BuildingCoder.CmdNewLightingFixture.PlaceFamilyInstanceOnFace C# (CSharp) Метод

        FamilyInstance PlaceFamilyInstanceOnFace(
            UIDocument uidoc,
            FamilySymbol symbol)
        {
            Document doc = uidoc.Document;

              Reference r = uidoc.Selection.PickObject(
            ObjectType.Face, "Please pick a point on "
            + " a face for family instance insertion" );

              Element e = doc.GetElement( r.ElementId );

              GeometryObject obj
            = e.GetGeometryObjectFromReference( r );

              if( obj is PlanarFace )
              {
            PlanarFace planarFace = obj as PlanarFace;

            // Handle planar face case ...
              }
              else if( obj is CylindricalFace )
              {
            CylindricalFace cylindricalFace = obj
              as CylindricalFace;

            // Handle cylindrical face case ...
              }

              // Better than specialised individual handlers
              // for each specific case, handle the general
              // case in a generic fashion.

              Debug.Assert(
            ElementReferenceType.REFERENCE_TYPE_SURFACE
              == r.ElementReferenceType,
            "expected PickObject with ObjectType.Face to "
            + "return a surface reference" );

              Face face = obj as Face;
              UV q = r.UVPoint;

            #if DEBUG
              XYZ p = r.GlobalPoint;
              IntersectionResult ir = face.Project( p );
              UV q2 = ir.UVPoint;
              Debug.Assert( q.IsAlmostEqualTo( q2 ),
            "expected same UV point" );
            #endif // DEBUG

              Transform t = face.ComputeDerivatives( q );
              XYZ v = t.BasisX; // or BasisY, or whatever...

              return doc.Create.NewFamilyInstance( r, p, v, symbol );
        }