Postprocessing of cutting square tube

I need some help in post-processing.
I have a rotary plasma cutting and need cut a square tube. For cutting we need switch off(M14 command) THC on tube before corners radius and switch on(M15command) THC after corners radius.
How can write this condition in postprocessor?


Do you mean where it hits the corner of the tube? I can’t think of any easy way to do that.