || -det >= errbound) {
        return det;
      }
      bvirt = ax - acx;
      acxtail = ax - (acx + bvirt) + (bvirt - cx);
      bvirt = bx - bcx;
      bcxtail = bx - (bcx + bvirt) + (bvirt - cx);
      bvirt = ay - acy;
      acytail = ay - (acy + bvirt) + (bvirt - cy);
      bvirt = by - bcy;
      bcytail = by - (bcy + bvirt) + (bvirt - cy);
      if (acxtail === 0 && acytail === 0 && bcxtail === 0 && bcytail === 0) {
        return det;
      }
      errbound = ccwerrboundC * detsum + resulterrbound * Math.abs(det);
      det += acx * bcytail + bcy * acxtail - (acy * bcxtail + bcx * acytail);
      if (det >= errbound || -det >= errbound) return det;
      s1 = acxtail * bcy;
      c = splitter * acxtail;
      ahi = c - (c - acxtail);
      alo = acxtail - ahi;
      c = splitter * bcy;
      bhi = c - (c - bcy);
      blo = bcy - bhi;
      s0 = alo * blo - (s1 - ahi * bhi - alo * bhi - ahi * blo);
      t1 = acytail * bcx;
      c = splitter * acytail;
      ahi = c - (c - acytail);
      alo = acytail - ahi;
      c = splitter * bcx;
      bhi = c - (c - bcx);
      blo = bcx - bhi;
      t0 = alo * blo - (t1 - ahi * bhi - alo * bhi - ahi * blo);
      _i = s0 - t0;
      bvirt = s0 - _i;
      u[0] = s0 - (_i + bvirt) + (bvirt - t0);
      _j = s1 + _i;
      bvirt = _j - s1;
      _0 = s1 - (_j - bvirt) + (_i - bvirt);
      _i = _0 - t1;
      bvirt = _0 - _i;
      u[1] = _0 - (_i + bvirt) + (bvirt - t1);
      u3 = _j + _i;
      bvirt = u3 - _j;
      u[2] = _j - (u3 - bvirt) + (_i - bvirt);
      u[3] = u3;
      const C1len = sum(4, B, 4, u, C1);
      s1 = acx * bcytail;
      c = splitter * acx;
      ahi = c - (c - acx);
      alo = acx - ahi;
      c = splitter * bcytail;
      bhi = c - (c - bcytail);
      blo = bcytail - bhi;
      s0 = alo * blo - (s1 - ahi * bhi - alo * bhi - ahi * blo);
      t1 = acy * bcxtail;
      c = splitter * acy;
      ahi = c - (c - acy);
      alo = acy - ahi;
      c = splitter * bcxtail;
      bhi = c - (c - bcxtail);
      blo = bcxtail - bhi;
      t0 = alo * blo - (t1 - ahi * bhi - alo * bhi - ahi * blo);
      _i = s0 - t0;
      bvirt = s0 - _i;
      u[0] = s0 - (_i + bvirt) + (bvirt - t0);
      _j = s1 + _i;
      bvirt = _j - s1;
      _0 = s1 - (_j - bvirt) + (_i - bvirt);
      _i = _0 - t1;
      bvirt = _0 - _i;
      u[1] = _0 - (_i + bvirt) + (bvirt - t1);
      u3 = _j + _i;
      bvirt = u3 - _j;
      u[2] = _j - (u3 - bvirt) + (_i - bvirt);
      u[3] = u3;
      const C2len = sum(C1len, C1, 4, u, C2);
      s1 = acxtail * bcytail;
      c = splitter * acxtail;
      ahi = c - (c - acxtail);
      alo = acxtail - ahi;
      c = splitter * bcytail;
      bhi = c - (c - bcytail);
      blo = bcytail - bhi;
      s0 = alo * blo - (s1 - ahi * bhi - alo * bhi - ahi * blo);
      t1 = acytail * bcxtail;
      c = splitter * acytail;
      ahi = c - (c - acytail);
      alo = acytail - ahi;
      c = splitter * bcxtail;
      bhi = c - (c - bcxtail);
      blo = bcxtail - bhi;
      t0 = alo * blo - (t1 - ahi * bhi - alo * bhi - ahi * blo);
      _i = s0 - t0;
      bvirt = s0 - _i;
      u[0] = s0 - (_i + bvirt) + (bvirt - t0);
      _j = s1 + _i;
      bvirt = _j - s1;
      _0 = s1 - (_j - bvirt) + (_i - bvirt);
      _i = _0 - t1;
      bvirt = _0 - _i;
      u[1] = _0 - (_i + bvirt) + (bvirt - t1);
      u3 = _j + _i;
      bvirt = u3 - _j;
      u[2] = _j - (u3 - bvirt) + (_i - bvirt);
      u[3] = u3;
      const Dlen = sum(C2len, C2, 4, u, D);
      return D[Dlen - 1];
    }
    function orient2d(ax, ay, bx, by, cx, cy) {
      const detleft = (ay - cy) * (bx - cx);
      const detright = (ax - cx) * (by - cy);
      const det = detleft - detright;
      const detsum = Math.abs(detleft + detright);
      if (Math.abs(det) >= ccwerrboundA * detsum) return det;
      return -orient2dadapt(ax, ay, bx, by, cx, cy, detsum);
    }

    /* Cross Product of two vectors with first point at origin */
    const crossProduct = (a, b) => a.x * b.y - a.y * b.x;

    /* Dot Product of two vectors with first point at origin */
    const dotProduct = (a, b) => a.x * b.x + a.y * b.y;

    /* Comparator for two vectors with same starting point */
    const compareVectorAngles = (basePt, endPt1, endPt2) => {
      const res = orient2d(basePt.x, basePt.y, endPt1.x, endPt1.y, endPt2.x, endPt2.y);
      if (res > 0) return -1;
      if (res < 0) return 1;
      return 0;
    };
    const length = v => Math.sqrt(dotProduct(v, v));

    /* Get the sine of the angle from pShared -> pAngle to pShaed -> pBase */
    const sineOfAngle = (pShared, pBase, pAngle) => {
      const vBase = {
        x: pBase.x - pShared.x,
        y: pBase.y - pShared.y
      };
      const vAngle = {
        x: pAngle.x - pShared.x,
        y: pAngle.y - pShared.y
      };
      return crossProduct(vAngle, vBase) / length(vAngle) / length(vBase);
    };

    /* Get the cosine of the angle from pShared -> pAngle to pShaed -> pBase */
    const cosineOfAngle = (pShared, pBase, pAngle) => {
      const vBase = {
        x: pBase.x - pShared.x,
        y: pBase.y - pShared.y
      };
      const vAngle = {
        x: pAngle.x - pShared.x,
        y: pAngle.y - pShared.y
      };
      return dotProduct(vAngle, vBase) / length(vAngle) / length(vBase);
    };

    /* Get the x coordinate where the given line (defined by a point and vector)
     * crosses the horizontal line with the given y coordiante.
     * In the case of parrallel lines (including overlapping ones) returns null. */
    const horizontalIntersection = (pt, v, y) => {
      if (v.y === 0) return null;
      return {
        x: pt.x + v.x / v.y * (y - pt.y),
        y: y
      };
    };

