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

        TopoDS_Face _MakeBendSectionFace(MakeContext context)
        {
            if (_Relief == ReliefFlags.None)
            {
                return(context.FlangeFace);
            }

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

            if (_Relief.HasFlag(Relief & ReliefFlags.Rectangular))
            {
                // Get notch depth = half distance between both bend and op edge
                var distTool    = new BRepExtrema_DistShapeShape(context.BendEdge, context.OppositeEdge);
                var notchDepth  = distTool.Value() * 0.5;
                var notchVector = context.TopDirection.ToVec().Multiplied(-notchDepth);

                // Get edge points
                var points = new Pnt[4];

                var bendEdgeAdaptor = new BRepAdaptor_Curve(context.BendEdge);
                points[0] = bendEdgeAdaptor.Value(bendEdgeAdaptor.FirstParameter());
                points[1] = bendEdgeAdaptor.Value(bendEdgeAdaptor.LastParameter());

                var opEdgeAdaptor = new BRepAdaptor_Curve(context.OppositeEdge);
                points[2] = opEdgeAdaptor.Value(opEdgeAdaptor.LastParameter());
                points[3] = opEdgeAdaptor.Value(opEdgeAdaptor.FirstParameter());

                // Move
                if (_Relief.HasFlag(ReliefFlags.OppositeSide))
                {
                    notchVector.Reverse();
                    points[2].Translate(notchVector);
                    points[3].Translate(notchVector);
                }
                else
                {
                    points[0].Translate(notchVector);
                    points[1].Translate(notchVector);
                }

                // Make face
                return(TopoUtils.MakeFace(points));
            }

            return(null);
        }
        //--------------------------------------------------------------------------------------------------

        bool _AddSectionToResult(MakeContext context, Section section, Trsf transformation)
        {
            if (section.IsBendSection)
            {
                // Calculate k-factor and bend allowance
                // k = 0.65 + 0.5 * log(r/s)
                // This is DIN/ISO value range of 0..2
                var thickness     = section.BendParameter.Radii[0].Distance(section.BendParameter.Radii[1]).Abs();
                var radius        = Math.Min(section.BendParameter.Radii[0], section.BendParameter.Radii[1]);
                var kfac          = (0.65 + 0.5 * Math.Log10(radius / thickness)).Clamp(0.0, 1.0);
                var bendAllowance = (radius + thickness * 0.5 * kfac) * section.BendParameter.AngleRad;
                if (context.DebugOutput)
                {
                    Messages.Trace($"The bend section has following parameters: thickness {thickness} radius {radius} kfactor {kfac} angle {section.BendParameter.AngleRad} bend allowance {bendAllowance}.");
                }

                var axes = new []
                {
                    section.BendParameter.Axes[0],
                    section.BendParameter.Axes[1]
                };

                // Which side of the bend section is our in-side?
                // A point translated along the XDirection of the axis using one of the radii must be on the edge.
                var swapSign    = 1.0;
                var edgeAdaptor = new BRepAdaptor_Curve(section.BendParameter.ConnectedInSharedEdges[0]);
                var pnt0        = axes[0].Location.Translated(axes[0].XDirection.ToVec() * section.BendParameter.Radii[0]);
                var pnt1        = axes[0].Location.Translated(axes[0].XDirection.ToVec() * section.BendParameter.Radii[1]);
                if (!(edgeAdaptor.Line().Contains(pnt0, 0.000001) || edgeAdaptor.Line().Contains(pnt1, 0.000001)))
                {
                    swapSign = -1.0;
                    axes[0].Rotate(section.BendParameter.Axes[0].Axis, section.BendParameter.AngleRad);
                    axes[1].Rotate(section.BendParameter.Axes[1].Axis, section.BendParameter.AngleRad);
                }
                axes[0].Transform(transformation);
                axes[1].Transform(transformation);

                // Create no bend section, if kfac==0
                if (kfac > 0.0)
                {
                    // Reconstruct faces
                    var pnts = new Pnt[4]; // Corner points of one section
                    pnts[0] = axes[0].Location.Translated(axes[0].XDirection.ToVec() * section.BendParameter.Radii[0]);
                    pnts[1] = axes[1].Location.Translated(axes[1].XDirection.ToVec() * section.BendParameter.Radii[0]);
                    pnts[2] = axes[0].Location.Translated(axes[0].XDirection.ToVec() * section.BendParameter.Radii[1]);
                    pnts[3] = axes[1].Location.Translated(axes[1].XDirection.ToVec() * section.BendParameter.Radii[1]);
                    var extrudeVec = axes[0].YDirection.ToVec() * swapSign * bendAllowance; // Vector to extrude to the other section

                    // Top/Bottom
                    context.Sewer.Add(TopoUtils.MakeFace(new[] { pnts[0], pnts[0].Translated(extrudeVec), pnts[1].Translated(extrudeVec), pnts[1] }));
                    context.Sewer.Add(TopoUtils.MakeFace(new[] { pnts[2], pnts[2].Translated(extrudeVec), pnts[3].Translated(extrudeVec), pnts[3] }));
                    // Sides
                    context.Sewer.Add(TopoUtils.MakeFace(new[] { pnts[0], pnts[0].Translated(extrudeVec), pnts[2].Translated(extrudeVec), pnts[2] }));
                    context.Sewer.Add(TopoUtils.MakeFace(new[] { pnts[1], pnts[1].Translated(extrudeVec), pnts[3].Translated(extrudeVec), pnts[3] }));
                }

                // Create transform for connected sections
                var rotTrsf = new Trsf(axes[0].Axis, swapSign * -section.BendParameter.AngleRad);
                transformation.PreMultiply(rotTrsf);
                var dispTrsf = new Trsf(axes[0].YDirection.ToVec() * swapSign * bendAllowance);
                transformation.PreMultiply(dispTrsf);

                //section.Faces.ForEach(f => context.Sewer.Add(f));
            }
            else
            {
                // Copy all faces to the result
                foreach (var face in section.Faces)
                {
                    var transformedFace = face.Moved(new TopLoc_Location(transformation));
                    context.Sewer.Add(transformedFace);
                    //context.Sewer.Add(face);
                }
            }

            // Process children
            foreach (var child in section.Children)
            {
                _AddSectionToResult(context, child, transformation);
            }

            return(true);
        }
        //--------------------------------------------------------------------------------------------------

        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);
        }