I'm writing an add-in. It's in C#, but solutions in other languages are fine too as I'm not new to programming.

I'm trying to project curves onto surfaces without planar guarantees. I finally got the calls to work despite the anemic documentation that is IModeler and IBody2::Display3(), however, my lines stay straight instead of being warped to stick to the surface. Is this expected behavior or am I doing something wrong?

This is the code I'm playing around with

static void Main(string[] args)
{
    SldWorks sld = new SldWorks();
    ModelDoc2 model = sld.ActiveDoc;
    Modeler modeler = sld.GetModeler();
    SelectionMgr sm = model.SelectionManager;
    Console.Write("Make a selection");
    Console.ReadLine();
    if (sm.GetSelectedObject6(1, -1) is Edge edge) // gets the edge whose curve you want to project
    {
        Console.WriteLine("Selection made");
        Console.WriteLine();
        Curve curve = edge.GetCurve();
        Curve copy = curve.Copy();
        // Start() and End() are my extensions. Returns an IVertex
        var start = edge.Start().GetPoint();
        var end = edge.End().GetPoint();
        Curve trimmed = copy.CreateTrimmedCurve2(start[0], start[1], start[2], end[0], end[1], end[2]);
        Console.WriteLine("Select a face");
        Console.ReadLine();
        if (sm.GetSelectedObject6(1, -1) is Face2 face) // gets the face to project onto
        {
            Console.WriteLine("Face selected");
            Surface surface = face.GetSurface(); // the surface to project onto
            MathUtility utility = sld.GetMathUtility();
            double[] norm = { 0, -1, 0 };
            MathVector vnorm = utility.CreateVector(norm);
            Curve converted = trimmed.MakeBsplineCurve2();
            Curve projected = modeler.ProjectCurveOnSurface(converted, surface, vnorm);
            
            Body2 temp = projected.CreateWireBody();
            temp.Display3(model, Information.RGB(255, 255, 0), (int)swTempBodySelectOptions_e.swTempBodySelectOptionNone);
            // ^^ displays it, we're done ^^
        }
        else
            Console.WriteLine("No face selected");
    }
    else
        Console.WriteLine("Bad selection");
    Console.WriteLine();
    Console.WriteLine("Exit with any key");
    Console.ReadKey();
    Marshal.FinalReleaseComObject(sld);
    sld = null;
    GC.Collect();
}