order of control points

[ROADCH]

I run the TF2 project on my computer. I think the control points in the examples in Geom_examples are arranged in a certain order, because when I change the order of control points, the drawing becomes very strange and irregular. I have read some NURBS materials but still haven't solved my confusion. What is the order of control points? How do I set up control points if I want to create a new pattern and run it the way the project does?

[canitesc]

The control points vary in the v-direction first and then in the u-direction. So to represent a unit square for example, the order of the control points would be (0,0), (0,1), (1,0), (1,1). This is somewhat counter-intuitive, but it is inherited from the NURBS-Geomdl package (see e.g. https://nurbs-python.readthedocs.io/en/5.x/file_formats_txt.html#surfaces ).