"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.Bezier = void 0;
// math-inlining.
const {
  abs,
  cos,
  sin,
  acos,
  atan2,
  sqrt,
  pow
} = Math; // cube root function yielding real roots

function crt(v) {
  return v < 0 ? -pow(-v, 1 / 3) : pow(v, 1 / 3);
} // trig constants


const pi = Math.PI,
      tau = 2 * pi,
      quart = pi / 2,
      // float precision significant decimal
epsilon = 0.000001,
      // extremas used in bbox calculation and similar algorithms
nMax = Number.MAX_SAFE_INTEGER || 9007199254740991,
      nMin = Number.MIN_SAFE_INTEGER || -9007199254740991,
      // a zero coordinate, which is surprisingly useful
ZERO = {
  x: 0,
  y: 0,
  z: 0
}; // Bezier utility functions

const utils = {
  // Legendre-Gauss abscissae with n=24 (x_i values, defined at i=n as the roots of the nth order Legendre polynomial Pn(x))
  Tvalues: [-0.0640568928626056260850430826247450385909, 0.0640568928626056260850430826247450385909, -0.1911188674736163091586398207570696318404, 0.1911188674736163091586398207570696318404, -0.3150426796961633743867932913198102407864, 0.3150426796961633743867932913198102407864, -0.4337935076260451384870842319133497124524, 0.4337935076260451384870842319133497124524, -0.5454214713888395356583756172183723700107, 0.5454214713888395356583756172183723700107, -0.6480936519369755692524957869107476266696, 0.6480936519369755692524957869107476266696, -0.7401241915785543642438281030999784255232, 0.7401241915785543642438281030999784255232, -0.8200019859739029219539498726697452080761, 0.8200019859739029219539498726697452080761, -0.8864155270044010342131543419821967550873, 0.8864155270044010342131543419821967550873, -0.9382745520027327585236490017087214496548, 0.9382745520027327585236490017087214496548, -0.9747285559713094981983919930081690617411, 0.9747285559713094981983919930081690617411, -0.9951872199970213601799974097007368118745, 0.9951872199970213601799974097007368118745],
  // Legendre-Gauss weights with n=24 (w_i values, defined by a function linked to in the Bezier primer article)
  Cvalues: [0.1279381953467521569740561652246953718517, 0.1279381953467521569740561652246953718517, 0.1258374563468282961213753825111836887264, 0.1258374563468282961213753825111836887264, 0.121670472927803391204463153476262425607, 0.121670472927803391204463153476262425607, 0.1155056680537256013533444839067835598622, 0.1155056680537256013533444839067835598622, 0.1074442701159656347825773424466062227946, 0.1074442701159656347825773424466062227946, 0.0976186521041138882698806644642471544279, 0.0976186521041138882698806644642471544279, 0.086190161531953275917185202983742667185, 0.086190161531953275917185202983742667185, 0.0733464814110803057340336152531165181193, 0.0733464814110803057340336152531165181193, 0.0592985849154367807463677585001085845412, 0.0592985849154367807463677585001085845412, 0.0442774388174198061686027482113382288593, 0.0442774388174198061686027482113382288593, 0.0285313886289336631813078159518782864491, 0.0285313886289336631813078159518782864491, 0.0123412297999871995468056670700372915759, 0.0123412297999871995468056670700372915759],
  arcfn: function (t, derivativeFn) {
    const d = derivativeFn(t);
    let l = d.x * d.x + d.y * d.y;

    if (typeof d.z !== "undefined") {
      l += d.z * d.z;
    }

    return sqrt(l);
  },
  compute: function (t, points, _3d) {
    // shortcuts
    if (t === 0) {
      points[0].t = 0;
      return points[0];
    }

    const order = points.length - 1;

    if (t === 1) {
      points[order].t = 1;
      return points[order];
    }

    const mt = 1 - t;
    let p = points; // constant?

    if (order === 0) {
      points[0].t = t;
      return points[0];
    } // linear?


    if (order === 1) {
      const ret = {
        x: mt * p[0].x + t * p[1].x,
        y: mt * p[0].y + t * p[1].y,
        t: t
      };

      if (_3d) {
        ret.z = mt * p[0].z + t * p[1].z;
      }

      return ret;
    } // quadratic/cubic curve?


    if (order < 4) {
      let mt2 = mt * mt,
          t2 = t * t,
          a,
          b,
          c,
          d = 0;

      if (order === 2) {
        p = [p[0], p[1], p[2], ZERO];
        a = mt2;
        b = mt * t * 2;
        c = t2;
      } else if (order === 3) {
        a = mt2 * mt;
        b = mt2 * t * 3;
        c = mt * t2 * 3;
        d = t * t2;
      }

      const ret = {
        x: a * p[0].x + b * p[1].x + c * p[2].x + d * p[3].x,
        y: a * p[0].y + b * p[1].y + c * p[2].y + d * p[3].y,
        t: t
      };

      if (_3d) {
        ret.z = a * p[0].z + b * p[1].z + c * p[2].z + d * p[3].z;
      }

      return ret;
    } // higher order curves: use de Casteljau's computation


    const dCpts = JSON.parse(JSON.stringify(points));

    while (dCpts.length > 1) {
      for (let i = 0; i < dCpts.length - 1; i++) {
        dCpts[i] = {
          x: dCpts[i].x + (dCpts[i + 1].x - dCpts[i].x) * t,
          y: dCpts[i].y + (dCpts[i + 1].y - dCpts[i].y) * t
        };

        if (typeof dCpts[i].z !== "undefined") {
          dCpts[i] = dCpts[i].z + (dCpts[i + 1].z - dCpts[i].z) * t;
        }
      }

      dCpts.splice(dCpts.length - 1, 1);
    }

    dCpts[0].t = t;
    return dCpts[0];
  },
  computeWithRatios: function (t, points, ratios, _3d) {
    const mt = 1 - t,
          r = ratios,
          p = points;
    let f1 = r[0],
        f2 = r[1],
        f3 = r[2],
        f4 = r[3],
        d; // spec for linear

    f1 *= mt;
    f2 *= t;

    if (p.length === 2) {
      d = f1 + f2;
      return {
        x: (f1 * p[0].x + f2 * p[1].x) / d,
        y: (f1 * p[0].y + f2 * p[1].y) / d,
        z: !_3d ? false : (f1 * p[0].z + f2 * p[1].z) / d,
        t: t
      };
    } // upgrade to quadratic


    f1 *= mt;
    f2 *= 2 * mt;
    f3 *= t * t;

    if (p.length === 3) {
      d = f1 + f2 + f3;
      return {
        x: (f1 * p[0].x + f2 * p[1].x + f3 * p[2].x) / d,
        y: (f1 * p[0].y + f2 * p[1].y + f3 * p[2].y) / d,
        z: !_3d ? false : (f1 * p[0].z + f2 * p[1].z + f3 * p[2].z) / d,
        t: t
      };
    } // upgrade to cubic


