Hi Laurent,
Have you seen this approach for constructing roofs that have variable-sloped faces?
https://www.sciencedirect.com/science/article/pii/S0010448517301240
Unfortunately, I can’t make much use of that article… I know that many Rhino and VisualARQ users would benefit from having a high-quality, flexible solution for complex roofs. In this case, I can only kindly ask if there is a chance that somebody could turn it into a Grasshopper component. I would be also the first on the list to crowdfund such an effort.