chartx/dist/utils/hull/convex.js

Data Visualization Chart Library

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = void 0;
function _cross(o, a, b) {
  return (a[0] - o[0]) * (b[1] - o[1]) - (a[1] - o[1]) * (b[0] - o[0]);
}
function _upperTangent(pointset) {
  var lower = [];
  for (var l = 0; l < pointset.length; l++) {
    while (lower.length >= 2 && _cross(lower[lower.length - 2], lower[lower.length - 1], pointset[l]) <= 0) {
      lower.pop();
    }
    lower.push(pointset[l]);
  }
  lower.pop();
  return lower;
}
function _lowerTangent(pointset) {
  var reversed = pointset.reverse(),
    upper = [];
  for (var u = 0; u < reversed.length; u++) {
    while (upper.length >= 2 && _cross(upper[upper.length - 2], upper[upper.length - 1], reversed[u]) <= 0) {
      upper.pop();
    }
    upper.push(reversed[u]);
  }
  upper.pop();
  return upper;
}

// pointset has to be sorted by X
function convex(pointset) {
  var upper = _upperTangent(pointset),
    lower = _lowerTangent(pointset);
  var convex = lower.concat(upper);
  convex.push(pointset[0]);
  return convex;
}
var _default = exports.default = convex;