public static Face3D ToSAM_Face3D(this CurveArray curveArray, XYZ normal = null, bool flip = false) { Polygon3D polygon3D = curveArray?.ToSAM_Polygon3D(normal); if (polygon3D == null) { return(null); } if (flip) { polygon3D.Reverse(); } return(new Face3D(polygon3D)); }