    f1 *= mt;
    f2 *= 1.5 * mt;
    f3 *= 3 * mt;
    f4 *= t * t * t;

    if (p.length === 4) {
      d = f1 + f2 + f3 + f4;
      return {
        x: (f1 * p[0].x + f2 * p[1].x + f3 * p[2].x + f4 * p[3].x) / d,
        y: (f1 * p[0].y + f2 * p[1].y + f3 * p[2].y + f4 * p[3].y) / d,
        z: !_3d ? false : (f1 * p[0].z + f2 * p[1].z + f3 * p[2].z + f4 * p[3].z) / d,
        t: t
      };
    }
  },
  derive: function (points, _3d) {
    const dpoints = [];

    for (let p = points, d = p.length, c = d - 1; d > 1; d--, c--) {
      const list = [];

      for (let j = 0, dpt; j < c; j++) {
        dpt = {
          x: c * (p[j + 1].x - p[j].x),
          y: c * (p[j + 1].y - p[j].y)
        };

        if (_3d) {
          dpt.z = c * (p[j + 1].z - p[j].z);
        }

        list.push(dpt);
      }

      dpoints.push(list);
      p = list;
    }

    return dpoints;
  },
  between: function (v, m, M) {
    return m <= v && v <= M || utils.approximately(v, m) || utils.approximately(v, M);
  },
  approximately: function (a, b, precision) {
    return abs(a - b) <= (precision || epsilon);
  },
  length: function (derivativeFn) {
    const z = 0.5,
          len = utils.Tvalues.length;
    let sum = 0;

    for (let i = 0, t; i < len; i++) {
      t = z * utils.Tvalues[i] + z;
      sum += utils.Cvalues[i] * utils.arcfn(t, derivativeFn);
    }

    return z * sum;
  },
  map: function (v, ds, de, ts, te) {
    const d1 = de - ds,
          d2 = te - ts,
          v2 = v - ds,
          r = v2 / d1;
    return ts + d2 * r;
  },
  lerp: function (r, v1, v2) {
    const ret = {
      x: v1.x + r * (v2.x - v1.x),
      y: v1.y + r * (v2.y - v1.y)
    };

    if (!!v1.z && !!v2.z) {
      ret.z = v1.z + r * (v2.z - v1.z);
    }

    return ret;
  },
  pointToString: function (p) {
    let s = p.x + "/" + p.y;

    if (typeof p.z !== "undefined") {
      s += "/" + p.z;
    }

    return s;
  },
  pointsToString: function (points) {
    return "[" + points.map(utils.pointToString).join(", ") + "]";
  },
  copy: function (obj) {
    return JSON.parse(JSON.stringify(obj));
  },
  angle: function (o, v1, v2) {
    const dx1 = v1.x - o.x,
          dy1 = v1.y - o.y,
          dx2 = v2.x - o.x,
          dy2 = v2.y - o.y,
          cross = dx1 * dy2 - dy1 * dx2,
          dot = dx1 * dx2 + dy1 * dy2;
    return atan2(cross, dot);
  },
  // round as string, to avoid rounding errors
  round: function (v, d) {
    const s = "" + v;
    const pos = s.indexOf(".");
    return parseFloat(s.substring(0, pos + 1 + d));
  },
  dist: function (p1, p2) {
    const dx = p1.x - p2.x,
          dy = p1.y - p2.y;
    return sqrt(dx * dx + dy * dy);
  },
  closest: function (LUT, point) {
    let mdist = pow(2, 63),
        mpos,
        d;
    LUT.forEach(function (p, idx) {
      d = utils.dist(point, p);

      if (d < mdist) {
        mdist = d;
        mpos = idx;
      }
    });
    return {
      mdist: mdist,
      mpos: mpos
    };
  },
  abcratio: function (t, n) {
    // see ratio(t) note on http://pomax.github.io/bezierinfo/#abc
    if (n !== 2 && n !== 3) {
      return false;
    }

    if (typeof t === "undefined") {
      t = 0.5;
    } else if (t === 0 || t === 1) {
      return t;
    }

    const bottom = pow(t, n) + pow(1 - t, n),
          top = bottom - 1;
    return abs(top / bottom);
  },
  projectionratio: function (t, n) {
    // see u(t) note on http://pomax.github.io/bezierinfo/#abc
    if (n !== 2 && n !== 3) {
      return false;
    }

    if (typeof t === "undefined") {
      t = 0.5;
    } else if (t === 0 || t === 1) {
      return t;
    }

    const top = pow(1 - t, n),
          bottom = pow(t, n) + top;
    return top / bottom;
  },
  lli8: function (x1, y1, x2, y2, x3, y3, x4, y4) {
    const nx = (x1 * y2 - y1 * x2) * (x3 - x4) - (x1 - x2) * (x3 * y4 - y3 * x4),
          ny = (x1 * y2 - y1 * x2) * (y3 - y4) - (y1 - y2) * (x3 * y4 - y3 * x4),
          d = (x1 - x2) * (y3 - y4) - (y1 - y2) * (x3 - x4);

    if (d == 0) {
      return false;
    }

    return {
      x: nx / d,
      y: ny / d
    };
  },
  lli4: function (p1, p2, p3, p4) {
    const x1 = p1.x,
          y1 = p1.y,
          x2 = p2.x,
          y2 = p2.y,
          x3 = p3.x,
          y3 = p3.y,
          x4 = p4.x,
          y4 = p4.y;
    return utils.lli8(x1, y1, x2, y2, x3, y3, x4, y4);
  },
  lli: function (v1, v2) {
    return utils.lli4(v1, v1.c, v2, v2.c);
  },
  makeline: function (p1, p2) {
    const x1 = p1.x,
          y1 = p1.y,
          x2 = p2.x,
          y2 = p2.y,
          dx = (x2 - x1) / 3,
          dy = (y2 - y1) / 3;
    return new Bezier(x1, y1, x1 + dx, y1 + dy, x1 + 2 * dx, y1 + 2 * dy, x2, y2);
  },
  findbbox: function (sections) {
    let mx = nMax,
        my = nMax,
        MX = nMin,
        MY = nMin;
    sections.forEach(function (s) {
      const bbox = s.bbox();
      if (mx > bbox.x.min) mx = bbox.x.min;
      if (my > bbox.y.min) my = bbox.y.min;
      if (MX < bbox.x.max) MX = bbox.x.max;
      if (MY < bbox.y.max) MY = bbox.y.max;
    });
    return {
      x: {
        min: mx,
        mid: (mx + MX) / 2,
        max: MX,
        size: MX - mx
      },
      y: {
        min: my,
        mid: (my + MY) / 2,
        max: MY,
        size: MY - my
      }
    };
  },
  shapeintersections: function (s1, bbox1, s2, bbox2, curveIntersectionThreshold) {
    if (!utils.bboxoverlap(bbox1, bbox2)) return [];
    const intersections = [];
    const a1 = [s1.startcap, s1.forward, s1.back, s1.endcap];
    const a2 = [s2.startcap, s2.forward, s2.back, s2.endcap];
    a1.forEach(function (l1) {
      if (l1.virtual) return;
      a2.forEach(function (l2) {
        if (l2.virtual) return;
        const iss = l1.intersects(l2, curveIntersectionThreshold);

