Polyline / Polygon (3D) GetZ() function

[amastrobera]

Given a Polyline3D and a Point2D (which belongs to it, in a 2D - XY view), find the corresponding Z coordinate.

Same for a Polygon3D.

something like this

              Func<G.Polyline3D, G.Point2D, double> GetZ = (G.Polyline3D _polyline, G.Point2D _p_2d) => {
                var _vertical_intersection =
                    _polyline.Intersection(G.Line3D.FromDirection(new G.Point3D(_p_2d.U, _p_2d.V, 0), G.Vector3D.AxisZ),
                                           decimal_precision);
                if (_vertical_intersection.ValueType == typeof(G.Point3D)) {
                  return ((G.Point3D)_vertical_intersection.Value).Z;
                }

                if (_vertical_intersection.ValueType == typeof(G.PointSet3D)) {
                  return ((G.PointSet3D)_vertical_intersection.Value).First().Z;
                }

                throw new Exception("failed to find z-coordinate for point (2D) on polyline (3D)");
              };