[Closed] Modifying SplineShapes from DotNet

Greetings ALL.

I’m having trouble modifying splines using Autodesk.Max.dll. I can’t seem to get a cast working from IShapeObject to ISplineShape. The contained object is the correct ClassID for a splineShape, but I only get null returned when I attempt the cast.

I get similar results when I try .ConvertToType(TIME, CLASS_ID)

Tried a few other casts and accessors, as well. I’m sure I must be glazing over the answer in the SDK docs. It’s gotta just be one of those one line simple solutions that’s eating hours.

/

/ create LiftLines
      for (var c = 0; c < AgxRopes.Count; c++)
      {
        var node = Ip.GetINodeByHandle((uint)ghostLiftlines[c]);

        var refWinch = AgxWinches[c];
        var precision = 10;
        var pulledInLength = refWinch.getPulledInWireLength();
        var RopeLength = AgxRopes[c].getCurrentLength(false);
        
IObjectState os = node.ObjectRef.Eval(Ip.Time);
        var obj = os.Obj;
        IShapeObject sShape = obj as IShapeObject;
        ISplineShape ssShape = sShape as ISplineShape; // returns null :(

        var sBez = ssShape.Shape;
        var s3D = sBez.GetSpline(0);

        for (int v = 0; v < precision; v++)
        {
          var pt = AgxRopes[c].findPoint(pulledInLength + v * (RopeLength / precision));
          s3D?.SetKnot(v, Global.SplineKnot.Create(0, 0, Global.Point3.Create(pt.x, pt.y, pt.z), Global.Point3.Create(0, 0, 0), Global.Point3.Create(0, 0, 0),
            -1, -1, -1, -1, -1, -1, -1, -1, -1, 0));
        }
        s3D.ComputeBezPoints();
        sBez.UpdateSels(true);
        sShape.InvalidateGeomCache();

        GhostLines.Add(node);
      }