        if (iss.length > 0) {
          iss.c1 = l1;
          iss.c2 = l2;
          iss.s1 = s1;
          iss.s2 = s2;
          intersections.push(iss);
        }
      });
    });
    return intersections;
  },
  makeshape: function (forward, back, curveIntersectionThreshold) {
    const bpl = back.points.length;
    const fpl = forward.points.length;
    const start = utils.makeline(back.points[bpl - 1], forward.points[0]);
    const end = utils.makeline(forward.points[fpl - 1], back.points[0]);
    const shape = {
      startcap: start,
      forward: forward,
      back: back,
      endcap: end,
      bbox: utils.findbbox([start, forward, back, end])
    };

    shape.intersections = function (s2) {
      return utils.shapeintersections(shape, shape.bbox, s2, s2.bbox, curveIntersectionThreshold);
    };

    return shape;
  },
  getminmax: function (curve, d, list) {
    if (!list) return {
      min: 0,
      max: 0
    };
    let min = nMax,
        max = nMin,
        t,
        c;

    if (list.indexOf(0) === -1) {
      list = [0].concat(list);
    }

    if (list.indexOf(1) === -1) {
      list.push(1);
    }

    for (let i = 0, len = list.length; i < len; i++) {
      t = list[i];
      c = curve.get(t);

      if (c[d] < min) {
        min = c[d];
      }

      if (c[d] > max) {
        max = c[d];
      }
    }

    return {
      min: min,
      mid: (min + max) / 2,
      max: max,
      size: max - min
    };
  },
  align: function (points, line) {
    const tx = line.p1.x,
          ty = line.p1.y,
          a = -atan2(line.p2.y - ty, line.p2.x - tx),
          d = function (v) {
      return {
        x: (v.x - tx) * cos(a) - (v.y - ty) * sin(a),
        y: (v.x - tx) * sin(a) + (v.y - ty) * cos(a)
      };
    };

    return points.map(d);
  },
  roots: function (points, line) {
    line = line || {
      p1: {
        x: 0,
        y: 0
      },
      p2: {
        x: 1,
        y: 0
      }
    };
    const order = points.length - 1;
    const aligned = utils.align(points, line);

    const reduce = function (t) {
      return 0 <= t && t <= 1;
    };

    if (order === 2) {
      const a = aligned[0].y,
            b = aligned[1].y,
            c = aligned[2].y,
            d = a - 2 * b + c;

      if (d !== 0) {
        const m1 = -sqrt(b * b - a * c),
              m2 = -a + b,
              v1 = -(m1 + m2) / d,
              v2 = -(-m1 + m2) / d;
        return [v1, v2].filter(reduce);
      } else if (b !== c && d === 0) {
        return [(2 * b - c) / (2 * b - 2 * c)].filter(reduce);
      }

      return [];
    } // see http://www.trans4mind.com/personal_development/mathematics/polynomials/cubicAlgebra.htm


    const pa = aligned[0].y,
          pb = aligned[1].y,
          pc = aligned[2].y,
          pd = aligned[3].y;
    let d = -pa + 3 * pb - 3 * pc + pd,
        a = 3 * pa - 6 * pb + 3 * pc,
        b = -3 * pa + 3 * pb,
        c = pa;

    if (utils.approximately(d, 0)) {
      // this is not a cubic curve.
      if (utils.approximately(a, 0)) {
        // in fact, this is not a quadratic curve either.
        if (utils.approximately(b, 0)) {
          // in fact in fact, there are no solutions.
          return [];
        } // linear solution:


        return [-c / b].filter(reduce);
      } // quadratic solution:


      const q = sqrt(b * b - 4 * a * c),
            a2 = 2 * a;
      return [(q - b) / a2, (-b - q) / a2].filter(reduce);
    } // at this point, we know we need a cubic solution:


    a /= d;
    b /= d;
    c /= d;
    const p = (3 * b - a * a) / 3,
          p3 = p / 3,
          q = (2 * a * a * a - 9 * a * b + 27 * c) / 27,
          q2 = q / 2,
          discriminant = q2 * q2 + p3 * p3 * p3;
    let u1, v1, x1, x2, x3;

    if (discriminant < 0) {
      const mp3 = -p / 3,
            mp33 = mp3 * mp3 * mp3,
            r = sqrt(mp33),
            t = -q / (2 * r),
            cosphi = t < -1 ? -1 : t > 1 ? 1 : t,
            phi = acos(cosphi),
            crtr = crt(r),
            t1 = 2 * crtr;
      x1 = t1 * cos(phi / 3) - a / 3;
      x2 = t1 * cos((phi + tau) / 3) - a / 3;
      x3 = t1 * cos((phi + 2 * tau) / 3) - a / 3;
      return [x1, x2, x3].filter(reduce);
    } else if (discriminant === 0) {
      u1 = q2 < 0 ? crt(-q2) : -crt(q2);
      x1 = 2 * u1 - a / 3;
      x2 = -u1 - a / 3;
      return [x1, x2].filter(reduce);
    } else {
      const sd = sqrt(discriminant);
      u1 = crt(-q2 + sd);
      v1 = crt(q2 + sd);
      return [u1 - v1 - a / 3].filter(reduce);
    }
  },
  droots: function (p) {
    // quadratic roots are easy
    if (p.length === 3) {
      const a = p[0],
            b = p[1],
            c = p[2],
            d = a - 2 * b + c;

      if (d !== 0) {
        const m1 = -sqrt(b * b - a * c),
              m2 = -a + b,
              v1 = -(m1 + m2) / d,
              v2 = -(-m1 + m2) / d;
        return [v1, v2];
      } else if (b !== c && d === 0) {
        return [(2 * b - c) / (2 * (b - c))];
      }

      return [];
    } // linear roots are even easier


    if (p.length === 2) {
      const a = p[0],
            b = p[1];

      if (a !== b) {
        return [a / (a - b)];
      }

      return [];
    }

    return [];
  },
  curvature: function (t, d1, d2, _3d, kOnly) {
    let num,
        dnm,
        adk,
        dk,
        k = 0,
        r = 0; //
    // We're using the following formula for curvature:
    //
    //              x'y" - y'x"
    //   k(t) = ------------------
    //           (x'² + y'²)^(3/2)
    //
    // from https://en.wikipedia.org/wiki/Radius_of_curvature#Definition
    //
    // With it corresponding 3D counterpart:
    //
    //          sqrt( (y'z" - y"z')² + (z'x" - z"x')² + (x'y" - x"y')²)
    //   k(t) = -------------------------------------------------------
    //                     (x'² + y'² + z'²)^(3/2)
    //

    const d = utils.compute(t, d1);
    const dd = utils.compute(t, d2);
    const qdsum = d.x * d.x + d.y * d.y;

    if (_3d) {
      num = sqrt(pow(d.y * dd.z - dd.y * d.z, 2) + pow(d.z * dd.x - dd.z * d.x, 2) + pow(d.x * dd.y - dd.x * d.y, 2));
      dnm = pow(qdsum + d.z * d.z, 3 / 2);
    } else {
      num = d.x * dd.y - d.y * dd.x;
      dnm = pow(qdsum, 3 / 2);
    }

    if (num === 0 || dnm === 0) {
      return {
        k: 0,
        r: 0
      };
    }

    k = num / dnm;
    r = dnm / num; // We're also computing the derivative of kappa, because
    // there is value in knowing the rate of change for the
    // curvature along the curve. And we're just going to
    // ballpark it based on an epsilon.

