site/node_modules/robust-predicates/umd/orient2d.js

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

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);
}

function orient2dfast(ax, ay, bx, by, cx, cy) {
    return (ay - cy) * (bx - cx) - (ax - cx) * (by - cy);
}

exports.orient2d = orient2d;
exports.orient2dfast = orient2dfast;

}));