Just looking at the figure, and assigning a few points to create a similar closed figure {(0,0), (25,15), (30,20), (35,15), (30,10), (30,0)}, I think the issue you are having is because you're changing orientations as you follow the vectors around the figure. Using the numbers above, you have the following directional vectors {(25i+15j), (5i+5j), (5i-5j), (-5i-5j), (0i-10j), (-30i+0j)}. When you progress from point (35,15) to (30,10) to (30,0), you actually swing counterclockwise on the figure, before making a clockwise swing back to the start point. This would seem to be the cause of your issue.

If I recall enough from my classes in algorithms, there are algorithms from graph theory regarding directional paths and determining if they cross themselves. Sadly, I am not where I can look them up at the moment to point you to a particular one.

I hope this helps, or that other monks can either add more detail, or point out that I am incorrect and point us both in the correct direction.

In reply to Re: Making CLOCKWISE work by atcroft
in thread Making CLOCKWISE work by stu96art

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