    if (!kOnly) {
      // compute k'(t) based on the interval before, and after it,
      // to at least try to not introduce forward/backward pass bias.
      const pk = utils.curvature(t - 0.001, d1, d2, _3d, true).k;
      const nk = utils.curvature(t + 0.001, d1, d2, _3d, true).k;
      dk = (nk - k + (k - pk)) / 2;
      adk = (abs(nk - k) + abs(k - pk)) / 2;
    }

    return {
      k: k,
      r: r,
      dk: dk,
      adk: adk
    };
  },
  inflections: function (points) {
    if (points.length < 4) return []; // FIXME: TODO: add in inflection abstraction for quartic+ curves?

    const p = utils.align(points, {
      p1: points[0],
      p2: points.slice(-1)[0]
    }),
          a = p[2].x * p[1].y,
          b = p[3].x * p[1].y,
          c = p[1].x * p[2].y,
          d = p[3].x * p[2].y,
          v1 = 18 * (-3 * a + 2 * b + 3 * c - d),
          v2 = 18 * (3 * a - b - 3 * c),
          v3 = 18 * (c - a);

    if (utils.approximately(v1, 0)) {
      if (!utils.approximately(v2, 0)) {
        let t = -v3 / v2;
        if (0 <= t && t <= 1) return [t];
      }

      return [];
    }

    const trm = v2 * v2 - 4 * v1 * v3,
          sq = Math.sqrt(trm),
          d2 = 2 * v1;
    if (utils.approximately(d2, 0)) return [];
    return [(sq - v2) / d2, -(v2 + sq) / d2].filter(function (r) {
      return 0 <= r && r <= 1;
    });
  },
  bboxoverlap: function (b1, b2) {
    const dims = ["x", "y"],
          len = dims.length;

    for (let i = 0, dim, l, t, d; i < len; i++) {
      dim = dims[i];
      l = b1[dim].mid;
      t = b2[dim].mid;
      d = (b1[dim].size + b2[dim].size) / 2;
      if (abs(l - t) >= d) return false;
    }

    return true;
  },
  expandbox: function (bbox, _bbox) {
    if (_bbox.x.min < bbox.x.min) {
      bbox.x.min = _bbox.x.min;
    }

    if (_bbox.y.min < bbox.y.min) {
      bbox.y.min = _bbox.y.min;
    }

    if (_bbox.z && _bbox.z.min < bbox.z.min) {
      bbox.z.min = _bbox.z.min;
    }

    if (_bbox.x.max > bbox.x.max) {
      bbox.x.max = _bbox.x.max;
    }

    if (_bbox.y.max > bbox.y.max) {
      bbox.y.max = _bbox.y.max;
    }

    if (_bbox.z && _bbox.z.max > bbox.z.max) {
      bbox.z.max = _bbox.z.max;
    }

    bbox.x.mid = (bbox.x.min + bbox.x.max) / 2;
    bbox.y.mid = (bbox.y.min + bbox.y.max) / 2;

    if (bbox.z) {
      bbox.z.mid = (bbox.z.min + bbox.z.max) / 2;
    }

    bbox.x.size = bbox.x.max - bbox.x.min;
    bbox.y.size = bbox.y.max - bbox.y.min;

    if (bbox.z) {
      bbox.z.size = bbox.z.max - bbox.z.min;
    }
  },
  pairiteration: function (c1, c2, curveIntersectionThreshold) {
    const c1b = c1.bbox(),
          c2b = c2.bbox(),
          r = 100000,
          threshold = curveIntersectionThreshold || 0.5;

    if (c1b.x.size + c1b.y.size < threshold && c2b.x.size + c2b.y.size < threshold) {
      return [(r * (c1._t1 + c1._t2) / 2 | 0) / r + "/" + (r * (c2._t1 + c2._t2) / 2 | 0) / r];
    }

    let cc1 = c1.split(0.5),
        cc2 = c2.split(0.5),
        pairs = [{
      left: cc1.left,
      right: cc2.left
    }, {
      left: cc1.left,
      right: cc2.right
    }, {
      left: cc1.right,
      right: cc2.right
    }, {
      left: cc1.right,
      right: cc2.left
    }];
    pairs = pairs.filter(function (pair) {
      return utils.bboxoverlap(pair.left.bbox(), pair.right.bbox());
    });
    let results = [];
    if (pairs.length === 0) return results;
    pairs.forEach(function (pair) {
      results = results.concat(utils.pairiteration(pair.left, pair.right, threshold));
    });
    results = results.filter(function (v, i) {
      return results.indexOf(v) === i;
    });
    return results;
  },
  getccenter: function (p1, p2, p3) {
    const dx1 = p2.x - p1.x,
          dy1 = p2.y - p1.y,
          dx2 = p3.x - p2.x,
          dy2 = p3.y - p2.y,
          dx1p = dx1 * cos(quart) - dy1 * sin(quart),
          dy1p = dx1 * sin(quart) + dy1 * cos(quart),
          dx2p = dx2 * cos(quart) - dy2 * sin(quart),
          dy2p = dx2 * sin(quart) + dy2 * cos(quart),
          // chord midpoints
    mx1 = (p1.x + p2.x) / 2,
          my1 = (p1.y + p2.y) / 2,
          mx2 = (p2.x + p3.x) / 2,
          my2 = (p2.y + p3.y) / 2,
          // midpoint offsets
    mx1n = mx1 + dx1p,
          my1n = my1 + dy1p,
          mx2n = mx2 + dx2p,
          my2n = my2 + dy2p,
          // intersection of these lines:
    arc = utils.lli8(mx1, my1, mx1n, my1n, mx2, my2, mx2n, my2n),
          r = utils.dist(arc, p1); // arc start/end values, over mid point:

    let s = atan2(p1.y - arc.y, p1.x - arc.x),
        m = atan2(p2.y - arc.y, p2.x - arc.x),
        e = atan2(p3.y - arc.y, p3.x - arc.x),
        _; // determine arc direction (cw/ccw correction)


    if (s < e) {
      // if s<m<e, arc(s, e)
      // if m<s<e, arc(e, s + tau)
      // if s<e<m, arc(e, s + tau)
      if (s > m || m > e) {
        s += tau;
      }

      if (s > e) {
        _ = e;
        e = s;
        s = _;
      }
    } else {
      // if e<m<s, arc(e, s)
      // if m<e<s, arc(s, e + tau)
      // if e<s<m, arc(s, e + tau)
      if (e < m && m < s) {
        _ = e;
        e = s;
        s = _;
      } else {
        e += tau;
      }
    } // assign and done.


