I need to create non-planar shape which is build from two planar shape, adjacent to each other.
When I build such a shape manually (or programmatically) , it renders as very strange, twisted shape, which seems non-coherent with delivered 3D coordinates.
I've attached sample DGN.
OpenCities Map Advanced 10.16
The following may help in understanding drawing in 3D:
From the file you provided to create a single element you can use the stitch surfaces tool