@visx/vendor/vendor-cjs/d3-geo/src/clip/rejoin.js

vendored packages for visx

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = _default;
var _pointEqual = _interopRequireDefault(require("../pointEqual.js"));
var _math = require("../math.js");
function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
function Intersection(point, points, other, entry) {
  this.x = point;
  this.z = points;
  this.o = other; // another intersection
  this.e = entry; // is an entry?
  this.v = false; // visited
  this.n = this.p = null; // next & previous
}

// A generalized polygon clipping algorithm: given a polygon that has been cut
// into its visible line segments, and rejoins the segments by interpolating
// along the clip edge.
function _default(segments, compareIntersection, startInside, interpolate, stream) {
  var subject = [],
    clip = [],
    i,
    n;
  segments.forEach(function (segment) {
    if ((n = segment.length - 1) <= 0) return;
    var n,
      p0 = segment[0],
      p1 = segment[n],
      x;
    if ((0, _pointEqual.default)(p0, p1)) {
      if (!p0[2] && !p1[2]) {
        stream.lineStart();
        for (i = 0; i < n; ++i) stream.point((p0 = segment[i])[0], p0[1]);
        stream.lineEnd();
        return;
      }
      // handle degenerate cases by moving the point
      p1[0] += 2 * _math.epsilon;
    }
    subject.push(x = new Intersection(p0, segment, null, true));
    clip.push(x.o = new Intersection(p0, null, x, false));
    subject.push(x = new Intersection(p1, segment, null, false));
    clip.push(x.o = new Intersection(p1, null, x, true));
  });
  if (!subject.length) return;
  clip.sort(compareIntersection);
  link(subject);
  link(clip);
  for (i = 0, n = clip.length; i < n; ++i) {
    clip[i].e = startInside = !startInside;
  }
  var start = subject[0],
    points,
    point;
  while (1) {
    // Find first unvisited intersection.
    var current = start,
      isSubject = true;
    while (current.v) if ((current = current.n) === start) return;
    points = current.z;
    stream.lineStart();
    do {
      current.v = current.o.v = true;
      if (current.e) {
        if (isSubject) {
          for (i = 0, n = points.length; i < n; ++i) stream.point((point = points[i])[0], point[1]);
        } else {
          interpolate(current.x, current.n.x, 1, stream);
        }
        current = current.n;
      } else {
        if (isSubject) {
          points = current.p.z;
          for (i = points.length - 1; i >= 0; --i) stream.point((point = points[i])[0], point[1]);
        } else {
          interpolate(current.x, current.p.x, -1, stream);
        }
        current = current.p;
      }
      current = current.o;
      points = current.z;
      isSubject = !isSubject;
    } while (!current.v);
    stream.lineEnd();
  }
}
function link(array) {
  if (!(n = array.length)) return;
  var n,
    i = 0,
    a = array[0],
    b;
  while (++i < n) {
    a.n = b = array[i];
    b.p = a;
    a = b;
  }
  a.n = b = array[0];
  b.p = a;
}