    arc.s = s;
    arc.e = e;
    arc.r = r;
    return arc;
  },
  numberSort: function (a, b) {
    return a - b;
  }
};
/**
 * Poly Bezier
 * @param {[type]} curves [description]
 */

class PolyBezier {
  constructor(curves) {
    this.curves = [];
    this._3d = false;

    if (!!curves) {
      this.curves = curves;
      this._3d = this.curves[0]._3d;
    }
  }

  valueOf() {
    return this.toString();
  }

  toString() {
    return "[" + this.curves.map(function (curve) {
      return utils.pointsToString(curve.points);
    }).join(", ") + "]";
  }

  addCurve(curve) {
    this.curves.push(curve);
    this._3d = this._3d || curve._3d;
  }

  length() {
    return this.curves.map(function (v) {
      return v.length();
    }).reduce(function (a, b) {
      return a + b;
    });
  }

  curve(idx) {
    return this.curves[idx];
  }

  bbox() {
    const c = this.curves;
    var bbox = c[0].bbox();

    for (var i = 1; i < c.length; i++) {
      utils.expandbox(bbox, c[i].bbox());
    }

    return bbox;
  }

  offset(d) {
    const offset = [];
    this.curves.forEach(function (v) {
      offset.push(...v.offset(d));
    });
    return new PolyBezier(offset);
  }

}
/**
  A javascript Bezier curve library by Pomax.

  Based on http://pomax.github.io/bezierinfo

  This code is MIT licensed.
**/
// math-inlining.


const {
  abs: abs$1,
  min,
  max,
  cos: cos$1,
  sin: sin$1,
  acos: acos$1,
  sqrt: sqrt$1
} = Math;
const pi$1 = Math.PI;
/**
 * Bezier curve constructor.
 *
 * ...docs pending...
 */

class Bezier {
  constructor(coords) {
    let args = coords && coords.forEach ? coords : Array.from(arguments).slice();
    let coordlen = false;

    if (typeof args[0] === "object") {
      coordlen = args.length;
      const newargs = [];
      args.forEach(function (point) {
        ["x", "y", "z"].forEach(function (d) {
          if (typeof point[d] !== "undefined") {
            newargs.push(point[d]);
          }
        });
      });
      args = newargs;
    }

    let higher = false;
    const len = args.length;

    if (coordlen) {
      if (coordlen > 4) {
        if (arguments.length !== 1) {
          throw new Error("Only new Bezier(point[]) is accepted for 4th and higher order curves");
        }

        higher = true;
      }
    } else {
      if (len !== 6 && len !== 8 && len !== 9 && len !== 12) {
        if (arguments.length !== 1) {
          throw new Error("Only new Bezier(point[]) is accepted for 4th and higher order curves");
        }
      }
    }

    const _3d = this._3d = !higher && (len === 9 || len === 12) || coords && coords[0] && typeof coords[0].z !== "undefined";

    const points = this.points = [];

    for (let idx = 0, step = _3d ? 3 : 2; idx < len; idx += step) {
      var point = {
        x: args[idx],
        y: args[idx + 1]
      };

      if (_3d) {
        point.z = args[idx + 2];
      }

      points.push(point);
    }

    const order = this.order = points.length - 1;
    const dims = this.dims = ["x", "y"];
    if (_3d) dims.push("z");
    this.dimlen = dims.length;
    const aligned = utils.align(points, {
      p1: points[0],
      p2: points[order]
    });
    this._linear = !aligned.some(p => abs$1(p.y) > 0.0001);
    this._lut = [];
    this._t1 = 0;
    this._t2 = 1;
    this.update();
  }

  static quadraticFromPoints(p1, p2, p3, t) {
    if (typeof t === "undefined") {
      t = 0.5;
    } // shortcuts, although they're really dumb


    if (t === 0) {
      return new Bezier(p2, p2, p3);
    }

    if (t === 1) {
      return new Bezier(p1, p2, p2);
    } // real fitting.


    const abc = Bezier.getABC(2, p1, p2, p3, t);
    return new Bezier(p1, abc.A, p3);
  }

  static cubicFromPoints(S, B, E, t, d1) {
    if (typeof t === "undefined") {
      t = 0.5;
    }

    const abc = Bezier.getABC(3, S, B, E, t);

    if (typeof d1 === "undefined") {
      d1 = utils.dist(B, abc.C);
    }

    const d2 = d1 * (1 - t) / t;
    const selen = utils.dist(S, E),
          lx = (E.x - S.x) / selen,
          ly = (E.y - S.y) / selen,
          bx1 = d1 * lx,
          by1 = d1 * ly,
          bx2 = d2 * lx,
          by2 = d2 * ly; // derivation of new hull coordinates

    const e1 = {
      x: B.x - bx1,
      y: B.y - by1
    },
          e2 = {
      x: B.x + bx2,
      y: B.y + by2
    },
          A = abc.A,
          v1 = {
      x: A.x + (e1.x - A.x) / (1 - t),
      y: A.y + (e1.y - A.y) / (1 - t)
    },
          v2 = {
      x: A.x + (e2.x - A.x) / t,
      y: A.y + (e2.y - A.y) / t
    },
          nc1 = {
      x: S.x + (v1.x - S.x) / t,
      y: S.y + (v1.y - S.y) / t
    },
          nc2 = {
      x: E.x + (v2.x - E.x) / (1 - t),
      y: E.y + (v2.y - E.y) / (1 - t)
    }; // ...done

    return new Bezier(S, nc1, nc2, E);
  }

  static getUtils() {
    return utils;
  }

  getUtils() {
    return Bezier.getUtils();
  }

  static get PolyBezier() {
    return PolyBezier;
  }

  valueOf() {
    return this.toString();
  }

  toString() {
    return utils.pointsToString(this.points);
  }

  toSVG() {
    if (this._3d) return false;
    const p = this.points,
          x = p[0].x,
          y = p[0].y,
          s = ["M", x, y, this.order === 2 ? "Q" : "C"];

    for (let i = 1, last = p.length; i < last; i++) {
      s.push(p[i].x);
      s.push(p[i].y);
    }

    return s.join(" ");
  }

  setRatios(ratios) {
    if (ratios.length !== this.points.length) {
      throw new Error("incorrect number of ratio values");
    }

    this.ratios = ratios;
    this._lut = []; //  invalidate any precomputed LUT
  }

  verify() {
    const print = this.coordDigest();

    if (print !== this._print) {
      this._print = print;
      this.update();
    }
  }

  coordDigest() {
    return this.points.map(function (c, pos) {
      return "" + pos + c.x + c.y + (c.z ? c.z : 0);
    }).join("");
  }

  update() {
    // invalidate any precomputed LUT
    this._lut = [];
    this.dpoints = utils.derive(this.points, this._3d);
    this.computedirection();
  }

  computedirection() {
    const points = this.points;
    const angle = utils.angle(points[0], points[this.order], points[1]);
    this.clockwise = angle > 0;
  }

  length() {
    return utils.length(this.derivative.bind(this));
  }

  static getABC(order = 2, S, B, E, t = 0.5) {
    const u = utils.projectionratio(t, order),
          um = 1 - u,
          C = {
      x: u * S.x + um * E.x,
      y: u * S.y + um * E.y
    },
          s = utils.abcratio(t, order),
          A = {
      x: B.x + (B.x - C.x) / s,
      y: B.y + (B.y - C.y) / s
    };
    return {
      A,
      B,
      C,
      S,
      E
    };
  }

  getABC(t, B) {
    B = B || this.get(t);
    let S = this.points[0];
    let E = this.points[this.order];
    return Bezier.getABC(this.order, S, B, E, t);
  }

  getLUT(steps) {
    this.verify();
    steps = steps || 100;

    if (this._lut.length === steps) {
      return this._lut;
    }

    this._lut = []; // We want a range from 0 to 1 inclusive, so
    // we decrement and then use <= rather than <:

    steps--;

    for (let i = 0, p, t; i < steps; i++) {
      t = i / (steps - 1);
      p = this.compute(t);
      p.t = t;

      this._lut.push(p);
    }

    return this._lut;
  }

  on(point, error) {
    error = error || 5;
    const lut = this.getLUT(),
          hits = [];

    for (let i = 0, c, t = 0; i < lut.length; i++) {
      c = lut[i];

      if (utils.dist(c, point) < error) {
        hits.push(c);
        t += i / lut.length;
      }
    }

    if (!hits.length) return false;
    return t /= hits.length;
  }

  project(point) {
    // step 1: coarse check
    const LUT = this.getLUT(),
          l = LUT.length - 1,
          closest = utils.closest(LUT, point),
          mpos = closest.mpos,
          t1 = (mpos - 1) / l,
          t2 = (mpos + 1) / l,
          step = 0.1 / l; // step 2: fine check

    let mdist = closest.mdist,
        t = t1,
        ft = t,
        p;
    mdist += 1;

    for (let d; t < t2 + step; t += step) {
      p = this.compute(t);
      d = utils.dist(point, p);

      if (d < mdist) {
        mdist = d;
        ft = t;
      }
    }

    ft = ft < 0 ? 0 : ft > 1 ? 1 : ft;
    p = this.compute(ft);
    p.t = ft;
    p.d = mdist;
    return p;
  }

  get(t) {
    return this.compute(t);
  }

  point(idx) {
    return this.points[idx];
  }

  compute(t) {
    if (this.ratios) {
      return utils.computeWithRatios(t, this.points, this.ratios, this._3d);
    }

    return utils.compute(t, this.points, this._3d, this.ratios);
  }

  raise() {
    const p = this.points,
          np = [p[0]],
          k = p.length;

    for (let i = 1, pi, pim; i < k; i++) {
      pi = p[i];
      pim = p[i - 1];
      np[i] = {
        x: (k - i) / k * pi.x + i / k * pim.x,
        y: (k - i) / k * pi.y + i / k * pim.y
      };
    }

    np[k] = p[k - 1];
    return new Bezier(np);
  }

  derivative(t) {
    return utils.compute(t, this.dpoints[0]);
  }

  dderivative(t) {
    return utils.compute(t, this.dpoints[1]);
  }

  align() {
    let p = this.points;
    return new Bezier(utils.align(p, {
      p1: p[0],
      p2: p[p.length - 1]
    }));
  }

  curvature(t) {
    return utils.curvature(t, this.dpoints[0], this.dpoints[1], this._3d);
  }

  inflections() {
    return utils.inflections(this.points);
  }

  normal(t) {
    return this._3d ? this.__normal3(t) : this.__normal2(t);
  }

  __normal2(t) {
    const d = this.derivative(t);
    const q = sqrt$1(d.x * d.x + d.y * d.y);
    return {
      x: -d.y / q,
      y: d.x / q
    };
  }

  __normal3(t) {
    // see http://stackoverflow.com/questions/25453159
    const r1 = this.derivative(t),
          r2 = this.derivative(t + 0.01),
          q1 = sqrt$1(r1.x * r1.x + r1.y * r1.y + r1.z * r1.z),
          q2 = sqrt$1(r2.x * r2.x + r2.y * r2.y + r2.z * r2.z);
    r1.x /= q1;
    r1.y /= q1;
    r1.z /= q1;
    r2.x /= q2;
    r2.y /= q2;
    r2.z /= q2; // cross product

    const c = {
      x: r2.y * r1.z - r2.z * r1.y,
      y: r2.z * r1.x - r2.x * r1.z,
      z: r2.x * r1.y - r2.y * r1.x
    };
    const m = sqrt$1(c.x * c.x + c.y * c.y + c.z * c.z);
    c.x /= m;
    c.y /= m;
    c.z /= m; // rotation matrix

    const R = [c.x * c.x, c.x * c.y - c.z, c.x * c.z + c.y, c.x * c.y + c.z, c.y * c.y, c.y * c.z - c.x, c.x * c.z - c.y, c.y * c.z + c.x, c.z * c.z]; // normal vector:

    const n = {
      x: R[0] * r1.x + R[1] * r1.y + R[2] * r1.z,
      y: R[3] * r1.x + R[4] * r1.y + R[5] * r1.z,
      z: R[6] * r1.x + R[7] * r1.y + R[8] * r1.z
    };
    return n;
  }

  hull(t) {
    let p = this.points,
        _p = [],
        q = [],
        idx = 0;
    q[idx++] = p[0];
    q[idx++] = p[1];
    q[idx++] = p[2];

    if (this.order === 3) {
      q[idx++] = p[3];
    } // we lerp between all points at each iteration, until we have 1 point left.


    while (p.length > 1) {
      _p = [];

      for (let i = 0, pt, l = p.length - 1; i < l; i++) {
        pt = utils.lerp(t, p[i], p[i + 1]);
        q[idx++] = pt;

        _p.push(pt);
      }

      p = _p;
    }

    return q;
  }

  split(t1, t2) {
    // shortcuts
    if (t1 === 0 && !!t2) {
      return this.split(t2).left;
    }

    if (t2 === 1) {
      return this.split(t1).right;
    } // no shortcut: use "de Casteljau" iteration.


    const q = this.hull(t1);
    const result = {
      left: this.order === 2 ? new Bezier([q[0], q[3], q[5]]) : new Bezier([q[0], q[4], q[7], q[9]]),
      right: this.order === 2 ? new Bezier([q[5], q[4], q[2]]) : new Bezier([q[9], q[8], q[6], q[3]]),
      span: q
    }; // make sure we bind _t1/_t2 information!