    /* Get the y coordinate where the given line (defined by a point and vector)
     * crosses the vertical line with the given x coordiante.
     * In the case of parrallel lines (including overlapping ones) returns null. */
    const verticalIntersection = (pt, v, x) => {
      if (v.x === 0) return null;
      return {
        x: x,
        y: pt.y + v.y / v.x * (x - pt.x)
      };
    };

    /* Get the intersection of two lines, each defined by a base point and a vector.
     * In the case of parrallel lines (including overlapping ones) returns null. */
    const intersection$1 = (pt1, v1, pt2, v2) => {
      // take some shortcuts for vertical and horizontal lines
      // this also ensures we don't calculate an intersection and then discover
      // it's actually outside the bounding box of the line
      if (v1.x === 0) return verticalIntersection(pt2, v2, pt1.x);
      if (v2.x === 0) return verticalIntersection(pt1, v1, pt2.x);
      if (v1.y === 0) return horizontalIntersection(pt2, v2, pt1.y);
      if (v2.y === 0) return horizontalIntersection(pt1, v1, pt2.y);

      // General case for non-overlapping segments.
      // This algorithm is based on Schneider and Eberly.
      // http://www.cimec.org.ar/~ncalvo/Schneider_Eberly.pdf - pg 244

      const kross = crossProduct(v1, v2);
      if (kross == 0) return null;
      const ve = {
        x: pt2.x - pt1.x,
        y: pt2.y - pt1.y
      };
      const d1 = crossProduct(ve, v1) / kross;
      const d2 = crossProduct(ve, v2) / kross;

      // take the average of the two calculations to minimize rounding error
      const x1 = pt1.x + d2 * v1.x,
        x2 = pt2.x + d1 * v2.x;
      const y1 = pt1.y + d2 * v1.y,
        y2 = pt2.y + d1 * v2.y;
      const x = (x1 + x2) / 2;
      const y = (y1 + y2) / 2;
      return {
        x: x,
        y: y
      };
    };

    class SweepEvent {
      // for ordering sweep events in the sweep event queue
      static compare(a, b) {
        // favor event with a point that the sweep line hits first
        const ptCmp = SweepEvent.comparePoints(a.point, b.point);
        if (ptCmp !== 0) return ptCmp;

        // the points are the same, so link them if needed
        if (a.point !== b.point) a.link(b);

        // favor right events over left
        if (a.isLeft !== b.isLeft) return a.isLeft ? 1 : -1;

        // we have two matching left or right endpoints
        // ordering of this case is the same as for their segments
        return Segment.compare(a.segment, b.segment);
      }

      // for ordering points in sweep line order
      static comparePoints(aPt, bPt) {
        if (aPt.x < bPt.x) return -1;
        if (aPt.x > bPt.x) return 1;
        if (aPt.y < bPt.y) return -1;
        if (aPt.y > bPt.y) return 1;
        return 0;
      }

      // Warning: 'point' input will be modified and re-used (for performance)
      constructor(point, isLeft) {
        if (point.events === undefined) point.events = [this];else point.events.push(this);
        this.point = point;
        this.isLeft = isLeft;
        // this.segment, this.otherSE set by factory
      }
      link(other) {
        if (other.point === this.point) {
          throw new Error("Tried to link already linked events");
        }
        const otherEvents = other.point.events;
        for (let i = 0, iMax = otherEvents.length; i < iMax; i++) {
          const evt = otherEvents[i];
          this.point.events.push(evt);
          evt.point = this.point;
        }
        this.checkForConsuming();
      }

      /* Do a pass over our linked events and check to see if any pair
       * of segments match, and should be consumed. */
      checkForConsuming() {
        // FIXME: The loops in this method run O(n^2) => no good.
        //        Maintain little ordered sweep event trees?
        //        Can we maintaining an ordering that avoids the need
        //        for the re-sorting with getLeftmostComparator in geom-out?

        // Compare each pair of events to see if other events also match
        const numEvents = this.point.events.length;
        for (let i = 0; i < numEvents; i++) {
          const evt1 = this.point.events[i];
          if (evt1.segment.consumedBy !== undefined) continue;
          for (let j = i + 1; j < numEvents; j++) {
            const evt2 = this.point.events[j];
            if (evt2.consumedBy !== undefined) continue;
            if (evt1.otherSE.point.events !== evt2.otherSE.point.events) continue;
            evt1.segment.consume(evt2.segment);
          }
        }
      }
      getAvailableLinkedEvents() {
        // point.events is always of length 2 or greater
        const events = [];
        for (let i = 0, iMax = this.point.events.length; i < iMax; i++) {
          const evt = this.point.events[i];
          if (evt !== this && !evt.segment.ringOut && evt.segment.isInResult()) {
            events.push(evt);
          }
        }
        return events;
      }

      /**
       * Returns a comparator function for sorting linked events that will
       * favor the event that will give us the smallest left-side angle.
       * All ring construction starts as low as possible heading to the right,
       * so by always turning left as sharp as possible we'll get polygons
       * without uncessary loops & holes.
       *
       * The comparator function has a compute cache such that it avoids
       * re-computing already-computed values.
       */
      getLeftmostComparator(baseEvent) {
        const cache = new Map();
        const fillCache = linkedEvent => {
          const nextEvent = linkedEvent.otherSE;
          cache.set(linkedEvent, {
            sine: sineOfAngle(this.point, baseEvent.point, nextEvent.point),
            cosine: cosineOfAngle(this.point, baseEvent.point, nextEvent.point)
          });
        };
        return (a, b) => {
          if (!cache.has(a)) fillCache(a);
          if (!cache.has(b)) fillCache(b);
          const {
            sine: asine,
            cosine: acosine
          } = cache.get(a);
          const {
            sine: bsine,
            cosine: bcosine
          } = cache.get(b);

          // both on or above x-axis
          if (asine >= 0 && bsine >= 0) {
            if (acosine < bcosine) return 1;
            if (acosine > bcosine) return -1;
            return 0;
          }

          // both below x-axis
          if (asine < 0 && bsine < 0) {
            if (acosine < bcosine) return -1;
            if (acosine > bcosine) return 1;
            return 0;
          }

          // one above x-axis, one below
          if (bsine < asine) return -1;
          if (bsine > asine) return 1;
          return 0;
        };
      }
    }

    // Give segments unique ID's to get consistent sorting of
    // segments and sweep events when all else is identical
    let segmentId = 0;
    class Segment {
      /* This compare() function is for ordering segments in the sweep
       * line tree, and does so according to the following criteria:
       *
       * Consider the vertical line that lies an infinestimal step to the
       * right of the right-more of the two left endpoints of the input
       * segments. Imagine slowly moving a point up from negative infinity
       * in the increasing y direction. Which of the two segments will that
       * point intersect first? That segment comes 'before' the other one.
       *
       * If neither segment would be intersected by such a line, (if one
       * or more of the segments are vertical) then the line to be considered
       * is directly on the right-more of the two left inputs.
       */
      static compare(a, b) {
        const alx = a.leftSE.point.x;
        const blx = b.leftSE.point.x;
        const arx = a.rightSE.point.x;
        const brx = b.rightSE.point.x;

        // check if they're even in the same vertical plane
        if (brx < alx) return 1;
        if (arx < blx) return -1;
        const aly = a.leftSE.point.y;
        const bly = b.leftSE.point.y;
        const ary = a.rightSE.point.y;
        const bry = b.rightSE.point.y;

        // is left endpoint of segment B the right-more?
        if (alx < blx) {
          // are the two segments in the same horizontal plane?
          if (bly < aly && bly < ary) return 1;
          if (bly > aly && bly > ary) return -1;

          // is the B left endpoint colinear to segment A?
          const aCmpBLeft = a.comparePoint(b.leftSE.point);
          if (aCmpBLeft < 0) return 1;
          if (aCmpBLeft > 0) return -1;

          // is the A right endpoint colinear to segment B ?
          const bCmpARight = b.comparePoint(a.rightSE.point);
          if (bCmpARight !== 0) return bCmpARight;

          // colinear segments, consider the one with left-more
          // left endpoint to be first (arbitrary?)
          return -1;
        }

        // is left endpoint of segment A the right-more?
        if (alx > blx) {
          if (aly < bly && aly < bry) return -1;
          if (aly > bly && aly > bry) return 1;

          // is the A left endpoint colinear to segment B?
          const bCmpALeft = b.comparePoint(a.leftSE.point);
          if (bCmpALeft !== 0) return bCmpALeft;

          // is the B right endpoint colinear to segment A?
          const aCmpBRight = a.comparePoint(b.rightSE.point);
          if (aCmpBRight < 0) return 1;
          if (aCmpBRight > 0) return -1;

          // colinear segments, consider the one with left-more
          // left endpoint to be first (arbitrary?)
          return 1;
        }

        // if we get here, the two left endpoints are in the same
        // vertical plane, ie alx === blx

        // consider the lower left-endpoint to come first
        if (aly < bly) return -1;
        if (aly > bly) return 1;

        // left endpoints are identical
        // check for colinearity by using the left-more right endpoint

        // is the A right endpoint more left-more?
        if (arx < brx) {
          const bCmpARight = b.comparePoint(a.rightSE.point);
          if (bCmpARight !== 0) return bCmpARight;
        }

        // is the B right endpoint more left-more?
        if (arx > brx) {
          const aCmpBRight = a.comparePoint(b.rightSE.point);
          if (aCmpBRight < 0) return 1;
          if (aCmpBRight > 0) return -1;
        }
        if (arx !== brx) {
          // are these two [almost] vertical segments with opposite orientation?
          // if so, the one with the lower right endpoint comes first
          const ay = ary - aly;
          const ax = arx - alx;
          const by = bry - bly;
          const bx = brx - blx;
          if (ay > ax && by < bx) return 1;
          if (ay < ax && by > bx) return -1;
        }

        // we have colinear segments with matching orientation
        // consider the one with more left-more right endpoint to be first
        if (arx > brx) return 1;
        if (arx < brx) return -1;

        // if we get here, two two right endpoints are in the same
        // vertical plane, ie arx === brx

        // consider the lower right-endpoint to come first
        if (ary < bry) return -1;
        if (ary > bry) return 1;

        // right endpoints identical as well, so the segments are idential
        // fall back on creation order as consistent tie-breaker
        if (a.id < b.id) return -1;
        if (a.id > b.id) return 1;

        // identical segment, ie a === b
        return 0;
      }

      /* Warning: a reference to ringWindings input will be stored,
       *  and possibly will be later modified */
      constructor(leftSE, rightSE, rings, windings) {
        this.id = ++segmentId;
        this.leftSE = leftSE;
        leftSE.segment = this;
        leftSE.otherSE = rightSE;
        this.rightSE = rightSE;
        rightSE.segment = this;
        rightSE.otherSE = leftSE;
        this.rings = rings;
        this.windings = windings;
        // left unset for performance, set later in algorithm
        // this.ringOut, this.consumedBy, this.prev
      }
      static fromRing(pt1, pt2, ring) {
        let leftPt, rightPt, winding;

        // ordering the two points according to sweep line ordering
        const cmpPts = SweepEvent.comparePoints(pt1, pt2);
        if (cmpPts < 0) {
          leftPt = pt1;
          rightPt = pt2;
          winding = 1;
        } else if (cmpPts > 0) {
          leftPt = pt2;
          rightPt = pt1;
          winding = -1;
        } else throw new Error(`Tried to create degenerate segment at [${pt1.x}, ${pt1.y}]`);
        const leftSE = new SweepEvent(leftPt, true);
        const rightSE = new SweepEvent(rightPt, false);
        return new Segment(leftSE, rightSE, [ring], [winding]);
      }

      /* When a segment is split, the rightSE is replaced with a new sweep event */
      replaceRightSE(newRightSE) {
        this.rightSE = newRightSE;
        this.rightSE.segment = this;
        this.rightSE.otherSE = this.leftSE;
        this.leftSE.otherSE = this.rightSE;
      }
      bbox() {
        const y1 = this.leftSE.point.y;
        const y2 = this.rightSE.point.y;
        return {
          ll: {
            x: this.leftSE.point.x,
            y: y1 < y2 ? y1 : y2
          },
          ur: {
            x: this.rightSE.point.x,
            y: y1 > y2 ? y1 : y2
          }
        };
      }

      /* A vector from the left point to the right */
      vector() {
        return {
          x: this.rightSE.point.x - this.leftSE.point.x,
          y: this.rightSE.point.y - this.leftSE.point.y
        };
      }
      isAnEndpoint(pt) {
        return pt.x === this.leftSE.point.x && pt.y === this.leftSE.point.y || pt.x === this.rightSE.point.x && pt.y === this.rightSE.point.y;
      }

      /* Compare this segment with a point.
       *
       * A point P is considered to be colinear to a segment if there
       * exists a distance D such that if we travel along the segment
       * from one * endpoint towards the other a distance D, we find
       * ourselves at point P.
       *
       * Return value indicates:
       *
       *   1: point lies above the segment (to the left of vertical)
       *   0: point is colinear to segment
       *  -1: point lies below the segment (to the right of vertical)
       */
      comparePoint(point) {
        if (this.isAnEndpoint(point)) return 0;
        const lPt = this.leftSE.point;
        const rPt = this.rightSE.point;
        const v = this.vector();

        // Exactly vertical segments.
        if (lPt.x === rPt.x) {
          if (point.x === lPt.x) return 0;
          return point.x < lPt.x ? 1 : -1;
        }

        // Nearly vertical segments with an intersection.
        // Check to see where a point on the line with matching Y coordinate is.
        const yDist = (point.y - lPt.y) / v.y;
        const xFromYDist = lPt.x + yDist * v.x;
        if (point.x === xFromYDist) return 0;

        // General case.
        // Check to see where a point on the line with matching X coordinate is.
        const xDist = (point.x - lPt.x) / v.x;
        const yFromXDist = lPt.y + xDist * v.y;
        if (point.y === yFromXDist) return 0;
        return point.y < yFromXDist ? -1 : 1;
      }

      /**
       * Given another segment, returns the first non-trivial intersection
       * between the two segments (in terms of sweep line ordering), if it exists.
       *
       * A 'non-trivial' intersection is one that will cause one or both of the
       * segments to be split(). As such, 'trivial' vs. 'non-trivial' intersection:
       *
       *   * endpoint of segA with endpoint of segB --> trivial
       *   * endpoint of segA with point along segB --> non-trivial
       *   * endpoint of segB with point along segA --> non-trivial
       *   * point along segA with point along segB --> non-trivial
       *
       * If no non-trivial intersection exists, return null
       * Else, return null.
       */
      getIntersection(other) {
        // If bboxes don't overlap, there can't be any intersections
        const tBbox = this.bbox();
        const oBbox = other.bbox();
        const bboxOverlap = getBboxOverlap(tBbox, oBbox);
        if (bboxOverlap === null) return null;

        // We first check to see if the endpoints can be considered intersections.
        // This will 'snap' intersections to endpoints if possible, and will
        // handle cases of colinearity.

        const tlp = this.leftSE.point;
        const trp = this.rightSE.point;
        const olp = other.leftSE.point;
        const orp = other.rightSE.point;

        // does each endpoint touch the other segment?
        // note that we restrict the 'touching' definition to only allow segments
        // to touch endpoints that lie forward from where we are in the sweep line pass
        const touchesOtherLSE = isInBbox(tBbox, olp) && this.comparePoint(olp) === 0;
        const touchesThisLSE = isInBbox(oBbox, tlp) && other.comparePoint(tlp) === 0;
        const touchesOtherRSE = isInBbox(tBbox, orp) && this.comparePoint(orp) === 0;
        const touchesThisRSE = isInBbox(oBbox, trp) && other.comparePoint(trp) === 0;

        // do left endpoints match?
        if (touchesThisLSE && touchesOtherLSE) {
          // these two cases are for colinear segments with matching left
          // endpoints, and one segment being longer than the other
          if (touchesThisRSE && !touchesOtherRSE) return trp;
          if (!touchesThisRSE && touchesOtherRSE) return orp;
          // either the two segments match exactly (two trival intersections)
          // or just on their left endpoint (one trivial intersection
          return null;
        }

        // does this left endpoint matches (other doesn't)
        if (touchesThisLSE) {
          // check for segments that just intersect on opposing endpoints
          if (touchesOtherRSE) {
            if (tlp.x === orp.x && tlp.y === orp.y) return null;
          }
          // t-intersection on left endpoint
          return tlp;
        }

        // does other left endpoint matches (this doesn't)
        if (touchesOtherLSE) {
          // check for segments that just intersect on opposing endpoints
          if (touchesThisRSE) {
            if (trp.x === olp.x && trp.y === olp.y) return null;
          }
          // t-intersection on left endpoint
          return olp;
        }

        // trivial intersection on right endpoints
        if (touchesThisRSE && touchesOtherRSE) return null;

        // t-intersections on just one right endpoint
        if (touchesThisRSE) return trp;
        if (touchesOtherRSE) return orp;

        // None of our endpoints intersect. Look for a general intersection between
        // infinite lines laid over the segments
        const pt = intersection$1(tlp, this.vector(), olp, other.vector());

        // are the segments parrallel? Note that if they were colinear with overlap,
        // they would have an endpoint intersection and that case was already handled above
        if (pt === null) return null;

        // is the intersection found between the lines not on the segments?
        if (!isInBbox(bboxOverlap, pt)) return null;

        // round the the computed point if needed
        return rounder.round(pt.x, pt.y);
      }

      /**
       * Split the given segment into multiple segments on the given points.
       *  * Each existing segment will retain its leftSE and a new rightSE will be
       *    generated for it.
       *  * A new segment will be generated which will adopt the original segment's
       *    rightSE, and a new leftSE will be generated for it.
       *  * If there are more than two points given to split on, new segments
       *    in the middle will be generated with new leftSE and rightSE's.
       *  * An array of the newly generated SweepEvents will be returned.
       *
       * Warning: input array of points is modified
       */
      split(point) {
        const newEvents = [];
        const alreadyLinked = point.events !== undefined;
        const newLeftSE = new SweepEvent(point, true);
        const newRightSE = new SweepEvent(point, false);
        const oldRightSE = this.rightSE;
        this.replaceRightSE(newRightSE);
        newEvents.push(newRightSE);
        newEvents.push(newLeftSE);
        const newSeg = new Segment(newLeftSE, oldRightSE, this.rings.slice(), this.windings.slice());

        // when splitting a nearly vertical downward-facing segment,
        // sometimes one of the resulting new segments is vertical, in which
        // case its left and right events may need to be swapped
        if (SweepEvent.comparePoints(newSeg.leftSE.point, newSeg.rightSE.point) > 0) {
          newSeg.swapEvents();
        }
        if (SweepEvent.comparePoints(this.leftSE.point, this.rightSE.point) > 0) {
          this.swapEvents();
        }

        // in the point we just used to create new sweep events with was already
        // linked to other events, we need to check if either of the affected
        // segments should be consumed
        if (alreadyLinked) {
          newLeftSE.checkForConsuming();
          newRightSE.checkForConsuming();
        }
        return newEvents;
      }

      /* Swap which event is left and right */
      swapEvents() {
        const tmpEvt = this.rightSE;
        this.rightSE = this.leftSE;
        this.leftSE = tmpEvt;
        this.leftSE.isLeft = true;
        this.rightSE.isLeft = false;
        for (let i = 0, iMax = this.windings.length; i < iMax; i++) {
          this.windings[i] *= -1;
        }
      }

      /* Consume another segment. We take their rings under our wing
       * and mark them as consumed. Use for perfectly overlapping segments */
      consume(other) {
        let consumer = this;
        let consumee = other;
        while (consumer.consumedBy) consumer = consumer.consumedBy;
        while (consumee.consumedBy) consumee = consumee.consumedBy;
        const cmp = Segment.compare(consumer, consumee);
        if (cmp === 0) return; // already consumed
        // the winner of the consumption is the earlier segment
        // according to sweep line ordering
        if (cmp > 0) {
          const tmp = consumer;
          consumer = consumee;
          consumee = tmp;
        }

        // make sure a segment doesn't consume it's prev
        if (consumer.prev === consumee) {
          const tmp = consumer;
          consumer = consumee;
          consumee = tmp;
        }
        for (let i = 0, iMax = consumee.rings.length; i < iMax; i++) {
          const ring = consumee.rings[i];
          const winding = consumee.windings[i];
          const index = consumer.rings.indexOf(ring);
          if (index === -1) {
            consumer.rings.push(ring);
            consumer.windings.push(winding);
          } else consumer.windings[index] += winding;
        }
        consumee.rings = null;
        consumee.windings = null;
        consumee.consumedBy = consumer;

        // mark sweep events consumed as to maintain ordering in sweep event queue
        consumee.leftSE.consumedBy = consumer.leftSE;
        consumee.rightSE.consumedBy = consumer.rightSE;
      }

      /* The first segment previous segment chain that is in the result */
      prevInResult() {
        if (this._prevInResult !== undefined) return this._prevInResult;
        if (!this.prev) this._prevInResult = null;else if (this.prev.isInResult()) this._prevInResult = this.prev;else this._prevInResult = this.prev.prevInResult();
        return this._prevInResult;
      }
      beforeState() {
        if (this._beforeState !== undefined) return this._beforeState;
        if (!this.prev) this._beforeState = {
          rings: [],
          windings: [],
          multiPolys: []
        };else {
          const seg = this.prev.consumedBy || this.prev;
          this._beforeState = seg.afterState();
        }
        return this._beforeState;
      }
      afterState() {
        if (this._afterState !== undefined) return this._afterState;
        const beforeState = this.beforeState();
        this._afterState = {
          rings: beforeState.rings.slice(0),
          windings: beforeState.windings.slice(0),
          multiPolys: []
        };
        const ringsAfter = this._afterState.rings;
        const windingsAfter = this._afterState.windings;
        const mpsAfter = this._afterState.multiPolys;

        // calculate ringsAfter, windingsAfter
        for (let i = 0, iMax = this.rings.length; i < iMax; i++) {
          const ring = this.rings[i];
          const winding = this.windings[i];
          const index = ringsAfter.indexOf(ring);
          if (index === -1) {
            ringsAfter.push(ring);
            windingsAfter.push(winding);
          } else windingsAfter[index] += winding;
        }

        // calcualte polysAfter
        const polysAfter = [];
        const polysExclude = [];
        for (let i = 0, iMax = ringsAfter.length; i < iMax; i++) {
          if (windingsAfter[i] === 0) continue; // non-zero rule
          const ring = ringsAfter[i];
          const poly = ring.poly;
          if (polysExclude.indexOf(poly) !== -1) continue;
          if (ring.isExterior) polysAfter.push(poly);else {
            if (polysExclude.indexOf(poly) === -1) polysExclude.push(poly);
            const index = polysAfter.indexOf(ring.poly);
            if (index !== -1) polysAfter.splice(index, 1);
          }
        }

        // calculate multiPolysAfter
        for (let i = 0, iMax = polysAfter.length; i < iMax; i++) {
          const mp = polysAfter[i].multiPoly;
          if (mpsAfter.indexOf(mp) === -1) mpsAfter.push(mp);
        }
        return this._afterState;
      }

      /* Is this segment part of the final result? */
      isInResult() {
        // if we've been consumed, we're not in the result
        if (this.consumedBy) return false;
        if (this._isInResult !== undefined) return this._isInResult;
        const mpsBefore = this.beforeState().multiPolys;
        const mpsAfter = this.afterState().multiPolys;
        switch (operation.type) {
          case "union":
            {
              // UNION - included iff:
              //  * On one side of us there is 0 poly interiors AND
              //  * On the other side there is 1 or more.
              const noBefores = mpsBefore.length === 0;
              const noAfters = mpsAfter.length === 0;
              this._isInResult = noBefores !== noAfters;
              break;
            }
          case "intersection":
            {
              // INTERSECTION - included iff:
              //  * on one side of us all multipolys are rep. with poly interiors AND
              //  * on the other side of us, not all multipolys are repsented
              //    with poly interiors
              let least;
              let most;
              if (mpsBefore.length < mpsAfter.length) {
                least = mpsBefore.length;
                most = mpsAfter.length;
              } else {
                least = mpsAfter.length;
                most = mpsBefore.length;
              }
              this._isInResult = most === operation.numMultiPolys && least < most;
              break;
            }
          case "xor":
            {
              // XOR - included iff:
              //  * the difference between the number of multipolys represented
              //    with poly interiors on our two sides is an odd number
              const diff = Math.abs(mpsBefore.length - mpsAfter.length);
              this._isInResult = diff % 2 === 1;
              break;
            }
          case "difference":
            {
              // DIFFERENCE included iff:
              //  * on exactly one side, we have just the subject
              const isJustSubject = mps => mps.length === 1 && mps[0].isSubject;
              this._isInResult = isJustSubject(mpsBefore) !== isJustSubject(mpsAfter);
              break;
            }
          default:
            throw new Error(`Unrecognized operation type found ${operation.type}`);
        }
        return this._isInResult;
      }
    }

    class RingIn {
      constructor(geomRing, poly, isExterior) {
        if (!Array.isArray(geomRing) || geomRing.length === 0) {
          throw new Error("Input geometry is not a valid Polygon or MultiPolygon");
        }
        this.poly = poly;
        this.isExterior = isExterior;
        this.segments = [];
        if (typeof geomRing[0][0] !== "number" || typeof geomRing[0][1] !== "number") {
          throw new Error("Input geometry is not a valid Polygon or MultiPolygon");
        }
        const firstPoint = rounder.round(geomRing[0][0], geomRing[0][1]);
        this.bbox = {
          ll: {
            x: firstPoint.x,
            y: firstPoint.y
          },
          ur: {
            x: firstPoint.x,
            y: firstPoint.y
          }
        };
        let prevPoint = firstPoint;
        for (let i = 1, iMax = geomRing.length; i < iMax; i++) {
          if (typeof geomRing[i][0] !== "number" || typeof geomRing[i][1] !== "number") {
            throw new Error("Input geometry is not a valid Polygon or MultiPolygon");
          }
          let point = rounder.round(geomRing[i][0], geomRing[i][1]);
          // skip repeated points
          if (point.x === prevPoint.x && point.y === prevPoint.y) continue;
          this.segments.push(Segment.fromRing(prevPoint, point, this));
          if (point.x < this.bbox.ll.x) this.bbox.ll.x = point.x;
          if (point.y < this.bbox.ll.y) this.bbox.ll.y = point.y;
          if (point.x > this.bbox.ur.x) this.bbox.ur.x = point.x;
          if (point.y > this.bbox.ur.y) this.bbox.ur.y = point.y;
          prevPoint = point;
        }
        // add segment from last to first if last is not the same as first
        if (firstPoint.x !== prevPoint.x || firstPoint.y !== prevPoint.y) {
          this.segments.push(Segment.fromRing(prevPoint, firstPoint, this));
        }
      }
      getSweepEvents() {
        const sweepEvents = [];
        for (let i = 0, iMax = this.segments.length; i < iMax; i++) {
          const segment = this.segments[i];
          sweepEvents.push(segment.leftSE);
          sweepEvents.push(segment.rightSE);
        }
        return sweepEvents;
      }
    }
    class PolyIn {
      constructor(geomPoly, multiPoly) {
        if (!Array.isArray(geomPoly)) {
          throw new Error("Input geometry is not a valid Polygon or MultiPolygon");
        }
        this.exteriorRing = new RingIn(geomPoly[0], this, true);
        // copy by value
        this.bbox = {
          ll: {
            x: this.exteriorRing.bbox.ll.x,
            y: this.exteriorRing.bbox.ll.y
          },
          ur: {
            x: this.exteriorRing.bbox.ur.x,
            y: this.exteriorRing.bbox.ur.y
          }
        };
        this.interiorRings = [];
        for (let i = 1, iMax = geomPoly.length; i < iMax; i++) {
          const ring = new RingIn(geomPoly[i], this, false);
          if (ring.bbox.ll.x < this.bbox.ll.x) this.bbox.ll.x = ring.bbox.ll.x;
          if (ring.bbox.ll.y < this.bbox.ll.y) this.bbox.ll.y = ring.bbox.ll.y;
          if (ring.bbox.ur.x > this.bbox.ur.x) this.bbox.ur.x = ring.bbox.ur.x;
          if (ring.bbox.ur.y > this.bbox.ur.y) this.bbox.ur.y = ring.bbox.ur.y;
          this.interiorRings.push(ring);
        }
        this.multiPoly = multiPoly;
      }
      getSweepEvents() {
        const sweepEvents = this.exteriorRing.getSweepEvents();
        for (let i = 0, iMax = this.interiorRings.length; i < iMax; i++) {
          const ringSweepEvents = this.interiorRings[i].getSweepEvents();
          for (let j = 0, jMax = ringSweepEvents.length; j < jMax; j++) {
            sweepEvents.push(ringSweepEvents[j]);
          }
        }
        return sweepEvents;
      }
    }
    class MultiPolyIn {
      constructor(geom, isSubject) {
        if (!Array.isArray(geom)) {
          throw new Error("Input geometry is not a valid Polygon or MultiPolygon");
        }
        try {
          // if the input looks like a polygon, convert it to a multipolygon
          if (typeof geom[0][0][0] === "number") geom = [geom];
        } catch (ex) {
          // The input is either malformed or has empty arrays.
          // In either case, it will be handled later on.
        }
        this.polys = [];
        this.bbox = {
          ll: {
            x: Number.POSITIVE_INFINITY,
            y: Number.POSITIVE_INFINITY
          },
          ur: {
            x: Number.NEGATIVE_INFINITY,
            y: Number.NEGATIVE_INFINITY
          }
        };
        for (let i = 0, iMax = geom.length; i < iMax; i++) {
          const poly = new PolyIn(geom[i], this);
          if (poly.bbox.ll.x < this.bbox.ll.x) this.bbox.ll.x = poly.bbox.ll.x;
          if (poly.bbox.ll.y < this.bbox.ll.y) this.bbox.ll.y = poly.bbox.ll.y;
          if (poly.bbox.ur.x > this.bbox.ur.x) this.bbox.ur.x = poly.bbox.ur.x;
          if (poly.bbox.ur.y > this.bbox.ur.y) this.bbox.ur.y = poly.bbox.ur.y;
          this.polys.push(poly);
        }
        this.isSubject = isSubject;
      }
      getSweepEvents() {
        const sweepEvents = [];
        for (let i = 0, iMax = this.polys.length; i < iMax; i++) {
          const polySweepEvents = this.polys[i].getSweepEvents();
          for (let j = 0, jMax = polySweepEvents.length; j < jMax; j++) {
            sweepEvents.push(polySweepEvents[j]);
          }
        }
        return sweepEvents;
      }
    }

    class RingOut {
      /* Given the segments from the sweep line pass, compute & return a series
       * of closed rings from all the segments marked to be part of the result */
      static factory(allSegments) {
        const ringsOut = [];
        for (let i = 0, iMax = allSegments.length; i < iMax; i++) {
          const segment = allSegments[i];
          if (!segment.isInResult() || segment.ringOut) continue;
          let prevEvent = null;
          let event = segment.leftSE;
          let nextEvent = segment.rightSE;
          const events = [event];
          const startingPoint = event.point;
          const intersectionLEs = [];

          /* Walk the chain of linked events to form a closed ring */
          while (true) {
            prevEvent = event;
            event = nextEvent;
            events.push(event);

            /* Is the ring complete? */
            if (event.point === startingPoint) break;
            while (true) {
              const availableLEs = event.getAvailableLinkedEvents();

              /* Did we hit a dead end? This shouldn't happen.
               * Indicates some earlier part of the algorithm malfunctioned. */
              if (availableLEs.length === 0) {
                const firstPt = events[0].point;
                const lastPt = events[events.length - 1].point;
                throw new Error(`Unable to complete output ring starting at [${firstPt.x},` + ` ${firstPt.y}]. Last matching segment found ends at` + ` [${lastPt.x}, ${lastPt.y}].`);
              }

              /* Only one way to go, so cotinue on the path */
              if (availableLEs.length === 1) {
                nextEvent = availableLEs[0].otherSE;
                break;
              }

              /* We must have an intersection. Check for a completed loop */
              let indexLE = null;
              for (let j = 0, jMax = intersectionLEs.length; j < jMax; j++) {
                if (intersectionLEs[j].point === event.point) {
                  indexLE = j;
                  break;
                }
              }
              /* Found a completed loop. Cut that off and make a ring */
              if (indexLE !== null) {
                const intersectionLE = intersectionLEs.splice(indexLE)[0];
                const ringEvents = events.splice(intersectionLE.index);
                ringEvents.unshift(ringEvents[0].otherSE);
                ringsOut.push(new RingOut(ringEvents.reverse()));
                continue;
              }
              /* register the intersection */
              intersectionLEs.push({
                index: events.length,
                point: event.point
              });
              /* Choose the left-most option to continue the walk */
              const comparator = event.getLeftmostComparator(prevEvent);
              nextEvent = availableLEs.sort(comparator)[0].otherSE;
              break;
            }
          }
          ringsOut.push(new RingOut(events));
        }
        return ringsOut;
      }
      constructor(events) {
        this.events = events;
        for (let i = 0, iMax = events.length; i < iMax; i++) {
          events[i].segment.ringOut = this;
        }
        this.poly = null;
      }
      getGeom() {
        // Remove superfluous points (ie extra points along a straight line),
        let prevPt = this.events[0].point;
        const points = [prevPt];
        for (let i = 1, iMax = this.events.length - 1; i < iMax; i++) {
          const pt = this.events[i].point;
          const nextPt = this.events[i + 1].point;
          if (compareVectorAngles(pt, prevPt, nextPt) === 0) continue;
          points.push(pt);
          prevPt = pt;
        }

        // ring was all (within rounding error of angle calc) colinear points
        if (points.length === 1) return null;

        // check if the starting point is necessary
        const pt = points[0];
        const nextPt = points[1];
        if (compareVectorAngles(pt, prevPt, nextPt) === 0) points.shift();
        points.push(points[0]);
        const step = this.isExteriorRing() ? 1 : -1;
        const iStart = this.isExteriorRing() ? 0 : points.length - 1;
        const iEnd = this.isExteriorRing() ? points.length : -1;
        const orderedPoints = [];
        for (let i = iStart; i != iEnd; i += step) orderedPoints.push([points[i].x, points[i].y]);
        return orderedPoints;
      }
      isExteriorRing() {
        if (this._isExteriorRing === undefined) {
          const enclosing = this.enclosingRing();
          this._isExteriorRing = enclosing ? !enclosing.isExteriorRing() : true;
        }
        return this._isExteriorRing;
      }
      enclosingRing() {
        if (this._enclosingRing === undefined) {
          this._enclosingRing = this._calcEnclosingRing();
        }
        return this._enclosingRing;
      }

      /* Returns the ring that encloses this one, if any */
      _calcEnclosingRing() {
        // start with the ealier sweep line event so that the prevSeg
        // chain doesn't lead us inside of a loop of ours
        let leftMostEvt = this.events[0];
        for (let i = 1, iMax = this.events.length; i < iMax; i++) {
          const evt = this.events[i];
          if (SweepEvent.compare(leftMostEvt, evt) > 0) leftMostEvt = evt;
        }
        let prevSeg = leftMostEvt.segment.prevInResult();
        let prevPrevSeg = prevSeg ? prevSeg.prevInResult() : null;
        while (true) {
          // no segment found, thus no ring can enclose us
          if (!prevSeg) return null;

          // no segments below prev segment found, thus the ring of the prev
          // segment must loop back around and enclose us
          if (!prevPrevSeg) return prevSeg.ringOut;

          // if the two segments are of different rings, the ring of the prev
          // segment must either loop around us or the ring of the prev prev
          // seg, which would make us and the ring of the prev peers
          if (prevPrevSeg.ringOut !== prevSeg.ringOut) {
            if (prevPrevSeg.ringOut.enclosingRing() !== prevSeg.ringOut) {
              return prevSeg.ringOut;
            } else return prevSeg.ringOut.enclosingRing();
          }

          // two segments are from the same ring, so this was a penisula
          // of that ring. iterate downward, keep searching
          prevSeg = prevPrevSeg.prevInResult();
          prevPrevSeg = prevSeg ? prevSeg.prevInResult() : null;
        }
      }
    }
    class PolyOut {
      constructor(exteriorRing) {
        this.exteriorRing = exteriorRing;
        exteriorRing.poly = this;
        this.interiorRings = [];
      }
      addInterior(ring) {
        this.interiorRings.push(ring);
        ring.poly = this;
      }
      getGeom() {
        const geom = [this.exteriorRing.getGeom()];
        // exterior ring was all (within rounding error of angle calc) colinear points
        if (geom[0] === null) return null;
        for (let i = 0, iMax = this.interiorRings.length; i < iMax; i++) {
          const ringGeom = this.interiorRings[i].getGeom();
          // interior ring was all (within rounding error of angle calc) colinear points
          if (ringGeom === null) continue;
          geom.push(ringGeom);
        }
        return geom;
      }
    }
    class MultiPolyOut {
      constructor(rings) {
        this.rings = rings;
        this.polys = this._composePolys(rings);
      }
      getGeom() {
        const geom = [];
        for (let i = 0, iMax = this.polys.length; i < iMax; i++) {
          const polyGeom = this.polys[i].getGeom();
          // exterior ring was all (within rounding error of angle calc) colinear points
          if (polyGeom === null) continue;
          geom.push(polyGeom);
        }
        return geom;
      }
      _composePolys(rings) {
        const polys = [];
        for (let i = 0, iMax = rings.length; i < iMax; i++) {
          const ring = rings[i];
          if (ring.poly) continue;
          if (ring.isExteriorRing()) polys.push(new PolyOut(ring));else {
            const enclosingRing = ring.enclosingRing();
            if (!enclosingRing.poly) polys.push(new PolyOut(enclosingRing));
            enclosingRing.poly.addInterior(ring);
          }
        }
        return polys;
      }
    }

    /**
     * NOTE:  We must be careful not to change any segments while
     *        they are in the SplayTree. AFAIK, there's no way to tell
     *        the tree to rebalance itself - thus before splitting
     *        a segment that's in the tree, we remove it from the tree,
     *        do the split, then re-insert it. (Even though splitting a
     *        segment *shouldn't* change its correct position in the
     *        sweep line tree, the reality is because of rounding errors,
     *        it sometimes does.)
     */

    class SweepLine {
      constructor(queue) {
        let comparator = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : Segment.compare;
        this.queue = queue;
        this.tree = new Tree(comparator);
        this.segments = [];
      }
      process(event) {
        const segment = event.segment;
        const newEvents = [];

        // if we've already been consumed by another segment,
        // clean up our body parts and get out
        if (event.consumedBy) {
          if (event.isLeft) this.queue.remove(event.otherSE);else this.tree.remove(segment);
          return newEvents;
        }
        const node = event.isLeft ? this.tree.add(segment) : this.tree.find(segment);
        if (!node) throw new Error(`Unable to find segment #${segment.id} ` + `[${segment.leftSE.point.x}, ${segment.leftSE.point.y}] -> ` + `[${segment.rightSE.point.x}, ${segment.rightSE.point.y}] ` + "in SweepLine tree.");
        let prevNode = node;
        let nextNode = node;
        let prevSeg = undefined;
        let nextSeg = undefined;

        // skip consumed segments still in tree
        while (prevSeg === undefined) {
          prevNode = this.tree.prev(prevNode);
          if (prevNode === null) prevSeg = null;else if (prevNode.key.consumedBy === undefined) prevSeg = prevNode.key;
        }

        // skip consumed segments still in tree
        while (nextSeg === undefined) {
          nextNode = this.tree.next(nextNode);
          if (nextNode === null) nextSeg = null;else if (nextNode.key.consumedBy === undefined) nextSeg = nextNode.key;
        }
        if (event.isLeft) {
          // Check for intersections against the previous segment in the sweep line
          let prevMySplitter = null;
          if (prevSeg) {
            const prevInter = prevSeg.getIntersection(segment);
            if (prevInter !== null) {
              if (!segment.isAnEndpoint(prevInter)) prevMySplitter = prevInter;
              if (!prevSeg.isAnEndpoint(prevInter)) {
                const newEventsFromSplit = this._splitSafely(prevSeg, prevInter);
                for (let i = 0, iMax = newEventsFromSplit.length; i < iMax; i++) {
                  newEvents.push(newEventsFromSplit[i]);
                }
              }
            }
          }

          // Check for intersections against the next segment in the sweep line
          let nextMySplitter = null;
          if (nextSeg) {
            const nextInter = nextSeg.getIntersection(segment);
            if (nextInter !== null) {
              if (!segment.isAnEndpoint(nextInter)) nextMySplitter = nextInter;
              if (!nextSeg.isAnEndpoint(nextInter)) {
                const newEventsFromSplit = this._splitSafely(nextSeg, nextInter);
                for (let i = 0, iMax = newEventsFromSplit.length; i < iMax; i++) {
                  newEvents.push(newEventsFromSplit[i]);
                }
              }
            }
          }

          // For simplicity, even if we find more than one intersection we only
          // spilt on the 'earliest' (sweep-line style) of the intersections.
          // The other intersection will be handled in a future process().
          if (prevMySplitter !== null || nextMySplitter !== null) {
            let mySplitter = null;
            if (prevMySplitter === null) mySplitter = nextMySplitter;else if (nextMySplitter === null) mySplitter = prevMySplitter;else {
              const cmpSplitters = SweepEvent.comparePoints(prevMySplitter, nextMySplitter);
              mySplitter = cmpSplitters <= 0 ? prevMySplitter : nextMySplitter;
            }

            // Rounding errors can cause changes in ordering,
            // so remove afected segments and right sweep events before splitting
            this.queue.remove(segment.rightSE);
            newEvents.push(segment.rightSE);
            const newEventsFromSplit = segment.split(mySplitter);
            for (let i = 0, iMax = newEventsFromSplit.length; i < iMax; i++) {
              newEvents.push(newEventsFromSplit[i]);
            }
          }
          if (newEvents.length > 0) {
            // We found some intersections, so re-do the current event to
            // make sure sweep line ordering is totally consistent for later
            // use with the segment 'prev' pointers
            this.tree.remove(segment);
            newEvents.push(event);
          } else {
            // done with left event
            this.segments.push(segment);
            segment.prev = prevSeg;
          }
        } else {
          // event.isRight

          // since we're about to be removed from the sweep line, check for
          // intersections between our previous and next segments
          if (prevSeg && nextSeg) {
            const inter = prevSeg.getIntersection(nextSeg);
            if (inter !== null) {
              if (!prevSeg.isAnEndpoint(inter)) {
                const newEventsFromSplit = this._splitSafely(prevSeg, inter);
                for (let i = 0, iMax = newEventsFromSplit.length; i < iMax; i++) {
                  newEvents.push(newEventsFromSplit[i]);
                }
              }
              if (!nextSeg.isAnEndpoint(inter)) {
                const newEventsFromSplit = this._splitSafely(nextSeg, inter);
                for (let i = 0, iMax = newEventsFromSplit.length; i < iMax; i++) {
                  newEvents.push(newEventsFromSplit[i]);
                }
              }
            }
          }
          this.tree.remove(segment);
        }
        return newEvents;
      }

      /* Safely split a segment that is currently in the datastructures
       * IE - a segment other than the one that is currently being processed. */
      _splitSafely(seg, pt) {
        // Rounding errors can cause changes in ordering,
        // so remove afected segments and right sweep events before splitting
        // removeNode() doesn't work, so have re-find the seg
        // https://github.com/w8r/splay-tree/pull/5
        this.tree.remove(seg);
        const rightSE = seg.rightSE;
        this.queue.remove(rightSE);
        const newEvents = seg.split(pt);
        newEvents.push(rightSE);
        // splitting can trigger consumption
        if (seg.consumedBy === undefined) this.tree.add(seg);
        return newEvents;
      }
    }

    // Limits on iterative processes to prevent infinite loops - usually caused by floating-point math round-off errors.
    const POLYGON_CLIPPING_MAX_QUEUE_SIZE = typeof process !== "undefined" && process.env.POLYGON_CLIPPING_MAX_QUEUE_SIZE || 1000000;
    const POLYGON_CLIPPING_MAX_SWEEPLINE_SEGMENTS = typeof process !== "undefined" && process.env.POLYGON_CLIPPING_MAX_SWEEPLINE_SEGMENTS || 1000000;
    class Operation {
      run(type, geom, moreGeoms) {
        operation.type = type;
        rounder.reset();

        /* Convert inputs to MultiPoly objects */
        const multipolys = [new MultiPolyIn(geom, true)];
        for (let i = 0, iMax = moreGeoms.length; i < iMax; i++) {
          multipolys.push(new MultiPolyIn(moreGeoms[i], false));
        }
        operation.numMultiPolys = multipolys.length;

        /* BBox optimization for difference operation
         * If the bbox of a multipolygon that's part of the clipping doesn't
         * intersect the bbox of the subject at all, we can just drop that
         * multiploygon. */
        if (operation.type === "difference") {
          // in place removal
          const subject = multipolys[0];
          let i = 1;
          while (i < multipolys.length) {
            if (getBboxOverlap(multipolys[i].bbox, subject.bbox) !== null) i++;else multipolys.splice(i, 1);
          }
        }

        /* BBox optimization for intersection operation
         * If we can find any pair of multipolygons whose bbox does not overlap,
         * then the result will be empty. */
        if (operation.type === "intersection") {
          // TODO: this is O(n^2) in number of polygons. By sorting the bboxes,
          //       it could be optimized to O(n * ln(n))
          for (let i = 0, iMax = multipolys.length; i < iMax; i++) {
            const mpA = multipolys[i];
            for (let j = i + 1, jMax = multipolys.length; j < jMax; j++) {
              if (getBboxOverlap(mpA.bbox, multipolys[j].bbox) === null) return [];
            }
          }
        }

        /* Put segment endpoints in a priority queue */
        const queue = new Tree(SweepEvent.compare);
        for (let i = 0, iMax = multipolys.length; i < iMax; i++) {
          const sweepEvents = multipolys[i].getSweepEvents();
          for (let j = 0, jMax = sweepEvents.length; j < jMax; j++) {
            queue.insert(sweepEvents[j]);
            if (queue.size > POLYGON_CLIPPING_MAX_QUEUE_SIZE) {
              // prevents an infinite loop, an otherwise common manifestation of bugs
              throw new Error("Infinite loop when putting segment endpoints in a priority queue " + "(queue size too big).");
            }
          }
        }

        /* Pass the sweep line over those endpoints */
        const sweepLine = new SweepLine(queue);
        let prevQueueSize = queue.size;
        let node = queue.pop();
        while (node) {
          const evt = node.key;
          if (queue.size === prevQueueSize) {
            // prevents an infinite loop, an otherwise common manifestation of bugs
            const seg = evt.segment;
            throw new Error(`Unable to pop() ${evt.isLeft ? "left" : "right"} SweepEvent ` + `[${evt.point.x}, ${evt.point.y}] from segment #${seg.id} ` + `[${seg.leftSE.point.x}, ${seg.leftSE.point.y}] -> ` + `[${seg.rightSE.point.x}, ${seg.rightSE.point.y}] from queue.`);
          }
          if (queue.size > POLYGON_CLIPPING_MAX_QUEUE_SIZE) {
            // prevents an infinite loop, an otherwise common manifestation of bugs
            throw new Error("Infinite loop when passing sweep line over endpoints " + "(queue size too big).");
          }
          if (sweepLine.segments.length > POLYGON_CLIPPING_MAX_SWEEPLINE_SEGMENTS) {
            // prevents an infinite loop, an otherwise common manifestation of bugs
            throw new Error("Infinite loop when passing sweep line over endpoints " + "(too many sweep line segments).");
          }
          const newEvents = sweepLine.process(evt);
          for (let i = 0, iMax = newEvents.length; i < iMax; i++) {
            const evt = newEvents[i];
            if (evt.consumedBy === undefined) queue.insert(evt);
          }
          prevQueueSize = queue.size;
          node = queue.pop();
        }

        // free some memory we don't need anymore
        rounder.reset();

        /* Collect and compile segments we're keeping into a multipolygon */
        const ringsOut = RingOut.factory(sweepLine.segments);
        const result = new MultiPolyOut(ringsOut);
        return result.getGeom();
      }
    }

    // singleton available by import
    const operation = new Operation();

    const union = function (geom) {
      for (var _len = arguments.length, moreGeoms = new Array(_len > 1 ? _len - 1 : 0), _key = 1; _key < _len; _key++) {
        moreGeoms[_key - 1] = arguments[_key];
      }
      return operation.run("union", geom, moreGeoms);
    };
    const intersection = function (geom) {
      for (var _len2 = arguments.length, moreGeoms = new Array(_len2 > 1 ? _len2 - 1 : 0), _key2 = 1; _key2 < _len2; _key2++) {
        moreGeoms[_key2 - 1] = arguments[_key2];
      }
      return operation.run("intersection", geom, moreGeoms);
    };
    const xor = function (geom) {
      for (var _len3 = arguments.length, moreGeoms = new Array(_len3 > 1 ? _len3 - 1 : 0), _key3 = 1; _key3 < _len3; _key3++) {
        moreGeoms[_key3 - 1] = arguments[_key3];
      }
      return operation.run("xor", geom, moreGeoms);
    };
    const difference = function (subjectGeom) {
      for (var _len4 = arguments.length, clippingGeoms = new Array(_len4 > 1 ? _len4 - 1 : 0), _key4 = 1; _key4 < _len4; _key4++) {
        clippingGeoms[_key4 - 1] = arguments[_key4];
      }
      return operation.run("difference", subjectGeom, clippingGeoms);
    };
    var index = {
      union: union,
      intersection: intersection,
      xor: xor,
      difference: difference
    };

    return index;

}));