The collision at the corners, and creating some sort of algorithm for deciding which get trimmed, is what I was talking about above when I said that in my manual process for dealing with 4+ valence miters, I think I’m following a fairly algorithmic process that might be able to be replicated in grasshopper.
It’s clearly more complicated than I think, though, if nobody’s cracked it yet. And it seems like it’s the important thing to crack, because if we want to be able to use any planar brep as input, that’s the only way.
Because a miter is by definition an even division of a crease angle, maybe there’s something that could be done here with plane intersection components? Or maybe there’s a way to run through multiple iterations of possible solutions and pick the ones certain criteria, like the most convex outline on the inner faces?