How to extrude a polygon in a slope in CityEngine

[DavoodShojaei]

I am going to extrude polygons in slope using CityEngine and would like to have horizontal roofs. As you know, when you extrude a polygon in slope, a sloped roof is generated. But in reality buildings in slope have horizontal roofs.

What is the best approach to do it?

Thanks.

[DanPatterson_Retired]

don't know in a practical sense, but in a logical sense, you will have to cut into the slope to produce a flat surface, place the feature on it, then extrude upwards.

[Joao_PedroMarques]

Anyone with a answer to this problem?

I'm getting the same thing when the terrain is not flat!

Already read and re-read the faq's and tutorials.  

example: