Cartesian bug? Clipping doesnt work

Hello. I am using points for clipping terrain below my tileset. I have managed to get it work - see this sandcastle. Now that was just testing so points not really lined up with my tileset and when I tried today to change coordinates of points and add more - clipping no longer works. For example if I change only 1 point coordinate (from those 3 in sandcastle), clipping stops working. No errors showing. I am using this geodetic to cartesian calc. I tried same height and different heights but none work.

Update: I found out that when adding more points, it is important in which order they are in code. And I was putting them in logical order - but that does not seems to work. Maybe there is certain logic/order in which I should add those points? ? ?