I can draw a curve using vtkContourWidget. The control points can be on the polydata, but I want the curve itself to be above the polydata. Is it possible to achieve that using vtkContourWidget?
Yes this can be controlled with vtkContourLineInterpolator. This example should help: https://examples.vtk.org/site/Cxx/PolyData/PolygonalSurfaceContourLineInterpolator/
I tried this example, but the rendering is jagged because it passes over the edges of the triangles. For a smoother appearance, the curve needs to follow the surface instead of cutting across the triangle edges.
Right, I don’t know a better interpolator