Boolean difference fail

Trying to subtract the red part from the blue part fails:

boolfail.3dm (291.6 KB)

Extract and trim works, but I don’t think I should have to.

I’m not near a computer right now so I can’t look at your model, but I’m prepared to bet that you have coincident, or near-coincident, surfaces, possibly at the bottom face of the red object, possibly near the ends of its vertical face.
Unfortunately, Rhino’s concept of an intersection between surfaces seems fatally flawed: it appears that Rhino assumes that an intersection is a collection of curves, whereas in reality it is potentially a collection of curves and surfaces. Thus it can’t handle situations where there are coincident surfaces.
I’d love to see McNeel rethink this, @pascal!

Hello - yep, there are indeed coincident, or near enough, surfaces, that are not planes, here - that does not work.


They’re only tangent, I think. :stuck_out_tongue:

Please tell me there’s an old case open to fix this at least?