Function intersectsPolygon

docs/app/js/sanddance-app.js:102055–102062

(a, b)

    return num > 0 ? 1 : num < 0 ? -1 : 0;
}
function intersectsPolygon(a, b) {
    let p = a;
    do {
        if (p.i !== a.i && p.next.i !== a.i && p.i !== b.i && p.next.i !== b.i && intersects(p, p.next, a, b)) return true;
        p = p.next;
    }while (p !== a);
    return false;
}
function locallyInside(a, b) {
    return area(a.prev, a, a.next) < 0 ? area(a, b, a.next) >= 0 && area(a, a.prev, b) >= 0 : area(a, b, a.prev) < 0 || area(a, a.next, b) < 0;
}