I am trying to obtain the surface intersection which results from the operation bewteen a surface and a brep. I have tried many Grasshopper options but all of them returns me breps, curves… All unless a surface.
I looked at this earlier today… The intersections (plural) between your list of seven breps and the surface (BBX) is a list of curves. You can use those curves to split the surface (SrfSplit). But in this case, the breps are so irregular that the intersection curves are very poorly formed and in some cases, broken leaving gaps. With that particular geometry, the process fails in many ways.
BTW: You can use the native thing included (Split) and compare results.
In case that you want an in depth explanation (what is a Surface, what is a BrepFace, what this (and that) etc etc) notify. Plus how the inside/outside option works in the attached C# (if is active: in relation with the “solid state” of cutters).
Note: no extensive tests are included (for the validity of the Brep/Cutters etc etc. This means that the C# MAY become red if you input bananas). Plus - as it is - no Brep List is supported.
Here’s a simplified demo “similar” with your task (where cutters are solid Breps [in order to activate the inside/outside option] out of closed Curves):
With List Item you are extracting only the first element of the list. The original brep has more than one element (it is a list), so the result must be as surfaces as breps intersect the original surface.