@gilboonet Thanks for the response. I believe you mean the "sides" are rendered using polygons. indeed they are lots of polygons. I might give that a try using the 2d constructive geometry. i've gotten the result right using the fromfakepolygons routine.
@z3dev
I have got it working using the routine pointed at by you. it was a bit confusing as it throws error for polygons with more than "2 dimension" and the axis was different.
@gilboonet The whole 2d contour is one single polygon of points. where should i get multiple polygons from? from the sides?