    result.left._t1 = utils.map(0, 0, 1, this._t1, this._t2);
    result.left._t2 = utils.map(t1, 0, 1, this._t1, this._t2);
    result.right._t1 = utils.map(t1, 0, 1, this._t1, this._t2);
    result.right._t2 = utils.map(1, 0, 1, this._t1, this._t2); // if we have no t2, we're done

    if (!t2) {
      return result;
    } // if we have a t2, split again:


    t2 = utils.map(t2, t1, 1, 0, 1);
    return result.right.split(t2).left;
  }

  extrema() {
    const result = {};
    let roots = [];
    this.dims.forEach(function (dim) {
      let mfn = function (v) {
        return v[dim];
      };

      let p = this.dpoints[0].map(mfn);
      result[dim] = utils.droots(p);

      if (this.order === 3) {
        p = this.dpoints[1].map(mfn);
        result[dim] = result[dim].concat(utils.droots(p));
      }

      result[dim] = result[dim].filter(function (t) {
        return t >= 0 && t <= 1;
      });
      roots = roots.concat(result[dim].sort(utils.numberSort));
    }.bind(this));
    result.values = roots.sort(utils.numberSort).filter(function (v, idx) {
      return roots.indexOf(v) === idx;
    });
    return result;
  }

  bbox() {
    const extrema = this.extrema(),
          result = {};
    this.dims.forEach(function (d) {
      result[d] = utils.getminmax(this, d, extrema[d]);
    }.bind(this));
    return result;
  }

  overlaps(curve) {
    const lbbox = this.bbox(),
          tbbox = curve.bbox();
    return utils.bboxoverlap(lbbox, tbbox);
  }

  offset(t, d) {
    if (typeof d !== "undefined") {
      const c = this.get(t),
            n = this.normal(t);
      const ret = {
        c: c,
        n: n,
        x: c.x + n.x * d,
        y: c.y + n.y * d
      };

      if (this._3d) {
        ret.z = c.z + n.z * d;
      }

      return ret;
    }

    if (this._linear) {
      const nv = this.normal(0),
            coords = this.points.map(function (p) {
        const ret = {
          x: p.x + t * nv.x,
          y: p.y + t * nv.y
        };

        if (p.z && nv.z) {
          ret.z = p.z + t * nv.z;
        }

        return ret;
      });
      return [new Bezier(coords)];
    }

    return this.reduce().map(function (s) {
      if (s._linear) {
        return s.offset(t)[0];
      }

      return s.scale(t);
    });
  }

  simple() {
    if (this.order === 3) {
      const a1 = utils.angle(this.points[0], this.points[3], this.points[1]);
      const a2 = utils.angle(this.points[0], this.points[3], this.points[2]);
      if (a1 > 0 && a2 < 0 || a1 < 0 && a2 > 0) return false;
    }

    const n1 = this.normal(0);
    const n2 = this.normal(1);
    let s = n1.x * n2.x + n1.y * n2.y;

    if (this._3d) {
      s += n1.z * n2.z;
    }

    return abs$1(acos$1(s)) < pi$1 / 3;
  }

  reduce() {
    // TODO: examine these var types in more detail...
    let i,
        t1 = 0,
        t2 = 0,
        step = 0.01,
        segment,
        pass1 = [],
        pass2 = []; // first pass: split on extrema

    let extrema = this.extrema().values;

    if (extrema.indexOf(0) === -1) {
      extrema = [0].concat(extrema);
    }

    if (extrema.indexOf(1) === -1) {
      extrema.push(1);
    }

    for (t1 = extrema[0], i = 1; i < extrema.length; i++) {
      t2 = extrema[i];
      segment = this.split(t1, t2);
      segment._t1 = t1;
      segment._t2 = t2;
      pass1.push(segment);
      t1 = t2;
    } // second pass: further reduce these segments to simple segments


    pass1.forEach(function (p1) {
      t1 = 0;
      t2 = 0;

      while (t2 <= 1) {
        for (t2 = t1 + step; t2 <= 1 + step; t2 += step) {
          segment = p1.split(t1, t2);

          if (!segment.simple()) {
            t2 -= step;

            if (abs$1(t1 - t2) < step) {
              // we can never form a reduction
              return [];
            }

            segment = p1.split(t1, t2);
            segment._t1 = utils.map(t1, 0, 1, p1._t1, p1._t2);
            segment._t2 = utils.map(t2, 0, 1, p1._t1, p1._t2);
            pass2.push(segment);
            t1 = t2;
            break;
          }
        }
      }

      if (t1 < 1) {
        segment = p1.split(t1, 1);
        segment._t1 = utils.map(t1, 0, 1, p1._t1, p1._t2);
        segment._t2 = p1._t2;
        pass2.push(segment);
      }
    });
    return pass2;
  }

  scale(d) {
    const order = this.order;
    let distanceFn = false;

    if (typeof d === "function") {
      distanceFn = d;
    }

    if (distanceFn && order === 2) {
      return this.raise().scale(distanceFn);
    } // TODO: add special handling for degenerate (=linear) curves.


    const clockwise = this.clockwise;
    const r1 = distanceFn ? distanceFn(0) : d;
    const r2 = distanceFn ? distanceFn(1) : d;
    const v = [this.offset(0, 10), this.offset(1, 10)];
    const points = this.points;
    const np = [];
    const o = utils.lli4(v[0], v[0].c, v[1], v[1].c);

    if (!o) {
      throw new Error("cannot scale this curve. Try reducing it first.");
    } // move all points by distance 'd' wrt the origin 'o'
    // move end points by fixed distance along normal.


    [0, 1].forEach(function (t) {
      const p = np[t * order] = utils.copy(points[t * order]);
      p.x += (t ? r2 : r1) * v[t].n.x;
      p.y += (t ? r2 : r1) * v[t].n.y;
    });

    if (!distanceFn) {
      // move control points to lie on the intersection of the offset
      // derivative vector, and the origin-through-control vector
      [0, 1].forEach(t => {
        if (order === 2 && !!t) return;
        const p = np[t * order];
        const d = this.derivative(t);
        const p2 = {
          x: p.x + d.x,
          y: p.y + d.y
        };
        np[t + 1] = utils.lli4(p, p2, o, points[t + 1]);
      });
      return new Bezier(np);
    } // move control points by "however much necessary to
    // ensure the correct tangent to endpoint".


    [0, 1].forEach(function (t) {
      if (order === 2 && !!t) return;
      var p = points[t + 1];
      var ov = {
        x: p.x - o.x,
        y: p.y - o.y
      };
      var rc = distanceFn ? distanceFn((t + 1) / order) : d;
      if (distanceFn && !clockwise) rc = -rc;
      var m = sqrt$1(ov.x * ov.x + ov.y * ov.y);
      ov.x /= m;
      ov.y /= m;
      np[t + 1] = {
        x: p.x + rc * ov.x,
        y: p.y + rc * ov.y
      };
    });
    return new Bezier(np);
  }

  outline(d1, d2, d3, d4) {
    d2 = typeof d2 === "undefined" ? d1 : d2;
    const reduced = this.reduce(),
          len = reduced.length,
          fcurves = [];
    let bcurves = [],
        p,
        alen = 0,
        tlen = this.length();
    const graduated = typeof d3 !== "undefined" && typeof d4 !== "undefined";

    function linearDistanceFunction(s, e, tlen, alen, slen) {
      return function (v) {
        const f1 = alen / tlen,
              f2 = (alen + slen) / tlen,
              d = e - s;
        return utils.map(v, 0, 1, s + f1 * d, s + f2 * d);
      };
    } // form curve oulines


    reduced.forEach(function (segment) {
      const slen = segment.length();

      if (graduated) {
        fcurves.push(segment.scale(linearDistanceFunction(d1, d3, tlen, alen, slen)));
        bcurves.push(segment.scale(linearDistanceFunction(-d2, -d4, tlen, alen, slen)));
      } else {
        fcurves.push(segment.scale(d1));
        bcurves.push(segment.scale(-d2));
      }

      alen += slen;
    }); // reverse the "return" outline

    bcurves = bcurves.map(function (s) {
      p = s.points;

      if (p[3]) {
        s.points = [p[3], p[2], p[1], p[0]];
      } else {
        s.points = [p[2], p[1], p[0]];
      }

      return s;
    }).reverse(); // form the endcaps as lines

    const fs = fcurves[0].points[0],
          fe = fcurves[len - 1].points[fcurves[len - 1].points.length - 1],
          bs = bcurves[len - 1].points[bcurves[len - 1].points.length - 1],
          be = bcurves[0].points[0],
          ls = utils.makeline(bs, fs),
          le = utils.makeline(fe, be),
          segments = [ls].concat(fcurves).concat([le]).concat(bcurves);
    return new PolyBezier(segments);
  }

  outlineshapes(d1, d2, curveIntersectionThreshold) {
    d2 = d2 || d1;
    const outline = this.outline(d1, d2).curves;
    const shapes = [];

    for (let i = 1, len = outline.length; i < len / 2; i++) {
      const shape = utils.makeshape(outline[i], outline[len - i], curveIntersectionThreshold);
      shape.startcap.virtual = i > 1;
      shape.endcap.virtual = i < len / 2 - 1;
      shapes.push(shape);
    }

    return shapes;
  }

  intersects(curve, curveIntersectionThreshold) {
    if (!curve) return this.selfintersects(curveIntersectionThreshold);

    if (curve.p1 && curve.p2) {
      return this.lineIntersects(curve);
    }

    if (curve instanceof Bezier) {
      curve = curve.reduce();
    }

    return this.curveintersects(this.reduce(), curve, curveIntersectionThreshold);
  }

  lineIntersects(line) {
    const mx = min(line.p1.x, line.p2.x),
          my = min(line.p1.y, line.p2.y),
          MX = max(line.p1.x, line.p2.x),
          MY = max(line.p1.y, line.p2.y);
    return utils.roots(this.points, line).filter(t => {
      var p = this.get(t);
      return utils.between(p.x, mx, MX) && utils.between(p.y, my, MY);
    });
  }

  selfintersects(curveIntersectionThreshold) {
    // "simple" curves cannot intersect with their direct
    // neighbour, so for each segment X we check whether
    // it intersects [0:x-2][x+2:last].
    const reduced = this.reduce(),
          len = reduced.length - 2,
          results = [];

    for (let i = 0, result, left, right; i < len; i++) {
      left = reduced.slice(i, i + 1);
      right = reduced.slice(i + 2);
      result = this.curveintersects(left, right, curveIntersectionThreshold);
      results.push(...result);
    }

    return results;
  }

  curveintersects(c1, c2, curveIntersectionThreshold) {
    const pairs = []; // step 1: pair off any overlapping segments

    c1.forEach(function (l) {
      c2.forEach(function (r) {
        if (l.overlaps(r)) {
          pairs.push({
            left: l,
            right: r
          });
        }
      });
    }); // step 2: for each pairing, run through the convergence algorithm.

    let intersections = [];
    pairs.forEach(function (pair) {
      const result = utils.pairiteration(pair.left, pair.right, curveIntersectionThreshold);

      if (result.length > 0) {
        intersections = intersections.concat(result);
      }
    });
    return intersections;
  }

  arcs(errorThreshold) {
    errorThreshold = errorThreshold || 0.5;
    return this._iterate(errorThreshold, []);
  }

  _error(pc, np1, s, e) {
    const q = (e - s) / 4,
          c1 = this.get(s + q),
          c2 = this.get(e - q),
          ref = utils.dist(pc, np1),
          d1 = utils.dist(pc, c1),
          d2 = utils.dist(pc, c2);
    return abs$1(d1 - ref) + abs$1(d2 - ref);
  }

  _iterate(errorThreshold, circles) {
    let t_s = 0,
        t_e = 1,
        safety; // we do a binary search to find the "good `t` closest to no-longer-good"

    do {
      safety = 0; // step 1: start with the maximum possible arc

      t_e = 1; // points:

      let np1 = this.get(t_s),
          np2,
          np3,
          arc,
          prev_arc; // booleans:

      let curr_good = false,
          prev_good = false,
          done; // numbers:

      let t_m = t_e,
          prev_e = 1; // step 2: find the best possible arc

      do {
        prev_good = curr_good;
        prev_arc = arc;
        t_m = (t_s + t_e) / 2;
        np2 = this.get(t_m);
        np3 = this.get(t_e);
        arc = utils.getccenter(np1, np2, np3); //also save the t values

        arc.interval = {
          start: t_s,
          end: t_e
        };

        let error = this._error(arc, np1, t_s, t_e);

        curr_good = error <= errorThreshold;
        done = prev_good && !curr_good;
        if (!done) prev_e = t_e; // this arc is fine: we can move 'e' up to see if we can find a wider arc

        if (curr_good) {
          // if e is already at max, then we're done for this arc.
          if (t_e >= 1) {
            // make sure we cap at t=1
            arc.interval.end = prev_e = 1;
            prev_arc = arc; // if we capped the arc segment to t=1 we also need to make sure that
            // the arc's end angle is correct with respect to the bezier end point.

            if (t_e > 1) {
              let d = {
                x: arc.x + arc.r * cos$1(arc.e),
                y: arc.y + arc.r * sin$1(arc.e)
              };
              arc.e += utils.angle({
                x: arc.x,
                y: arc.y
              }, d, this.get(1));
            }

            break;
          } // if not, move it up by half the iteration distance


          t_e = t_e + (t_e - t_s) / 2;
        } else {
          // this is a bad arc: we need to move 'e' down to find a good arc
          t_e = t_m;
        }
      } while (!done && safety++ < 100);

      if (safety >= 100) {
        break;
      } // console.log("L835: [F] arc found", t_s, prev_e, prev_arc.x, prev_arc.y, prev_arc.s, prev_arc.e);


      prev_arc = prev_arc ? prev_arc : arc;
      circles.push(prev_arc);
      t_s = prev_e;
    } while (t_e < 1);

    return circles;
  }

}

exports.Bezier = Bezier;