Code

layeredLayout.Arrange(diagram);

foreach (var link in diagram.Links)
{
	var points = link.ControlPoints.Clone();

	// insert Bezier control points for each segment of polyline link
	for (int i = points.Count - 1; i > 0; i--)
	{
		var segmentStart = points[i - 1];
		var segmentEnd = points[i];
		var vector = new Vector(segmentStart, segmentEnd);

		var cp1 = segmentStart + vector / 3;
		var cp2 = segmentStart + 2 * vector / 3;

		var dx = vector.X;
		if (dx == 0)
		{
			cp1.X -= 2;
			cp2.X += 4;
		}
		else
		{
			cp1.X += dx / 6;
			cp2.X += dx / 6;
		}

		points.Insert(i, cp1);
		points.Insert(i + 1, cp2);
	}

	for (int i = 3; i < points.Count - 1; i += 4)
	{
		var pp = points[i - 1];
		pp.X = points[i].X;
		points[i - 1] = pp;
		var pn = points[i + 1];
		pn.X = points[i].X;
		points[i + 1] = pn;
	}

	link.Shape = LinkShape.Bezier;
	link.ControlPoints.Clear();
	link.ControlPoints.AddRange(points);
	link.UpdateFromPoints(false, true);
}