I had a quite unpleasant surprise today when trying to get an algorithm to detect overlapping working. Volume overlapping was quite straight forward: just call Common with a Solid and a Compound of all other Solids you want to check. To detect area overlapping I used Shells instead, but the first issue I found was that calling Common between a Shell and a Compound of Shells does not work. Then, I decided to try a slower approach: call Common for each pair of Shells. The result is effectively a Shell of the overlapping area, but what I have been completely unable to acquire is which Faces from Shell_1 and Shell_2 produced which Faces in the result. Actually, it half works. In the current test case (only 1 overlapping Face) I get which Face from one of the Shells became a Face in result, but I cannot get the corresponding Face from the other Shell.
I am completely clueless as to how to proceed now. I do really need to know the overlapping Faces and their result, not just one of them.
Any insight is highly appreciated.