Drawing links on one half of the ideogram circle

[mostafa eltejaee]

Hi,

I'm trying to draw some links on an ideogram but I have confused about the position of them. 

As you see in the image below the blue link and white link have drawn on upper half and the green and red links on lower half. why it happens and how can I draw all of the links on one half of the ideogram circle?

I have manipulated bezier_radious, cest, bezier_radius_purity so many times but it doesn't work.

Thanks to all