TreeTriangle b = (TreeTriangle) o1;
TreeTriangle b = (TreeTriangle) o2;
        public int compare(Object o1, Object o2) {            TreeTriangle a = (TreeTriangle) o1;            TreeTriangle b = (TreeTriangle) o1;            if (a.projection < b.projection) { return -1; }            if (a.projection > b.projection) { return 1; }            return 0;        }