If an actor has polygons, then the polygons will always be rendered in “solid” mode.
So my question is, when you prep your polydata, why do you add polygons to it?
polyData = vtkPolyData();
polyData.SetPoints(points);
- polyData.SetPolys(polys);
polyData.SetLines(lines);
Try removing the SetPolys() line. If there are no polygons in the data, just lines, then it seems to me that your problem is solved. The vtkContourTriangulator only needs lines as input, anyway.
It looks like there is also something funny going on with the vtkContourTriangulator here, but I’ll have to do a thorough check of the input data connectivity to be sure.