Revit API request: EdgeArrayArray should have an Outerloop property

[BKSpurgeon]

This is an issue creating a headache and unexpected results for Revit API users:

Please refer to the following for some background. Mr Jeremy  Tammik jeremy_tammik recommended that an idea be created for this.

https://forums.autodesk.com/t5/revit-api-forum/is-the-first-edgeloop-still-the-outer-loop/m-p/130110...

What is happening?

• The API ought to implement a new functionality that would be very handy for API users.
• Right now, API users have to do a lot of work that is uncessessary, and that should be (in my opinion) a core part of the library.

I want to be able to do this, for example:

EdgeArray edgeArray = edgeArrayArrays.OuterLoop;

One single line of code. Instead, I have to implement all of this - and the only reason we have this code is because @stefanome very generously provided it to the community.

https://forums.autodesk.com/t5/revit-api-forum/is-the-first-edgeloop-still-the-outer-loop/m-p/102428...

public static List<List<CurveLoop>> SortCurveLoops(Face face)
{
    var allLoops = face.GetEdgesAsCurveLoops().Select(loop => new CurveLoopUV(loop, face)).ToList();

    var outerLoops = allLoops.Where(loop => loop.IsCounterclockwise).ToList();
    var innerLoops = allLoops.Where(loop => !outerLoops.Contains(loop)).ToList();

    // sort outerLoops putting last the ones that are outside all the preceding loops
    bool somethingHasChanged;
    do
    {
        somethingHasChanged = false;
        for (var i = 1; i < outerLoops.Count(); i++)
        {
            var point = outerLoops[i].StartPointUV;
            var loop = outerLoops[i - 1];
            if (loop.IsPointInside(point) is CurveLoopUV.PointLocation.Inside)
            {
                var tmp = outerLoops[i];
                outerLoops[i] = outerLoops[i - 1];
                outerLoops[i - 1] = tmp;

                somethingHasChanged = true;
            }
        }
    } while (somethingHasChanged);

    var result = new List<List<CurveLoop>>();
    foreach (var outerLoop in outerLoops)
    {
        var list = new List<CurveLoop> {outerLoop.Loop3d};

        for (var i = innerLoops.Count - 1; i >= 0; i--)
        {
            var innerLoop = innerLoops[i];
            if (outerLoops.Count() == 1 // skip testing whether the inner loop is inside the outer loop
                || outerLoop.IsPointInside(innerLoop.StartPointUV) == CurveLoopUV.PointLocation.Inside)
            {
                list.Add(innerLoop.Loop3d);
                innerLoops.RemoveAt(i);
            }
        }

        result.Add(list);
    }

    return result;
}

class CurveLoopUV : IEnumerable<Curve>
{
    public enum PointLocation
    {
        Outside,
        OnTheEdge,
        Inside,
    }

    public CurveLoop Loop3d { get; }
    private readonly CurveLoop _loop2d;

    public readonly double MinX, MaxX, MinY, MaxY;

    public CurveLoopUV(CurveLoop curveLoop, Face face)
    {
        Loop3d = curveLoop;
        _loop2d = new CurveLoop();
        
        var points3d = Loop3d.SelectMany(curve => curve.Tessellate().Skip(1));
        var pointsUv = points3d.Select(point3d => face.Project(point3d).UVPoint);
        var points2d = pointsUv.Select(pointUv => new XYZ(pointUv.U, pointUv.V, 0)).ToList();

        MinX = MinY = 1.0e100;
        MaxX = MaxY = -1.0e100;
        var nPoints = points2d.Count();
        for (var i = 0; i < nPoints; i++)
        {
            var p1 = points2d[i];
            var p2 = points2d[(i + 1) % nPoints];
            _loop2d.Append(Line.CreateBound(p1, p2));
            if (p1.X < MinX) MinX = p1.X;
            if (p1.Y < MinY) MinY = p1.Y;
            if (p1.X > MaxX) MaxX = p1.X;
            if (p1.Y > MaxY) MaxY = p1.Y;
        }
    }

    public PointLocation IsPointInside(XYZ point)
    {
        if (point.Y + Eps < MinY || point.Y + Eps > MaxY)
            return PointLocation.Outside;

        if (_loop2d.Any(curve => curve.Distance(point) < Eps))
            return PointLocation.OnTheEdge;

        var line = Line.CreateBound(point, new XYZ(1.0e100, point.Y, 0));
        var nIntersections = _loop2d.Count(edge => edge.Intersect(line) == SetComparisonResult.Overlap);
        return nIntersections % 2 == 1 ? PointLocation.Inside : PointLocation.Outside;
    }

    public bool IsCounterclockwise => _loop2d.IsCounterclockwise(XYZ.BasisZ);

    public XYZ StartPointUV => _loop2d.First().GetEndPoint(0);

    public IEnumerator<Curve> GetEnumerator() => _loop2d.GetEnumerator();

    IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
}