<!-- SOLUV · part 182 -->
= p.y) {
            const x = p.x + (hy - p.y) * (p.next.x - p.x) / (p.next.y - p.y);
            if (x <= hx && x > qx) {
                qx = x;
                m = p.x < p.next.x ? p : p.next;
                if (x === hx) return m; // hole touches outer segment; pick leftmost endpoint
            }
        }
        p = p.next;
    } while (p !== outerNode);

    if (!m) return null;

    // look for points inside the triangle of hole point, segment intersection and endpoint;
    // if there are no points found, we have a valid connection;
    // otherwise choose the point of the minimum angle with the ray as connection point

    const stop = m;
    const mx = m.x;
    const my = m.y;
    let tanMin = Infinity;

    p = m;

    do {
        if (hx >= p.x && p.x >= mx && hx !== p.x &&
                pointInTriangle(hy < my ? hx : qx, hy, mx, my, hy < my ? qx : hx, hy, p.x, p.y)) {

            const tan = Math.abs(hy - p.y) / (hx - p.x); // tangential

            if (locallyInside(p, hole) &&
                (tan < tanMin || (tan === tanMin && (p.x > m.x || (p.x === m.x && sectorContainsSector(m, p)))))) {
                m = p;
                tanMin = tan;
            }
        }

        p = p.next;
    } while (p !== stop);

    return m;
}

// whether sector in vertex m contains sector in vertex p in the same coordinates
function sectorContainsSector(m, p) {
    return area(m.prev, m, p.prev) < 0 && area(p.next, m, m.next) < 0;
}

// interlink polygon nodes in z-order
function indexCurve(start, minX, minY, invSize) {
    let p = start;
    do {
        if (p.z === 0) p.z = zOrder(p.x, p.y, minX, minY, invSize);
        p.prevZ = p.prev;
        p.nextZ = p.next;
        p = p.next;
    } while (p !== start);

    p.prevZ.nextZ = null;
    p.prevZ = null;

    sortLinked(p);
}

// Simon Tatham's linked list merge sort algorithm
// http://www.chiark.greenend.org.uk/~sgtatham/algorithms/listsort.html
function sortLinked(list) {
    let numMerges;
    let inSize = 1;

    do {
        let p = list;
        let e;
        list = null;
        let tail = null;
        numMerges = 0;

        while (p) {
            numMerges++;
            let q = p;
            let pSize = 0;
            for (let i = 0; i < inSize; i++) {
                pSize++;
                q = q.nextZ;
                if (!q) break;
            }
            let qSize = inSize;

            while (pSize > 0 || (qSize > 0 && q)) {

                if (pSize !== 0 && (qSize === 0 || !q || p.z <= q.z)) {
                    e = p;
                    p = p.nextZ;
                    pSize--;
                } else {
                    e = q;
                    q = q.nextZ;
                    qSize--;
                }

                if (tail) tail.nextZ = e;
                else list = e;

                e.prevZ = tail;
                tail = e;
            }

            p = q;
        }

        tail.nextZ = null;
        inSize *= 2;

    } while (numMerges > 1);

    return list;
}

// z-order of a point given coords and inverse of the longer side of data bbox
function zOrder(x, y, minX, minY, invSize) {
    // coords are transformed into non-negative 15-bit integer range
    x = (x - minX) * invSize | 0;
    y = (y - minY) * invSize | 0;

    x = (x | (x << 8)) & 0x00FF00FF;
    x = (x | (x << 4)) & 0x0F0F0F0F;
    x = (x | (x << 2)) & 0x33333333;
    x = (x | (x << 1)) & 0x55555555;

    y = (y | (y << 8)) & 0x00FF00FF;
    y = (y | (y << 4)) & 0x0F0F0F0F;
    y = (y | (y << 2)) & 0x33333333;
    y = (y | (y << 1)) & 0x55555555;

    return x | (y << 1);
}

// find the leftmost node of a polygon ring
function getLeftmost(start) {
    let p = start,
        leftmost = start;
    do {
        if (p.x < leftmost.x || (p.x === leftmost.x && p.y < leftmost.y)) leftmost = p;
        p = p.next;
    } while (p !== start);

    return leftmost;
}

// check if a point lies within a convex triangle
function pointInTriangle(ax, ay, bx, by, cx, cy, px, py) {
    return (cx - px) * (ay - py) >= (ax - px) * (cy - py) &&
           (ax - px) * (by - py) >= (bx - px) * (ay - py) &&
           (bx - px) * (cy - py) >= (cx - px) * (by - py);
}

// check if a point lies within a convex triangle but false if its equal to the first point of the triangle
function pointInTriangleExceptFirst(ax, ay, bx, by, cx, cy, px, py) {
    return !(ax === px && ay === py) && pointInTriangle(ax, ay, bx, by, cx, cy, px, py);
}

// check if a diagonal between two polygon nodes is valid (lies in polygon interior)
function isValidDiagonal(a, b) {
    return a.next.i !== b.i && a.prev.i !== b.i && !intersectsPolygon(a, b) && // doesn't intersect other edges
           (locallyInside(a, b) && locallyInside(b, a) && middleInside(a, b) && // locally visible
            (area(a.prev, a, b.prev) || area(a, b.prev, b)) || // does not create opposite-facing sectors
            equals(a, b) && area(a.prev, a, a.next) > 0 && area(b.prev, b,