converthull.cs

  public static List<XYZ> ComputeConvexHull(List<XYZ> points)
    {
        if (points == null || points.Count < 3)
            throw new ArgumentException("At least 3 points are required to compute a convex hull");

        List<XYZ> hull = new List<XYZ>();

        // Find the leftmost point
        XYZ leftmost = points[0];
        foreach (var point in points)
        {
            if (point.X < leftmost.X)
            {
                leftmost = point;
            }
        }

        XYZ currentPoint = leftmost;
        do
        {
            hull.Add(currentPoint);
            XYZ nextPoint = points[0];

            foreach (var point in points)
            {
                if (nextPoint == currentPoint || IsLeftTurn(currentPoint, nextPoint, point))
                {
                    nextPoint = point;
                }
            }

            currentPoint = nextPoint;

        } while (currentPoint != leftmost);

        return hull;
    }

    private static bool IsLeftTurn(XYZ a, XYZ b, XYZ c)
    {
        return ((b.X - a.X) * (c.Y - a.Y) - (b.Y - a.Y) * (c.X - a.X)) > 0;
    }