//--------------------------------------------------------------------------------------------------

        bool _MakeFlangeFace(MakeContext context)
        {
            if (_StartGap <= 0 && _EndGap <= 0)
            {
                context.FlangeFace = context.TargetFace;
                return(true);
            }

            // Get points from bend edge and opposite edge
            var points          = new Pnt[4];
            var bendEdgeAdaptor = new BRepAdaptor_Curve(context.BendEdge);

            points[0] = bendEdgeAdaptor.Value(bendEdgeAdaptor.FirstParameter());
            points[1] = bendEdgeAdaptor.Value(bendEdgeAdaptor.LastParameter());
            if (points[0].Distance(points[1]) <= (_StartGap + _EndGap))
            {
                Messages.Error("The sum of start and end gap is higher than the length of the bending edge.");
                return(false);
            }

            if (context.OppositeEdge == null)
            {
                Messages.Error("No opposite edge found for building flange face.");
                return(false);
            }

            // Move vertices from bend edge to op edge
            var distTool = new BRepExtrema_DistShapeShape(context.BendEdge, context.OppositeEdge);
            var upVector = context.TopDirection.ToVec().Reversed() * distTool.Value();

            points[2] = points[0].Translated(upVector);
            points[3] = points[1].Translated(upVector);

            // Sort points, Short edges must be 1->2 and 3->0
            if (context.BendEdge.Orientation() == TopAbs_Orientation.TopAbs_REVERSED)
            {
                points.Swap(0, 1);
            }
            if (points[0].Distance(points[3]) > points[0].Distance(points[2]))
            {
                points.Swap(2, 3);
            }

            // Move
            if (_StartGap > 0)
            {
                var startVector = context.BendAxis.Direction.ToVec().Multiplied(_StartGap);
                points[0].Translate(startVector);
                points[3].Translate(startVector);
            }

            if (_EndGap > 0)
            {
                var endVector = context.BendAxis.Direction.ToVec().Multiplied(-_EndGap);
                points[1].Translate(endVector);
                points[2].Translate(endVector);
            }

            // Generate face and new edges
            context.FlangeFace = TopoUtils.MakeFace(points);
            if (context.FlangeFace == null)
            {
                Messages.Error("Failed making flange face with gaps.");
                return(false);
            }

            context.BendEdge     = new BRepBuilderAPI_MakeEdge(points[0], points[1]).Edge();
            context.OppositeEdge = new BRepBuilderAPI_MakeEdge(points[3], points[2]).Edge();

            // Split original face to avoid problems with additional flanges on the same face
            TopoDS_Edge startGapEdge = null, endGapEdge = null;
            var         splitOp = new BRepFeat_SplitShape(context.TargetShape);

            if (_StartGap > 0)
            {
                startGapEdge = new BRepBuilderAPI_MakeEdge(points[0], points[3]).Edge();
                splitOp.Add(startGapEdge, context.TargetFace);
            }
            if (_EndGap > 0)
            {
                endGapEdge = new BRepBuilderAPI_MakeEdge(points[1], points[2]).Edge();
                splitOp.Add(endGapEdge, context.TargetFace);
            }
            splitOp.Build();
            if (!splitOp.IsDone())
            {
                Messages.Error("Failed spliting gap edges into target face.");
                return(false);
            }

            UpdateModifiedSubshapes(context.TargetShape, splitOp);

            context.ModifiedTargetShape = splitOp.Shape();

            // Update named shapes
            var splitFaceList = splitOp.Modified(context.TargetFace).ToList();

            foreach (var splitShape in splitFaceList)
            {
                var edges = splitShape.Edges();
                foreach (var edge in edges)
                {
                    if (startGapEdge != null && context.StartGapFace == null &&
                        edge.Orientation() == splitShape.Orientation() &&
                        edge.IsSame(startGapEdge))
                    {
                        context.StartGapFace = splitShape;
                        break;
                    }
                    if (endGapEdge != null && context.EndGapFace == null &&
                        edge.Orientation() != splitShape.Orientation() &&
                        edge.IsSame(endGapEdge))
                    {
                        context.EndGapFace = splitShape;
                        break;
                    }
                }
            }

            return(true);
        }