In the previous render, my crease angle was 30. Both the 45 degree and the 60 degree angles were above that, and shown as sharp edges.

Here I set the crease angle to 50 degrees. So I'd expect that the vertical/horizontal edges, which are at 45 degrees, would be smooth shaded. And I'd expect that the diagonal edges that are at 60 degrees would be hard shaded. And so they are.

There is no surprise here.

What may be surprising is the shape of some of the shading artifacts. Why is the top/bottom different from the left/right? Because of the way I made the frame. Go back and look at the wireframe. You'll see that some points cannot be welded to adjacent polygons because of how I made it. As a result, there are strange compromises being made by the shader.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)