Function indexCurve

docs/app/js/sanddance-app.js:101944–101955

(start, minX, minY, invSize)

    return area(m.prev, m, p.prev) < 0 && area(p.next, m, m.next) < 0;
}
function indexCurve(start, minX, minY, invSize) {
    let p = start;
    do {
        if (p.z === null) 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);
}
function sortLinked(list) {
    let e;
    let i;