getting these 2 surfaces out of grasshopper and after joining the bottom surface won’t shade.
the only thing that helps is removing the inner trim.
the trim curve is an intersection between the two surfaces.
I tried to rebuild and refit it before making the surface split, but it
won’t change the shading problem. So I think it bight be some rare glitch here.
Thanks for that. This is more of a general issue with Rhino and not specific to Grasshopper. I tried the same operations with the geometry in Rhino, and the same thing happens. It seems when these two pieces are joined, the render mesh gets destroyed from the lofted surface. I thought it could have to do with the fact your input curves for that loft are Degree 4 curves, but rebuilding them didn’t do anything to sort that out.
@pascal or @Rodri, if you check out the .3dm in the attached .zip, you’ll find a Polysrf where one of the faces (after exploding or Extracting) has a Render Mesh with 2 vertices and 0 polygons. What would cause this?