private IEnumerable <SolidRouteState> GenerateSplitterStates(Func <Searchspace, IPhysicalBuilding, double> costFunction, Building splitter)
        {
            var offsets = new BuildingRotation[] {
                BuildingRotation.West,
                BuildingRotation.North,
                BuildingRotation.West,
                BuildingRotation.North,
            };
            var     offsetDir = offsets[(int)Direction];
            Vector2 nextpos   = _position + (_transportState == RoutingCoordinate.CoordinateType.Belt ? _direction.ToVector() : Vector2.Zero);

            var endPoint1 = nextpos + offsetDir.ToVector();
            var endPoint2 = nextpos - offsetDir.ToVector();

            var target = FlowBuilding.Item.Item;
            var dir    = Direction;

            var matches1 = Space.CalculateCollisions(endPoint1).OfType <Belt>().Where((b) => b.Item.Item == target && b.Rotation == dir);
            var matches2 = Space.CalculateCollisions(endPoint2).OfType <Belt>().Where((b) => b.Item.Item == target && b.Rotation == dir);

            if (matches1.Any())
            {
                var building = new Splitter(FlowBuilding.Item, splitter, endPoint1, Direction);
                building.Previous.Add(Building);
                yield return(new SolidRouteState(building, _cost + costFunction(_space, building), endPoint1, _space.AddRoute(building), RoutingCoordinate.CoordinateType.Splitter));
            }

            if (matches2.Any())
            {
                var building = new Splitter(FlowBuilding.Item, splitter, nextpos, Direction);
                building.Previous.Add(Building);
                yield return(new SolidRouteState(building, _cost + costFunction(_space, building), endPoint2, _space.AddRoute(building), RoutingCoordinate.CoordinateType.Splitter));
            }
        }